Preventing Excessive Noise Exposure in Infants, Children, and Adolescents

This technical report provides background information and summarizes available research on noise and its effects on hearing. The accompanying policy statement contains guidance from the American Academy of Pediatrics (AAP) on reducing risks of noise-induced hearing loss in infants, children, and adolescents.¹ 

Sound is created by the vibrations that travel through a medium, such as air or water. The common characteristics of sound include frequency, intensity, periodicity, and duration.²  Intensity is perceived as loudness; frequency is also referred to as pitch. Frequency is measured in cycles per second; the unit of this is Hertz (Hz). Speech frequencies generally are in the range of 250 to 8000 Hz. Sound intensity is measured in Pascals (Pa) or decibels (dB). The dynamic range of normal human hearing extends from a minimal audible intensity of about 0.00002 Pa or about 1.9 dB (softest) to the threshold of pain at about 20 Pa or 120 dB (loudest). This range is expressed in a logarithmic scale, which is represented in units of dB SPL (sound pressure level). The logarithmic scale means that there is a 10-fold difference in sound energy with a 10-dB difference, a 100-fold difference with a 20-dB difference, a 1000-fold difference with a 30-dB difference, and so forth. Similarly, an increase of 3 dB represents a doubling of noise energy; a decrease of 3 dB represents a halving of noise energy.

Humans do not hear all frequencies equally. The amount of dB SPL necessary for a human to perceive a sound varies depending on the frequency of the sound being heard. The growth of dB SPL with the increase in frequency, based on the minimal levels of hearing for the average normal-hearing adult, is plotted on a measurement curve and leads to the creation of the weighted scale referred to as the “decibel weighted by the A scale”—“A-weighted dB” or dBA. The dBA measurement adjusts for the varying sensitivity of the human ear to different sound frequencies. In this way, comparisons can be made about the frequencies of sound perceived by the human ear.

The loudness of human speech is approximately 50 to 60 dB SPL.

Noise is often defined as unwanted or objectionable sound.²  The distinguishing characteristics of noise include intensity (measured in dBA) and duration (length of time exposed).

According to the World Health Organization (WHO), “Physically, there is no difference between sound and noise. Sound is a sensory perception and noise corresponds to undesired sound.”³  The literature is inconsistent in its use of “sound” versus “noise.” In this report, the term “noise” is used except when referring to positive sounds or specific measurement modalities.

The meaning of sound to an individual often determines a person’s reaction to the same sound. “One person’s music is another’s noise.”²  Too little sound, leading to sensory deprivation, can be harmful. Because too little and too much sound can result in harm, it has been stated that people should have the right to decide about the quality of the acoustic environment in which they live.⁴ 

In the literature on noise and sound, various terms are used to describe sounds and sound level measurements. Table 1 lists commonly used terminology.

The world was quieter before the Industrial Revolution—the main sources of noise then were thunder, church bells, and cannon fire.⁵  Since the Industrial Revolution and because of the development of cities, noise has been accepted as a part of routine life.

Occupational noise is noise experienced in the workplace. Loss of hearing attributable to occupational noise exposure has been recognized for centuries. High exposures to noise and resulting noise-induced hearing loss (NIHL) began around the time of the Industrial Revolution, but sustained efforts to evaluate NIHL and reduce exposure to noise were not initiated until after World War II.⁶  The WHO estimated that 16% of disabling hearing loss in adults results from workplace exposure.³  In the United States, data from the National Health and Nutrition Examination Survey (NHANES), a periodic, nationally representative survey of the US civilian population conducted by the Centers for Disease Control and Prevention (CDC), showed that approximately 22 million workers (17%) reported exposure to hazardous workplace noise; more than one-third of those workers reporting hazardous workplace exposure reported nonuse of hearing protection.⁷  There continues to be a high prevalence of hearing loss in US workers in occupations including construction, manufacturing, and mining.⁶ 

Environmental noise usually refers to noise from outdoor settings generated by human activity, mostly powered by fossil fuels. Sources include vehicular traffic, railways, airplanes and airports, industrial sites, and leaf blowers⁸  and lawn mowers. Wind turbines and “wind farms” (also known as wind parks or wind power stations, a group of wind turbines used to create electricity) are relatively new sources. Environmental noise exposure has been characterized as “one of the most important environmental stressors affecting public health throughout the world.”⁹ 

Indoor sources of noise include equipment such as power tools, appliances, infant sleep machines (ISMs), video games, toys, and TVs.

Recreational noise (also known as leisure noise) has been defined as noise sought out for pleasure.¹⁰ 

Listening to music and attending events are sources of joy, pleasure, and relaxation for many people. Recreational sources include personal listening devices (PLDs), music at parties, dances, concerts, weddings, and other celebratory events, sports events, and recreational firearm use.

Some common sources of noise, their intensities, and effects are listed in Table 2.¹¹ 

Noise exposure, NIHL, and the physiologic and psychologic effects of noise have typically been considered as problems for adults. Noise exposure is also a pediatric issue because of the susceptibility of the developing auditory system and because the effects of noise on hearing and quality of life at early stages of development can affect a child’s life trajectory. Research demonstrates that the auditory systems of infants and children—who are developing rapidly—are different from the mature auditory system. Compared with adults, children have unique susceptibilities to the effects of noise.

The inner ear is fully formed in humans by the 16^th week of embryonic gestation. It is the only sensory organ to reach adult size by fetal midterm. Fetal responses to external low-frequency sounds occur as early as the 19^th week of gestation at high SPLs (115 dB). Fetal responses to low- and high-frequency sounds increase throughout gestation at lower external SPLs (85 dB).¹³  The amount of attenuation to external sounds by amniotic fluid and organs depends on the frequencies of the sound. Lower-frequency sound (ie, <500 Hz) is not attenuated as much as higher-frequency sound.¹⁴  The extent of fetal exposure to noise is highly dependent on the amount of time exposed and the sound frequencies to which the mother and fetus are exposed.¹⁵ 

Young animals show different, often greater, sensitivities to environmental agents and stimuli compared with adult animals. The time periods during which these sensitivities exist are usually called “critical periods” or “sensitive periods.”¹⁶  Studies in experimental animals show that the inner ear of developing mammals is more susceptible to external factors, such as noise, compared with the adult inner ear. Studies in pregnant guinea pigs and sheep show that intense and sustained noise exposure during pregnancy can induce hearing dysfunction in offspring.¹⁷  Young rats experience greater temporary and permanent decreases in hearing thresholds compared with their adult counterparts when exposed to the same noise. Young rats that experience noise exposures that cause temporary decreases in hearing thresholds have accelerated age-related hearing loss later in their lives.¹⁸  The normal physiologic development of resting potentials and sound-evoked potential responses are significantly impaired after acoustic trauma and/or exposure to ototoxic agents such as aminoglycoside antibiotics. Studies in multiple animal species reveal that “…effects of these extrinsic factors during critical periods of development may produce permanent destruction of cochlear structures and severe hearing loss in the mammal, including the human.”¹⁹  Mice exposed to 2 hours of high noise levels (123 dB SPL) resulting in permanent hearing loss showed declines in hippocampal learning and memory function and neurogenesis.²⁰  Because it is not possible to conduct studies in humans like those conducted in animals, experimental information about noise sensitivity is not known for infants and children; therefore, “…a conservative attitude to noise exposure in children would seem a most appropriate course.”²¹ 

The auricle and ear canal collect, funnel, and modify sound intensity. Ear canal resonance refers to the exact amount of modification of the particular canal. The resonance frequency—the frequency at which the ear best transforms the sound intensity—is based on the physiology and anatomy of the ear, including factors such as the length, volume, and curvature of the canal. The resonance frequency is inversely related to the size of the external ear; in general, the smaller the canal, the more intensity there will be at higher frequencies. Studies of children from birth to age 3 years were conducted using probes placed in the ear canals of sleeping infants and children. External ear resonance frequency was significantly higher at birth (∼6 kHz) and decreased to adult values (2.7 kHz) by the second year of life. According to the author, this difference in resonance frequency should be considered when selecting and fitting hearing aids for young children.²²  This information may also be useful when assessing how newborn infants perceive noise in high-noise settings such as NICUs.

The ear canal reaches adult size and orientation by approximately age 9 years, but the middle ear cavity does not reach adult size until adolescence.²³  The maturation of auditory pathways—central and peripheral—and of the auditory cortex is not complete until approximately 20 years of age.^24–26 

Exposures in early life, including in utero exposures, are out of children’s control. Infants and young children rely on adults to understand potential noise hazards and remove them from excessively noisy situations, including sporting events and fireworks displays. Older children, such as those in elementary school, may not understand that noise is hazardous; their exploratory behavior may place them in high-risk situations. Children may have less well-developed coping strategies when exposed to excessive noise, compared with adults.

Children, including young children, use PLDs for entertainment purposes, for computer-based in-school learning, and for remote learning opportunities that became prevalent during the coronavirus disease 2019 (COVID-19) pandemic. Adolescents and young adults often seek loud sounds through PLDs and in recreational settings.

Noise exposures that affect hearing, attention, and sleep have effects on children’s learning trajectories. Young children have longer sleep periods compared with older children and adults, potentially increasing exposures and effects from nighttime environmental noise. Preterm infants have a higher incidence of sensorineural hearing loss because of multiple factors, compared with full-term infants.

Children have long lives ahead of them. Effects of early life exposures that have long latency periods, as well as cumulative effects, can manifest in adolescence and adulthood, as is the case with many other environmental exposures.²⁷ 

Many children with autism spectrum disorder (ASD) exhibit decreased sound tolerance.²⁸  Hyperacusis (increased sensitivity to sound at levels that would not trouble most individuals), misophonia (excessive and inappropriate emotional responses to specific “trigger” sounds), and phonophobia (phobia to specific sounds or classes of sounds) have been described. Tomcheck and Dunn²⁹  compared sensory processing abilities in children ages 3 to 6 years with ASD and age-matched controls. Sensory sensitivity was reported in 69.1% of children with ASD compared with 22.6% of controls. Abnormal auditory filtering was reported in 92.2% of children with ASD compared with 12.2% of controls. Auditory processing issues are also reported in children with attention-deficit hyperactivity disorder (ADHD),³⁰  including hypersensitivity and hyposensitivity to sounds.³¹  A case-control study from Italy compared 30 normal hearing children with ADHD to 30 age- and sex-matched controls. Hyperacusis was more common in children with ADHD (36.7%) compared with controls (13.3%).³¹  Hyperacusis has been reported in children with tinnitus (an auditory phantom defined as the perception of noise in the ear in the absence of an external sound source),³²  William syndrome, epilepsy, sensorineural and conductive hearing loss, migraine, head trauma, cerebral palsy, Down syndrome, prematurity, hydrocephalus, Klinefelter syndrome, Leigh syndrome, otitis media, hypercalcemia, dyspraxia, microcephaly and microdeletion, glue ear, and motion sickness.³³ 

When playing with toys, some children with ASD may display atypical play methods, such as prolonged and repetitive use, potentially increasing their risk of hearing damage from noisy toys.³⁴ 

Children with sensory processing difficulties may benefit from noise-canceling headphones and hearing-protection earmuffs, which lessen harmful loud noises without completely concealing other ambient background noise. Auditory distraction from noise can hinder academic performance in children with and without learning disabilities. Children with learning disabilities benefit to a greater degree from noise-reduction headphones compared with children who do not have learning disabilities. Mitigating noise exposure with earmuffs or noise-canceling headphones has been effective at allowing children with ASD to better control behavior related to unpleasant auditory stimuli.³⁵  Not all students, however, benefit from headphones in their reading comprehension performance.³⁶  Educators and parents can best determine who benefits by monitoring learning in vulnerable children with and without headphones and comparing individual outcomes.

Noise is perceived at an individual level, but when a critical mass of individuals experiences noise that causes hearing problems, disturbs cognitive function, and reduces well-being, then noise becomes a public health concern.³⁷  A substantial body of evidence links noise to health effects, more than for many environmental hazards. Although commonly encountered, excessive noise exposure is treated differently than other pollutants.³⁸  Few communities consider the health risks of noise in policy making, and noise often is not on clinicians’ agendas when talking to patients and parents. High levels of noise at recreational and celebratory events often are accepted as a given—and often sought out—rather than viewed as potentially hazardous. Many people have experienced situations in which they are unable to have a conversation with someone nearby because of loud music at an event³⁹ ; yet, this uncomfortable, often painful common scenario usually is not appreciated as a health threat.

Studies in the United States and internationally demonstrate sociodemographic disparities in noise exposure. Children attending US public schools most highly exposed to road and aviation noise were more likely to be eligible for free or reduced-price meals and to be part of a historically marginalized racial or ethnic group. Schools with higher student burdens, those in urban settings, and those serving younger populations had higher odds of exposure to road and aviation noise.⁴⁰  Another study of racial and ethnic and socioeconomic inequalities in the contiguous United States found higher nighttime and daytime noise levels in locations with more nonwhite populations and residents of lower socioeconomic status. The association was present in urban and suburban or rural areas. Individuals with less than a high school education, those living in poverty, those who were linguistically isolated, those who were renting, and those with children <5 years of age were also more likely to experience higher daytime and nighttime noise levels. Additionally, areas with high racial segregation had higher noise exposures compared with areas less racially segregated, irrespective of racial composition.⁴¹  The CDC analyzed data collected from a survey of youths aged 12 to 17 years in the United States and found that the proportion of youth reporting exposure to loud sounds at school did not vary by race or income. Students from households with an average income ≥$150 000, however, were significantly less likely to have hearing protection provided by the school.⁴² 

Studies from the European Union also report disparities in noise exposures, with people of lower socioeconomic position disproportionately affected by high noise burden.⁴³  According to the WHO, the prevalence of hearing loss in children decreases exponentially as national income increases, and there is an inverse relationship between prevalence of disabling hearing loss in children and parents’ literacy rates.⁴⁴ 

Excessive environmental noise exposure has been framed as a disability rights issue for people with hearing loss, tinnitus, and hyperacusis. Noisy situations worsen the ability of people with hearing impairments to understand speech; noise worsens symptoms in people with tinnitus and hyperacusis. Elevated environmental noise levels turn these disorders into disabilities in restaurants, social dance event spaces, and other venues. These sensory impairments meet the legal standard of having disabilities. Advocates have stated that legislation and regulations are needed to establish ambient noise standards that then must be enforced.^45,46 

To better understand the following discussion about the magnitude of children’s and adolescents’ exposures to noise in their environments, it is helpful to put these exposures into a broader context of standards and regulations set for occupational noise. US regulations about workplace noise are set by 2 federal agencies, the Occupational Safety and Health Administration (OSHA, part of the US Department of Labor), and the National Institute of Occupational Safety and Health (NIOSH, part of the CDC). OSHA creates and enforces regulations, whereas NIOSH is a research and educational institution without legal enforcement powers.^47,48  In general, NIOSH sets evidence-based recommended exposure limits (RELs) to protect workers from the effects of exposure to hazardous substances and agents at work. In 1998, the REL for occupational noise exposures was set at 85 dBA as an 8-hour time-weighted average, with exposures equal to or higher than this level considered hazardous.⁴⁹  This REL assumes that a person is exposed to this level at work 5 days per week with the remaining 16 hours plus weekends spent in quieter settings. NIOSH also sets a maximum allowed daily dose for noise; this is expressed as a percentage. An individual exposed to 8 hours at 85 dBA will reach 100% of the daily dose. NIOSH also uses an “exchange rate” (also referred as a “time-intensity exchange rate” or “trading ratio”) of 3 dB to provide guidance on allowable exposure durations at different exposure levels. Because the decibel scale is logarithmic, the allowable exposure duration decreases by half for every 3-dB increase in time-weighted average noise level, or, alternatively, doubles for every 3 dB decrease in time-weighted average noise level. For instance, if the time-weighted average exposure level increases from 85 to 88 dBA, the allowable duration is reduced from 8 to only 4 hours.⁵⁰  The NIOSH REL aims to protect workers from developing NIHL—resulting in difficulty hearing or understanding speech—over a 40-year career. Even at 85 dBA 8-hour time-weighted average, approximately 8% of workers could still develop hearing loss⁵¹ ; therefore, hearing protection is recommended when noise levels are greater than 85 dBA regardless of duration.⁵²  OSHA mandates availability of hearing protection and implementation of other preventive measures, including monitoring, education, and training at work sites that meet or exceed that agency’s Action Level, which is an 85 dBA time-weighted average using a 5 dB exchange rate. Table 3 shows workplace exposure levels and recommended exposure durations according to NIOSH. Information about occupational protections is discussed in Section VII: Guidelines for Noise Exposure.

The NIOSH exposure limit for hazardous noise exposure of >85 dBA time-weighted average over 8 hours is not meant to be used to protect the public from general environmental noise or recreational noise, such as listening to music with earbuds or attending noisy events.⁵⁰  This exposure limit is, therefore, also not meant to apply to infants, children, and adolescents in their various environmental and recreational exposure settings. For nonoccupational exposures, other guidelines are available from the US Environmental Protection Agency (EPA) and the WHO, as discussed in section VII: Guidelines for Noise Exposure.

Hearing is important to verbal communication, quality of life, safety, and sometimes to survival. Our early human ancestors listened for tiny sounds—“… a crack of a branch in the woods, for example, or a bird call, indicators of prey they wanted to eat or predators that wanted to eat them.”⁵⁴ 

The perception of sound begins as sound waves travel through the outer ear and ear canal to vibrate the tympanic membrane. This vibration is then amplified and transmitted by the middle ear ossicles (incus, malleus, and stapes, the smallest of human bones). The footplate of the stapes is connected to the membrane of the oval window of the cochlea and moves this membrane, transmitting sound-related vibratory energy to the middle ear fluid.

This movement then causes the fluid within the cochlea to move along the basilar membrane. The basilar membrane has mechanosensory cells (inner and outer hair cells) that are stimulated by the motion of the fluid. The basilar membrane is organized tonitopically (meaning that the spatial arrangement of the membrane corresponds to specific frequencies) with high-frequency sounds stimulating inner hair cells near the opening of the cochlea and low-frequency sounds stimulating outer hair cells further down the cochlea near the center or modiolus. The hair cells contain projections called stereocilia. When the stereocilia are activated by movement along the basilar membrane, activation of mechanoelectrical transduction channels results in depolarization. This depolarization creates electric signals that are sent through the afferent neurons of the auditory nerve, also known as the eighth cranial nerve (CN VIII).⁵⁵  The auditory nerve is composed of 2 branches—the cochlear nerve and the vestibular nerve.^56,57  The cochlear nerve transmits auditory signals from the cochlea to the auditory cortex in the temporal lobe of the brain where they are interpreted as sound.

Sound vibration also may be transmitted through temporal bone conduction.

Damage or blockage along the path of hearing can result in hearing loss. There are 3 types of hearing loss. Conductive hearing loss (CHL) is caused by obstruction to conduction of sound to the inner ear. The obstruction can be caused by a congenital malformation or can be acquired as a result of otitis media or occluding cerumen in the outer ear. CHL usually is reversible and medical intervention can be used to treat most causes. Sensorineural hearing loss (SNHL) is caused by damage to either the inner or outer hair cells of the cochlea, or to the auditory nerve. Excessive noise exposure is one of the causes of SNHL. Damage to hair cells is permanent and usually cannot be restored with medical treatment. Mixed hearing loss is a combination of CHL and SNHL. Figure 1 illustrates cochlear tissues susceptible to damage.^56–58 

Hearing loss is categorized into mild, moderate, severe, and profound (Table 4). The hearing threshold is the softest sound a person can hear.

Damage to cochlear hair cells has many causes, including presbycusis (hearing loss that gradually occurs in most individuals as they become older; some writers believe that presbycusis is not a normal part of aging but is noise-related),⁶⁰  ototoxic medications, trauma, viral infections, and noise exposure.

Hearing loss caused by noise exposure affects the cochlea in several ways. Intense noise exposure can affect cochlear mechanics by breaching the endolymph and perilymph barrier and disrupting hair cell stereocilia and support cells. Noise exposure can also begin an extracellular response involving ion channels that initiate the overproduction of free radicals in cochlear cells; free radical levels can remain at measurable levels in the cochlea for 7 to 10 days after noise exposure. The presence of sustained high levels of free radicals triggers an inflammatory response in cochlear cells. This can also lead to apoptosis or necroptosis of hair cells, which also contribute to the inflammatory response.⁶¹  Hair cells and spiral ganglia that are permanently damaged cannot regenerate; the effects on these cells accumulate over time and are permanent. New research into the oral administration of antioxidant vitamins to assist in cell survival after noise exposure shows that antioxidants affect cochlear free radical levels and reduce damage to hearing.⁶² Figure 2 illustrates normal and damaged cochlear hair cells.

SNHL can occur after a single loud sound, such as a gunshot, near the ear. Hearing loss more commonly results over time from damage caused by repeated exposures to loud sounds. The louder the sound, the shorter the amount of time it takes for damage to occur. The longer the exposure, the greater the risk for hearing loss (especially if hearing protection is not used or if there is not enough time for the ears to rest between exposures).⁶⁴  Damage is cumulative; the “equal energy principle” states that the total effect of sound is proportional to the total amount of sound energy received by the ear, irrespective of the distribution of that energy in time.⁴ 

To fully recognize the significance of noise exposure in children and adolescents, it is important to understand noise exposures, hearing loss, and the impact of hearing loss in adults. For many adults, hearing loss is likely to have origins, at least in part, in earlier exposures to noise. Because harms from excessive noise exposures are cumulative, effects could be lessened with preventive efforts through individual counseling and public health efforts.

The number of people with hearing loss is growing rapidly. Globally, the WHO estimates that approximately 466 million people have disabling hearing loss; of these, 432 million (93%) are adults and 34 million (7%) are children. Unless action is taken, the WHO projects that 630 million people will live with disabling hearing loss by 2030 and >900 million will have disabling hearing loss by 2050. This will be accompanied by a proportionate rise in the current annual cost of more than US $750 billion (in international dollars) globally if hearing loss is not addressed.⁶⁵ 

In the United States, hearing loss is the third most common chronic physical condition, twice as prevalent as cancer or diabetes. Significant hearing loss may eventually lead to loneliness, depression, impaired job performance, limited job opportunities, and isolation. Hearing loss has been linked to cognitive decline, Alzheimer disease, dementia,^66,67  and Parkinson disease.⁶⁸  People with hearing loss may miss a great deal of what goes on around them; optimizing good hearing in adulthood, often with the assistance of hearing aids, is one crucial element of preserving cognitive function.⁶⁹ 

Although NIHL is common, other potential causes of hearing loss over a lifetime include congenital hearing loss from genetic conditions, intrauterine infections with cytomegalovirus, and hearing loss caused by other infections and ototoxic drugs. Susceptibility to NIHL is highly variable; some individuals tolerate high noise levels for prolonged periods, whereas others in the same conditions may lose some hearing.⁷⁰  Noise-induced hearing loss usually results from repeated exposures to loud sounds experienced over time. Continuous exposure to hazardous noise levels tends to cause maximum damage to high-frequency areas of the cochlea and is usually most severe around 4000 Hz.

Hearing loss also can occur after a single high-intensity traumatic impulse. Impulse noise occurs over a very short duration and can have much higher SPLs than continuous noise. Because impulse noise bypasses the body’s natural protective mechanism—the eighth nerve-mediated efferent dampening of the ossicles—it usually is more hazardous than continuous noise.¹¹  At high enough levels, impulse noise can cause immediate, irreversible acoustic trauma.¹⁰ 

NIHL impacts understanding of speech. Consonants are disproportionately affected in the higher frequencies, whereas lower-frequency vowel sounds remain relatively normal. Because softly spoken, high-frequency consonants such as “f,” “s,” and “h” convey more of the intelligibility of words in speech compared with vowels, an individual with NIHL can have difficulty understanding in background noise as well as when trying to follow higher-pitched voices of women and children.

The CDC analyzed data collected from adults ages 20 to 69 years who participated in the 2011 to 2012 NHANES. Questionnaires and audiometric tests were used to determine the presence of audiometric notches indicative of NIHL. An audiometric notch is a deterioration in the hearing threshold. Using standard NHANES protocols, audiograms were analyzed to identify high-frequency audiometric notches that suggested hearing loss caused by exposure to noise. Nearly 1 in 4 adults (24%) had audiometric notches, suggesting a high prevalence of NIHL. The prevalence of notches was higher in males. The presence of notches increased with age: 19.2% of people ages 20 to 29 years and 27.3% of people ages 50 to 59 years had notches. People with noise-induced damage often did not recognize this: almost one-quarter of participants reporting good or excellent hearing had bilateral (5.5%) or unilateral (18.0%) notches. Almost one-third of participants reporting loud noise at work had a notch. This study indicates that NIHL hearing loss is a significant but often unrecognized health problem among US adults.⁵¹  According to the CDC, the high prevalence of notches (almost 1 in 5) among the young adults in this study suggests that early life interventions are needed. Figure 3 illustrates the high-frequency audiometric notch pattern characteristic of NIHL.⁷¹ 

Hearing loss treatment has substantial economic impacts.⁷²  Hearing loss is associated with low educational attainment in US adults.⁷³ 

In addition to hearing loss, exposure to loud or excessive noise may result in tinnitus,³²  the sensation usually described as “ringing,” “buzzing,” “roaring,” “whooshing,” or “hissing” in the absence of external sound. Tinnitus has recently received more attention because of reports that it can result from COVID-19.⁷⁴  Tinnitus in the setting of noise exposure is an indication of injury to the inner ear. Hyperacusis is defined as reduction of normal tolerance of everyday sounds that are not uncomfortably loud or bothersome to an average person. NIHL can precipitate this condition.⁷⁵ 

National data reveal that in 2014, approximately 11.2% of adults had tinnitus and 5.9% had hyperacusis. A study based on NHANES 2005 to 2008 data estimated that 2.5 million youths ages 12 to 19 years had tinnitus.³⁷  A systematic review of 25 articles conducted in a population ages 5 to 19 years showed an estimated prevalence of tinnitus ranging from 6% to 41.9%.⁷⁶  Study designs, research populations, and questions asked varied widely.

Several researchers have examined the prevalence of hearing loss in children, often stating that although most hearing loss is apparent later in life, hearing acuity likely declines gradually as people age and, therefore, should also be examined during youth. Hearing loss in youth is significant, because even small amounts of hearing loss at younger ages can have adverse effects on learning and life trajectory.

Some studies include examination of the association of hearing loss with reported exposure to loud noise; others do not. Le Clerq et al evaluated the prevalence of hearing loss among 9- to 11-year-old children in a large study conducted in Rotterdam, South Holland, Netherlands before children were exposed to risk factors for acquired hearing loss, such as smoking, alcohol use, and exposure to loud music. Audiometric data from this prospective cohort study of 5368 children showed a prevalence of SNHL (low-frequency or high-frequency hearing loss of at least 16 dB in 1 or both ears) of 7.8%. Associations were found with lower maternal educational level and a history of recurrent otitis media.⁷⁷ 

In a study for which the aim was to understand the need for a hearing conservation program for children, Blair et al measured the prevalence of high frequency hearing loss in 2939 second through 12^th graders in Georgia. Third graders were presented with questions about their personal noise exposure and given information about conserving their hearing. High-frequency hearing loss was defined as >15 dB hearing loss or higher thresholds for frequencies between 500 and 2000 Hz and at least 1 threshold >25 dB hearing loss for frequencies >2000 Hz, as measured by pure-tone audiometry. The prevalence of hearing loss ranged from 0% in third and fourth graders to 2.1% in seventh and 12^th graders. The average prevalence of hearing loss in the total sample was 0.92% (0.59% in grades 2 through 5 and 1.13% in grades 6 through 12). The researchers noted that noise is the most frequently cited cause of high frequency hearing loss.⁷⁸  Most third graders (97%) reported exposure to at least 1 source of noise.

Exposure to loud noise may result in a temporary decrease in the hearing sensitivity, known as “temporary threshold shift” or “temporary noise-induced threshold shift” (TNITS). This may last for several hours and resolve or may become permanent, depending on the severity and duration of noise exposure. Investigators using data from NHANES 1988 to 1994 found that the prevalence of TNITS in children ages 6 to 19 years was 12.5% (or 5.2 million children affected). Most children had TNITS in only 1 ear and involving only a single frequency. However, among all affected children, 4.9% had moderate to profound TNITS.⁷⁹  The prevalence of TNITS was 16.4% (95% confidence interval [CI]: 13.1% to 20.0%) in the 2005 to 2006 NHANES, somewhat higher than found in the NHANES 1988 to 1994.⁸⁰ 

In a pilot study of nonoccupational NIHL in 60 students ages 16 to 25 years, 40% of subjects had evidence of NIHL. There was a significant correlation between NIHL and reports of noisy leisure-time activities.⁸¹  Another study by Su and Chan examined how the prevalence of hearing loss in US children and adolescents changed from 1988 to 2010 and how changes were associated with risk factors that included reported noise exposures.⁸²  Survey participants were children and adolescents ages 12 to 19 years in NHANES 1988 to 1994 (n = 3425), 2005 to 2006 (n = 2288), 2007 to 2008 (n = 1238), and 2009 to 2010 (n = 1339). The prevalence of hearing loss increased from NHANES 1988 to 1994 to NHANES 2007 to 2008 (17.0% to 22.5%) for >15 dB hearing loss but decreased in the NHANES 2009 to 2010 to 15.2%. The most current NHANES data thus illustrated that about 1 in 6 middle and high school students had evidence of hearing loss. Participants reported an increase in their exposure to loud noise or music through headphones during the 24 hours before audiometric testing from NHANES 1988 to 1994 to NHANES 2009 to 2010. This study did not, however, demonstrate a consistent association between exposure to loud music with an increased risk of hearing loss. Nonwhite race or ethnicity and low socioeconomic status were demonstrated as independent risk factors for hearing loss in the most recent survey.⁸² 

In a commentary written in response to Su and Chan, it was noted that published estimates of hearing loss in children and adolescents vary widely.⁸³  Reasons for this include varying definitions for hearing loss; differences in how data on hearing are collected; and biases in data collection. The commentary author concluded that differences in reported prevalence more likely reflect differences in identifying temporary CHL, such as from otitis media, rather than a true change in the prevalence of SNHL or mixed hearing loss. Differing estimates for SNHL in different countries more likely reflect differences in defining hearing levels; more studies are needed to determine the prevalence of permanent hearing loss in children and adolescents.⁸³ 

A 2006 study of 2526 young adults ages 17 to 25 years entering the US workforce between 1985 and 2004 showed that approximately 16% had evidence of high-frequency hearing loss >15 dB at 3000, 4000, or 6000 Hz. This study did not find evidence that rates of hearing loss were increasing.⁸⁴ 

A review published in 2020 concluded that hearing loss is common by age 18 years, with nearly 1 in 5 children affected. Noise was mentioned as a type of trauma resulting in hearing loss, but noise was not further discussed.⁸⁵  The author of a letter to the editor about this article objected to this omission and highlighted the importance of prevention.⁸⁶  The authors’ reply included the statement that they “…did not delve into noise-induced hearing loss, which has a growing body of literature that is not yet specific to children.”⁸⁷ 

Studies confirm that hearing loss is commonly found in children, adolescents, and young adults and is not a problem found only in adults. Studies do not consistently show positive associations between reported noise exposure and hearing loss. However, adolescents and young adults typically underestimate symptoms caused by exposure to loud sound, tinnitus, and temporary hearing impairment during music exposure. Youth also typically underreport concern for these symptoms.⁸⁰  Although more research is needed to demonstrate the association of noise exposure with early hearing loss, it is likely that noise exposure contributes to hearing loss in children and adolescents.

Because exposure to excessive noise is preventable, there is reason to believe that pediatricians can play a role in identifying and counseling about noise exposure.

Children and adolescents may have special susceptibility to nonauditory effects of noise because “…children are exposed to environmental noise and associated pollutants at a time of rapid growth and cognitive development and will perhaps have less developed coping repertoires than adults to deal with environmental noise and less control over noise.” Despite these vulnerabilities, there is more research about environmental noise in adults compared with children.⁸⁸ 

Several physiologic effects resulting from excessive noise exposure have been documented or postulated. The stress resulting from noise exposure is believed to cause dysregulation of the autonomic nervous and endocrine systems, thus affecting long-term cardiovascular health. The pituitary-adrenal-cortical and sympathetic-adrenal-medullary axes are activated by noise, leading to a stress response including the release of cortisol. Noise-related effects on the cardiovascular system may also result from a decrease in sleep quantity and quality from nighttime noise exposure and other mechanisms. These reactions may also adversely affect the metabolic system.

European researchers commissioned by the WHO reviewed observational studies, mainly conducted in adults, that examined associations between environmental noise exposure and the cardiovascular and metabolic systems.⁸⁹  Their aim was to conduct a systematic assessment of evidence on noise exposure-response relationships to inform new WHO environmental noise guidelines for the European Region. Six hundred references (published between January 2000 and August 2015) were identified relating to the effects of noise from road, rail, and air traffic and wind turbines on the cardiometabolic system. The studies were evaluated for quality, rated on a scale from “high” to “very low.” The best evidence was available for road traffic noise and ischemic heart disease (IHD). Seven longitudinal studies were combined to reveal a relative risk of 1.08 (95% CI: 1.01–1.15) per 10 dB (L_den) for the association between road traffic noise and IHD incidence. The risk of IHD increases continuously for noise from road traffic from about 50 dB (L_den). The 1999 WHO guidelines stated: “epidemiological studies show that cardiovascular effects occur after long-term exposure to noise with L_Aeq24hr values of 65–70 dB.”

Evidence for the association of road traffic noise with hypertension was assessed as suffering from a high degree of bias. There were few studies relating transportation noise to stroke, diabetes, and/or obesity, with the quality of these studies rated as moderate to very low. The researchers concluded that more evidence from longitudinal studies is needed.

The above research included information about the effects of noise on children’s blood pressure, recognizing that people exposed to noise early in life may be at higher risk for cardiovascular and other problems later in life. The number of studies of blood pressure in relation to noise exposure in children increased since the last WHO guidelines published in 1999. Eight studies were evaluated in the current analysis. Most showed positive but not significant associations between exposure to road traffic and children’s blood pressure; one study demonstrated a significant association of road traffic noise with systolic blood pressure. The quality of these studies was rated as very low overall; researchers concluded that it is difficult to ascertain the effect of noise on blood pressure in children. More recently, as part of the Iranian Childhood and Adolescence Surveillance and Prevention of Adult Noncommunicable Diseases (CASPIAN-V) study, researchers investigated the association of noise annoyance and psychological distress with blood pressure in a population of 14 274 students ages 7 to 18 years (mean, 12.28 years). Psychological distress was assessed using questions from the Global School-based Student Health Survey, a survey designed by the WHO. Noise annoyance was measured using a validated questionnaire. Participants’ diastolic blood pressure and mean arterial blood pressure were positively correlated with noise annoyance. Participants with higher psychological distress were more likely to have high blood pressure compared with students without distress or with mild distress (odds ratio [OR]: 1.15; 95% CI: 1.003–1.34).⁹⁰ 

Although the quality of evidence in the 2018 WHO review was often rated as low, the authors advise that this does not mean that noise is without effect on the cardiovascular system. There is strong biologic plausibility regarding the effects of noise on physiology and health. It is likely that the same mechanism by which noise affects adult health—whereby noise exposure increases physiologic arousal through repeated stimulation of the endocrine and autonomic nervous systems—also applies to children.⁸⁸  For example, a recent study of 82 12-month-old infants demonstrated autonomic dysregulation related to noise exposure. Results suggested mechanisms through which high environmental noise exposure could lead to an increased risk of adverse mental health and impaired cognitive performance later in life.⁹¹ 

Although more research on these health effects is needed, noise affects millions of people⁹² ; excessive noise is not merely a nuisance but a threat to public health.

Sleep is sensitive to environmental factors. Although the sleeping person is not conscious of the presence of external stimuli, these still are processed by the sleeper’s sensory functions.⁹³  Exposure to noise leads to fragmented sleep and decreased total sleep time, resulting in reductions in daytime alertness and performance, quality of life, and overall health. Overwhelming evidence from epidemiologic studies shows that chronically disturbed or curtailed sleep is associated with these negative health outcomes; therefore, sleep disturbance is one of the most important nonauditory effects of environmental noise exposure.⁹⁴ 

In Europe, an estimated 6.5 million people are affected by “chronic high sleep disturbance.” The European Union’s Seventh Environment Action Program defines “high noise levels” as noise levels for L_den above 55 dB and for L_night above 50 dB. Nighttime environmental noise levels even below 40 dB can cause negative effects including body movements, awakenings, and self-reported sleep disturbance.

A systemic review commissioned by the WHO evaluated the quality of evidence about the effects of environmental noise exposure on sleep. A meta-analysis of studies of road, rail, and aircraft noise exposure to self-reported sleep disturbance was performed. The OR for the percentage of highly sleep disturbed for a 10 dB increase in L_night was significant for aircraft (OR: 1.94; 95% CI: 1.61–2.3), road (OR: 2.13; 95% CI: 1.82–2.48), and rail (OR: 3.06; 95% CI: 2.38–3.93) noise when the specific survey questions referred to noise. Results were not significant for aircraft (OR: 1.17; 95% CI: 0.54–2.53), road (OR: 1.09; 95% CI: 0.94–1.27), and rail (OR: 1.27; 95% CI: 0.89–1.81) noise when the specific questions did not refer to noise. An analysis of polysomnographic studies about acute effects of transportation noise also was performed. Results showed that the unadjusted OR for the probability of awakening for a 10 dBA increase in indoor L_max was significant for aircraft (OR: 1.35; 95% CI: 1.22–1.50), road (OR: 1.36; 95% CI: 1.19–1.55), and rail (OR: 1.35; 95% CI: 1.21–1.52) noise.⁹⁴  The evidence regarding the effects of wind turbine noise on sleep was limited, but 4 of 6 studies reviewed showed an association between wind turbine noise levels and increased sleep disturbance.

There are few studies in children examining the relationship of noise to sleep; most conclude that noise may lead to self-reports of poorer sleep. In a cross-sectional study of 9- to 12-year-olds, there was a moderate exposure-response relationship between nighttime exposure to road traffic noise with sleep quality and daytime sleepiness; no significant association was found with problems falling asleep.⁹⁵  In a study of third and fourth graders, a small but significant relationship was found between road and rail noise (L_den) and sleep disturbance.⁹⁶  Noise levels were measured in the bedrooms of 56 children ages 7 to 13 years and correlated with self-reported measures of sleep. Children exposed to higher maximum noise levels were more likely to report problems sleeping.⁹⁷  A study of predicted noise levels and self-reported sleep disturbances in 287 children with a mean age of 10 years revealed a significant relationship between noise levels (L_night) at the least exposed façade and sleeping problems (OR: 1.79; 95% CI: 1.10–2.92) and difficulty falling asleep (OR: 1.96; 95% CI: 1.16–3.32). There was, however, no significant relationship between noise levels at the most exposed façade and sleep disturbance.⁹⁸ 

Studies in children also suggest that they are less likely to awaken after noise events compared with adults, with a sensitivity difference of about 10 dBA. Children, however, are considered more vulnerable to these events because of ongoing development and differences in sleep patterns. Young children generally have earlier bedtimes and longer sleep durations than adults. This pattern may coincide with periods of high traffic not accounted for by standard metrics such as L_night.⁹⁴ 

Children with chronic conditions may be more susceptible to noise-induced sleep effects. Children in hospitals were more likely to have disturbed sleep before they were admitted and to be woken by alarms and hospital staff, potentially leading to delays in recovery.⁹⁹ 

More research is needed in children to determine the effect of noise on subjective and objective measures of sleep.

Excessive noise exposure is one of many factors potentially causing hearing loss in children. Even mild unilateral hearing loss has detrimental effects on academic success and speech and language outcomes.¹⁰⁰  Lieu¹⁰¹  found that 22% to 33% of those with unilateral hearing loss had to repeat a year academically and 12% to 41% required special services at school. Additional studies reported behavioral problems in 59% of students with hearing loss, with 22% failing at least 1 grade and 36% needing individualized education programs (IEPs). Tharpe¹⁰²  corroborated these negative effects and reported that 50% of children with unilateral hearing loss have academic difficulties that require an individualized education program, tutoring, or therapy. Unilateral hearing loss diminishes binaural function, resulting in difficulty with sound localization, which then negatively impacts the ability to localize and identify the speaker. Without sound localization in a classroom or in virtual learning, a child may not be able determine who is talking and miss out on critical learning. An additional effect—worsening speech recognition secondary to synaptopathy, essentially a “hidden hearing loss,”—causes reduced speech perception in noise for those suffering from NIHL while still maintaining higher pure tone averages (PTAs).

According to the WHO, children with as low as 30 dB of hearing loss have a global language impairment: a “disabling level of hearing loss.”¹⁰³  In a study of 1638 6- to 11-year-old children in the United Kingdom, testing was performed at 4 thresholds (1000 Hz and 4000 Hz in each ear). Testing included speech perception in noise, a measure of how well speech is perceived in a noisy environment. Children without hearing loss had thresholds and PTAs <15 dB hearing level. Those with “minimal” hearing loss (≥15 dB hearing level for at least 1 threshold and PTA <20 dB) or “mild” hearing loss (PTA ≤20 dB and <40 dB hearing level) showed deficits in speech perception in noise compared with children without hearing loss. Children with mild hearing loss were also impaired in working memory and reading, generally performing more poorly than those with minimal loss. Asymmetric hearing loss produced as much impairment on both auditory and cognitive tasks as symmetric loss. Hearing loss between 15 and 30 dB PTA was found in approximately 20% of students. Authors recommended a wider use of speech-in-noise testing to diagnose and assess hearing loss and reducing the hearing loss threshold for children to 15 dB hearing level.¹⁰⁴ 

Although environmental noise is less likely to affect children’s hearing—hearing loss is more likely to result from excessive recreational exposures—environmental noise affects learning. Young children have difficulty learning when exposed to loud background noise and noisy conversations and are even distracted with as little as a 5 dB of sound-to-noise ratio. Noise prevents optimal learning and interferes with an infant’s attention span, which shifts more quickly with intruding noise.¹⁰⁵  Preterm infants have the greatest difficulty because they are unable to habituate to noise stimuli; loud acoustic events alter blood flow patterns to the brain and trigger stress mechanisms.¹⁰⁶  Speech patterns (pitch, tone, coding) are easier to learn in quiet environments.

Unlike adults, children are less capable of using stored phonological understanding to reconstruct noise-degraded speech.¹⁰⁷  Conversational speech is typically in the 50 to 60 dB range. Noise in the classroom can approach and even exceed 60 dB.

Background noise can disrupt cognitive tasks, especially short- and long-term memory.¹⁰⁸  Loud noise exposure (ie, >85 dB) has lasting effects on cognitive function (memory, attention, reaction time) even after the noise exposure is withdrawn, with higher noise intensity causing greater negative shifts in all areas of testing.¹⁰⁹  Noise negatively impacts speech comprehension and speech intelligibility.¹¹⁰ 

Stansfeld and Clark summarized the nonauditory health effects of environmental noise on children as of 2015, emphasizing that there is robust evidence concerning the cognitive effects of noise exposure.⁸⁸  One natural experiment illustrates the effects of noise on children’s cognition. A longitudinal, prospective study of the Munich Airport in Germany showed that high noise exposure was associated with poorer reading comprehension and long-term memory in 10-year-olds. Two years after the airport was closed and relocated, these cognitive impairments were no longer present.¹¹¹  After a new Munich airport was opened, children living near the new airport showed impairments in memory and reading comprehension that developed after 2 years. These findings suggest that impairments may be reversible if noise exposure stops and that it takes a few years for memory and comprehension deficits to develop. The study of the Munich airport is one of few longitudinal studies about noise and cognition and gives evidence for a cause-effect relationship. In a cross-sectional study of noise exposure in 6000 schools located near 46 US airports, significant associations were demonstrated between increases in aircraft noise and decreases in scores on standardized tests of mathematics and reading. Analysis of a subsample of 119 schools showed that the noise effects on learning disappeared once sound insulation was installed, suggesting that installing insulation may have positive effects on learning.¹¹² 

German investigators conducted a meta-analysis of 3 eligible studies (reported up to February 2019) that examined transportation noise exposure on children’s mental health. These studies focused mainly on European children and adolescents ages 9 to 10 years and 15 to 17 years that predominately used the Strength and Difficulties Questionnaire. The odds for hyperactivity and inattention and total difficulties were significantly increased by 11% (OR: 1.11; 95% CI: 1.04–1.19) and 9% (OR: 1.09; 95% CI: 1.02–1.16) respectively per 10 dB of road traffic noise.¹¹³ 

A panel of international experts conducted a state-of-the-science review about the effects of aircraft noise on learning in children, sleep disturbance, and health.¹¹⁴  Aircraft noise exposure in schools or homes was associated with children having poorer reading and memory skills.¹¹⁵  Children exposed to aircraft noise in school had poorer performance on standardized achievement tests, compared with children not exposed. The Road traffic and Aircraft Noise and children’s Cognition and Health (RANCH) study, a cross-sectional multination study of 2844 9- to 10-year-old children from schools around 3 European airports, showed dose–response negative associations between increasing levels of aircraft noise with reading comprehension and recognition memory.¹¹⁶  Stansfeld and Clark postulate that noise may affect cognition directly and/or through indirect mechanisms, although they state that the evidence for these mechanisms is “fairly sparse.” Teachers may have to interrupt lessons to wait for aircraft to pass overhead, leading to increased communication interruptions and fatigue in pupils and teachers and lowering teacher motivation and morale. The annoyance caused by noise may contribute to loss of focus. When the home is close to an airport or road noise, disturbances in sleep can plausibly result in learning difficulties.⁸⁸ 

A systematic review of studies on the effects of environmental noise (road traffic, aircraft, and train and railway noise) on different aspects of cognitive performance was conducted by the WHO. Most studies were cross-sectional in design. The authors concluded that studies were of moderate quality for an effect including aircraft noise on reading comprehension and long-term memory. Studies also of moderate quality showed no effect for other outcomes including attention and executive function and for some noise sources such as noise from road traffic and railways. Authors concluded that even though evidence was of low quality for some cognitive domains and some noise sources, this did not necessarily imply absence of effects. Instead, more and better studies are needed.¹¹⁷ 

Although some studies show that noise abatement strategies through sound insulation or airport relocation are effective in reducing external sound, more research in this area is needed to determine the influence of these strategies on learning.

The WHO conducted a systematic review and meta-analyses of 57 studies of environmental noise exposure and annoyance in adults.¹¹⁸  Annoyance, estimated as the second major health effect of noise exposure after sleep disturbance, is characterized by 3 factors: “…(1) an often repeated disturbance because of noise (repeated disturbance of intended activities, eg, communicating with other persons, listening to music or watching TV, reading, working, sleeping), and often combined with behavioral responses in order to minimize disturbances; (2) an emotional and attitudinal response (anger about the exposure and negative evaluation of the noise source); and (3) a cognitive response (eg, the distressful insight that one cannot do much against this unwanted situation).” Many researchers view this response as a stress reaction. There were statistically significant correlations between traffic noise levels and annoyance scores with moderate strength of the relationship. The statistical relations between wind turbine noise levels and annoyance were less clear.

Few studies of the relationship of noise to annoyance have been conducted in children. Aircraft noise causes annoyance, in part, because of its intermittent nature. In the cross-sectional RANCH study, an exposure-response relationship was shown between aircraft noise exposure at school and severe annoyance in children, after adjusting for confounding variables. The percentage of severely annoyed children increased as noise increased, with 5.1% reporting annoyance at 50 dB compared with 12.1% at 60 dB. There were similar associations found with exposure to aircraft noise at home. A relationship was also found between exposure to road traffic noise and annoyance.¹¹⁹  A longitudinal study of South African children in fifth through eighth grades showed that aircraft noise exposure was related to annoyance in children over time.¹²⁰  Children ages 8 to 14 years, however, were less annoyed by road traffic noise compared with adults.¹²¹ 

Prenatal exposures to environmental noise may cause adverse effects on the fetus because of stress, sleep disturbances, and other factors. An updated systemic review of 14 studies (6 on aircraft noise, 5 on road traffic noise, 3 on total ambient noise) was conducted on studies conducted through 2016. Evidence of very low quality was found for associations between aircraft noise and preterm birth (PTB), low birth weight (LBW), and congenital anomalies; evidence of low quality was found for associations between road traffic noise and LBW, PTB, and small for gestational age (SGA). Authors concluded that studies of higher quality are needed to better establish these associations.¹²² 

A later meta-analysis examined the relationship of residential exposures to road noise on birth outcomes (birth weight, LBW, SGA, and PTB). This systematic review showed a decrease of 8.26 g in birth weight associated with a 10 dBA increase in L_den. Nonsignificant trends for LBW and SGA were found. Evidence quality for birth weight was graded as “moderate” and “very low” for other outcomes. There was only minor confounding attributable to air pollution effects.¹²³ 

Research supports associations between outdoor (ambient) air pollution exposure during pregnancy and adverse birth outcomes, such as PTB and lower birth weight.¹²⁴  Because noise and outdoor air pollution share traffic as a common source, researchers questioned whether some effects attributed to air pollution could be attributable to noise exposure. Associations of birth outcomes and exposures to residential noise and air pollution were examined in a population-based cohort study of 68 238 singleton births in Vancouver, British Columbia, Canada. The same researchers previously found positive associations between maternal prenatal exposure to traffic-related air pollution and PTB, SGA, and full-term LBW. In the current study focused on noise, they described adverse effects of residential traffic noise exposure to SGA, term birth weight, and term LBW but not on PTB or very PTB. Similar results were found both for road traffic noise alone and all transportation noise. Independent effects of noise and air pollution on SGA were found in the joint noise-air pollution models. Although the effect of noise exposure on term birth weight did not change after adjusting for air pollution, the effects of air pollution on term birth weight decreased after findings were adjusted for noise exposure.¹²⁵ 

The WHO calculated the “burden of disease” resulting from environmental noise as expressed in disability-adjusted life years (DALYs). DALYs, based on quantitative risk assessment, “are the sum of the potential years of life lost because of premature death and the equivalent years of ‘healthy’ life lost by virtue of being in states of poor health or disability.” Conservatively estimated DALYs lost from environmental noise were “61 000 years for ischemic heart disease, 45 000 years for cognitive impairment of children, 903 000 years for sleep disturbance, 22 000 years for tinnitus and 654 000 years for annoyance in the EU Member States and other western European countries.” WHO estimates indicate that “at least 1 million healthy life years are lost every year from traffic-related noise in western Europe. Sleep disturbance and annoyance, mostly related to road traffic noise, comprise the main burden of environmental noise.”¹²⁶ 

According to NIOSH, about 22 million workers are exposed to possibly damaging levels of noise at work.⁷  Workers exposed to ototoxic chemicals are at increased risk. In addition to emotional, financial, and physical impacts, hearing loss constitutes a major safety concern for workers such as law enforcement officers and air traffic controllers who rely on hearing accurate information. NIHL may result in difficulty communicating, understanding verbal instructions, and perceiving events (eg, alarms, auditory backup signals on heavy machinery), leading to an increased risk of injury.¹²⁷ 

OSHA mandates hearing conservation programs designed to protect individuals from significant noise levels that can lead to hearing impairment. Hearing conservation programs use a variety of measures to reduce noise exposures, including engineering controls and administrative controls as well as use of personal protective equipment (PPE) where other controls fail or are not feasible. Examples of hearing conservation measures include monitoring of noise levels, regular audiometric evaluation of hearing with establishment of baseline hearing at the start of employment, annual hearing checks, availability of hearing protectors (such as earmuffs and earplugs) to reduce noise exposure below 85 dBA, and training for employers and employees about noise effects and the best ways to lessen exposure levels.¹²⁸  Avoiding loud environments and properly using PPE have been shown to prevent hearing loss.¹²⁹ 

OSHA does not have specific guidelines about noise exposure levels for pregnant women or fetuses. NIOSH does, however, identify that increased noise levels are a stress factor on a developing fetus.¹³⁰  NIOSH also acknowledges that sound travels through the body, and therefore, high levels of noise may be muffled but still sufficient to damage hearing in the fetuses of workers exposed to noise. Hearing protection provided to workers will not protect the fetus, so the recommendation is to distance the mother away from the noise as much as possible.

There is limited research about adolescents’ exposure to noise in the workplace. To our knowledge, there are no special protections in place for adolescents exposed to workplace noise. One study examined self-reported chemical, biologic, and physical exposures in a representative sample of US adolescents ages 14 to 17 years who had held a paying retail or service sector job for at least 2 months within the last 12 months. More than two-thirds of respondents (67%) reported having been exposed to “continuous, very loud noise.” Less than 2% of those with noise exposures reported using hearing protection. Authors concluded that more attention is needed to ensure that PPE is available and used properly; that clinicians take careful work histories from adolescents; and that parents engage with adolescents’ employers to increase the probability that regulations are obeyed and safety procedures are adequate.¹³¹ 

The WHO highlights environmental noise as a public health issue to inform the development of guidelines for noise exposure. Environmental noise is considered “…among the top environmental hazards to physical and mental health and wellbeing in Europe.” Noise from transport was identified as the second most significant environmental cause of ill health in Western Europe, with the first being air pollution from fine particulate matter.¹³²  In 2010, updated guidelines on noise were requested by the Member States of the WHO European Region¹³³  after their adoption of the Parma Declaration on Environment and Health. The WHO was asked to develop updated evidence-based guidance to protect human health from environmental sources, including transportation (road traffic, railway, and aircraft), wind turbines, and leisure activities. Stakeholders were asked to reduce children’s exposure to noise, including from PLDs. A special issue on noise published in 2018—“WHO Noise and Health Evidence Reviews”—contains evidence reviews related to specific “critical” and “important” health endpoints.¹³⁴ 

WHO guidelines for environmental noise exposure are summarized in Table 5. Depending on the noise source, different exposure measures are recommended. These include the day-evening-night noise level (L_den), the nighttime noise level (L_night), and the 24-hour equivalent continuous average noise level (L_Aeq,24h). The L_den provides different weighting of noise levels during daytime (7 am to 7 pm), evening (7 pm to 10 pm), and nighttime (10 pm to 7 am) periods, whereas the L_night is restricted to nighttime hours (10 pm to 7 am). The L_AEQ,24h is a 24-hour average that does not differentially weight noise levels depending on time of day.

In contrast to the focus on noise in Europe, environmental noise exposure in the United States has been less emphasized as a serious health threat, including to children and youth. Although scientific knowledge about the effects of environmental noise has substantially grown over the last decades, this has not led to federal policy. The Noise Control Act, passed by Congress in 1972, establishes ways to coordinate federal research on noise and noise control, authorizes the establishment of federal noise standards for commercial products, and authorizes the dissemination of information to the public regarding the noise characteristics of commercial products.¹³⁶  The Office of Noise Abatement and Control (ONAC) was created within the EPA in 1972 to enforce the Noise Control Act, thus giving the EPA a mandate to regulate environmental noise.¹³⁶ 

There are no federal regulations regarding exposure to nonoccupational noise.⁵¹  In 1974, an EPA report put forth recommended environmental noise exposure limits for the general public. The EPA recommended an average exposure limit of 70 dBA over 24 hours (ie, a 70 dBA L_Aeq,24h) and 75 dBA over 8 hours (ie, a 75 dBA time-weighted average limit, referred to in some countries as an L_EX,8h). This report was not meant as a standard or regulation. It specified 2 additional limits for speech interference and annoyance (55 dBA for outdoor activities and 45 dBA for indoor activities). The 70 dBA recommendation aimed to protect 96% of the population from developing hearing loss; the others were designed to promote personal comfort and to protect “public health and welfare” from annoyance and mental anguish.¹³⁷  Lower exposure limits are in place for nighttime noise. During the night, background noises from exterior sources generally drop from daytime values. In addition, activity in most households decreases at night. Therefore, “noises become more intrusive at night, since the increase in noise levels of the event over background noise is greater than it is during the daytime.”¹³⁷  Although teaching activities and classrooms were mentioned in this report, at that time there was no mention of children (or other groups) as specific vulnerable populations.

The EPA’s ONAC closed in 1982. According to Noise Free America, a nonprofit organization whose mission is “…to elevate the issue of noise pollution with federal, state, and local officials, as well as to educate the public about the dangers of noise pollution,”¹³⁸  all ONAC funding was eliminated through an Executive Order by President Ronald Reagan in 1981 “…because of pressure from industries affected by ONAC’s noise regulations.”¹³⁹  The Noise Control Act of 1972, however, remains in effect, with the EPA legally responsible for enforcing its provisions but lacking funding to do so.¹⁴⁰  Now, state and local governments are tasked with responding to noise pollution concerns and to protect the public from exposure to excessive environmental noise.¹⁴¹  Exposure limits for environmental noise, however, focus on the general population and are not specifically intended for infants, children, and adolescents.

Compared with adults, children and adolescents are more likely to experience noise exposure through recreational activities. Standards promulgated for adult occupational and environmental exposures do not necessarily apply to children and adolescents experiencing recreational noise.¹⁴²  It often is difficult to control recreational noise; because the exposure is sought after, children may not understand or have control over the hazard, and the duration, frequency, and intensity of exposure vary from individual to individual. Researchers conducting a review of children’s noise exposure assumed that the most appropriate limit for children’s recreational noise exposure would protect 99% from hearing loss exceeding 5 dB at 4000 Hz (the frequency most susceptible to NIHL) after 18 years of exposure. They estimated that “…noise exposure equivalent to an 8-h average exposure (L_EX) of 82 dBA would result in about 4.2 dB or less of hearing loss in 99% of children after 18 years of exposure. The L_EX was reduced to 80 dB to include a 2-dB margin of safety. This L_EX of 80 dBA is estimated to result in 2.1 dB or less of hearing loss in 99% of children after 18 years of exposure. This is equivalent to 75 dBA as a 24-h equivalent continuous average sound level.”¹⁴²  This 75 dBA L_Aeq,24h recommended limit, intended solely to prevent noise-induced hearing loss, is slightly less conservative than the leisure noise limit of a 70 dBA L_Aeq,24h recommended by the WHO European Region (Table 5), which is intended to prevent multiple adverse health impacts.

The WHO suggested a practical rule of thumb—that PLD volume be set no higher than 60% of the maximum volume—to guide families to safer listening habits.¹⁴³  Because this recommendation could be considered too restrictive by adolescent users, Portnuff wrote that it may be more realistic to suggest that PLD users limit exposure to 80% of the maximum volume for 90 minutes per day.¹⁴⁴  Regardless of the volume level recommended, the main educational concept is that listening at maximum volume is undesirable and is likely to result in excessive exposure.¹⁰ 

The intrauterine environment is full of sound. Fetuses can hear their mother’s heartbeat and voice well before birth; there is evidence that this sound positively benefits the auditory cortex and neuroplasticity of the newborn.¹⁴⁵  Investigators examined noise levels of 9 women in labor who were at term and presented with ruptured membranes. A microphone was placed transcervically in a position adjacent to the anterior fetal ear. Baseline sound levels in the uterus ranged from 72 and 88 dB.¹⁴⁶  The majority of this noise is felt to derive from the maternal vasculature. Other investigators seeking to characterize the sound environment experienced by the fetus conducted recordings of in utero sound in 50 pregnant women in their second and third trimesters. Recordings were conducted with externally placed electronic stethoscopes. As gestation progressed, the pregnant woman’s abdomen filtered high-frequency (500–5000 Hz) and midfrequency (100–500 Hz) energy bands, but there was no change in low-frequency signals (10–100 Hz).¹⁵ 

Infants exposed to noises mimicking in utero noise are soothed by these noises.¹⁴⁵  Sound simulation, which replicated the pregnant patient’s voice and heartbeat sounds, had direct benefit on NICU infants (especially in infants whose gestational age at birth was more than 33 weeks), who showed less apnea and bradycardia daily.¹⁴⁷  Some investigators suggest that creating NICU environments with sound characteristics similar to the intrauterine environment may facilitate infant development by providing an environment that reflects fetal life.

Although occupational noise exposure causes hearing impairment in adults, less is known about the effects on children of occupational noise exposure experienced by their mothers during pregnancy. A Turkish study examined hearing screening results of 2653 infants from January 2013 to May 2017 who were evaluated using Transient Evoked Otoacoustic Emissions and Auditory Brainstem Responses. Infants of 65 mothers prenatally exposed to noise (L_Aeq 80–85 dBA for 8 hours per day) (gestation week ± SD; 32.58 ± 2.71) were compared with infants born to 2588 mothers without prenatal occupational noise exposure. No significant differences were found between the groups.¹⁴⁸ 

Researchers in Sweden investigating the relationship of occupational noise exposure during pregnancy to hearing dysfunction in offspring conducted a population-based cohort study of 1 422 333 single births from 1986 to 2008. The researchers state that although the fetus is exposed to internal noise from the mother’s body, “…the total noise exposure in utero to a large extent depends on the sound exposure outside the abdomen.” Data on mothers’ occupation and other factors were obtained from interviews conducted by prenatal care unit staff and from the Swedish national register. Noise exposure was classified through a job-exposure matrix. Registry information was obtained on every child born between 1986 and 2008 and in whom any kind of hearing dysfunction was diagnosed in 2003 through 2008 that could be related to noise exposure. The full sample of mothers contained women who worked either part-time or full-time during pregnancy. For the full sample, the adjusted hazard ratio for children’s hearing dysfunction associated with prenatal occupational noise exposure ≥85 versus <75 dB L_Aeq8h was 1.27 (95% CI: 0.99–1.64; 60 exposed cases). For children of mothers who worked full time and had <20 days leave of absence during pregnancy, the corresponding hazard ratio was 1.82 (95% CI: 1.08–3.08; 14 exposed cases). The authors stated that their results are consistent with 2 earlier epidemiologic studies as well as with studies in animals. These associations led the authors to conclude that women should not be exposed to high noise levels—including high-level impulse sounds—during pregnancy.¹⁷ 

Studies on the effects of occupational noise exposure on gestational duration and fetal growth have shown conflicting results; some studies showed an association with gestational duration and fetal growth and others did not.¹²⁵ 

ISMs (“white noise” machines) produce sound in an infant’s room when the infant sleeps. The intent is to soothe the infant and to mask other noises to promote uninterrupted sleep for the infant and potentially sleep-deprived parents. The machines are popular with many parents, and information on the internet encourages parents to play the machines at loud volumes.

One randomized trial of 40 newborn infants examined the effects on neonates of exposure to a commercially available white noise machine placed between 12 and 20 inches from the infant’s head. Noise levels were measured (at 12 in) at 72.5 dB for the first 30 seconds and 67 dB for the remaining 4 minutes. Infants exposed to noise were >3 times more likely to fall asleep within 4.5 minutes compared with nonexposed infants.¹⁴⁹  In a Turkish randomized controlled study of 1-month-old infants who had colic (“gas pains’), playing white noise was found to be superior to swinging in decreasing infants’ crying and increasing their sleep duration. The white noise was set at 55 dB and placed 30 to 50 cm (12 to 20 in) away from the infants.¹⁵⁰ 

Another Turkish study examined the effects of brief white noise exposure (55 dB placed 10 cm [4 in] from the infant’s head) on crying before and after administration of the second dose of hepatitis B vaccine. Subjects were 1-month-old infants in the NICU. There was a significant decrease in crying in infants exposed to white noise compared with a control group.¹⁵¹  Another Turkish study examined 3 groups of infants after blood draws. Infants in the first group were held on their parent’s lap; infants in the second group were held by their parent and listened to white noise (55 dB at 50 cm [20 in] away from the infant); infants in the third group lay in their crib and listened to white noise while they underwent the blood draw. The Neonatal Infant Pain Scale was used to evaluate the behavioral responses to pain. Crying was the shortest and behavioral reactions were the lowest for infants lying in their crib and listening to white noise. Infants who listened to white noise while held by their parent had the next lowest time of crying and behavioral reactions. The highest behavioral reaction was in infants held by their parent but not exposed to noise. Authors concluded that white noise is an effective nonpharmacologic pain-control method for infants.¹⁵² 

None of these studies commented on any potential adverse effects of exposing infants to noise.

Other researchers examined the sound levels of 14 ISMs played at maximum volume measured at 30, 100, and 200 cm (12, 40, and 80 in) from the machine. The 30-cm distance was chosen to simulate placement on a crib rail; 100 and 200 cm were chosen to simulate placement near the crib or across a room, respectively. Correction factors were applied to account for a 6-month-old’s ear canal. Maximum sound levels at 30 cm were >50 dBA for all tested devices, exceeding current recommended noise limits for infants in hospital nurseries. For 3 machines, output levels were >85 dBA. Authors commented that if played at these levels for more than 8 hours, this exposure would exceed current occupational limits for accumulated noise exposure, thus potentially risking NIHL.¹⁵³  Authors recommended that if ISMs are used, it may be safer to locate them as far away as possible from the infant, to set the volume as low as possible, and to limit the duration of use by using a timed shut-off or turning off the ISM once the infant is asleep.

“Foreground exposure” is defined as direct TV-watching. It is estimated that the average US child, birth to 6 years of age, watches approximately 80 minutes of TV on typical days. Background TV exposure is defined as the TV being on when the child is occupied with another activity. Investigators surveyed a national sample of 1454 US parents of children ages 8 months to 8 years to determine how much time children were exposed to background exposure from TVs. The average child in this study was exposed to almost 4 hours of background TV daily. Younger children and African American children were more likely to have greater exposure.¹⁵⁴  Authors did not address levels of noise or possible effects of this noise on hearing and cognition.

Background exposure from TVs has negative effects on children’s cognitive functioning and social play. In one study, investigators examined play behavior in 12-, 24-, and 36-month-olds (n = 50) who played with toys for an hour. During half of that hour, an adult game show (“Jeopardy”) and its commercials played in the background at about 57 dBA, approximating the level of typical human speech. The TV was turned off during the other half hour. Although children looked at the TV for just seconds at a time and less than 1 time each minute, this exposure was associated with a significant reduction in the length of playing with toys and with focused attention during play. The investigators concluded that background TV is disruptive to young children’s play behavior even when they are not overtly paying attention to it.¹⁵⁵  This disruption could be attributable to the TV taking up some of the cognitive resources needed for play or could be related to the effects of noise on performance.

Toys are potential sources of excessive noise. In a study published in 1985, researchers reported levels measured in 5 separate toy categories at different distances.²¹  Sound levels for 7 squeaking toys at 10 cm (4 in) were 78 to 108 dBA. Squeaking toys appear benign because of their small size, round form, and soft colors. Exposure at <10 cm, however, may result in high noise exposure, especially if the toy is close to a child’s ear. Analysis of 11 moving toys (all vehicles) showed sound levels of 82 to 100 dBA at 10 cm. Sound levels varied when the toys were in motion and achieved a lower mean level than that measured at 10 cm. Authors concluded that exposure of several hours per day for “a long time” would be needed before there was a risk of NIHL. Analysis of 11 stationary toys, including 5 that emitted pure tones, varied from 74 to 102 dBA at 10 cm. Very high sound levels at 10 cm were found in 4 toys emitting pure tones. Authors noted that levels of 130 to 140 dBA could be achieved if toys were held close to the ear, creating a closed chamber effect with a high risk of NIHL. Sound levels measured 50 cm (20 in) behind 6 toy weapons showed mean peak values of 143 to 153 dB (AP^*). The researchers recommended that ear protectors are needed when toy weapons are used and that manufacturers add warning labels about the risk of NIHL. The average sound levels of firecrackers measured at 3 m (approximately 3.3 ft) was 125 to 156 dB (AP). The researchers concluded that the risk of NIHL for firecrackers was similar to that of toy weapons.

Other studies have documented potentially hazardous noise exposures from toys.^156–158  A New Zealand study³⁴  evaluating 28 commercially available toys revealed that 21% did not meet acoustic criteria in the ISO standard, ISO 8124-1:2009 Safety of Toys, adopted by Australia and New Zealand.^† Only one of a secondary set of toys known to be played with atypically, by children with conditions such as ASD, cleanly passed the standard, with the remainder failing or showing a marginal pass.³⁴  Another study measured noise levels of toys introduced into several national store chains during 4 consecutive years (2008–2011).¹⁵⁸  Toys labeled for use by children ages 6 months to 5 years were screened for noise levels. The 90 toys with peak sound outputs of >80 dBA at speaker level were remeasured in a soundproof audiometry booth at speaker level and 30 cm (arm’s length, 12 in) from the speaker. At speaker level, mean (SD) noise amplitude was 100 (8) dBA (range, 80–121 dBA); at 30 cm, mean (SD) was 80 (11) dBA (60–109 dBA). Most toys (98%) had >85-dBA noise amplitude at speaker level; 19 (26%) had >85-dBA noise amplitude at 30 cm. Although the mean noise amplitude at 30 cm significantly decreased during the 4-year period (P < .001), the mean noise level at speaker level did not. The mean noise amplitude of different toys did not vary by the age group specified for appropriate use. Authors concluded that manufacturers continue to produce extremely loud toys for very young children. Some toys exceed the toy industry’s standards for noise. Acoustic trauma from these toys remains a potential risk for this young age group; authors state that regulatory action should be considered for the manufacture and marketing of toys.¹⁵⁸ 

Often, sound levels of toys are tested while the toy is in its packaging. Working with The Sight and Hearing Association (SHA), a Minnesota-based nonprofit organization aiming to enhance children’s lifetime learning by identifying preventable losses of hearing and vision, researchers designed a study to test a hypothesis that some noisy toys are even louder once packaging is removed. Every year, the SHA selects and tests toys making some level of noise to determine the toys’ dB level. The results are available on its Web site so that parents may make informed selections.¹⁵⁹  The dB levels of speakers of 35 toys selected from the 2009 to 2011 SHA “Noisy Toys List” were tested at 0 cm and 25 cm (10 in) from the speaker using a handheld digital sound meter. Speakers were categorized as exposed, partially exposed, or covered, based on packaging. Significant dB increases were found after removing packaging (mean change, 11.9 dB at 0 cm and 2.5 dB at 25 cm; P < .001). Of toys designated as covered, 64% had levels >85 dB when packaged; this increased to 100% when unpackaged. Authors concluded that many toys have dangerous sound levels. Parents and health care providers should know that toys tested in stores may be louder at home after being removed from packaging, especially when toys are packaged with the speaker covered or partially exposed; national limits on and disclosure of dB levels of toys should be considered.¹⁶⁰  Tape and glue can be used to alter toys, thus significantly decreasing the noise levels they can produce and diminishing the sound a child may experience when playing with the toy. Some toys, however, may still produce potentially hazardous sound levels even after they are altered in this manner.¹⁶¹ 

In 2021, 19 of 24 toys chosen for the SHA 24th annual Noisy Toys List tested louder than 85 dB, “…the level set by the National Institute of Occupational Health and Safety (NIOSH) for mandatory hearing protection.” The SHA acknowledged that parents were more likely to spend time shopping online than in stores in 2021 because of the continuing COVID-19 pandemic. To keep homes quieter and children’s toys “ear-safe,” the SHA recommended adjusting the volume control on toys, placing tape over speakers, removing batteries, or returning toys that are too loud.¹⁵⁹ 

Standards are in place for toy safety, including for noise levels. In 2017, the American Society for Testing and Materials (ASTM) updated voluntary noise standards for toys. The most recent standards (designated F963–17) recommend that toys designed to emit sound should produce less than 85 dBA at 50 cm (20 in) away from the microphone (previously, 90 dBA at 25 cm [10 in]). For the toys classified as “close-to-the-ear,” a maximum of 65 dBA measured from 2.5 cm (1 in) is required.”^158,162 

Regarding the ATSM standards, the SHA states: “While ASTM has acknowledged that 25 cm would be considered an average use distance for toys, they found 50 cm was a superior distance for measurement. And while there is no known sound limits that apply specifically for children, ASTM bases compliance on OSHA and U.S. military noise level limits for adults… ASTM’s testing standard is unreasonable. Toys should be tested based on how a child would play with it, not how an adult would play with it. If you watch a child playing with a sound-producing toy you will see them hold it close to their face, next to their ears, which is much closer than a child’s arm’s length of approximately 10 inches (25 cm), let alone 50 cm for an adult.”¹⁵⁹ 

The ATSM standard is based, in part, on the following: “A9.2.1.2 The requirements in 4.5.1.1 and 4.5.1.3 are intended to address those hazards presented by continuous sounds (eg, speech, music). These hazards are chronic and typically manifest themselves after years of exposure. OSHA has set acceptable limits at 85 dB(A) for 8 h of exposure. An independent audiologist consulted by the ASTM work group recommended a similar exposure level. His recommendations for an 8 h exposure level, Leq, 8h, were 85 dB(A) for continuous sound and 82 dB(A) for the continuous sound emitted from toys that produce both continuous and impulsive sound.”

“A9.2.1.3 Exposure to noise from toys is intermittent and integrated with other daily noises. It is unlikely that a toy would present 8 h continuous exposure to sound. These assumptions are consistent with the findings of European research conducted by ISVR Consultancy Services in Southampton UK and published as ‘Noise from Toys and its Effect on Hearing.’ Based on that study, the probable duration of play with a sound producing toy was determined by the ISVR to be 1.5 h per day.”¹⁶² 

The ISVR report referenced above states: “Most published literature that relates noise levels and exposures to hearing damage is based on occupational noise exposures for adults. Reviewing the literature, it can be concluded that to prevent any significant measurable hearing loss in adult subjects,

• their regular daily noise exposures (L_EX,8h) should not exceed 80 dB(A) which is equivalent to a noise level of 80 dB(A) for 8 hours, and

• the peak levels to which they are exposed should not exceed 140 dB(C).”

The ISVR document concludes, “There is no compelling evidence that children are more sensitive than adults to the effects of noise on hearing, with the possible exception of new-born infants. The above exposure limits can therefore be applied to children.”¹⁶³ 

Noise may have especially harmful effects on younger children who are developing language and auditory discrimination skills.¹⁶⁴ Caring for Our Children: National Health and Safety Performance Standards; Guidelines for Early Care and Education Programs, fourth Edition, is a set of national standards for the United States “…representing the best evidence, expertise, and experience in the country on quality health and safety practices and policies that should be followed in today’s early care and education settings.”¹⁶⁵  Recommendations about noise include that “Measures should be taken in all rooms or areas accommodating children to maintain the decibel (db) level at or below 35 dB for at least 80% of the time as measured by an acoustical engineer or, more practically, by the ability to be clearly heard and understood in a normal conversation without raising one’s voice.” When considering new construction, thought should be given to decreasing noise from the outside. Interventions inside include installing acoustical tile ceilings, curtains or other soft treatments over windows, wall-mounted cork boards, and area rugs secured with nonslip mats.

A noisy classroom can make it difficult for students to hear and understand. “Classroom acoustics” refers to how sound travels in a classroom. Factors affecting classroom acoustics include students talking and aspects of design such as ceiling type, floor rugs, and air ducts. Poor classroom acoustics can result from background noise (originating from inside or outside the school building) and reverberation—how sound bounces off surfaces acts in a room after the sound first occurs.¹⁶⁶ 

According to the Acoustical Society of America, the speech intelligibility rating in many US classrooms is less than 75%, meaning that in speech intelligibility tests, listeners with normal hearing can only understand 75% of words read from a list. Even children with normal hearing suffer in these situations. Children with learning disabilities, children with auditory processing issues, and children for whom English is a second language generally have more difficulty. Young children, who are not able to “predict from context” because of their limited vocabulary and experience, are less able than older children to “fill in” missing thoughts.¹⁶⁷ 

A Brazilian study that aimed to establish a program of hearing conservation included sound level measurements in classrooms.¹⁶⁸  Noise levels ranged from 71.8 to 94.8 dBA. The classroom environment promoted sound reverberation, potentially hindering communication. In a study of 817 students aged 12 to 17 years, the CDC analyzed data from respondents to the 2020 web-based YouthStyles survey. The survey requested information about the frequency of respondents’ exposures to loud sounds in schools (such as music or industrial arts classes, cafeteria, sporting events, dance events), whether they were provided with hearing protection devices during exposure, and whether their educational curricula included prevention techniques. Loud sounds were defined as “sounds so loud that you had to raise your voice to be heard by someone at arm’s length.” Almost three-quarters (73.6%) of respondents reported exposure to loud sound at school for >15 minutes daily; almost half (46.5%) reported exposure 1 to 4 times per week. Most (85.9%) reported they were not provided with hearing protection devices during noisy classes or activities. Most (70.4%) reported they were never given coursework or other information about how to protect their hearing from noise. Authors concluded: “Increasing youth’s awareness about the adverse health effects of excessive noise exposure and simple preventive measures to reduce risk can help prevent or reduce NIHL. Health care providers and educators have resources and tools available to prevent NIHL among school-aged children. Increased efforts are needed to promote prevention.” Authors also noted that US schools have policies and practices to prevent students and staff from exposure to physical hazards, including excessive noise. About half of schools (56.5%) and school districts (61.3%) require the use of hearing protection when students are potentially exposed to hazardous noise during classes or activities. In 2014, fewer K through 12 students (35%) were educated in preventing vision and hearing loss compared with 2004 (49.4%).⁴² 

The WHO promulgated noise standards for different settings. For schools,⁴  the WHO emphasizes the critical effects of noise on speech interference, comprehension, reading acquisition, message communication, and annoyance. For classrooms, the WHO recommends that background SPL should not exceed 35 dB L_Aeq during teaching sessions. Children who have hearing impairments may require an even lower SPL.⁴ 

Standards for acoustics in classrooms in different nations were summarized by Mealings.¹⁶⁹  In the United States, recommended acoustic guidelines for an unoccupied enclosed classroom for typically developing children with normal hearing were <35 dBA according to the American National Standards Institute and <30 dBA according to the American Speech Language-Hearing Association. The same study also compiled data from research papers that examined the acoustic levels found in classrooms around the world. In the United States, noise levels ranged from 30 to 65.9 dBA in unoccupied classrooms and from 55 to 85 in occupied classrooms, based on several studies.

NIHL from exposure to loud music (also discussed as “music-induced hearing loss”) has been widely investigated in musicians and others who work in music venues.¹⁷⁰  There is increasing concern about other people, including adolescents, who voluntarily expose themselves when listening to music with earphones or earbuds, playing electronic or traditional musical instruments, and/or attending events such as concerts, raves, and dances. Common Sense, a nonprofit organization “…dedicated to improving the lives of kids and families by providing the trustworthy information, education, and independent voice they need to thrive in the 21st century,”¹⁷¹  reported that 47% of 8- to 12-year-olds listen to music daily, as do 82% of teenagers ages 13 to 18 years, according to a 2019 survey comprising more than 1600 participants.¹⁷²  Listening through cell phones is a common practice.

NIHL results from 2 factors: volume and duration of exposure. The WHO estimates that globally, almost 50% of people ages 12 to 35 years, or 1.1 billion young people, risk hearing loss as a result of prolonged and excessive exposure to loud sounds, including music they listen to through PLDs.¹⁷³ 

In a systematic literature review, researchers examined whether “personal listening levels” and durations of music listening through PLDs in adolescents and young adults exceeded the recommended 100% daily noise dose. This dose was defined as the occupational standard used in the majority of world’s countries: “a permissible exposure limit (PEL) of 85 dBA and the 3-dB exchange rate as the formula for calculating an individual’s daily noise dose and durations, ie, the recommended maximum (or 100%) daily noise dose over an 8-hour period should not exceed an average of 85 dBA.” As background, the authors cited studies showing that maximum volume outputs of PLDs can be >125 dBA and that average listening levels of young adults range from 71 to 105 dBA. Almost 60% of participants exceeded the 100% daily noise dose, particularly in the presence of background noise. The authors also examined the impact on hearing and potential influences on listening behaviors. Significantly positive correlations were found among background noise levels and mean personal listening levels; the presence of background noise often results in the user increasing the volume. Worse hearing thresholds were noted in PLD users, even when participants reported “normal hearing.” The authors concluded that more appropriate standards for safe listening are needed, as well as education for adolescents and young adults.¹⁷⁴ 

A 2009 study of 1687 Dutch secondary school students ages 12 to 19 years evaluated responses to questionnaires about their music-listening behaviors. The study’s aim was to assess “risky” and protective listening behaviors of adolescents using a type of PLD, the MP3 player, and associations of behaviors with demographic characteristics and frequency of use. Ninety percent reported listening to music on MP3 players using earphones. Thirty-two percent were frequent users; 48.0% used high volume settings; just 6.8% always or almost always used a noise-limiting device. Compared with infrequent users, frequent users were >4 times more likely to listen to high-volume music. Compared with those in preuniversity education, respondents in prevocational schools were more than twice as likely to listen to music at high volume. Girls listened to music via MP3 players more often than boys did; boys listened at high volume relatively more often than did girls. The researchers concluded that because MP3 player use starts early in life, prevention efforts starting in elementary school could increase children’s awareness of the risks of high-volume music.¹⁷⁵  Although MP3 players are no longer in frequent use, individuals using other devices, including earbuds linked to smartphones, may receive exposures similar to those described in this study. Risky music-listening behaviors often are associated with other risky behaviors in teenagers, such as cannabis use.¹⁷⁶ 

Adolescents and young adults often are not fully aware of the consequences of their actions. Messaging appropriate to age development has been suggested to prevent hearing damage.¹⁷⁷  Biweekly text message reminders were found to increase short-term self-reported responsible PLD use in a group of college students.¹⁷⁸ 

Music students face a special kind of noise exposure. In a study of classical music students ages 18 to 25 years at the University of North Carolina Greensboro, the prevalence of NIHL in at least 1 ear was 45%.¹⁷⁹  The prevailing notch frequency was at 6000 Hz. Bilateral NIHL was found in 11.5% of all tested subjects. The results of this study led to a hearing conservation program at the school. Another study examined 100 university students attending various undergraduate popular music classes. Participants responded to questionnaires about their hearing loss symptoms; noise levels of their studios and recording spaces and other noisy venues were measured. More than three quarters of subjects reported a history of symptoms associated with hearing loss; only 18% reported using hearing protection devices. Their rehearsals, averaging 11.5 hours per week, had a mean level of 98 dB_LAeq. Ninety-four percent reported attending concerts or nightclubs at least weekly; measured noise levels in 2 venues ranged from 98 to 112 dB_LAeq with a mean of 98.9 dB_LAeq over a 4.5-hour period. The results suggest that hazardous, excessive noise exposure from social and study-based music activities is common among this group.¹⁸⁰ 

Many younger children use headphones to listen to music and other entertainment on various devices. Many children began to use headphones during remote learning sessions that became prevalent during the COVID-19 pandemic.

There is no mandatory standard to restrict the maximum sound output for headphones or other listening devices sold in the United States. Many manufacturers claim to limit the volume of headphones to 85 dB, but this often is not the case; the most hazardous headphones can produce volumes high enough to be hazardous to hearing in minutes (using occupational standards).¹⁸¹  Wirecutter, a New York Times company that evaluates and recommends products, tested children’s headphones on children ages 3 to 11 years. Testing showed that although many headphones have volume-reduction features, some have design flaws allowing children to bypass them.⁵⁴  Volume control is one way that parents can decrease a child’s risk of acoustic injury; information for parents about setting volume controls on various devices is available.¹⁸²  Children and adolescents are most likely to use headphones with Apple (iPhone, iPad, etc) or Android products; these products have media settings that allow for safer listening.¹⁸³ 

Noise cancellation is also an important feature to consider,¹⁸³  because children often wear headphones in noisy places such as the back seats of cars and airplanes. Without noise cancellation, they often increase volume to hear over background noise. Noise cancellation technology can be “passive” (relying on an “acoustic seal” over the ear to block out sounds) or “active” (whereby the electronics in the headphone cancels out surrounding sounds without diminishing sound quality). “Active” noise cancellation generally is preferred since “passive” cancellation relies too heavily on a perfect seal to the user’s head.¹⁸³ 

Although there is no mandatory standard restricting volume output, the International Telecommunications Union, working in conjunction with the WHO, developed exposure limits for inclusion in the voluntary H.870 safety standard guidelines for the manufacture and use of personal audio devices, including smartphones and audio players. The standard was developed under WHO’s “Make Listening Safe” initiative, a program that aims to improve listening practices, especially among young people “…in response to the growing prevalence of hearing loss and the threat to hearing posed by unsafe listening.”^65,173  The guidelines include a recommendation for personal devices that they be programmed with a monitoring function that sets a weekly sound exposure limit and provides alerts as users reach 100% of their weekly sound allowance. The recommendations include options to limit the volume, including automatic volume reduction and parental volume control, as well as an educational component aimed at helping users to track, interpret, and learn from their behaviors.¹⁸⁴ 

The WHO also promotes a “60/60” recommendation for children and adults: listening at approximately 60% of mobile-device volume and doing so for no more than 60 minutes at a time.¹⁸⁵ 

The WHO also recommends protecting ears by wearing earplugs at noisy venues and moving away from the sources of sound, such as loudspeakers; limiting time in noisy settings by taking breaks; and monitoring sound levels through smartphone apps.¹⁴³  Foam earplugs can reduce noise by up to 20 dB but only if inserted correctly.¹⁸⁶  Even when noise levels are decreased using properly inserted earplugs, levels still can be hazardous.

Because damage from noise is cumulative, parents and caregivers should be aware of total noise exposure. For example, the daily noise dose greatly increases for a child who frequently uses headphones and spends time also practicing drums or mowing the lawn or banging on pots and pans. For these situations, children can use protective earmuffs or earplugs¹⁸⁷ ; earplugs, however, may pose a choking hazard for younger children.

There is scarce evidence about the effectiveness of earplugs in preventing hearing damage directly after exposure to recreational music. A systematic review found just 1 well-conducted randomized clinical trial, which compared a group using earplugs to an unprotected group during a 4.5-hour music festival event. The time-averaged, equivalent A-weighted sound pressure level experienced was 100 dBA during the event. Wearing earplugs was effective in reducing threshold shifts measured after users attended the concert. Although more research is needed, authors recommended that physicians increase awareness of recreational noise risks and recommended using earplugs in these venues.¹⁸⁸ 

Protective earmuffs—padded plastic cups connected by a flexible headband—reduce noise by completely covering both ears. Protective earmuffs come in sizes that fit most people, including infants and children. They are easier to use than earplugs, especially for young children. They may not, however, work as well for people wearing glasses because of gaps between the earmuff cushion and the skull, with certain hairstyles, and if a child is wearing a hat. Wearing earmuffs and earplugs together can further reduce sound, which may be useful in very noisy environments including shooting sports events.¹⁸⁹ 

Recreational firearm use, a popular sport in rural settings, is a high-risk situation for NIHL for adolescents and young adults. According to the US Department of the Interior Fish and Wildlife Service, an estimated 3.8 million children ages 6 to 15 years went target shooting with firearms in 2015, and 1.4 million engaged in hunting activities in 2016.¹⁹⁰  Among young firearm users ages 10 to 17 years, 78% of those surveyed reported they began shooting before age 10. Only 1 of 4 reported wearing a hearing protection device “usually or always” while hunting and “never or rarely” during target practice. Although more than one-fourth reported they knew about specifically designed electronic hearing protection devices for the shooting sports, only 3% reported wearing them during these activities.¹⁹¹ 

The peak SPLs from firearms range from approximately 140 to 175 dB. Most recreational firearms generate between 150 to 165 dB peak SPLs. Researchers have advocated for the development and dissemination of accurate information and resources to support hearing loss prevention efforts for people engaging in shooting sports.¹⁹²  Both extended high-frequency audiometry above the frequency of 8 kHz and distortion product otoacoustic emission testing may provide early evidence and detection of NIHL in youth firearm users.¹⁹³ 

NICU environments generally are louder than most homes and offices. Sources of noise include telephones, ventilators, pumps, monitors, incubators, alarms, air conditioners, and an infant’s own crying while in an incubator. Preterm infants may be especially sensitive to noise; there is increasing awareness of potentially adverse impacts of the environment, including noise, on the rapidly growing and developing brain of a preterm infant.^194–196  Quieter environments have been a goal of many hospitals to promote the well-being of medically fragile, stressed NICU infants.

Physiologic changes in infants exposed to NICU noise have been reported. Preterm infants exposed to NICU noise have behavioral and vital sign changes,^197–199  impaired tactile learning,²⁰⁰  and disrupted sleep.²⁰¹  The impacts of NICU noise on infant physiologic parameters has also been reported in intervention studies designed to reduce NICU noise (detailed below).

In 1974, the AAP Committee on Environmental Hazards recommended reducing incubator noise to <58 dBA and eliminating unnecessary noise in the hospital setting.²⁰²  This level was chosen because of the findings in animals that noise potentiates the ototoxicity of aminoglycoside antibiotics above this level. In the 1997 AAP policy statement, the recommended safe level of noise exposure in the NICU was decreased to 45 dBA, and NICUs were advised to adopt strategies to reduce noise.²⁰³ 

The “Recommended Standards” for NICU design, developed in 1992 by a multidisciplinary group of experts, also include recommendations for noise levels. Throughout the years, these Recommended Standards have been updated and subsequent editions published, most recently in 2020 (Table 6). These recommendations aim to promote speech intelligibility, speech privacy, physiologic stability, uninterrupted sleep, and freedom from acoustic distraction.²⁰⁴ 

In most studies of NICU noise published since the 1997 AAP guidelines, measured noise levels are above recommended standards. Even when patient rooms are unoccupied, average noise levels in traditional, open design NICUs are often above the recommended 45 dBA. Structural factors such as noisy hospital heating, ventilation, and air conditioning systems contribute to the high baseline noise levels.^205–207 

Multiple studies have examined the noise levels associated with different modes of respiratory support. All modalities produce noise levels above the recommended standards (Table 7).^208–212 

Most studies investigating the role of incubators on noise levels experienced by NICU infants demonstrate environmental noise attenuation by incubators.^{211,213–216}  The degree of attenuation is significantly diminished when the incubator motor is turned on versus when the motor is off^215,216  and varies by incubator brand.²¹⁵  The degree of attenuation also varies by type of respiratory support. With nasal continuous positive airway pressure (CPAP), for example, one study found no difference in noise measured inside versus outside the incubator. With the high-frequency ventilator, average noise levels were significantly lower inside the incubator.²¹¹  Older incubators are noisier than newer models.^217,219  Despite attenuation of environmental noise, noise levels inside incubators are still above recommended standards, likely from the intrinsic noise produced by the incubator motor and cooling fan.^{211,213,216,220,221}  Lower-frequency noises arising from the incubator motor are louder inside versus outside the incubator,²¹⁵  and the incubator can increase noise generated within its enclosure because of a reverberance effect.²¹⁶  One study measured higher noise levels inside versus outside the incubator. In this study, the greatest contributors to noise inside the incubator were ventilator and suction equipment.²²²  Altuncu et al studied noise levels in the incubator and the impact of sound-absorbing panels on infant crying. Noise from infant crying was higher in the incubator versus under the radiant warmer (79 dBA vs 75 dBA; P = .051). Noise levels from the infant crying inside the incubator decreased to 69 dBA with introduction of sound-absorbing panels (P < .0001).²²³ 

Noise levels vary with NICU design (open versus pods versus private rooms).^{106,224–227}  Studies report lower average noise levels in private rooms^106,225,226  and pods²²⁴  compared with the traditional open NICU design. In one study, peak noise levels exceeding 84 dBA occurred 600% more in the open room compared with the private room. Because of lower background noise levels in the private rooms, however, the sound-to-noise ratio of acoustic events is higher in private rooms compared with the open unit design.¹⁰⁶  Only when private rooms are built for noise abatement is it possible to achieve average noise levels below recommended levels.^225,226,228 

In 1989 and 2005, Thomas reported noise levels associated with NICU equipment and caregiving activities.^220,221  Although ambient nursery noises decreased (47 dBA vs 58–62 dBA during quiet condition), noise levels related to the various NICU equipment and caregiving activities were the same or higher than in 1989 (Table 8). Major contributors include door closings, portable radiographic examinations, high-volume personnel, visitor traffic,²³⁰  alarms,^229,230  physician rounding,²³¹  shift changes,²³²  staff talking,^207,230  and infant fussiness.²³⁰  NICU noise increases with higher NICU acuity (level 3 versus level 2),^233,234  sicker patients,²³⁵  higher patient census,^234,236  more ventilators and CPAP machines in use²³⁶  and other noisy equipment,²³⁵  and higher number of admissions.²³⁶  Some studies report higher noise levels during the day compared with the night.^{219,224,234,236,237}  Others, however, found no difference.^238,239  Similarly, some studies report higher noise levels on weekdays compared with weekends,^236,237,240  whereas others find no difference.²³⁴ 

Neonates in the NICU are exposed to high frequencies not typically present in utero (500–3150 Hz 55% of the time, 3151–6300 Hz 1.6% of the time, and 6310–16 000 Hz <1% of the time).²⁴¹  High frequency exposure varies by proximity to windows, outer walls, and the direction of mounted monitors. Infants treated with extracorporeal membrane oxygenation are exposed to very high frequencies (16 000 Hz) at levels that exceed the recommended 45 dBA.²⁴² 

Providing an environment without excessive noise and stimulation decreases duration of oxygen requirements, days on respiratory support, and length of stay. Preterm infants demonstrate better physiologic stability and improved sleep when protected from excessive exogenous noise.^{213,243–245}  The goal of interventions is to reduce the noise levels that reach newborn infants’ ears to <45 dBA. Behavioral and operational changes, major and minor structural redesign, and barrier methods have been attempted to reduce NICU noise levels. Most of these studies, however, involve only brief interventions and assess the immediate physiologic state of the newborn infant. More research is needed to better understand sustained impacts of various NICU interventions.

When evaluating results of interventions, it is important to recall that the decibel scale is logarithmic. For example, a decrease of 3 dBA represents a halving of noise energy.

Behavioral and operational interventions in isolation without concurrent structural changes reduce noise levels in the NICU, but not enough to meet recommended standards.^{206,236,246–248}  Examples include staff educational sessions, “quiet time,” written noise policies, direct visual feedback using noise meters, and care schedules coordinated to infant sleep states. Most NICUs choose to take a multipronged quality improvement approach to reduce noise levels.^{206,236,247,248}  Chawla et al reduced noise levels by initiating an intervention that included a “quiet time” taskforce, staff noise reduction education program, and visual feedback using noise meters.²⁴⁶  Wang et al implemented direct visual feedback using noise meters, quiet times, staff education, a written policy, and nursing care that was coordinated with infant sleep states. In 2 of 3 NICU locations, average noise levels decreased after their intervention. Additionally, direct visual feedback using noise meters resulted in a statistically significant increase in the proportion of noise measurements less than 50 dBA (7.3% to 9.9%).^206,236  In low-resource settings where noise meters are not cost-effective, it is possible to achieve sustained reductions in noise as far out as 18 months using operant conditioning techniques, such as giving feedback on noise levels at staff meetings and displaying weekly average noise levels in the unit.²⁴⁹  “Quiet hour” interventions not only reduce noise but also have been shown to increase infant sleep and reduce parent and caregiver self-reported stress levels.²⁴⁰  Education of staff about noise-reduction strategies without adding other interventions reduced noise peaks in the NICU but not average noise levels.²⁴⁷ 

Major structural redesign, such as adding private rooms or pods built with noise-abatement techniques, can result in noise levels that meet recommended standards, but only if rooms are unoccupied^226,227  or occupied with infants not on respiratory support.²²⁸  With patients requiring higher respiratory support, and with open room design, it is more difficult to achieve recommended levels even with major structural changes. In an open design NICU, for example, even after installing carpets, plastic drawers, and trash bins and reconstructing the space to move staff work areas outside of the NICU, only newborn infants in open beds and who were breathing room air or using the nasal cannula or oxygen hood met the AAP recommended 45 dBA; improvements were achieved only 35.7% (interquartile range: 20.7% to 40.7%) and 21% (interquartile range: 0.0% to 34.0%) of the time for infants on room air and nasal cannula or oxygen hood, respectively. The recommended noise levels were almost never achieved for all other types of respiratory support and within incubators.²¹⁷  Williams observed reduced median noise levels in a NICU built for noise abatement compared with a traditional NICU, but noise levels still were above recommended guidelines.²⁵⁰  Other studies report reductions in noise levels after major reconstruction but not to the levels recommended by the AAP.^230,236,251  In some cases, NICU renovations, such as adding motion-sensing towel dispensers and a voice-activated communication system, inadvertently increased average noise levels.²¹⁹ 

Minor structural changes, such as adding noise-absorbing panels to incubators^223,243,252  and incubator covers,²²²  result in reduced noise levels within the incubator, particularly for infants on ventilators.²⁴³  In one study, adding noise-absorbing panels to an unoccupied incubator reduced background noise levels in the incubator from 47 dBA to 42 dBA (P = .004). With panels in place, the noise produced by the temperature alarm and monitor alarm, by closing the incubator portholes, and from infants crying were significantly reduced. High-frequency noises are attenuated by noise-absorbing panels by as much as 9 dBA.²⁵²  The reduction in noise secondary to noise-absorbing panels is associated with improved sleep states and oxygen saturation.²⁴³  Using incubator covers can reduce noise levels transmitted to NICU infants.²²² 

Other studies combine operational changes with structural redesign. Ramesh reduced noise levels in their NICU ventilator room by 9.58 dBA (95% CI: 6.73–12.42; P < .001) using a behavioral intervention combined with minor structural changes (rubber soles on furniture, replacing metal with plastic, turning down alarms to less than 55 dBA, and using visual alarms).²⁵³  Johnson installed a fully carpeted “quiet” room in conjunction with a noise-reduction educational program. These efforts led to a decrease in overall environmental noise by 9.26 dBA to a mean of 54.85 dBA that was sustained over a 14-month period.²²⁹  Philbin implemented operational changes followed by structural redesign (plastic garbage cans, reconfigured heating, ventilation, and air conditioning with noise-reducing registers, carpeted floor, acoustic ceiling tiles, dimmer lights). After a staff education intervention, noise was reduced by half. With the addition of structural redesign, the NICU was 3 to 4 times quieter than baseline.²⁵⁴  Laubach reduced noise levels from a baseline of 58 to 60 dBA to 46.32 dBA after transitioning from an open to private room design and implementing an operational noise-reduction protocol.²⁵⁵  Liu did not demonstrate improvements in noise levels after introducing a quality improvement intervention involving operational changes (staff education, pagers on vibrate, silence alarms quickly, quiet times and quiet zones) and small structural modifications (discouraged audiovisual use in unit, padded cabinet door latches, plastic garbage cans, turned off intercom in unit) in 2 open design NICUs.²³⁴ 

Earmuffs^{213,244,245,256}  and earplugs²⁵⁷  are low-cost barrier methods to decrease the noise intensity delivered to NICU infants. Earmuffs and earplugs attenuate NICU noise up to 17.7 dBA.²⁵⁷  Both positive and negative effects of earplugs and earmuffs on infant physiologic parameters in response to noise have been reported. Khalesi et al found that infants wearing earmuffs have lower heart rates and respiratory rates and higher arterial oxygen saturations.²⁴⁵  Zahr and de Traversay found that infants with earmuffs have higher mean oxygen saturations with less fluctuations.²⁴⁴  Aita et al, however, reported more stress responses and higher maximum heart rates in infants wearing both earmuffs and eye goggles. The measured difference in maximum heart rates was only 4.5 beats per minute with unclear clinical significance.²⁵⁶  Duran et al found no change in infant physiologic parameters in response to noise with and without earmuffs.²¹³  Most studies agree that earmuffs increase infant sleep and improve behavioral states.^213,244,245  A randomized controlled trial looked at the impact of wearing silicone earplugs on infant weight gain. At 34 weeks’ postmenstrual age, infants randomly assigned to wear silicone ear plugs weighed significantly more than infants in the control group, even after adjusting for birth weight. Additionally, in a subset of infants followed until 18 to 22 months of age, the earplug group was heavier and taller, had larger heads, and had higher scores on a mental developmental assessment.²⁵⁷  This is the only randomized controlled study on NICU noise interventions and the only study deemed sufficient quality to be included in a 2020 Cochrane review.²⁵⁸  More research is needed about risks and benefits to NICU babies of earplugs and earmuffs.

Because auditory pathways continue to develop for more than 12 months after an infant leaves the NICU, it has been recommended that parents are informed about the importance of creating a quiet environment in the home. Although more research is needed, quieter home environments may be helpful in improving growth and development of infants after discharge.²⁵⁹ 

The EPA recommends keeping noise levels <45 dBA in hospital settings to prevent “activity interference and annoyance.”²⁶⁰ 

Average noise levels in PICU settings are significantly above recommended levels, ranging between 46 to 79 dBA in published studies.^{205,261–271}  Noise levels produced by PICU equipment and activities consistently exceed the 65 dBA L_max recommendation (Table 9). The biggest contributors to PICU noise include medical alarms,^261,262,272  medical equipment,^261,262,267  nursing sign-out,²⁶¹  physician rounds,²⁶¹  conversation between staff,^267,272  and other patients.²⁶¹  Studies report peak noise levels >100 dBA for more than 10% of the time,²⁶¹  >65 dBA²⁶³  and 75 dBA²⁶⁷  for a third of the time, and >75 dBA for 20% of the time, specifically at night.²⁶⁶  Some studies report no difference in noise levels measured in open unit design compared with private rooms.^261,270  Shoemark et al found no difference in average noise levels after a transition from 4-bed rooms to private rooms but did report fewer noise peaks >65 dBA after the transition.²⁷¹  In an unoccupied private room, Kawai measured noise levels below the recommended standards (42.8 dBA). However, in occupied beds, noise levels exceeded recommendations during the day and night.²⁷³  The PICU is generally noisier during the day than at night.^{261,263–266,269,270,273}  However, the difference is minimal and nighttime levels are still high enough to disrupt sleep.^266,274  Some studies report no difference between weekday and weekend noise,^264,270  but others report higher levels on weekdays.²⁷³  Higher census is associated with higher PICU noise levels,^265,273  as is change in shift.²⁶⁹  High-frequency ventilators are noisier than conventional ventilators^269,275 ; rooms with any ventilator equipment are noisier than rooms without ventilator equipment.²⁷¹  PICU noise levels predict patient sedation needs.²⁷⁰ 

The impact of hospital noise on patient sleep and sedation needs have been studied in the PICU.^{261,265,267–269}  When noise levels in one PICU were >75 dBA for 3 consecutive minutes, patients woke up from sleep more than half the time (57%).²⁶⁶  Another PICU study found that the greater the noise, the greater the likelihood a child was awake at night and not sleeping.²⁷⁴ 

PICU nurses and patient families suggest the following interventions to reduce PICU noise: closing room doors, designating quiet times, silencing inappropriate alarms, decreasing phone and alarm volumes,^205,262  audits with feedback, visual reminders, noise “champions,” and investing in less noisy equipment.²⁰⁵  Jousselme et al aimed to reduce noise in the unit using a centrally located visual noise meter. Average noise levels were lowered by 2 to 3 dBA centrally and inside patient rooms when the device was present, regardless of whether the noise meter was turned on or off. Levels were still significantly above the recommendations (62.9 vs 61.1 dBA centrally and 64.3 vs 61.3 dBA in patient rooms).²⁶⁴  Kol et al reduced average noise levels from 72.1to 56 dBA during the day and from 60 to 53 dBA at night after transitioning from 4-bed rooms to private room design.²⁷⁶ 

Early studies of noise on pediatric medical-surgical units come from Australia in the 1980s and 1990s when open design was common. The measured noise levels were consistently above recommendations. Peak noise levels occurred with infants crying (70–90 dBA), pagers beeping (76–78 dBA), bedrails moving (82–85 dBA), telephones ringing (78 dBA), parents and children talking (80–90 dBA), toys squeaking (75 dBA), and overhead announcements (80 dBA).^277,278  Higher foot traffic was associated with increased noise levels.²⁷⁸  In more modern pediatric units, measured noise levels are still above the recommended standards.^279–281  Although pediatric units are noisier during the day than at night,²⁸⁰  noise levels at night are significantly higher than in home bedrooms (48.6 dBA vs 34.7 dBA; P = .017).²⁸¹ 

Children hospitalized in a pediatric medical-surgical unit experience more nighttime awakenings in the hospital than at home; 38% of these awakenings are attributed to hospital noise.²⁸⁰  Noise from patients, staff, and medical equipment are contributors to poor sleep in the hospital.²⁸²  Hospitalized children undergoing chemotherapy similarly experience average nighttime noise levels above recommended levels with peaks as high as 80 dBA^283,284 ; these levels are associated with disrupted sleep in this population.²⁸⁴ 

Implementation of “quiet time” on the pediatric medical-surgical unit reduces average, minimum, and peak noise levels at the nursing station (72 dBA to 68.2 dBA average, 124.4 dBA to 99.66 dB peak, 68.3 dBA to 66 dBA minimum) but not within the patient rooms. Parents and staff respond positively to “quiet time” and feel less fatigued because of its implementation.²⁷⁹ 

Noise levels experienced by nurses can be even higher than those experienced by patients, most frequently resulting from staff communication, equipment, and alarms.^267,285  Nurses describe noise from equipment alarms as “noxious,” “unnerving,” “ominous,” and “shrill” and feel desensitized because of alarm frequency, false-positive alarms, and inability to distinguish between nonemergent and life-threatening alarm tones.²⁸⁶ 

Workplace noise is associated with changes in nursing physiologic parameters. Higher average noise levels predict higher nursing heart rates. The mean heart rates, however, do not exceed normal ranges.^265,267,285 

Two studies investigated whether physical environmental factors influence nursing turnover intentions.^287,288  In one, workplace noise was significantly associated with nursing turnover intentions and was a stronger predictor than other environmental factors, such as perceptions of safety hazards and comfortable temperature.²⁸⁷  Another study, however, found no association between noise and nursing turnover intentions.²⁸⁸  Studies of the impact of noise on nursing stress also have conflicting results. Applebaum et al found that higher noise levels were associated with lower nurse stress.²⁸⁸  Watson et al and Daraiseh et al found no association between perceived stress and noise levels.^267,285  Morrison et al and Kudchadkar et al, however, reported higher stress and annoyance ratings with higher noise levels²⁶⁵  or perceived noise levels,²⁷²  respectively.

Communication between caregivers is affected by noise levels. In a survey of pediatric emergency department physicians, over one-third of respondents reported that noise levels affect their interactions with residents and teaching.²⁸⁹  In the operating room, music playing is associated with significantly more repeated requests, longer operation times, and increased tensions because of frustration at ineffective communication.²⁹⁰  Noise peaks in the operating room reduce case-relevant communication within a surgical team, specifically in situations when junior, less experienced surgeons are operating.²⁹¹  In a study of surgical resident handoffs, the most common distractions observed relate to noise including pages (37.5%), telephone calls (32.8%), residents and medical students (9.3%), and talking (5.2%).²⁹² 

Noise reduction in hospitals has benefits for patients and caregivers. Relatively minor changes, such as creating a dedicated service corridor and the use of visual cues, have been found to improve staff stress and patient satisfaction levels.^293,294  Hedges et al found improvements in patient satisfaction and sleep scores in shared rooms when quiet initiatives were implemented to reduce ambient noise levels from an average of 59.3 to 53.5 dBA during quiet hours. This initiative included changes to rounding schedules, creation of quiet hours, reduction in visitation hours, rounding to explain quiet time to patients and staff, and providing patients with sleep aids, ear plugs, pillows, and blankets.²⁹⁵  A “quiet time” intervention consisting of turning down the lights on a unit for 2 hours was associated with a nonstatistically significant decrease in noise levels and a statistically significant decrease in nurses’ stress levels.²⁹⁶  Another intervention included using noise-canceling headphones.²⁹⁷  Although noise-canceling headphones are effective at decreasing caregiver noise perception, nurses preferred not using them.²⁹⁷ 

The use and incorporation of quiet rooms or quiet spaces is not new in hospitals. It has, however, taken a larger role in the discussion of hospital construction and design for the benefit of patients and caregivers. Originally used for “patient isolation,” quiet spaces are now used more as a place for reflection, prayer, and healing for families, patients, and providers. The term was first discussed in the early 1990s regarding burnout or compassion fatigue noted in emergency department staff. This fatigue resulted in higher staff turnover, emotional exhaustion, lower patient satisfaction, and risks to patient safety.²⁹⁸  Excessive noise in hospitals and health care facilities has also been found to cause headaches, increased irritability, prolonged healing times, and increased sensitivity to pain.²⁹⁹  Dr Jean Watson has advocated and researched the use of quiet spaces, also called “Watson rooms,” based on the “needs of nurses and caregivers to allow for self-healing to care for another person.”²⁹⁸ 

MRI technology provides an alternative to computed tomography scanning because it avoids exposure to ionizing radiation. In addition to other potential safety risks, the MRI may pose a risk to pediatric patients because of the prolonged noise exposure generated from the polarizing gradient magnetic fields during the imaging sequences. Noise is generated by loud coils near the patient and can be disturbing and unnerving. It is characterized as a “banging,” “clicking,” and “squawking,” sound, as highlighted in an audio clip provided in this link (https://www.chop.edu/health-resources/mri-sounds).³⁰⁰  Hearing protection during MRI is critical, because acoustic noise in the MRI scanner can reach the level of a jackhammer.³⁰¹ 

Noise levels increase with increasing MRI field strengths, ranging from 1.5 Tesla to 3 Tesla and as high as 7 Tesla.³⁰²  More powerful and wider scanners are louder and generate more noise. Newer-generation 3 Tesla MRI scanners aim to reduce acoustic noise by implementing T2 PROPELLER (“periodically rotated overlapping parallel lines with enhanced reconstruction”) sequence of 73.3 dB as compared with conventional PROPELLER sequence at 92.1 dB. This translates into a 20% reduction of SPL.

TNITS occurs in 43% of patients undergoing MRI without hearing protection after a single scan and can result in shifts from which it can take weeks to recover. In some instances, the hearing loss may be permanent, especially at higher frequencies. Infants are particularly vulnerable given their still-developing anatomy and smaller ears and heads. Fluctuation in vital signs can be seen in this group during the MRI scans secondary to machine noise.³⁰³  Anesthetized children are particularly vulnerable because they cannot move their heads or shield themselves from noise if ear plugs are not properly fitted or secured. Noise levels can range as high as 111 dB near the magnet bores of MRI systems while sequences are obtained. At these high decibels, only brief amounts of time in the MRI scanner are considered acceptable according to occupational standards; these standards do not necessarily apply to infants, children, and adolescents. It is critical that children have appropriate well-fitted ear protection to mitigate against noise induced hearing loss during the imaging procurement.³⁰⁴  All pediatric patients should be given hearing protection during an MRI and typically do, according to protocols at imaging centers.³⁰¹  A study by Lim et al showed that foamed ear plugs prevented any MRI noise-induced hearing threshold shifts in 3 Tesla scanners.³⁰⁵ 

The AAP recommends counseling patients and parents about noise exposure. Advice includes avoiding loud noise, especially impulse noise, and loud toys; reducing the volume on TVs, computers, and other devices; protecting young children with ear protection when at noisy events; teaching children and adolescents to turn down volumes when using PLDs; and creating “stimulus havens.”¹¹  Other authors state that they incorporate education about reducing noise exposure into their clinical practices with children.⁸⁷ 

Authorities have suggested that not enough attention has been paid to teaching parents and children about the value of preserving hearing. This was highlighted by a quote from parent in a New York Times article: “People are more worried about social media, video games, and screen time…the doctor gives you a checklist: Does anybody smoke in the house? How much TV does he watch? What kind of food is he eating? But they never ask about headphones or volume or anything like that.”¹⁸⁷ 

Advocates have recommended teaching children about protecting hearing: “Just as you teach your children to wear sunscreen, a seatbelt, and a bicycle helmet, you can teach them how and when to wear hearing protectors.” Tips include setting rules for when parents expect them to wear hearing protectors, especially when parents are not available to supervise; shopping for hearing protection with children to encourage participation and respecting their preferences about visibility and style; ensuring that the hearing protectors’ size and type fit well with the activity and environment (if the hearing protector blocks too much sound, the child may not hear important information and take off the protectors); making sure that hearing protectors are within reach in areas where loud noises are common but out of reach of small children or pets; and becoming a good role model for hearing health.¹⁸⁹  Recommendations also include teaching children to use hearing protectors during activities that are loud enough to damage their hearing over time. Examples include attending movies, auto races, sporting events, fireworks shows, and music concerts; riding a motorcycle, dirt bike, snowmobile, all-terrain vehicle, tractor, or in an airplane; playing an instrument in a band; and participating in or attending shooting sports.¹⁸⁹  Parents also can advocate for reduced noise spaces in early child care and educational settings and for using earmuffs or over-the-ear headsets for children with audio sensitivity.

Impulse noise can be especially harmful. Children should be shielded from impulse noise whenever possible. When impulse noise is expected (eg, firearms, explosives, etc), double hearing protection (ie, ear plugs and earmuffs) has been recommended to reduce the risk of hearing loss.¹⁰ 

Although a comprehensive review of positive sounds is outside the scope of this paper, we will briefly summarize results of a systematic review and meta-analysis. The literature is replete with studies investigating the impact of language and maternal sound exposure in NICUs and other settings. Studies may mention the so-called “Mozart effect,” defined as improved spatial reasoning skills after listening to Mozart’s music. The Mozart effect was originally defined by Rauscher et al in 1993, who found improved spatial reasoning skills in college student subjects after listening to Mozart compared with relaxing or no music.³⁰⁶  Over the years, the “Mozart effect” has been extended to newborn infants and fetuses with claims including that listening to Mozart and other classic composer-themed commercial products during pregnancy or infancy will stimulate cognitive development. These claims have never been validated by scientific evidence.

The impact of music and parental sounds on infant language and cognitive development, physiologic stability, sleep, behavioral state, brain development, growth and feeding, pain relief, length of stay, and maternal stress have been studied in NICU settings. The interventions employed vary by sound levels, whether the sounds are presented in live or recorded form, whether music (lullabies, classic, instrumental) or maternal sounds (speaking, singing, heartbeat) are used, and whether there is a music therapist involved. Some studies specifically tried to mimic womb sounds via recordings of maternal pulse sounds³⁰⁷  or through live music therapy³⁰⁸  simulating womb sounds. In 2016, Bieleninik et al undertook a systematic review and meta-analysis of music therapy for preterm infants during NICU hospitalization and after discharge. They included 16 randomized controlled trials in the systematic analysis and 14 in the meta-analysis. All included studies had music therapist involvement. Overall, music therapy decreased infant respiratory rate and parental anxiety. They noted significant heterogeneity between studies for most outcomes and not enough evidence to confirm or refute the effects of music therapy on other physiologic and behavioral outcomes.³⁰⁹ 

Studies in non-NICU hospital settings examined the impact of music exposure on outcomes including anxiety, coping, procedural pain, and physiologic parameters. Other studies, often conducted in specialized populations such as oncology patients, examined the impact of music on parent caregivers and health care providers. A Cochrane review of music therapy that included hospitalized adult and pediatric patients with cancer found that music interventions have beneficial effects on anxiety, pain, fatigue, and quality of life and may lead to small reductions in heart rate, respiratory rate, and blood pressure. There is not enough evidence to say whether music impacts depression, immunologic functioning, coping, resilience, or communication in patients with cancer. There was no support for music impacting mood, distress, physical functioning, spiritual well-being, or oxygen saturation. Because only 5 of the 52 studies included pediatric patients and most studies had a high risk of bias, the results of this review should be interpreted with caution.³¹⁰ 

Noise negatively impacts other living organisms. Although noise is invisible, its deleterious health effects can be observed in many creatures and their respective habitats. Kunc et al performed a meta-analysis showing that noise has an impact across all species including amphibians, arthropods, birds, fish, mammals, reptiles, and even mollusks.³¹¹ 

Anthropogenic noise directly and indirectly disturbs the natural environment and has negative effects on ecosystems, animal communities, and global health. Noise has significantly increased the past few decades because of increased travel secondary to globalization, urbanization, and human population growth. Excessive anthropogenic noise adversely affects biodiversity as animals migrate from native habitats to quieter environments. This effect of noise directly alters the delicate balance between animal and plant-life ecosystems, as many florae and animals depend on each other for survival. For example, many trees and plants rely on animals to cross-pollinate their flowers as well as spread their seeds for fertilization. Lush gardens and tree lines can lower noise pollution by 5 to 10 dB. As nature disappears from the urban landscape, noise pollution escalates. This pollution further drives away animals, notably birds and bees, which in turn deteriorates the environment.

Noise is a global pollutant, and like greenhouse gases, researchers are uncovering unintended planetary consequences with ripple effects. The WHO described noise pollution as particularly threatening, problematic, and pervasive in marine and terrestrial sanctuaries and ecosystems.¹²⁶  In particular, the ocean has become increasingly noisy, placing aquatic life under strain because of noise generated from motor engines and propellers on large ships, oil drilling machinery, sonar stations, dynamite fishing, and deep-sea mining. Noise levels in the ocean have essentially doubled in modern times. Noise travels thousands of miles underwater without the natural barriers on land to absorb sound, thus disrupting animal communication, navigation, and their ability to find mates, and echolocate. Noise interrupts the natural sound signal that seals, whales, clownfish, and dolphins use to communicate, navigate, and find mating partners in the ocean.^312,313 

Land-dwelling animals face similar challenges. In particular, noise affects the ability of songbirds to communicate. Studies show that calling birds use morning songs to mark their territory and attract mates. Early morning rush hour commutes and attendant noise create a roar of distraction for these birds. Noise pollution prevented tufted titmice and northern cardinals from hearing warning calls from fellow birds signaling dangerous predators nearby, thus jeopardizing their survival.³¹⁴ 

Mating birds appear to alter their calling signals in high-traffic corridors, subsequently affecting survival by diminishing their reproductive chances.³¹⁵  Bluebirds in noisy areas lay fewer eggs that hatch. Baby chicks exposed to loud environmental noises around birth demonstrate stunted growth, diminishing survival chances. The link between noise and stress-induced physiologic response is corroborated in nesting birds: birds in the natural gas fields of New Mexico showed diminished overall fitness from chronic environmental noise, eliciting glucocorticoid-signaling dysfunction.³¹⁶ 

Environmental noise pollution is particularly concerning, given the overall rise in such pollution. Buxton et al discovered that anthropogenic noise doubled background sound in 63% of US protected wildlife areas with 21% of protected areas demonstrating a 10-fold increase.³¹⁷ 

COVID-19 lockdowns significantly dampened anthropogenic noise. Researchers analyzed environmental sound data from volunteers who used Apple watches and iPhone headphones in Florida, New York, California, and Texas. More than 500 000 daily noise levels were measured before and during the pandemic. Average sound levels dropped about 3 dB after governments issued stay-at-home orders in March and April 2020, representing a halving of people’s average noise exposures compared with prepandemic levels in January and February.^318,319 

Birds also were beneficiaries of noise-free streets and parks. Researchers from San Francisco found that urbanized bird songs quickly changed during COVID-19 lockdowns becoming lower in pitch, more dominant in the soundscape, and better able to travel longer distances.³²⁰ 

Endangered flamingos and pelicans appeared to be returning to the mating lagoons in Divjaka National Park, Albania, allowing the population of birds to return to emptied-out parks normally congested with tourists.³²¹ 

As cities emerge from COVID-19 restrictions and traffic resumes, this unique respite from noise pollution served as a social experiment highlighting the benefits of less urban sounds, more natural sounds, and a better balance between the 2 soundscapes.

Although some people welcome the return of urban clamor as a sign of economic resurgence, in the post-COVID-19 era, many cities may more effectively manage and regulate their noise levels to essentially build back “quieter” after the pandemic subsides.³²² 

The effects of noise on infants, children, and adolescents deserve special consideration because of their anatomic, behavioral, and developmental differences from adults, unique exposure settings such as NICUs, common exposures including infant sleep machines and noisy toys, increasingly ubiquitous use of PLDs, and long life spans ahead to experience the effects of excessive and cumulative exposures. The effects of environmental noise in classrooms and other settings often lead to difficulties in learning with potential lifelong consequences for those exposed. Children with existing hearing impairments, developmental differences such as ASD, and other conditions are disproportionately impacted. Children from historically marginalized populations also experience greater adverse effects.

Numerous studies document hearing loss in children and adolescents, although there is inconsistent evidence that this hearing loss is attributable to noise exposure. Evidence from national studies of NIHL (as evidenced by audiometric notches characteristic of NIHL) among young adults, however, suggests that earlier life exposure to noise contributes to hearing loss later in life.

Newborn infants, especially those who spend time in NICUs, may be especially sensitive to noise. Standards for NICUs and hospitals to protect these vulnerable children have been set but have usually not been met.

The relatively recent emergence and rise of PLDs, popular with young people including young children, has introduced a source of intense noise exposure. Although the recommended standard of 85 dBA over 8 hours for occupational settings is well-known, it is not meant to apply to nonoccupational settings, including PLD use, nor to infants, children, and adolescents who are growing and developing and have many years of living ahead. Not enough time has passed to understand the long-term effects of these often-excessive exposures on the young.

In the United States, the EPA indicated that maintaining environmental noise exposure below an average of 70 dBA over 24 hours will essentially eliminate the risk of NIHL. Researchers in Europe and within the WHO-European Region have recommended far lower levels of environmental noise to protect from various nonauditory health effects. Although reducing daily average noise levels to at or below 70 dBA should protect against hearing loss, much lower levels are needed to protect against heart disease, annoyance, sleep disturbance, and effects on learning. Reducing excessive exposure is likely to save lives⁵¹  and to improve the quality of life for the millions of individuals exposed to excessive levels of environmental noise.

More research is needed about some effects of children’s exposures to excessive noise. There is enough evidence in multiple areas of research, however, to warrant a precautionary approach. Excessive noise exposure is preventable. Although extreme impulse noise can be immediately damaging, most NIHL is attributable to the cumulative effect of excessive noise exposure, listening to fairly loud noises over longer periods of time. Counseling by pediatricians about noise and preventing or decreasing noise exposure is recommended by the AAP. It is not known whether or how these recommendations are being implemented.

Much akin to knowledge and perceptions about smoking and secondhand smoke more than a half century ago, noise exposure is not generally seen as hazardous by the general public.³²³  Excessive noise from personal devices and at celebratory events is often sought out. More attention to noise at the public health level is needed to increase awareness of these hazards to begin changing this perception. It is possible to enjoy music and attend events in ways that do not risk hearing loss and other adverse outcomes. The responsibility for raising awareness and creating safe listening environments lies with the public health community, governments, device manufacturers, and others.¹⁸⁴ 

Other creatures on the planet also are affected by noise. A greater appreciation of these effects on these inhabitants must be considered. Mitigation efforts are likely to benefit many living creatures.

Sophie J. Balk, MD, FAAP

Risa E. Bochner, MD, FAAP

Mahindra A. Ramdhanie, AuD, FAAA, CCC-A

Brian K. Reilly, MD, FAAP, FACS

Aparna Bole, MD, FAAP, Chairperson

Sophie J. Balk, MD, FAAP

Lori G. Byron, MD, FAAP

Gredia Maria Huerta-Montañez, MD, FAAP

Steven M. Marcus, MD, FAAP

Abby L. Nerlinger, MD, FAAP

Nicholas C. Newman, DO, FAAP

Lisa H. Patel, MD, FAAP

Rebecca Philipsborn, MD, FAAP

Alan D. Woolf, MD, MPH, FAAP

Lauren Zajac, MD, MHP, FAAP

Aaron Bernstein, MD, MPH, FAAP

Philip J. Landrigan, MD, FAAP

Jeanne Briskin – US Environmental Protection Agency

Nathaniel G. DeNicola, MD, MSc – American College of Obstetricians and Gynecologists

Kimberly A. Gray, PhD – National Institute of Environmental Health Sciences

CDR Matt Karwowski, MD, MPH, FAAP – Centers for Disease Control and Prevention, National Center for Environmental Health, and Agency for Toxic Substances and Disease Registry

Mary H. Ward, PhD – National Cancer Institute

Paul Spire

Steven E. Sobol, MD, FAAP, Chairperson

Kristina W. Rosbe, MD, FAAP, Immediate Past Chairperson

Cristina Marie Baldassari, MD, FAAP

G. Paul DiGoy, MD, FAAP

Kris R. Jatana, MD, FAAP

Anna Katrine Meyer, MD, FAAP

Peggy Elaine Kelley, MD, FAAP

Eileen Margolies Raynor, MD, FAAP

Brian Kip Reilly, MD, FAAP

Jeffrey Philip Simons, MD, FAAP

Vivian B. Thorne

The authors thank Dr Richard Neitzel for his review and comments during the development of this document.

AAP

American Academy of Pediatrics

ADHD

attention-deficit/hyperactivity disorder

ASD

autism spectrum disorder

CDC

Centers for Disease Control and Prevention

CHL

conductive hearing loss

CI

confidence interval

CPAP

continuous positive airway pressure

dB

decibel

dBA

decibel weighted by the A scale

EPA

US Environmental Protection Agency

Hz

Hertz

IHD

ischemic heart disease

ISM

infant sleep machine

LBW

low birth weight

NHANES

National Health and Nutrition Examination Survey

NIHL

noise-induced hearing loss

ONAC

Office of Noise Abatement and Control

OR

odds ratio

PLD

personal listening device

PPE

personal protective equipment

PTB

preterm birth

REL

recommended exposure limit

SGA

small for gestational age

SHA

Sight and Hearing Association

SNHL

sensorineural hearing loss

SPL

sound pressure level

TNITS

temporary noise-induced threshold shift

WHO

World Health Organization