New American Academy of Pediatrics Practice Recommendations Address the Hazards of Noise

Abstract

Noise exposures experienced by infants, children, and adolescents can be hazardous. Teens—and even young children—use headphones, ear buds, and other personal listening devices. Young people attend concerts, dances, and celebratory events where music is often painfully loud. Noise experienced at young ages can cause hearing loss; other noise effects can adversely affect learning, quality of life, and life trajectories.www.shutterstock.com. American Academy of Pediatrics, AAP, noise, technical report, policy statement, pediatrics, hearing loss, prevention.Noise exposure is poorly understood as a public health hazard. Despite scientific evidence to the contrary, noise is treated differently than many other environmental hazards. If fact, noisy environments—such as restaurants where holding nearby conversations can be difficult without shouting—are often accepted as a given. Two reports from the American Academy of Pediatrics (AAP) highlight children’s susceptibilities to the effects of noise. The Technical Report (https://bit.ly/3tLk80x) provides a scientific basis for a Policy Statement; the Policy Statement (https://bit.ly/46JL27u) gives key information and recommendations to pediatricians, government, and medical and other organizations. AAP reports inform clinical practice and advocacy efforts for 67,000 AAP members and other pediatric clinicians. This article includes concepts and recommendations from these publications. UPDATED DEFINITION Noise has often been defined as “unpleasant or unwanted sound.” A new definition—noise is “unwanted and/or harmful sound”—was adopted by the International Commission on Biological Effects of Noise (ICBEN) in June 2023.1 This definition is more accurate, since harmful noise levels are frequently sought during leisure activities. NOISE CATEGORIES Occupational noise is experienced in the workplace. Environmental noise usually arises from fossil fuel-powered sources. Outdoor sources include road traffic, railways, airplanes and airports, industrial sites, wind farms, leaf blowers, and lawn mowers. Environmental noise has disproportionate effects on underserved communities. Indoor sources include equipment, infant sleep machines, video games, toys, televisions, and classrooms. Recreational noise (“leisure noise”) sources include personal listening devices; restaurants; music at events; sports venues; and recreational firearm use. Listening to music and attending social and celebratory events are very important to many, yet noise from these sources can be hazardous. OCCUPATIONAL STANDARDS Noise-induced hearing loss in adults resulting from workplace and military exposure has been known for centuries. Standards for workplace safety in the United States are set by the National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA). These standards are designed to protect workers from noise-induced hearing loss over 40-year careers. The Recommended Exposure Limit (REL) for noise is set at 85 dBA as an 8-hour time-weighted average; exposures greater than this are considered hazardous.2 Even at this level, however, about eight percent of workers could still develop hearing loss. Hearing protection is recommended when levels are greater than 85 dBA, regardless of duration.3 It is important to understand this occupational standard when evaluating children’s exposures. Exposure to 85 dBA over 8 hours is often assumed as safe for recreational or environmental settings experienced by children and others. The standard, however, is meant only for occupational settings.4 This standard should not be assumed safe for infants, children, or adolescents in their various exposure settings. UNIQUE SUSCEPTIBILITIES Immature, rapidly growing, and developing organ systems, such as the auditory system, are often more highly susceptible to environmental hazards compared with mature systems, illustrating the concept of “critical periods of vulnerability.”5 Young children’s external ear anatomy differs from that of adults, with intensification of higher frequency sounds.6 Hearing loss—including from noise exposure—can affect learning, potentially impacting a child’s life trajectory. Children have long life spans, allowing for repeated and cumulative exposures. Children’s behavior and development affect noise exposures. For example, young children have less control over their environments compared with adults and older children and must rely on others to remove them from hazardous situations; teens listening to loud music may feel invulnerable to potential harm. Children with developmental differences, including learning differences, autism spectrum disorder, and attention deficit hyperactivity disorder often have heightened sensitivity to noise.7,8 Children with autism may play atypically with noisy toys—including repeated and long use—possibly risking hearing damage.9 NOISE EFFECTS Effects on hearing. One cause of sensorineural hearing loss is excessive noise. Sensorineural hearing loss results from damage to hair cells of the cochlea and/or the auditory nerve. Damage to hair cells usually cannot be remediated with medical treatment and is permanent. Sensorineural hearing loss can happen immediately, as can occur after being near a blast or fireworks. Most noise-induced hearing loss results from repeated exposures to less loud (but too loud) noise accumulated over time. The duration of noise exposures, not just the volume, is significant. Studies confirm that hearing loss is common among children, adolescents, and young adults. A nationally representative study of adolescents ages 12–19 years showed that hearing loss prevalence of > 15 dB increased from 17.0% to 22.5% from 2007 to 2008, then decreased to 15.2% from 2009 to 2010. These data illustrated that about one in six middle and high school students had evidence of hearing loss; this study did not demonstrate a consistent association between exposure to loud music with hearing loss risk.10 In an earlier sample of more than 5,200 children and adolescents ages 6–19 years, about 12.5% had noise-induced threshold shifts (NITS) in one or both ears.11 Even small amounts of hearing loss can have adverse effects on speech, comprehension of language, communication, learning in classrooms and social development.12,13 Studies do not consistently illustrate a relationship between noise exposure and early hearing loss or hearing loss in adulthood; more research in this area is recommended. Because it is likely that noise contributes to hearing loss in youth, and also plays a part in adult hearing loss, preventive measures starting in early life are warranted. Tinnitus and hyperacusis are other auditory effects of excessive noise exposure. Effects on learning. Environmental noise is less likely to cause hearing loss compared with occupational and recreational noise. Noisy environments can, however, negatively impact aspects of learning such as speech comprehension and speech intelligibility.14,15 Cognitive tasks including long-term and short-term memory can be disrupted by background noise.16 Noise may be especially harmful to younger children in classrooms as they work to develop language and auditory discrimination skills.17 Younger children lack the ability to “predict from context” because of limited experiences and vocabulary, and thus are less able to “fill in” missing thoughts.18 Other effects. Environmental noise causes the release of cortisol, indicating a physiologic stress response. In adults, chronic exposure to high levels of environmental noise increases the risk of cardiovascular diseases, including myocardial infarction.19 Studies in children show associations of road traffic noise and higher blood pressure. Sleep disturbance is considered the main health effect of environmental noise: nighttime levels even < 40 dB can cause body movements, awakenings, and self-reported sleep disturbance.20 Children are considered vulnerable to nighttime noise due to their ongoing development and generally longer sleep patterns. Annoyance is considered the second major health effect of environmental noise exposure.21 In adults, significant correlations between traffic noise and measures of annoyance have been found; fewer such studies have been done in children. SPECIFIC PEDIATRIC EXPOSURES Noise exposures can begin right after birth. Hospital settings, including neonatal intensive care units (NICUs), are usually louder than many homes and offices. Preterm infants admitted to NICUs risk long-term neurodevelopmental impairments; environmental stressors such as noise may affect the rapidly growing and developing preterm infant’s brain. Many hospitals work to create quieter environments to improve the health of these medically fragile infants. NICU noise sources include ventilators, monitors, incubators, alarms, telephones, staff conversations, and infants’ own crying in incubators. Preterm infants exposed to NICU noise have shown adverse behavioral and vital sign changes22–24, and disrupted sleep. To reduce stress and promote healthier outcomes, sound reduction strategies aim to decrease the sound reaching NICU babies’ ears to < 45 dB.25 Strategies include lowering sound levels for the entire NICU, placing infants in “private” rooms, and having them wear earmuffs or earplugs.26 Most interventions decrease the sound reaching babies’ ears, but they usually don’t reach recommended levels. Infant sleep machines (ISMs)—“white noise” machines—aim to increase uninterrupted sleep by masking other sounds in the baby’s room. They are situated near a crib or mounted directly on its side rail. Parents are advised to operate ISMs continuously while the baby sleeps and to adjust the volume equal to or louder than the baby’s cry. Some studies showed potential benefits with falling asleep, decreased crying, and increased pain threshold when receiving vaccines. One study of 14 ISMs, however, showed that sound levels of three machines exceeded occupational limits, raising the concern for potential hearing damage.27 Toys can create noise hazards. Every year, the Sight and Hearing Association (SHA), a Minnesota-based nonprofit organization, selects and tests sound-producing toys to determine their dB level. In 2021, 19 of 24 toys in the SHA’s 24th Annual Noisy Toys List tested louder than 85 dB. The SHA recommended adjusting volume control on toys, placing tape over speakers, removing batteries, or returning too-loud toys. The SHA emphasized that occupational standards may not be suitable to evaluate toy safety.28 Personal listening devices are commonly used. One study of teens and young adult listeners demonstrated that average listening levels ranged from 71 to 105 dBA. Close to 60% of participants exceeded the occupational noise standard, particularly when there was background noise29; background noise makes listening more difficult so that users turn up the volume. The United States has no mandatory standard to limit maximum sound output for headphones or other listening devices sold here. Although some manufacturers claim that their maximum headphone volume is 85 dB, some devices can produce volumes high enough to harm hearing in minutes, using occupational standards.30 Other noise sources discussed in the AAP documents are background noise, childcare centers and classrooms, magnetic resonance imaging (MRIs), and recreational firearm use. BRINGING MORE ATTENTION TO NOISE The relative inattention to noise as a serious public health hazard is reminiscent of knowledge and perceptions about secondhand smoke more than 50 years ago.31 Noise contributes to hearing loss in adults; hearing loss, the third most common chronic physical condition in adults32, is linked to many medical and psychological consequences. Not only can early life exposure to excessive noise result in hearing loss at young ages, but early exposures also are likely to contribute to adult hearing loss. Children’s and youth’s common use of personal listening devices raises concern that hearing loss prevalence will continue to increase even before young people enter the workplace. Pediatric clinicians can have key roles in preventing hearing loss and other consequences. Pediatricians can discuss headphone use with teenagers during the confidential portion of their health visits, or when examining ears. The World Health Organization suggests that volume on personal listening -devices be set no higher than 60% of its maximum.33 This rule of thumb is one way for families to promote safer listening. Other guidelines for recreational listening have been published. Parents purchasing headphones for children can be made aware of volume controls. Noise cancellation is important, especially in the presence of background noise as when riding in a car or airplane. Parents can avoid or leave noisy events such as sports events and fireworks displays or use hearing protection for infants and children. If ISMs are used, it may be safer to locate them as far away as possible from the infant, set the volume as low as possible, and limit duration of use. Guidelines to protect the public from environmental noise-induced health problems have been published by World Health Organization.34 There has been less attention to environmental noise exposure in the United States. There are no federal regulations in the United States about exposure to environmental noise35; state and local governments are responsible for protecting the public from noise. In addition to educating patients and families, pediatric clinicians can work at local, regional, national, and international levels to raise awareness and aid in crafting legislation and regulations to promote safer listening and quieter environments. Thoughts on something you read here? Write to us at [email protected].