Preventing Excessive Noise Exposure in Infants, Children, and Adolescents

Noise exposure is a major cause of hearing loss in adults. Yet, noise affects people of all ages, and noise-induced hearing loss is also a problem for young people. Sensorineural hearing loss caused by noise and other toxic exposures is usually irreversible. Environmental noise, such as traffic noise, can affect learning, physiologic parameters, and quality of life. Children and adolescents have unique vulnerabilities to noise. Children may be exposed beginning in NICUs and well-baby nurseries, at home, at school, in their neighborhoods, and in recreational settings. Personal listening devices are increasingly used, even by small children. Infants and young children cannot remove themselves from noisy situations and must rely on adults to do so, children may not recognize hazardous noise exposures, and teenagers generally do not understand the consequences of high exposure to music from personal listening devices or attending concerts and dances. Environmental noise exposure has disproportionate effects on underserved communities. In this report and the accompanying policy statement, common sources of noise and effects on hearing at different life stages are reviewed. Noise-abatement interventions in various settings are discussed. Because noise exposure often starts in infancy and its effects result mainly from cumulative exposure to loud noise over long periods of time, more attention is needed to its presence in everyday activities starting early in life. Listening to music and attending dances, concerts, and celebratory and other events are sources of joy, pleasure, and relaxation for many people. These situations, however, often result in potentially harmful noise exposures. Pediatricians can potentially lessen exposures, including promotion of safer listening, by raising awareness in parents, children, and teenagers. Noise exposure is underrecognized as a serious public health issue in the United States, with exposure limits enforceable only in workplaces and not for the general public, including children and adolescents. Greater awareness of noise hazards is needed at a societal level.

Hazardous sound outputs of white noise devices intended for infants

OBJECTIVES

To measure the sound intensity of popular infant white noise machines and Apple iPhone applications (apps) as they vary with volume setting and distance, and compare these output levels with current National Institute for Occupational Safety and Health (NIOSH) noise exposure threshold recommendations.

METHODS

A total of eight infant white noise machines and six iPhone applications were included in the study based on product rating, number of ratings, and cost. The NIOSH Sound Level Meter application through the Apple App Store was used to measure output levels in A-weighted decibels (dBA). Each device was tested at its lowest and highest volume setting and at speaker-to-microphone distances simulating placement within a crib (10 cm), just outside of a crib rail (30 cm), and on a nightstand across the room (100 cm).

RESULTS

At the minimum volume setting, no device exceeded the NIOSH recommended noise exposure threshold of 85 dBA at any distance tested. At maximum volume setting, nine out of fourteen (64.3%) devices exceeded output levels of 85 dBA at a speaker-to-microphone distance of 10 cm. No device exceeded the recommended threshold at its maximal volume when placed 30 cm or 100 cm away.

CONCLUSION

Excessive white noise exposure has the potential to lead to noise-induced hearing loss and other adverse health effects in the neonatal and infant population. We recommend conservative use of white noise machines and apps by avoiding maximal volume setting and placing any device well outside of the crib or at least 30 cm away from the child. To promote safe use of white noise devices, future studies are needed to fully understand the association between early noise exposure and hearing loss in infants.

Modeling individual noise-induced hearing loss risk with proxy measurements of external-ear amplification

Significant variability in noise-induced hearing loss (NIHL) susceptibility suggests there are factors beyond sound level and duration of exposure that contribute to individual susceptibility. External-ear amplification (EEA) from external-ear structures varies significantly due to ear size and shape, potentially influencing NIHL susceptibility. This study tested the hypothesis that EEA can be predicted using non-technical proxy measurements including pinna height (cm), body height (m), and earcanal volume (cm³). 158 participants (4-78 years) completed otoscopy, tympanometry, pinna measurements, body height measurements, and two EEA measurements: (1) total real-ear unaided gain (REUG) of the open ear and (2) real-ear to coupler difference (RECD), representing unaided gain from the earcanal. Participants' individual noise doses were compared in hypothetical exposures. REUG ranged from 5 to 19 dBA and was correlated with pinna height. High-REUG participants were estimated to accrue noise doses at least 5 times higher than low-REUG participants. RECD ranged from 7 to 24 dBA and was correlated with earcanal volume and body height. The results support the hypothesis that EEA measurement could significantly improve estimation of an individual's position along the NIHL risk spectrum. Non-technical proxy measurements of EEA (pinna height, body height, earcanal volume) were statistically significant but yielded high variability in individual EEA prediction.

Loud Music and Leisure Noise Is a Common Cause of Chronic Hearing Loss, Tinnitus and Hyperacusis

High sound levels capable of permanently damaging the ear are experienced not only in factories and war zones but in concert halls, nightclubs, sports stadiums, and many other leisure environments. This review summarizes evidence that loud music and other forms of "leisure noise" are common causes of noise-induced hearing loss, tinnitus, and hyperacusis, even if audiometric thresholds initially remain within clinically normal limits. Given the huge global burden of preventable noise-induced hearing loss, noise limits should be adopted in a much broader range of settings, and education to promote hearing conservation should be a higher public health priority.

Noise-dose estimated with and without pre-cochlear amplification

Amplification from natural ear canal resonance has been documented as highly variable across individuals. However, individual variability in total pre-cochlear amplification (i.e., combined external and middle ear mechanisms) remains understudied in relevance to noise-induced hearing loss (NIHL). It is well-known that more noise means more risk of hearing loss, yet the current risk-models do not consider individually variable pre-cochlear amplification, also referred to as the transfer function of the open ear (TFOE). The present study principally documented individual TFOE variability and explored the feasibility and accuracy of simple proxy metrics, which could be used to estimate TFOE. Participants' TFOE values were used to estimate their NIHL risk in hypothetical free-field exposures. Forty-eight adult participants (42 female, 6 male, ages 21-60 years) met inclusion criteria of 2 healthy pinnae and ear canals (<10% cerumen occlusion) and type-A tympanometric examination. Participants underwent otoscopy, tympanometry, pinna size measurement, real-ear-to-coupler-difference, and TFOE measurement. TFOE ranged from 5 to 15 dB-A (mean = 10 dB-A); given that NIHL risk is estimated to double in either 3 or 5 dB-A increments, the observed variability could explain a substantial portion of individual vulnerability to NIHL. A simple regression model with eardrum compliance (ml) was correlated with individual TFOE (p < 0.05). TFOE variability has the potential to substantially explain why two individuals with the same noise-exposure can develop significantly different degrees of NIHL. Eardrum compliance (ml) was a correlated proxy measurement of TFOE in this principally adult, female dataset; additional research is needed to confirm this relationship in a unique, heterogeneous dataset.

Hazardous noise exposure from noisy toys may increase after purchase and removal from packaging: A call for advocacy

OBJECTIVE

Previous studies identified hazardous noise levels from packaged toys. Sound levels may increase when packaging is removed and therefore, complicate the ability to accurately assess noise levels before purchase. The goal of this study was to evaluate how packaging affects the decibel (dB) level of toys by: 1) Assessing dB level of toys with and without packaging. 2) Evaluating the percentage of packaged and unpackaged toys that exceed a safety limit of 85 dB.

METHODS

Thirty-five toys were selected from the 2009-2011 Sight and Hearing Association (SHA) based on availability for purchase. Toys' speakers were categorized as Exposed, Partially Exposed, or Covered, based on its packaging. The dB level of each toy was tested at 0 cm and 25 cm from the speaker using a handheld digital sound meter in a standard audiometric booth. T tests and ANOVA were performed to assess mean change in sound level before and after packaging removal.

RESULTS

Significant dB increases were noted after packaging was removed (mean change 11.9 dB at 0 cm; and 2.5 dB at 25 cm, p < 0.001). Sixty-four percentage of Covered toys (n = 14) had dB greater than 85 dB when packaged and this increased to 100% when unpackaged.

CONCLUSION

Many manufactured toys have hazardous sound levels. Caregivers and healthcare providers should be aware that toys tested in the store may actually be louder when brought home and removed from their packaging. Limits on and disclosure of dB level of toys should be considered nationally.

A Hearing Screening Program for Children in Primary Schools in Tajikistan: A Telemedicine Model

Background

According to the guidelines of the European Scientific Consensus on Hearing (European Federation of Audiology Societies ‘EFAS’ Congress, June 2011, Warsaw, Poland), the detection and treatment of communication disorders in early school-age children is of the highest importance. This objective was adopted by the Polish president of the EFAS Council from the second half of 2011; as a result, pilot programs on children’s hearing screening were initiated in various European countries. This paper reports data from a pilot program in Dushanbe, Tajikistan.

Material/Methods

We randomly selected 143 children from 2 primary schools. Each child was assessed by pure tone audiometry and 2 questionnaires (dedicated to parents and children). The study allowed the validation of: (i) hearing screening procedures in young children, and (ii) data collection via a telemedicine model.

Results

Hearing impairments were identified in 34 cases (23.7%) with a 50% ratio between unilateral and bilateral losses. We found a higher incidence of hearing impairment in children than that reported in previous Polish studies.

Conclusions

The data from the present study suggest that it is possible to use a telemedicine model to assess the hearing status of children and to provide a long-distance expert assistance. The latter is very important for rural areas without specialized medical services.

Loudness and acoustic parameters of popular children's toys

OBJECTIVE

This project was conducted to evaluate the loudness and acoustic parameters of toys designed for children. In addition, we investigated whether occluding the toys' speaker with tape would result in a significant loudness reduction; thereby potentially reducing the risk of noise induced hearing loss.

METHODS

Twenty-six toys were selected after an initial screening at two national retailers. Noise amplitudes at 0.25, 0.5, 1, 2, 4, and 8kHz were measured using a digital sound level meter at a distance of 0 and 30cm. The toys' speakers were then occluded using adhesive tape and the same acoustic parameters were re-measured.

RESULTS

Mean maximum noise amplitude of the toys at 0cm and 30cm was 104dBA (range, 97-125dBA) and 76dBA (range, 67-86dBA), respectively. Mean maximum noise amplitude after occlusion at 0cm and 30cm distances was 88dBA (range, 73-110dBA) and 66dBA (range, 55-82dBA), respectively, with a p-value <0.001.

CONCLUSIONS

Proper use of the loudest toys at a distant of 30cm between the speaker and the child's ear will likely not pose a risk of noise-induced hearing loss. However, since most toys are used at closer distances, use of adhesive tape is recommended as an effective modification to decrease the risk of hearing loss.