In 2017, the Centers for Disease Control and Prevention (CDC) reported that almost 25% of American adults age 20-69 had noise-induced hearing loss (NIHL), with 53% of them reporting no significant noise exposure. 1 If we were in the movie business, our recent paper in Proceedings of Meetings on Acoustics2 might be called a prequel to the CDC report because it explains why so many Americans are losing hearing without occupational noise exposure: They are exposed to too much noise.
Occupational hearing loss has been known from stonemasons in the Middle Ages to factory workers in the industrial era, but nonoccupational noise exposure was not recognized as a problem until the 1960s. 3 Before World War II, noise exposure outside the workplace was rare. That changed in postwar America. Convenient electric appliances, home stereo systems boasting about their wattage outputs, the advent of rock and roll music, and the use of amplified sound at parties and life cycle celebrations such as weddings became common. By the end of the 20th century, personal audio systems (PAS), also called personal music players or personal listening devices, were common, with their use accelerating dramatically after PAS became available on MP3 players and then smartphones. Young people especially use PAS to listen to loud music and audio content for hours a day. Often, users must turn up the volume to overcome high ambient noise, especially while commuting.
Flamme, et al., found that although people spend most of their time in relatively quiet environments when not at work, total noise exposure is dominated by a small number of high-level exposures. 4 Occupational and nonoccupational noise and auditory risk relationships are based on the time-weighted average (TWA) of regular and intermittent sound levels, commonly measured in A-weighted decibels (dBA), over a specified exposure duration, typically 8-h daily for occupational noise and 24-h for non-occupational noise. 5,6 In the United States, 85 dBA is the recommended occupational noise exposure limit, not a safe noise exposure level for the public. 6
In adult workers, the risk of hearing impairment is 1% at 80 dBA, 8% at 85 dBA, and 25% at 90 dB TWA. 5 Although other etiologies can’t be ruled out on the basis of an audiogram, NIHL typically first develops in the 3-6 kHz speech frequency range. Risk estimates don’t consider additional auditory impairments characteristic of noise damage, including tinnitus, hyperacusis or decreased sound tolerance, speech-in-noise performance deficits, impaired otoacoustic emissions, and extended high-frequency hearing loss. 7,8
CALCULATING SAFE NOISE LEVELS
What is the safe noise level for the public? As calculated by the Environmental Protection Agency (EPA), the only evidence-based safe noise exposure level to prevent NIHL is a 24-h daily average of 70 dBA, 6 and even that may be too high. One thing is known for sure: The oft-cited 85 dB threshold is not the sound pressure level at which hearing loss begins. The auditory injury threshold is only 75-78 dBA regardless of listening time. 4 Auditory systems process total sound intensity instantaneously in real-time, not as a TWA.
Nonoccupational noise sources are ubiquitous, and most Americans are now exposed to sufficient noise in everyday life to cause NIHL. Flamme, et al., 4 found that 70% of research subjects in Grand Rapids, MI, exceeded the EPA safe noise level. Neitzel, et al., reported that 90% of New York City transit users and 87% of nonusers exceeded the EPA 70 dB safe daily noise limit, 9 as did about 88% of subjects in Sweden, 84% of people studied in Spain, and 85% in China. 10 Smith, et al., analyzing data collected by the Apple Hearing Study, found average daily noise exposure in the United States to be 73 dBA before COVID-19-related lockdowns began in March 2020. 11 These noise exposures, not ear infections, ototoxic drugs, or aging alone, are most likely the cause of the high prevalence of hearing loss reported in industrialized countries.
In our paper, we summarized published sound levels from six categories of nonoccupational noise sources common in everyday life. All research was done meeting ethical requirements, using standard equipment (e.g., OSHA Type II noise dosimeters), following accepted audiometric protocols (e.g., ISO 8253-1:2010), with study designs appropriate to the specific question being investigated. Each study cited used different methods in different populations in different settings, but even allowing for variations in instrumentation, possible errors in calibration, observer error, and lack of standardization of measurement, the sound levels were generally consistent among reports from different authors and with our own unpublished measurements. The consistency of the numbers provides great confidence in the generalizability of this research.
As shown in Table 1, common nonoccupational noise exposures range from 70 dBA on average at the low end to as much as 111 dBA. The cumulative daily noise dose from all these activities is clearly sufficient to cause NIHL.
NIHL is entirely preventable but once acquired is permanent and irreversible. Hearing loss is an invisible disability with major social, health, and economic consequences for individuals and society, costing the global economy $980 billion annually. 12 Early hearing loss is associated with lower educational attainment and decreased lifetime income. Untreated hearing loss in older adults is correlated with increased hospital use and greater total health care costs. Among the elderly, hearing loss is strongly correlated with social isolation, depression, dementia, falls, and accidents, all in turn associated with increased mortality.
ROLE OF HEARING CARE PROFESSIONALS
Audiologists and physicians, particularly otolaryngologists, have a responsibility to educate the public about nonoccupational noise risk from daily average exposures >70 dBA. Especially in this era of concern about the accuracy of public health -advice, it is no longer acceptable for audiologists to post inaccurate information on their practice websites or to make inaccurate statements in media reports. Misleading statements such as, “Sounds at 85 dBA can lead to hearing loss if you listen to them for more than 8 hours at a time” are still available on the American Speech-Language Hearing Association website, but the National Institute on Deafness and Other Communication Disorders recently removed the factually incorrect statement, “Know which noises can cause damage (those at or above 85 dBA),” from its webpage about NIHL. An 85-dBA noise exposure that doesn’t prevent hearing loss in working adults is far too high for a child’s delicate ears that have to last an entire lifetime.
Society should no longer accept common nonoccupational noise exposures. Prevention of NIHL is both better and less expensive than the long-term health care and socioeconomic costs of hearing loss. Smoking was once seen as something normal, a harmless habit. Cigarette smoke was everywhere—in buses, trains, airplanes, offices, even hospitals, and doctors’ waiting rooms. Then science showed that smoking caused cancer, that secondhand smoke was a Class A carcinogen with no safe lower level of exposure, and the air became smoke free. Similarly, excessive noise is now just part of everyday life. We hope that awareness of the dangers of noise will lead to a quieter world. Depending on the source, required noise control includes mandatory noise emission limits and venue noise policies, including hearing protection requirements.
Editor’s note: This article is adapted from Fink, D., Mayes, J. Too loud: non-occupational noise exposure is causing hearing loss. Proc. Mtgs. Acoust. 43, 004002 (2021) https://doi.org/10.1121/2.0001436, with the permission of the Acoustical Society of America.
1. Carroll Y I, Eichwald J, Scinicariello F, et al. 2017 Vital Signs: Noise-induced hearing loss among adults- United States- 2011-2012 MMWR Morb Mort Wkly Rep 66 139 144 https://www.cdc.gov/mmwr/volumes/66/wr/mm6605e3.htm
2. Fink D, Mayes J Too loud! Non-occupational noise exposure causes hearing loss Proceedings of Meetings on Acoustics 2021 43 040002 https://doi.org/10.1121/2.0001436
3. Dougherty JD, Welsh OL Environmental hazards-community noise and hearing loss New Engl J Med 1966 275 759765 https://doi.org/10.1056/NEJM196610062751405
4. Flamme G A, Stephenson M R, Deiters K, et al. 2012 Typical noise exposure in everyday life International Journal of Audiology 51 S 3 11 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4685462/
5. National Institute for Occupational Safety and Health. (1998). Criteria for a Recommended Standard: Occupational Noise Exposure. Cincinnati, OH https://www.cdc.gov/niosh/docs/98-126/pdfs/98-126.pdf
6. Fink DJ 2017 What is a safe noise level for the public? Am J PublHlth 107 45 46 https://ajph.aphapublications.org/doi/pdf/10.2105/AJPH.2016.303527
8. Pienkowski M 2017 On the etiology of listening difficulties in noise despite clinically normal audiograms. Ear & Hearing 38 135 148 https://dx.doi.org/10.1097/AUD.0000000000000388
9. Neitzel RL, Gershon RR, McAlexander TP, et al. 2012 Exposures to transit noise and other sources of noise among New York City residents. Environ Sci Technol 46 500 508 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4336190/
10. Neitzel RL, Svensson EB, Salyer SK, et al. 2014 A comparison of occupational and non-occupational noise exposures in Sweden Noise Health 26 270 278 https://pubmed.ncbi.nlm.nih.gov/25209036/
11. Smith LM, Wang L, Mazur K, et al. 2020 Impacts of COVID-19-related social distancing measures in personal environmental sound Environ Res Lett 15 1049 https://iopscience.iop.org/article/10.1088/1748-9326/abb494/pdf
12. World Health Organization. (2021). World Report on Hearing. License CC-By-NC-SA 2.0 IGO. https://www.who.int/publications/i/item/world-report-on-hearing