What’s the safe noise exposure level to prevent noise-induced hearing loss?

Photo credit: Bryan Thatcher licensed under CC BY-NC-SA 2.0

by Daniel Fink, MD, Chair, The Quiet Coalition

I developed tinnitus and hyperacusis in 2007 after a one-time exposure to loud noise at a New Year’s Eve dinner in a restaurant. As midnight approached, the recorded music was turned up louder and louder. My wife could tell I was uncomfortable and suggested that we leave, but I didn’t want to offend our friends who had made the dinner reservations. I wish I had listened to my wife. My ears were ringing when we left the restaurant, and that has never stopped. And I found that noise that didn’t bother her or others was actually painful for me.

Eight years ago, after reading this article about hyperacusis in The New York Times, I decided to see what I could do to make the world a quieter place.

As an internist, I’m used to finding information I need to care for my patients. Federal agencies and professional societies provide evidence-based information for health professionals and for the public. For example, the Food and Drug Administration recommends daily sodium intake of less than 2,300 milligrams a day, about one teaspoon of table salt. The U.S. Department of Agriculture has dietary guidelines for Americans. But I couldn’t find any noise exposure recommendations for the public.

The National Institute for Occupational Safety and Health recommended an occupational noise exposure of 85 A-weighted decibels but that didn’t protect workers from noise-induced hearing loss. The National Institute on Deafness and Other Communication Disorders webpage about noise-induced hearing loss stated, “[k]now which noises cause hearing loss (those at or above 85 decibels),” but I knew that couldn’t be correct. The National Institutes of Health recommended 75 dBA for eight hours a day. And the Environmental Protection Agency had calculated that a time-weighted average of 70 decibels for 24 hours would prevent hearing loss, but emphasized that this level was not a standard or recommendation.

The EPA’s 70 dB noise exposure level remains the only evidence-based safe noise exposure level that I have been able to find. I wrote about that in the American Journal of Public Health in 2017. But over the next five years, I realized that the actual safe noise level to prevent noise-induced hearing loss had to be lower than 70 dB, for two main reasons. First, the EPA adjusted the NIOSH occupational exposure level for additional exposure time–24 hours a day instead of eight hours in the factory, 365 days a year instead of 240 days at work–to calculate that 70 dB would prevent hearing loss, but didn’t adjust for lifetime exposure of almost 80 years instead of 40 years at work. So the actual safe noise level has to be lower than 70 dB. Second, NIOSH assumed that workers had quiet when not at work, something no longer true.

An analysis of existing data that I presented at the December meeting of the Acoustical Society of America in Nashville suggests that the safe noise exposure level to prevent hearing loss may be as low as 55 decibels.The safe noise level to prevent hearing loss is probably lower than you think. I will be submitting a more formal manuscript to Proceedings of Meetings on Acoustics after I make my presentation.

But you don’t need a sound level meter or noise meter app to protect your hearing.

If something sounds loud, it’s too loud, and your auditory health is at risk.

Turn down the volume, leave the noisy environment, or use hearing protection devices.

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