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Photo credit: G.M. Briggs
by Daniel Fink, MD, Chair, The Quiet Coalition
This article out of Toronto reports that transit noise can make you deaf. The author of the article, and the underlying study on which it’s based, are right. And not just in Toronto, but in other cities with noisy public transit systems, especially New York City.
But there is one statement in the article with which I disagree:
Lin said the concern is with peak exposures, which in some of the testing, measures way above the 85-decibel limit for safe prolonged exposure with some occurrences checking in as high as 115 decibels.
Simply put, 85 decibels is not a safe limit for prolonged noise exposure. At that exposure level, after 40 years of occupational exposure–8 hours a day, 240 days a year, for 40 years–at least 8% of workers will have excess hearing loss.
As I wrote in the January 2017 issue of the American Journal of Public Health, 85 decibels is not a safe noise level for the public. And the concept of excess hearing loss assumes that hearing loss with age is normal, when it isn’t. Without noise damage, good hearing should be preserved well into old age. The only evidence-based safe noise exposure level is a time-weighted average of 70 decibels for 24 hours. The NIOSH Science Blog on February 8, 2016, also addressed this topic.
Auditory damage starts at noise exposure levels as low as 75 A-weighted decibels. This is called the auditory injury threshold. I don’t know about Canadians, but most U.S. citizens get deafening total daily noise doses, as reported by Flamme and colleagues. This is the reason the Centers for Disease Control reported in February 2017 that 24% of U.S. adults age 20-69 have noise-induced hearing loss.
I am convinced that there is already an epidemic of noise-induced hearing loss that is only going to get worse when today’s young people reach middle age. The occupational noise exposure studies on which the 85 decibel occupational noise exposure standard used a 40 year occupational exposure. When toddlers as young as 3 years old use headphones marketed as safe for hearing using the 85 decibel occupational standard as a safe noise exposure level, they are likely to be severely hard of hearing when only in their 40s, if not earlier.
Hearing is an important sense, and hearing aids don’t work as well at helping users understand speech as many think. And the consequences of suffering hearing loss are severe and life changing. As Helen Keller said, “[b]lindness separates people from things, [but] deafness separates people from people.”
Transit riders and everyone else should protect their hearing now.