That occupational noise exposure causes hearing loss has long been known, but non-occupational noise exposure was not recognized as a problem until the 1960s. Today, most Americans are regularly exposed to non-occupational noise sufficient to cause hearing loss, perhaps because of an erroneous belief that 85-decibel noise exposure, based on occupational standards, is safe for the public without time limit. Common noise sources include personal audio systems, especially among young people; public transit; social, sports, and entertainment venues; household appliances; and power tools and landscape maintenance equipment. As a result, approximately 25% of American adults age 20-69 have noise-induced hearing loss, 53% without significant occupational exposure. Why? The Equal Energy Hypothesis states that equal amounts of sound energy produce equal amounts of hearing loss, regardless of how that sound is distributed over time. The response to sound is non-linear, though, and brief high-level exposures may have disproportionate impacts on hearing. How loud is too loud? The Auditory Injury Threshold is only 75-78 A-weighted decibels. The Environmental Protection Agency calculated a time-weighted daily average of 70 decibels to prevent hearing loss, but the true safe noise level may be 60 decibels or lower. Recommendations are made to reduce public noise exposure.

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