What is the safe noise exposure level to prevent noise-induced hearing loss?
D J Fink
Abstract
Exposure to noise causes noise-induced hearing loss (NIHL) [ 1 ] and two other auditory disorders, tinnitus and hyperacusis [ 2 ]. This Comment will focus on answering the question, “What is the safe noise exposure level to prevent NIHL?” The exposure-response relationship between noise and hearing loss in humans has been studied in the occupational setting for decades [ 3 ]. Based on thousands of laboratory studies in a variety of animal models, the mechanisms by which noise exposure causes NIHL are also well understood, down to the ultrastructural, biochemical, and genetic effects of noise on cochlear hair cells and synaptic junctions [ 4 , 5 ]. The exposure-response relationships for tinnitus and hyperacusis have not been established, though, and the mechanisms of injury are not yet understood. Ninety per cent of people with tinnitus also have hearing loss [ 6 ]. Knowledge of the safe noise exposure level to prevent NIHL should also help people avoid developing noise-induced tinnitus, and probably hyperacusis as well.