[Occupational deafness].

Abstract

Occupational deafness is usually caused by acoustic traumas and is particularly frequent in developed industrial countries. It proceeds very insidiously and characterized by bilateral perceptive hypoacusis of cochlear origin, centred on the 4000 Hz frequency. The social impairment is obvious and is often accompanied by tinnitus when the weighted mean hearing loss reaches 35/dB on conversation frequencies of 500 to 4000 Hz. The degree of deafness depends on multiple factors such as the physical characteristics of the traumatic noise (the critical level being 90 dBA), the highly variable individual susceptibility, the age of the subject and any previous or concomitant ear disease. In the absence of effective treatment one must rely entirely on prophylactic measures. Dysbaric occupational deafness if increasingly frequent in aeronautical and hyperbaric environments. It is usually of the mixed type, affecting both the middle and the inner ears. Deafness due to a hyperbaric environment figures on the list of occupational diseases. Occupational deafness of toxic origin is exceptional nowadays.