[Risk of damaging effect of noise on the hearing organ]

Hearing measurement of 6,784 workers exposed to industrial noise helped to determine the prevalence of occupation-related hypoacusis, which was estimated to vary from 4.5 to 53%. The work record of 10 to 14 years was found to be most risky for the development of cochlear neuritis. During the first 10 years of exposure to industrial noise occupation-related hypoacusis developed in 2% workers, which is within the 5% limits of noise susceptible subjects. Considering hearing integrity during 10-year exposure to industrial noise, it can be assumed that maximaly allowable levels equal to 85 dB are acceptable. Numerous observations of the hearing condition allow the conclusion that the zero degree of hearing impairment, i.e. "signs of noise effects on the hearing organ", should be viewed as an initial form of occupational disease (prenosological form), which requires close follow-up of such workers.