A tentative proposal for classification of audiograms in noise-induced deafness: relationship between audiogram and...

Audiograms obtained from workers exposed to occupational noise were classified into six stages, namely, "normal" and stages I-V of noise-induced deafness, using the audiometric chart and the classification table designed by the authors. Close correlations were observed between the severity of the stage and the degree of hearing in daily life, which support our classification method. On the other hand, the prevalence rate of tinnitus also showed a linear increase in proportion to the severity of the stage, although the mechanism of tinnitus in noise-induced deafness has not yet been elucidated. From the viewpoint of protecting workers from hearing damage due to noise exposure, further investigation is required to make the best use of our classification method in noisy workplaces.