某騒音職場労働者の聴力検査結果

概要

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It has generally been recognized that noise-induced hearing loss (NIHL) often demonstrates a dip at 4000 Hz, the so-called C5dip, in its early stage. So far, hearing conservation in noisy plants has been needed to test for the C5dip. When hearing tests were made near frequencies of 4000 Hz, however, the so-called C5dip which was shown on the audiogram disappeared and correct locations of the dip occurred at other frequencies. In this study, we investigated the actual state of noise in a certain plant using a noise badge, and demonstrated that testing for the C5dip alone passes over the early signs of NIHL. As the result, it is indispensable to measure hearing thresholds at high frequencies of 3000 Hz,4000 Hz and 6000 Hz for control of the NIHL, and to advise workers about the effects of protectors.
耳鼻咽喉科臨床学会の論文