1992 Volume 35 Issue 2 Pages 187-192
We have investigated the changes of hearing threshold levels in 24 individuals who work in the rotary press room of a local daily newspaper company. They were exposed to the noise at the sound level ranging from 80 to 100dB A for 5 hours every day. Pure-tone audiograms were obtained annually from 1983 to 1991. Twentyone out of 24 individuals showed minimal threshold changes, which were apparently comparable to those due to aging. In the remaining 3 individuals, c5 dip was developed at various onset during this period. Deferences in the depth of c5 dip between the left and right ears and fluctuation of 4 and 8kHz thresholds suggested that inner ear damages were still in progress in the 3 cases with c5 dip.
