An Exprimental Study on NITTS Growth Curve and NIPTS Occurence

Abstract

Prevention of noise induced hearing damage is assuming great importance and this study was performed to uncover the relations between NITTS and NIPTS.NITTSs were examined after exposing cats to wide and narrow bands of noise for increasing durations. NITTS audiogram showed that hearing loss was greatest at the highest frequency of bands of noise at the shorter exposure, however, there was a progressive high frequency loss at the longer exposure.The growth curves of NITTSs were almost linear with logarithmic exposure time. However, the curves at 16kHz showed an accelerated rate for the narrow band noise. The growth rate was smaller at 1kHz than the ones at 2, 4, 8, and 16kHz.On the occurrence of NIPTS, the NITTS curve had a distinct acceleration at growth rate following a saturation or a slight acceleration. Curiously enough, NIPTS did not necessarily appear at the frequencies of the distinct acceleration.