Abstract
Using 40 albino ginea pigs, the effect of an intense sound (2 kHz, 100 to 130 db, 3 or 30 minutes) upon the threshold of AP and CM was investigated at frequencies ranging from 2 to 16 kHz. The threshold shift in AP was severer than that in CM at almost all frequencies. This finding seems to reflect the morphological results of other investigators that the damages to the stereocilia of the inner and first row outer hair celis are the most sensitive in case of a permanent threshold shift. As a greatest shift in the AP threshold became severer, the frequency at which the threshold was the greatest moved toward the higher frequency. Assuming that the half-octave shift in TTS is a phenomenon reflecting the basilar membrane nonlinearities, our resuslts suggest that the maximum amplitude point of the traveling wave envelope moves toward the stapes beyond the half-octave point along the basilar mombrane with increase of the stimulus strength
