Abstract
It has been reported by Lierle and Reger that 1-minute exposure to pure tone at 20 dB SL produced more PI-TTS (Pure Tone-Induced Temporary Threshold Shift) at the exposure frequencies than exposures at 80 dB SL. The purpose of this study is to investigate possible effects of auditory fatigue due to the SISI (Short Increment Sensitivity Index) test tone in Jerger's method on the responses to the 1 dB-intensity increment.
A PI-TTS test was presented at 14 patients with a unilateral inner ear deafness, who were diagnosed by Jerger's SISI test and Fowler's balance test. The PI-TTS following a 1-minute exposure to pure tone (as a rule, 1000 Hz and 4000 Hz) at 20 dB above patient's threshold was determined by means of Békèsy technique. As a results, PITTS exceeded 20 dB was not found in all subjects, in whom the maximum amount of TTS was 16 dB. On the other hand, all subjects showed narrow excursion of amplitude, below 3 dB at 1000Hz and below 2 dB at 4000 Hz, in Békèsy audiometryafter exposure. If subjects of cochlear and retrocochlear deafness with high tone decay heard the SISI test tone for longer period of time, the SISI test tone might fade to inaudibility to the 1 dB-intensity increment.
