Abstract: The articla investigated the bounce appearing 2 minutes afterexposure to 500-1000Hz octave band noise at 80-110dB SPL, and itsrelation to the transferring of maximum TTS to high frequency alongwith the level of exposure. The results indicated that when exposureintensity exceeded 90dB SPL, the bounce at 2000Hz and 4000Hz increasedsharply with the level of exposure. When the exposure intensity reached98dB SPL, the bounce no longer increased with the level of exposure.The critical intensity of maximum TTS which began to transfer to highfrequency was 95dB SPL, which was just the time when the bounce wasin the process of sharp increase at high frequency. Therefore 90dB SPLmay be regarded as the maximum tolerable sound pressure level of 500-1000Hz octave band noise.

Key words: NULL