Abstract
The temporary threshold shifts (TTS) were examined after exposing cats to wide and narrow bands of noise for increasing durations.
At the shorter exposure to the narrow band noise, hearing loss was greatest at 4kHz. However, at the longer exposure, there was a progressive high frequency loss. After exposure to broad band noise there was a progressive high frequency loss at all durations.
The growth of TTS was almost linear with log exposure time for 1, 2, and 16kHz. However the threshold shift at 4 and 8kHz showed a reversal in growth at 15 minutes exposure for the broad band noise. For the narrow band noise, 16kHz had a very accerelated growth rate and 4 and 8kHz showed agreater growth rate compared with broad band noise exposure.
Recovery curves of TTSs were almost linear with log time up to 4 hours after exposure. Then their recovery slope increased. When TTSs at 30 minutes after exposure was less than 10dB, the cats showed complete recovery from TTS within 8 hours, and there was no summating effect on TTS in daily exposure to noise.
