Temporary threshold shift in man resulting from four-hour exposures to octave bands of noise centered at 63 and 1000 Hz

Burdick et al. [J. Acoust. Soc. Am. 61, S78(A) (1977)] presented data showing threshold shifts in chinchillas exposed to octave bands of noise centered at 63 and 1000 Hz. Their results indicated that a large temporary and moderate permanent threshold shift at high frequency resulted from exposure to the 63 Hz noise and that when the 63 and 1000 Hz noises were equated in A-weighted sound pressure levels, the 63 Hz noise was relatively more hazardous. The present study used identical exposure bands for human subjects with the exposure duration reduced to four hours. The results indicate that in man, as in chinchilla, sizable temporary threshold shifts are induced at high frequencies (1.0–3.0 kHz) by the 63 Hz octave band noise. When these results are compared to the four hour exposure point on the growth curves presented by Burdick et al. it appears that man may be as sensitive to low-frequency noise as the chinchilla. This is in contrast to the usual finding that the chinchilla is more sensitive to higher-frequency noise.