Comparison of susceptibility to impulse‐noise‐induced threshold shift: chinchilla and man

Species‐specific differences in susceptibility to threshold shift induced by impulse noise are often important considerations in noise research. Luz and Hedge (1971) and Luz and Lipscomb (1973) have suggested that the chinchilla is more susceptible to very brief (A) duration (50 μsec) impulse‐noise‐induced threshold shift than is man. The present study was undertaken to make a direct comparison between chinchilla and man as to threshold shift produced by impulse noise. Two chinchilla and two humans determined to have hearing and middle‐ear function within normal limits were exposed to five impulses of 154‐dB intensity, 15 msec (A) duration, at a rate of 1/30 sec. Auditory threshold was estimated via the auditory evoked response method with the chinchilla while human subjects tracked threshold. Each subject was tested on a fixed schedule following exposure. Threshold shift in the chinchilla at 2‐h postexposure was found to be up to 40 dB more severe than for the human subjects. Recovery to pre‐exposure levels required up to seven days for the chinchilla, while the human subjects recovered within 48 h.