Susceptibility to auditory fatigue: Comparison of changes in cochlear nerve potentials in the guinea pig and chinchilla

Abstract

The susceptibilities of the guinea pig and chinchilla to acoustic fatigue are compared. For this comparison they were exposed to a 6‐kHz tone. The exposures were within the range of 60–110 dB SPL. The N 1 potential of the cochlear nerve and the cochlear potential were recorded before and after exposure. Both species suffered greatest N 1 changes a 1/2 octave above the exposure tone. No appreciable changes in cochlear potential were observed. In agreement with previous studies for equal SPL’s, the chinchilla was found to be more susceptible to fatigue than the guinea pig. However, when the exposures are based on maximum cochlear‐potential output, these animals suffer similar losses in N 1. This suggests that impedance differences in their ears accounts for the susceptibility difference. Nerve fatigue is described and found related to hair cell distortion. Subject Classification: [43]65.66, [43]65.40, [43]65.42.