Auditory system comparisons between sand cats and other felid species : acoustic input admittance of ears and auditory brainstem responses

Abstract

The sand cat, one species of the cat family, is found only in deserts and has unusually large ear canals and middle-ear air cavities. Recent work has shown that sand cat ears absorb acoustic power at low frequencies (<1 kHz) better than those of domestic cats (Huang et al. 2002). In this thesis, we test this hypothesis by comparing acoustic input- admittance, which determines acoustic power absorption, and thresholds of auditory- brainstem responses. In a zoo, measurements were made in 37 ears of 23 anesthetized specimens, including sand cats and five other felid species. Sand cats have lower mean thresholds at frequencies between 0.25 and 5 kHz by 6-9 dB than other felid species measured. However, the mean power absorption does not differ significantly. The results are consistent with the hypothesis that sand-cat hearing is unusually sensitive, but this specialization is not associated with increased power absorbed at the tympanic membrane.