Auditory Sensitivity in the Agouti (Dasyprocta punctata)

Abstract

A conditioned suppression technique has been applied to five agoutis and behavioral thresholds measured. Each animal was water deprived and allowed to drink only in the experimental situation. Training was effected by pairing audible tone pulses with shock until the subject learned to cease drinking reliably in the presence of a signal. Auditory thresholds were then assessed at octave intervals. Maximum sensitivity occurred at 8 kHz (0 dB re 2 × 10−4 dyn/cm2), a high frequency cutoff at 64 kHz, and a low-frequency cutoff at 500 Hz. Low-frequency sensitivity may have been impaired by masking or TTS resulting from the loud licking noises produced by this species, although control studies have not verified this hypothesis. It is the authors' opinion that hearing in the Agouti is oriented toward the higher frequencies despite the presence of certain low-frequency structures such as the large bulla. The observed high-frequency bias supports previous findings regarding this animal's basilar membrane.