The acoustics and psychoacoustics of sound localization in the cat

Abstract

Cats are a common model system for the anatomy, physiology, and psychophysics of sound localization. There are three main cues to location: Interaural differences in time (ITD) and level (ILD) and monaural spectral shape. Here, the cues were derived from measurements of directional transfer functions, the directional components of head‐related transfer functions. In the frontal hemisphere, spectral notches were present for frequencies from ∼8–16 kHz; the notch frequency increased with increases in source elevation and in azimuth towards the ipsilateral ear. The maximum ITDs were ∼380 s. Maximum ILDs depended on source azimuth and frequency, but were as large as 35 dB at some frequencies. For the psychophysics of localization, cats were trained using operant conditioning to indicate the apparent locations of sounds via gaze shift (combined eye and head movements); eye and head position were measured using the search coil technique. Auditory targets consisted of noise bursts of varying duration, intensities, and spectral content. Localization of long duration, moderately intense, and broadband targets were accurate and precise, but deteriorated for sounds that were short‐duration, narrow‐band, or that were very intense or faint. Cat sound localization capabilities are in many ways similar to humans. [NIH grants DC006865 and DC02840.]