Sound location: Monaural cues and spectral cues for elevation

This article summarizes the acoustic basis of monaural sound localization. The ascending auditory representations of spectral cues for sound localization are followed as they change from generalized population codes in the auditory nerve to directionally sensitive neural integration patterns in the dorsal cochlear nucleus and on to spatially tuned receptive fields in the inferior colliculus. The functional implications of these transformations are examined by comparing basic response properties, spatial tuning, and the impact of surgical lesions on the major nuclei of the auditory brainstem. The concept of a spectral processing pathway is introduced as an organizing principle for this extensive literature. Laboratory experiments in domestic cats are a rich source of evidence for the existence of an auditory pathway that is dedicated to the processing of monaural localization cues. The article points out some important qualifications of this influential animal model, then propose new directions for research on monaural localization and spectral processing.