A matter of time: internal delays in binaural processing.

Laboratory of Auditory Neurophysiology, University of Leuven, Campus Gasthuisberg, O&N2 Herestraat 49, Bus 1021, B-3000 Leuven, Belgium. philip.joris@med.kuleuven.be

As an animal navigates its surroundings, the sounds reaching its two ears change in waveform similarity (interaural correlation) and in time of arrival (interaural time difference, ITD). Humans are exquisitely sensitive to these binaural cues, and it is generally agreed that this sensitivity involves coincidence detectors and internal delays that compensate for external acoustic delays (ITDs). Recent data show an unexpected relationship between the tuning of a neuron to frequency and to ITD, leading to several proposals for sources of internal delay and the neural coding of interaural temporal cues. We review the alternatives, and argue that an understanding of binaural mechanisms requires consideration of sensitivity not only to ITDs, but also to interaural correlation.

PMID: 17188761 [PubMed - indexed for MEDLINE]