Sound localization by interaural time differences at high frequencies

Abstract

It is possible for human listeners to lateralize high-frequency noise on the basis of interaural time differences in the fine structure of the envelope. However, the ability to do so makes great demands on the interaural coherence of the noise. This paper explores listeners’ ability to lateralize a broadband, high-passed, coherent-noise signal in the presence of a broadband incoherent masker. Results showed that as the high-pass cutoff frequency increased through the critical region from 1 to 4 kHz, the required interaural coherence increased rapidly, especially for the smaller changes in lateral position. The observed functional behavior can be successfully predicted by a neural model of lateralization based on the centroids of bandwise cross-correlation functions of model peripheral inputs that have been rectified and low-pass filtered [e.g., Bernstein and Trahiotis, J. Acoust. Soc. Am. 100, 1754–1763 (1996)]. The results have implications for the localization of broadband sounds in rooms, where the interaural coherence tends to increase with increasing frequency, but often not rapidly enough to allow the envelope timing information to contribute usefully. [Work supported by NIDCD.]