Neural basis of spatial hearing in reverberant environments.

Abstract

In reverberant environments, acoustic reflections interfere with the direct wavefront reaching a listener’s ears, distorting the spatial cues for sound localization. Yet, human listeners have little difficulty localizing sounds in everyday settings. Our research aims to elucidate the neural basis of spatial hearing in reverberant environments. Using a virtual acoustic space (VAS) technique, we investigated the effects of reverberation on the directional sensitivity of binaural neurons in the inferior colliculus (IC) of anesthetized cats and awake rabbits, focusing on neurons sensitive to interaural time differences. Consistent with the buildup of reverberant energy in a sound stimulus, we find that reverberation increasingly degrades the directional sensitivity of single neurons over time, although the amount of degradation depends on the characteristic frequency and the type of binaural cues available. The neurophysiological data can account for results from recent human psychophysical studies of spatial hearing in reverberant environments. In particular, we show how a population rate model for decoding the observed midbrain responses predicts the main trends in human lateralization performance, suggesting a subcortical origin for robust sound localization in reverberant environments. [Work supported by National Institutes of Health (NIH) Grant Nos. R01 DC002258 (BD), P30 DC005209 (BD), and R01 DC05778‐02 (BGSC). SD partially supported by NIH Grant No. T32 DC00038 and the Helen Carr Peake Fund.]