Modulation by Intensity of the Processing of Interaural Timing Cues for Localizing Sounds

Features of sounds such as time and intensity are important binaural cues for localizing their sources. Interaural time differences (ITDs) and interaural level differences are extracted and processed in parallel by separate pathways in the brainstem auditory nuclei. ITD cues are small, particularly in small-headed animals, and processing of these cues is optimized by both morphological and physiological specializations. Moreover, recent observations in mammals and in some birds indicate that interaural time and level cues are not processed independently but cooperatively to improve the detection of interaural differences. This review will specifically summarize what is known about how inhibitory circuits improve the measurements of ITD in a sound-level-dependent manner.