Electronic Thesis and Dissertation Repository


Master of Science


Health and Rehabilitation Sciences


Dr. Ewan Macpherson


Sound localization in the horizontal plane depends on interaural time difference (ITD) and interaural level difference (ILD) cues, which are both available in wideband sounds. Previous studies have directly measured listener weighting of those cues only under quiet, anechoic conditions, but not in the presence of noise and reverberation, which can degrade both ITD and ILD. This study examined the effects of changes in target spectral profile, background noise, and reverberation on sound localization performance and cue weighting strategies. Listeners reported locations of targets that were presented over headphones in virtual auditory space. ITD and ILD were manipulated by attenuating or delaying the sound at one ear, and their weighting was computed by comparing the listener’s localization response bias to the imposed cue bias. Results suggest that ITD dominates for any wideband target in quiet conditions, but that listeners increase their weighting of ILD in more adverse listening conditions.