Neural Coding and Auditory Perception

The long-term goal of this research is to understand the neural mechanisms that mediate the ability of normal-hearing people to understand speech and localize sounds in complex acoustic environments comprising reverberation and competing sound sources. In the past year, we continued work on two research projects: (1) Physiological studies of sound localization in reverberant environments; (2) Spatio-temporal representation of pitch in the auditory nerve and cochlear nucleus. We also started a new project on the dynamic range problem, which impacts all aspects of auditory perception. Sound localization in reverberant environments Most listening environments contain acoustically reflective boundary surfaces e.g., ground, walls, trees, and rocks. Listeners are thus faced with the task of localizing sound sources in the presence of interfering reflections and reverberation. Despite this interference, normal-hearing listeners localize sounds quite accurately in moderate reverberation. We showed previously that inferior-colliculus (IC) neurons sensitive to interaural time differences (ITD) are more robust to reverberation than predicted by current models of binaural processing based on interaural crosscorrelation [4]. This work was done in anesthetized animals, and focused on low-frequenc