Nov 9th 2012 (Fri)
HRC Seminar with Antje Ihlefeld

Dr. Antje Ihlefeld, Post-Doctoral Scientist, New York University

Title: Bilateral cochlear implants: How and why restoration of spatial cues can improve speech intelligibility

Spatial release from masking refers to an important benefit for speech understanding. It can occur when a target talker and a masker talker are spatially separated. In cochlear implant listeners, spatial release from masking is much reduced or absent compared with normal hearing listeners. Perhaps this reduced spatial release occurs because cochlear implant listeners cannot effectively attend to spatial cues. In the first part of this talk I will describe a behavioral study with normal-hearing listeners. In that study, we simulated cochlear implant listening with a novel vocoding technique. Three experiments examined factors that may interfere with deploying spatial attention to a target talker masked by another talker. Results show that faithful long-term average interaural level differences were insufficient for producing spatial release from masking. This suggests that appropriate interaural time differences (ITDs) are necessary for restoring spatial release from masking, at least for a situation where there are few viable alternative segregation cues. One possibility for restoring ITDs in cochlear implant users is to impose ITDs on the envelope of amplitude-modulated high-rate carrier pulse trains. In the second part of this talk I will show results from a direct stimulation experiment that examined envelope ITD sensitivity in cochlear implant listeners.

Seminar Information

Seminars are generally held on Fridays at 10:30 AM in Room 203 of 44 Cummington Street. (Exceptions in time or location will be noted for any talks that are different).