|Jan 11th 2013 (Fri)|
HRC Seminar with Michael Heinz
Dr. Michael G. Heinz, Ph.D., Associate Professor of Speech, Language and Hearing Sciences and Biomedical Engineering, Purdue University
Physiological correlates of degraded temporal fine structure sensitivity with sensorineural hearing loss
Recent perceptual studies have suggested that listeners with sensorineural hearing loss (SNHL) have a reduced ability to use temporal fine-structure cues for speech and pitch perception. These results have fueled an active debate about the role of temporal coding in normal and impaired hearing, and have important implications for improving the ability of hearing aids and cochlear implants to restore speech perception in noise. This talk will describe some of our recent studies exploring the physiological bases for these perceptual results through a combination of neurophysiological, perceptual, and computational modeling approaches. Recordings from auditory-nerve fibers in chinchillas with noise-induced hearing loss suggest that the fundamental ability of fibers to phase lock to temporal fine structure in quiet conditions is not degraded by SNHL, but that degraded phase locking emerges in background noise. In addition, a number of other effects of SNHL have been observed that may also contribute to perceptual deficits in temporal processing of complex stimuli. These effects include changes in the relative encoding of envelope and fine structure, loss of tonotopicity, and reduced across-CF traveling-wave delays. Furthermore, our correlated neural modeling and human perception results using vocoded speech stimuli suggest the possibility that reported fine-structure deficits could be related (at least in part) to a reduction in recovered envelope cues, which result from cochlear transformations between acoustic fine structure and neural envelope.
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).Close