BME PhD Defense Announcement for Agudemu Borjigin (H. Bharadwaj, advisor) Everyone is invited to attend the public presentation beginning at 1:00 PM EDT. Title: The Role of Temporal Fine Structure in Everyday Hearing Date: April 22nd Time: 1:00 PM EDT Location: Zoom (link and info below) Advisory committee: Dr. Hari M. Bharadwaj, advisor Dr. Michael G. Heinz Dr. Edward L. Bartlett Dr. Daniel B. Polley Abstract: This thesis aims to investigate how one fundamental component of the inner-ear (cochlear) response to all sounds, the temporal fine structure (TFS), is used by the auditory system in everyday hearing. Although it is well known that neurons in the cochlea encode the TFS through exquisite phase locking, how this initial/peripheral temporal code contributes to everyday hearing and how its degradation contributes to perceptual deficits are foundational questions in auditory neuroscience and clinical audiology that remain unresolved despite extensive prior research. This is largely because the conventional approach to studying the role of TFS involves performing perceptual experiments with acoustic manipulations of stimuli (such as sub-band vocoding), rather than direct physiological or behavioral measurements of TFS coding, and hence is intrinsically limited. The present thesis addresses these gaps in three parts: 1) developing assays that can quantify TFS coding at the individual level 2) comparing individual differences in TFS coding to differences in speech-in-noise perception across a range of real-world listening conditions, and 3) developing deep neural network (DNN) models of speech separation/enhancement to complement the individual-difference approach. By comparing behavioral and electroencephalogram (EEG)-based measures, Part 1 of this work identified a robust test battery that measures TFS processing in individual humans. Using this battery, Part 2 subdivided a large sample of listeners (N=200) into groups with "good" and "poor" TFS sensitivity. A comparison of speech-in-noise scores under a range of listening conditions between the groups revealed that good TFS coding reduces the negative impact of reverberation on speech intelligibility, and leads to reduced reaction times suggesting lessened listening effort. These results raise the possibility that cochlear implant (CI) sound coding strategies could be improved by attempting to provide usable TFS information, and that these individualized TFS assays can also help predict listening outcomes in reverberant, real-world listening environments. Finally, the DNN models (Part 3) introduced significant improvements in speech quality and intelligibility, as evidenced by all acoustic evaluation metrics and test results from CI listeners (N=6). These models can be incorporated as "front-end" noise-reduction algorithms in hearing assistive devices, as well as complement other approaches by serving as a research tool to help generate and rapidly sub-select the most viable hypotheses about the role of TFS coding in complex listening scenarios. Zoom information: Topic: Agudemu Borjigin PhD Defense Time: Apr 22, 2022 01:00 PM America/Indiana/IndianapolisJoin Zoom Meeting https://purdue-edu.zoom.us/j/93613037748?pwd=OGpCSjdEV2NqTVJKdjF4T1h1dldhdz0... ID: 936 1303 7748 Passcode: 777827 One tap mobile +13017158592<tel:+13017158592>,,93613037748#,,,,*777827# US (Washington DC) +13126266799<tel:+13126266799>,,93613037748#,,,,*777827# US (Chicago)Dial by your location +1 301 715 8592<tel:+13017158592> US (Washington DC) +1 312 626 6799<tel:+13126266799> US (Chicago) +1 646 558 8656<tel:+16465588656> US (New York) +1 253 215 8782<tel:+12532158782> US (Tacoma) +1 346 248 7799<tel:+13462487799> US (Houston) +1 669 900 6833<tel:+16699006833> US (San Jose) Meeting ID: 936 1303 7748 Passcode: 777827 Find your local number: https://purdue-edu.zoom.us/u/ad14UZtB1M