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=OGpCSjdEV2NqTVJKdjF4T1h1dldhdz09Meeting
ID: 936 1303 7748
Passcode: 777827
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