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Computational modelling of neural mechanisms underlying natural speech perception

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Title: Computational modelling of neural mechanisms underlying natural speech perception
Authors: Kegler, Mikolaj Aleksander
Item Type: Thesis or dissertation
Abstract: Humans are highly skilled at the analysis of complex auditory scenes. In particular, the human auditory system is characterized by incredible robustness to noise and can nearly effortlessly isolate the voice of a specific talker from even the busiest of mixtures. However, neural mechanisms underlying these remarkable properties remain poorly understood. This is mainly due to the inherent complexity of speech signals and multi-stage, intricate processing performed in the human auditory system. Understanding these neural mechanisms underlying speech perception is of interest for clinical practice, brain-computer interfacing and automatic speech processing systems. In this thesis, we developed computational models characterizing neural speech processing across different stages of the human auditory pathways. In particular, we studied the active role of slow cortical oscillations in speech-in-noise comprehension through a spiking neural network model for encoding spoken sentences. The neural dynamics of the model during noisy speech encoding reflected speech comprehension of young, normal-hearing adults. The proposed theoretical model was validated by predicting the effects of non-invasive brain stimulation on speech comprehension in an experimental study involving a cohort of volunteers. Moreover, we developed a modelling framework for detecting the early, high-frequency neural response to the uninterrupted speech in non-invasive neural recordings. We applied the method to investigate top-down modulation of this response by the listener's selective attention and linguistic properties of different words from a spoken narrative. We found that in both cases, the detected responses of predominantly subcortical origin were significantly modulated, which supports the functional role of feedback, between higher- and lower levels stages of the auditory pathways, in speech perception. The proposed computational models shed light on some of the poorly understood neural mechanisms underlying speech perception. The developed methods can be readily employed in future studies involving a range of experimental paradigms beyond these considered in this thesis.
Content Version: Open Access
Issue Date: Feb-2022
Date Awarded: May-2022
URI: http://hdl.handle.net/10044/1/97669
DOI: https://doi.org/10.25560/97669
Copyright Statement: Creative Commons Attribution NonCommercial Licence
Supervisor: Reichenbach, Johann David Tobias
Barahona, Mauricio
Leech, Robert
Sponsor/Funder: NIHR Biomedical Research Council (BRC)
Engineering and Physical Sciences Research Council (EPSRC)
Funder's Grant Number: WBCN P64187
Department: Department of Bioengineering
Publisher: Imperial College London
Qualification Level: Doctoral
Qualification Name: Doctor of Philosophy (PhD)
Appears in Collections:Bioengineering PhD theses

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