Thesis defense : Moïra-Phoebé HUET

On The September 17, 2020

at 2:00 PM
Amphithéâtre CRNL

"Voice mixology at a cocktail party: Combining behavioural and neural tracking for speech segregation. »

abstract :

It is not always easy to follow a conversation in a noisy environment. In order to discriminate two speakers, we have to mobilize many perceptual and cognitive processes to maintain attention on a target voice and avoid shifting attention to the background. In this thesis, the processes underlying speech segregation are explored through behavioural and neurophysiological experiments. In a preliminary phase, the development of an intelligibility task – the Long- SWoRD test – is introduced. This protocol allows participants to benefit from cognitive resources, such as linguistic knowledge, to separate two talkers in a realistic listening environment. The similarity between the two speakers, and thus by extension the difficulty of the task, was controlled by manipulating the acoustic parameters of the target and masker voices. In a second phase, the performance of the participants on this task is evaluated through three behavioural and neurophysiological (EEG) studies. Behavioural results are consistent with the literature and show that the distance between voices, spatialisation cues, and semantic information influence participants’ performance. Neurophysiological results, analysed with temporal response functions (TRF), indicate that the neural representations of the two speakers differ according to the
difficulty of listening conditions. In addition, these representations are constructed more quickly when the voices are easily distinguishable. It is often presumed in the literature that participants’ attention remains constantly on the same voice. The experimental protocol presented in this work provides the opportunity to retrospectively infer when participants were listening to each voice. Therefore, in a third stage, a combined analysis of this attentional information and EEG signals is presented. Results show that information about attentional focus can be used to improve the neural representation of the attended voice in situations where the voices are similar.

Composition of the Jury :

- McGettigan Carolyn, Prof., University College London, Rapporteuse
- Meunier Fanny, Directrice de Recherche, Université Côté d’Azur, Rapporteuse
- Pressnitzer Daniel, Directeur de Recherche, ENS Paris Examinateur
- Parizet Etienne, Prof., INSA Lyon, Directeur de thèse
- Gaudrain Etienne, Chargé de Recherche, CRNL Lyon, Co-encadrant