PhD defense of Monica Ashokumar (ESR 6)

Date and time: 30 April 2024 at 13h00

THESIS ABSTRACT Orofacial somatosensory inputs alter speech perception. However, it is still unclear whether hearing-impaired (HI) individuals also show this auditory-somatosensory integration as the changes of speech perception due to somatosensory stimulation. For HI individuals, hearing devices such as hearing aids and/or cochlear implants help speech perception and allow to acquire speech production. Factors concerning these devices such as age at implantation, type and usage duration of hearing devices can affect their ability of speech production and perception, which in turn can affect the acquisition of auditory-somatosensory integration. This thesis investigates the role of orofacial somatosensory inputs in speech perception and production and how hearing-impairment affects the auditory-somatosensory integration. The main experimental paradigm consists of somatosensory stimulations associated with the facial skin deformation that provide speech related information without producing any articulatory movement. We found that the amount of auditory-somatosensory integration in speech perception is related to precision during production performance, suggesting that acquisition level of speech production can be related to the development of auditory-somatosensory integration. Additionally, the current findings showed that repetitive exposure to specific pairs of auditory-somatosensory inputs can be important for speech motor learning. In HI individuals, the auditory-somatosensory integration was dependent on their hearing profiles considering factors such as age at implantation, type of hearing device used (hearing aids or cochlear implants) and the duration of usage of hearing devices. The development of auditory-somatosensory integration in HI individuals could be related to their hearing experience. Finally, HI individuals showed sensorimotor adaptation using altered auditory feedback when their hearing was sufficiently corrected by hearing devices for the detection of small difference of altered auditory feedback. The findings from the current work expand the knowledge on the existing literature on the role of orofacial somatosensory inputs in speech perception by exploration on normal hearing participants and HI participants. These findings could be used for the development of clinical applications such as improving speech therapy and rehabilitation procedures using orofacial somatosensory inputs to rehabilitate articulatory movement. It also has potential in education purposes such as developing tools for second language acquisition where somatosensory inputs could be used for production training.

Lucie MÉNARD FULL PROFESSOR, Université du Québec à Montréal Douglas SHILLER PROFESSEUR DES UNIVERSITES, Université de Montréal Axelle CALCUS ASSISTANT PROFESSOR, Université Libre de Bruxelles Pascal PERRIER PROFESSEUR DES UNIVERSITES, Université Grenoble Alpes Takayuki ITO CHARGE DE RECHERCHE HDR, CNRS GIPSA Lab Jean-luc SCHWARTZ DIRECTEUR DE RECHERCHE EMERITE, CNRS GIPSA Lab