Brain dynamics of speech mode: Whispered versus Standard speech
Poster D58 in Poster Session D with Social Hour, Friday, October 7, 5:30 - 7:15 pm EDT, Millennium Hall
Bryan Sanders1, Monica Lancheros1, Marina Laganaro1; 1Faculty of Psychology and Educational Sciences, University of Geneva, Geneva, Switzerland
Speech production (SP) involves a complex interplay of several sub-systems that result in the production of intelligible and normally phonated speech in typical speakers. Multiple studies have investigated the main brain regions responsible for Speech Motor Control (i.e., Tourville & Guenther, 2011). However, the temporal dynamics of the brain regions involved in Speech Motor Control remains largely unexplored (Tourville & Guenther, 2011). Studying speech modes, which are specific variations of SP (Kelly & Hansen, 2021; Zhang & Hansen, 2007), could provide relevant insights on the mechanisms that underly the encoding of speech. More precisely, whispered speech is a speech mode which is unique to humans (Tsunoda et al., 2011). Whispering means speaking without vibration of the vocal folds (Kelly & Hansen, 2021) resulting in reduced intelligibility and perceptibility (Zhang, 2012). Behavioral observation of whispered speech suggests intentionality and adaptation of the vocal tract. Therefore, whispering can be conceptualized as a switching mechanism which overlay onto the mechanisms of normal SP (Tsunoda et al., 2011). In this study, we will investigate the electrophysiological signatures of the brain processes that differ between normal and whispered speech and the encoding time-window at which the switching mechanism occur. 20 participants produced non-words in a delayed production task under high density Electroencephalography (EEG) recording. They did several blocks alternating between normal SP and whispered SP. Event related potential (ERP) were extracted aligned to the vocal onset of speech backwards (response-locked). Waveform amplitudes, microstates and time frequency analyses will be analysed by comparing the standard to the whispered condition. As the analyses are in progress, only preliminary results on six participants are presented here. Participants had overall good accuracy in both conditions, although slightly inferior in the standard condition (91.74% versus 93.02%). Reaction times were 18 ms slower in the whispering condition (653.75 versus 636.62 ms). On ERPs, the microstate analyses highlighted a difference on topographies between the two conditions around 150 ms before the vocal onset. The preliminary analyses do show different ERP correlates in the response-locked signal, which will have to be confirmed on the entire group of participants and with further analyses. The investigation on brain mechanisms underlying different speech modes is promising and will probably contribute to a better comprehension of the different mechanisms underlying Motor Speech Control.
Topic Areas: Speech Motor Control, Language Production