Poster E57, Thursday, August 22, 2019, 3:45 – 5:30 pm, Restaurant Hall
Lateralized control of spectral and temporal speech features in speech production
Mareike Flögel1, Susanne Fuchs2, Christian Kell1;1Goethe University, 2Leibniz Center for General Linguistics (ZAS)
Albeit the traditional view that speech processing is especially performed by the left cerebral hemisphere, the analysis of acoustic speech feedback information to adapt speech production in the presence of disturbances seems to rely on the right hemisphere [Tourville, J. A., & Guenther, F.H. (2011). Language and Cognitive Processes, 26(7), 952–81]. While feedback control circuits for the control of spectral speech features (e.g. pitch, formant structure) have been well characterized by means of altering the acoustic speech feedback of speaker’s in near realtime [Tourville, J. A., Reilly, K. J., & Guenther, F. H. (2008). NeuroImage, 39(3), 1429–1443; Toyomura et al. (2007). Neuroscience, 146(2), 499-503], comparable investigations for the control of temporal speech features (e.g. length of phonemes and their transitions) are lacking. The current study investigated whether the proposed right-lateralization of feedback control reflects a right hemisphere preference for sensory processing during speech production or a right hemisphere preference for spectral processing [Zatorre, R.J., & Belin, P. (2001). Cerebral Cortex, 11(10), 946-953]. Healthy, native German speakers’ auditory speech feedback was manipulated spectrally or temporally [Tourville, J.A., Cai, S. & Guenther, F.H. (2013). Proceedings of Meeting on Acoustics, 9:060180] during the production of CVC monosyllabic pseudowords. Spectral manipulations either increased the first formant of vowels or the spectral center of gravity of fricatives by 20% relative to production. Time warping prolonged the vowel or fricative by 20% and thus altered phoneme timing. A dichotic speech feedback alteration experiment (n = 40) and a binaural altered auditory feedback functional magnetic resonance experiment (n = 44) revealed a left ear/right hemisphere advantage for speaking with spectrally altered speech feedback compared to normal speaking and a right ear/left hemisphere advantage for speaking with temporally altered auditory feedback compared to normal speaking. Further, resting state functional connectivity was performed to identify the consequences of adaptive learning. Learning to adapt temporal feedback manipulations was associated with increased frontotemporal coupling in the left hemisphere while learning to adapt to spectral feedback manipulations showed increased frontotemporal coupling in the right hemisphere. Our results suggest that the right hemisphere preferentially processes auditory speech feedback information to control spectral speech features while the left hemisphere preferentially analyses the acoustic speech signal to control temporal speech features during speech production. Our results extent current models of speech motor control by showing that feedback control relies on contributions of both cerebral hemispheres that can be differentiated along the spectro-temporal axis.
Themes: Speech Motor Control, Language Production
Method: Functional Imaging