Initiation and maintenance of lingual bracing posture

Abstract

Lateral tongue bracing is a posture in which the tongue makes contact with the sides of the palate and the upper molars [Gick et al., 2017, JSLHR, 60(3), 494-506]. This cross-linguistic posture is pervasively maintained throughout speech and is only released for the production of some laterals and low vowels [Liu, et al., JIPA, in press]. We hypothesize that the raised (braced) and lowered (unbraced) speech postures may be initiated by a preceding postural “trigger.” Participants were asked to read stimuli aloud while audio and coronal ultrasound video of the tongue were simultaneously recorded. Stimuli consisted of sentences, each of which contained the lingually “neutral” target stimulus “Hubba-Bubba” (HB). HB was surrounded by various combinations of braced and unbraced phonetic environments. HB production timeframes were extracted and the relevant image sequences were converted into videokymographs to measure tongue position. Preliminary findings from three participants suggest that the tongue remained at a higher position during production of HB when it was preceded by a braced sound and remained at a lower position during production of HB when preceded by an unbraced sound. This suggests that the preceding sound may act as a trigger for braced or unbraced tongue posture. We also report on the acoustics of HB in braced and unbraced environments as well as the correlation between the center and the sides of the tongue. Results and implications of these analyses will be discussed.