Vowel production in sighted children and congenitally blind children

Abstract

It is well known that vision plays an important role in speech perception. At the production level, we have recently shown that speakers with congenital visual deprivation produce smaller displacements of the lips (visible articulator) compared to their sighted peers [L. Ménard, C. Toupin, S. Baum, S. Drouin, J. Aubin, and M. Tiede, J. Acoust. Soc. Am. 134, 2975–2987 (2013)]. To further investigate the impact of visual experience on the articulatory gestures used to produce intelligible speech, a speech production study was conducted with blind and sighted school-aged children. Eight congenitally blind children (mean age: 7 years old, from 5 years to 11 years) and eight sighted children (mean age: 7 years old, from 5 years to 11 years) were recorded using a synchronous ultrasound and Optotrak imaging system to record tongue and lip positions. Repetitions of the French vowels /i/, /a/, and /u/ were elicited in a /bVb/ sequence in two prosodic conditions: neutraland under contrastive focus. Tongue contours, lip positions, and formant values were extracted. Acoustic data show that focused syllables are less differentiated from their unfocused counterparts in blind children than in sighted children. Trade-offs between lip and tongue positions are examined.