A laryngeal and lingual ultrasound study of the Canadian French voicing contrast

Abstract Vocal fold vibrations are more difficult to achieve in obstruents than sonorants due to the aerodynamic voicing constraint (AVC), i.e., the fact that a buildup of air pressure in the supraglottal cavity during oral closures reduces the transglottal airflow. The AVC can be circumvented by various voicing adjustment gestures, such as larynx lowering, tongue root advancement and tongue body lowering. The current study employed laryngeal and lingual ultrasound to investigate the use of these strategies in Canadian French. The vertical movement of the larynx was measured using optical flow analysis, while lingual movement was analyzed by tracking X and Y coordinates at distinct fanlines across consecutive images. Results revealed that there was more pronounced larynx lowering in voiced obstruents and that it tended to be greater in voiced stops than in voiced fricatives. Tongue-related maneuvers displayed more interspeaker variation but tendencies showed that the tongue root was more advanced in voiced stops than in voiced fricatives and slightly more for /d/ than /b/. Significant tongue body lowering was observed for both voiced stops and voiced fricatives only preceding the vowel /a/. Finally, larynx lowering was strongly correlated with voicing duration in voiced obstruents. A similar but weaker correlation was found for tongue root advancement. Overall, this study suggests that larynx lowering is an efficient strategy to circumvent the AVC in Canadian French but that some speakers may also resort to lingual adjustments. Additional strategies that are known to play a role, such as nasal or oral leakage, were not considered.