How Rhythm Stabilizes Speech Production: Adaptation of Coordinative Rhythmic Patterns in Sensorimotor Control Processes

During speech production, articulators engage in coordinated movements to achieve specific linguistic objectives, facilitating rapid adaptation within the motor system in response to perturbations. At a broader organizational level, syllables are grouped into prosodic units (e.g., accentual phrases in French). However, it is conceivable that syllable grouping may also interact with sensorimotor control during speech production. Specifically, we hypothesize that under conditions of delayed auditory feedback (DAF), consecutive syllables grouped together may exhibit heightened cohesion, leading to the emergence of a supra-syllabic level organization that strongly influences syllable-level organization. To investigate this hypothesis, we conducted experiments wherein French female speakers completed a sentence repetition task under varying levels of DAF. The results reveal that under DAF conditions, the duration difference between accented and unaccented vowels within accentual phrases increases. Correspondingly, patterns of spectral changes show a tendency toward hypo-articulation and an increase in temporal control. Moreover, we observe stronger coordination between the modulations of acoustic amplitude due to the production of individual syllables and those aimed at regulating syllabic saliency. These results indicate stronger cohesion between grouped syllables and suggest an interaction between the rhythmic organization of speech and sensorimotor control.

Keywords: sensorimotor control, delayed auditory feedback, speech rhythm, prosody, syllable grouping, amplitude modulation, spectral analysis