The current study examined the change in articulatory patterns when speakers were asked to increase and decrease their speaking rate by matching metered and rhythmic audio recordings and by matching metered and rhythmic audiovisual recordings. There were 10 participants, five male and five female, ranging in age from 20 to 36 with a mean age of 25. Participants spoke the sentence "Don't fight or pout over a toy car"under rhythmic, metered, fast and slow conditions and in response to audio only or audiovisual models, resulting in eight speaking conditions: audio metered fast, audiovisual metered fast, audio metered slow, audiovisual metered slow, audio rhythmic fast, audiovisual rhythmic fast, audio rhythmic slow, and audiovisual rhythmic slow. Each participant had five sensors glued to their tongue, teeth and lips and articulatory movements were recorded with an NDI Wave electromagnetic articulograph. 10 tokens of the target utterance were analyzed for duration and Spatiotemporal Index (STI). STI was then computed for the vertical movements of the tongue, jaw and lower lip, as well as lip aperture in order to measure variability of speech movements over multiple sentence repetitions. Stroke metrics based on the speed history of the articulators were also computed in order to reveal average kinematic features of articulatory gestures, or the individual. movement strokes that occurred between successive speed minima in running speech. Statistical analysis revealed that STI measures did not change significantly in response to the different rate conditions. This study demonstrated that in neurotypical individuals, articulatory patterns including stroke count, onset speed, peak speed and hull area changed significantly in faster or slower speech. Additionally, the results revealed that both metered and rhythmic cues and both audio and audiovisual cues are effective in decreasing and increasing speaking rate without significantly impacting the STI (i.e., consistency) of articulatory movements. Therefore, it may be that a speaker's efforts to match the audio and audiovisual cues in real-time more significantly affected articulation patterns than whether cues were rhythmic, metered, audio or audiovisual.

The current study examined the effect of different rate change approaches on speech movement patterns, including increasing and decreasing speaking rate volitionally, as well as with delayed auditory feedback (DAF). There were 10 participants, five male and five female, with a mean age of 25 years. All were typical speakers. Participants spoke the sentence “Don’t fight or pout over a toy car” under slow, fast and DAF speaking conditions. A total of 5 sensors were glued to each participant’s tongue, teeth, and lips. NDI Wave electromagnetic articulography recorded the articulatory movements from these sensors as the participants spoke. Metrics for the individual movement strokes, or articulatory gestures, were calculated based on the movement speed of the articulators during the target utterance. Ten tokens of the target utterance were analyzed for stroke count, stroke speed, duration, and hull area. Vertical movements of the tongue, jaw, lips, and lip aperture were used to calculate the spatiotemporal index to assess variability in speech movements across 10 sentence repetitions. Statistical analysis revealed that articulatory patterns changed significantly in slower speech. A speaker’s efforts to naturally decrease speech rate affected articulation patterns more than did the fast and DAF conditions. Findings from this study can be used as a foundation for future studies with dysarthric individuals, which may increase our understanding of mechanisms of change in the remediation of disordered speech.