Figure 2.

Illustration indicates the data used in analyses for poly-syllable speech task. Left vertical line is identified as the instance of peak closing velocity right before the initial opening of the lower lip marker. Right vertical line is defined as the instance when the lower lip was at the peak velocity of its closing movement during the final syllable of the lower lip marker. Both vertical lines mark the displacement period for spatiotemporal index (STI) analysis and the time interval between two points used to measure overall utterance duration in the poly-syllable speech task.