Lip muscle activity related to speech rate and loudness.

Changes in suprasegmental speech parameters may require adjustments in oral motor control that are reflected in the activity of perioral musculature. In order to evaluate possible patterns of difference, perioral surface electromyographic (EMG) signals were obtained from 20 adults who read a paragraph aloud at habitual rate and at self-judged proportionately slower and faster rates, at habitual loudness and at proportionately softer and louder levels, and in a "precise" manner. EMG amplitude analysis showed significant task effects, with higher average amplitudes for fast, loud, and precise speech and lower average amplitudes for slow and soft speech. These results are compatible with a model of multidimensional reorganization of speech motor control for suprasegmental changes applied to connected speech.