Lip movement in apraxia of speech.

Peak articulatory velocity of the lower lip and temporal coordination between the upper and lower lips were studied in 5 neurologically impaired subjects with speech behaviors consistent with a diagnosis of apraxia of speech. Differences in velocity and the timing between the movement onset of the two lips were compared for accurate and inaccurate productions of words. Peak articulatory velocity also was measured during the productions of the syllable [pae] and during a nonverbal movement. There were no systematic differences across accurate and inaccurate productions of words in peak articulatory velocity or movement onsets of the two lips. Furthermore, there were no systematic changes in movement velocity related to speech rate. We conclude that some apraxic speakers do not have a defect in the ability to produce high movement velocities.