Levator veli palatini muscle activity in relation to intraoral air pressure variation in cleft palate subjects.

A comparison of the ranges of levator veli palatini EMG activity for speech versus a nonspeech task for subjects with cleft palate was the focus of this study. EMG values are also compared with subjects without cleft palate obtained in a previous study. Hooked-wire electrodes were inserted into the levator muscle of five adult subjects with cleft palate exhibiting mild hypernasality. Intraoral air pressure was measured concurrently. A blowing task was used to determine the subject's operating range for the levator muscle. Both the nonspeech and speech tasks were designed to sample the widest possible ranges of levator EMG activity. It was found that the subjects with cleft palate used a relatively high activation level for the levator muscle during speech, in relation to their total activation range, compared with the subjects without cleft palate. Implications are discussed in relation to possible anatomic and physiologic differences for cleft palate subjects compared to normal.