An Electromyographic Study of Velopharyngeal Function in Speech

Abstract

Electromyographic (EMG) recordings were obtained from the levator palatini, superior pharyngeal constrictor, middle pharyngeal constrictor, palatoglossus, and palatopharyngeus muscles of three talkers of American English. Bipolar hooked-wire electrodes were used. Each subject read nonsense words composed of three vowels (/i, a, u/), six stop consonants (/p, b, t, d, k, g/), and two nasal consonants (/m, n/) to form various stop-nasal and nasal-stop contrasts. Multiple repetitions of each utterance type were recorded and subsequently processed by computer. The levator palatini was found to be the primary muscle of velopharyngeal closure for each of the subjects. The palatopharyngeus also showed consistent oralization activity for each of the subjects, although the activity of this muscle was strongly affected by vowel environment. Two subjects showed pharyngeal constrictor muscle activity related to oral articulation, but pharyngeal constrictor activity for the third subject was related to vowel quality. Nasal articulation was accomplished by suppression of oral articulation for each subject. Vowel quality affected the strength of EMG signals for lateral and posterior pharyngeal wall muscles. In those cases where activity was different for the three vowels, activity was greatest for /a/.