Velopharyngeal sphincter physiology in deaf individuals.

Fifty-three deaf subjects with a history of prelingual profound bilateral sensorineural hearing loss, similar language habilitation with hearing aids, and normal velopharyngeal structures underwent a study protocol including speech evaluation, behavioral pure-tone audiometry, videonasopharyngoscopy, multiview videofluoroscopy, and electromyography of the velopharyngeal muscles. Subjects were divided into two groups: the first group included 13 subjects with normal nasal resonance or mild hypernasality (four normals and nine with mild hypernasality); the second group had subjects with severe hypernasality and severe articulation deficits. Pure-tone thresholds, velopharyngeal closure patterns, and electromyographic activity of velopharyngeal muscles were similar for both groups of subjects. However, in subjects with severe hypernasality, despite normal muscle activity as observed by electromyography, velopharyngeal valving activity lacked rhythm and strength during speech. It is concluded that deaf subjects may present a functional disorder of the velopharyngeal sphincter related to absence of auditory regulation during phonation. Visual biofeedback using videonasopharyngoscopy may be useful for treating this disorder.