Nasopharyngoscopy of the normal velopharyngeal sphincter: an experiment of biofeedback.

In a single normal subject, nasopharyngoscopy was used as an instrument for visual biofeedback of the velopharyngeal sphincter during speech. The goal of the experiment was for the subject to alter the velopharyngeal valving pattern observed during spontaneous speech by manipulating the relative contributions of the velum and pharyngeal walls. After six sessions, each lasting twenty minutes, the subject was able to change velopharyngeal valving pattern at will during short samples of connected speech. This implies the role of learning in velopharyngeal valving and a degree of physiologic plasticity in the velopharyngeal sphincter. The procedure is felt to have possible application to a variety of conditions which have velopharyngeal insufficiency as a symptom.