Technical advances toward an endoscopic-phototransducer approach to investigation of velopharyngeal physiology.

Abstract

This study aimed to examine the response characteristics of a new generation phototransducer and to test new recording and processing procedures when used with endoscopy to track velopharyngeal closure during normal speech. Integrated phototransducer-endoscopy response linearity was laboratory tested using a wide range of simulated velopharyngeal orifice areas. In vivo speech testing was completed to determine the effect of endoscope to light receptor distance on measurements documenting variations in normal velopharyngeal closure. Phototransducer response linearity was excellent (r = .99) provided an indirect (reflected light) orientation was used between the endoscope and the light-sensing fiber coupled with the phototransducer. Phototransducer response time exceeded expected velopharyngeal movement rates by an order of magnitude. In vivo speech measurements were affected by the distance between the light-emitting endoscope and the light-receiving tip of the light-sensing fiber. Data normalization to a light-out condition effectively controlled for this expected phenomenon. Patterns of velopharyngeal valving during speech were found to be stable and appropriate given the phonetic content of the utterance. Technological and data-processing advances support further exploration of an integrated phototransducer-endoscopic approach to studying velopharyngeal closure for speech. Additional studies involving normal speakers are under way.