Comparison of cineradiographic and photodetection techniques for assessing velopharyngeal function during speech.

This study investigated the extent to which high-speed lateral-view cineradiography and a photodetector system described by Dalston (1982) provided comparable information concerning velopharyngeal activity. We observed the production of isolated utterances and running speech for 2 subjects in three contexts. A comparison was made between the times at which the velopharyngeal port was observed by each method to begin opening, reach maximal opening, begin closing, and initially attain closure. The photodetector system was found to be sensitive to changes in velar position observed by cineradiography. The correlation between the magnitude of photodetector output and the magnitude of velar displacement from the posterior pharyngeal wall was .89 for Subject 1 and .78 for Subject 2. The lack of a perfect relation between the output of the photodetector device and movements of the velum observed by cineradiography was not unexpected given the two-dimensional limitation of lateral cineradiography and the complexity of events associated with changing port size. The significance of these findings is discussed with respect to the potential research and clinical uses of this photodetector system.