Phototransduction as A Velopharyngeal Biofeedback

Dalston, Rodger

Abstract

Despite improved surgical care available to individuals born with a cleft palate, a significant number of individuals will continue to manifest velopharyngeal inadequacy following primary closure of the cleft. Unfortunately, speech therapy generally is ineffective in eliminating hypernasality and nasal emission that persist following surgery. This inability to improve speech performance may reflect the therapeutic approach used by speech clinicians. Clinicians must listen to the patient's speech, judge its accuracy and then suggest modifications. The potential effect of such suggestions may be compromised since the patient's programming of articulatory movements occurs well in advance of clinician-generated feedback. A recently developed device which monitors light transmission through the velopharyngeal port has the potential for providing readily understandable, instantaneous information about spatio-temporal relationships among speech structures, in advance of speech output. This capability suggests a new behavioral approach to modifying articulatory movements. Such an approach could cue the speaker to errors prior to speech output and then assess the success of any response alterations made by the speaker. Simultaneous recording of photodetector output and speech would allow treatment outcome to be quantified objectively through physiological response measures, acoustic analysis and perceptual judgments. The current proposal is intended to allow development and assessment of biofeedback intervention paradigms designed to alter the temporal characteristics of velopharyngeal movement patterns in normal and cleft palate adult speakers. It is anticipated that information gained from this pilot work will enable us to proceed with a long-term effort (RO1) directed toward development of biofeedback treatment strategies whose purpose will be to eliminate hypernasality, nasal emission of air and abnormal articulatory patterns such as glottal stops and pharyngeal fricatives in selected individuals with cleft palate.