Velopharyngeal orifice areas during tasks used clinically to stimulate improved velopharyngeal closure.

Abstract

Data-based evidence supporting behavioral treatments of velopharyngeal impairment is sparse. This study examined the initial step in some behavioral treatments--testing stimulability for improved velopharyngeal closure--to explore whether velopharyngeal orifice areas for obstruents produced during stimulability tasks are smaller than areas for the consonants produced without special stimulability instructions. Subjects were eight children between 5 and 15 years of age who had audible nasal emission during pressure consonants. Six subjects were born with overt or submucous palatal clefts and two showed no evidence of palatal clefting. Three kinds of tasks were used to probe each subject's stimulability for reduced velopharyngeal orifice during one or more pressure consonants: (a) increasing a consonant's intraoral air pressure and slowing rate of syllable production, (b) moving from oral blowing to production of a consonant, and (c) moving from an obstruent produced with a relatively smaller velopharyngeal opening to production of another obstruent that was typically produced with a relatively larger velopharyngeal opening. Velopharyngeal orifice areas were computed during obstruents produced in the stimulability task conditions and during the obstruents produced with no special instructions. Performance of each subject on each task was classed as meeting criteria for strong, moderate, weak, or no evidence of stimulability. For each stimulability task, the performance of all subjects was summarized. One subject's velopharyngeal areas were consistently reduced when she produced obstruents with greater intraoral air pressure during single syllables. None of the children had smaller velopharyngeal areas when speaking at a slower rate. Obstruents shaped from oral blowing were produced with smaller velopharyngeal areas in five of the eight subjects. Of the six subjects for whom production of /s/ was shaped from /∫/, /Θ/, or /t/, three showed smaller velopharyngeal areas. These results indicate that, for at least some individuals with velopharyngeal impairment, the stimulability tasks involving shaping from oral blowing or other obstruents may yield relatively immediate reductions in velopharyngeal area. However, the reductions in velopharyngeal area will be of clinical significance only if they are accompanied by improvements in speech and if the child can learn to use the improved velopharyngeal behavior in spontaneous speech.