An aerodynamic and nasometric assessment of velopharyngeal functioning in hearing-impaired speakers
The purpose of this study was to compare two groups of subjects, normal-hearing and "nasal" hearing-impaired, utilizing data collected from pressure-flow analyses, nasometry, and listener judgments of nasality. No significant differences were found between the two hearing- impaired groups for listener judgments. Nasometric data were used to separate the hearing-impaired into two groups, "non-nasal" and "nasal," with the "nasal" hearing- impaired subjects having higher mean nasalance scores than the remaining two groups. Results of pressure - flow analyses revealed adequate velopharyngeal closure during a bilabial plosive production for all subject groups and no significant differences among the groups for velar timing characteristics during production of a nasal-plosive blend. Overall, the results suggest that hypernasality exhibited by the hearing-impaired subjects may not be due to an inappropriate timing of the control of the velopharyngeal mechanism during the production of oral consonants and oral-nasal consonant blends. The inappropriate opening may be occurring during vowel production. The need for the use of direct assessment of the velopharyngeal mechanism is discussed. In addition, the need for quantification of hypernasality in hearing-impaired speakers is stressed.