Ames Vocal Dynamics Lab., Lenox Hill Hospital, 100 E. 77th St., New York, NY 10021
City College of New York
Stanley M. Blaugrund
Ames Vocal Dynamics Lab., Lenox Hill Hospital
The purpose of this study is to design a method to reconstruct the shapes of articulators including the vocal tract and nasal tract during phonation and to quantitatively identify velopharyngeal dysfunction when it occurs. Voice in patients with velopharyngeal insufficiency have the psychoacoustic impression of hypernasality that results from an over abundance of sounds resonating in the nasal tract. Patients with unrepaired soft palate clefts typically demonstrate this abnormal speech. The articulation model of velopharyngeal dysfunction is predicated upon the lossless tube model. During recording of the sustained /a/ sound, subjects were asked to block their nostrils with two fingers. The resulting closed nasal tract introduces zeros and the opened vocal tract contributes poles. Therefore, an ARMA model is formed. PARCOR analysis and the inverse filter technique are used to reconstruct both the shapes of the vocal tract and the nasal tract. The sufficiency of the velopharynx can be determined by measuring the cross-sectional area of velopharynx.