A Radiographic Study of Nasality

Abstract

It is generally accepted that the degree of perceived hypernasal voice quality is related to the configuration of the entire oral—pharyngeal-nasal tract resonance system and not just to the degree of velopharyngeal aperture. Subtelny (4) found relationships between degree of nasality and a number of vocal tract measures. She noted that, for the vowel /i/, the tongue was placed in a more anterior position in cleft palate sub— jects than in normal subjects and that the anterior oral cavity tended to be shorter and the posterior oral cavity longer in the cleft palate group than in normals. Warren and Ryon (5), in an analog study, concluded that in the presence of a velopharyngeal aperture, air pressure and airflow characteristics are determined by oral opening, nasal resistance , and respiratory effort rather than the degree of velopharyngeal aperture. Lubker and Moll (3) reported that " nasal air flow is dependent not only upon the amount of velopharyngeal opening but also upon the amount of oral constriction " (p. 271). In addition, Fant (2) and various other authors have stressed the variability of acoustic output of the vocal system from subject to subject and from vowel to vowel prob— ably due to individual differences in the physical properties of vocal tracts. In an earlier report (1), the results of an acoustic study of nasality were presented. The present study serves as an extension of this and was designed to investigate certain physical correlates of nasality and their relationships to the acoustic results reported earlier. Procedures Three groups of subjects were selected for study. The groups consisted of twenty normal speakers, twenty speakers classified as having func— tional nasality, and twenty speakers with cleft palate and nasality. All subjects were adult males. Lateral head X rays were taken of each subject during the center portion of the vowel /i/ in plosive consonant en— vironment by means of an Angra'brite stereocep'halostat triggered by a voice—operated relay.