A COMPARATIVE STUDY OF VOWELS PRODUCED BY CLEFT PALATE SPEAKERS OF ENGLISH IN SINGAPORE

Abstract

Although research in the description of Singapore English abounds, they are mainly auditory or articulatory in nature. Lim's (1992) spectrographic vowels on six Chinese male adults was the first attempt to describe the formant patterns of the normal non-nasal vowels. This study is based on the same procedure and similar criterion of Lim's Academic Exercise (AE). However, the main difference lies in the handicap of the subjects in this research. They are female and male Singaporean Chinese adults with the congenital malformation, cleft lip and palate. Due to this · birth defect, the velopharyngeal competence of the subjects suffers and they produce nasalized vowels. To attempt at an objective description and understanding of their nasality, the spectrograph was used. This study attempts to establish the acoustic correlates of the nasalized vowels of Singapore English (SE) as produced by speakers with cleft palate. Spectrographic analysis was performed on the vowels of SE is spoken by adult Chinese males and females. The vowels were recorded in the environment of [b-V-t], which were further embedded in the carrier phrase "Say --- again". The values for the first formant (FI) were plotted against the difference between the first and second formant (F2') on a vowel chart using the mel scale. The resulting vowel quadrilateral was then compared with similar studies on normal Singaporean speakers. Interpretation of the data was found to be problematical because some formants were found to be absent (especially F2 in [i] and [t]) while information from some peaks was difficult to extract. This led to the use of the computer-based software (Speech 4) for the location of the "missing" and the false formants. The other findings include the establishment of the acoustic correlates of nasality as described by authors such as Fant, Flanagan and Fujimura. The peculiar clustering of vowels in the female disordered subjects appears in the vowel formant chart and is worth noting. This arose because of the presence of the nasal poles. The vowels tended to be clustered in certain regions. There is also the shift in the relative frequency positions, usually in the F2s. The frequency positions of Fls are mildly affected in the vowels of the male disordered subjects, quite unlike those of the disordered female subjects. In conclusion, the use of spectrographic studies in the linguistic sciences needs to be reconsidered, especially in the study of nasalized vowels produced by a special population such as this. Undoubtedly spectrographic analysis through computer-implemented techniques still provides an objective and a more accurate description of speech sounds.