Acoustic Analysis and Perception of Cantonese Vowels Produced by Profoundly Hearing Impaired Adolescents

This study investigated mid-vocalic F1 and F2 frequencies as cues to the perception of three Cantonese vowels (/a/, /i/, /Á/) in monosyllabic words produced by ten profoundly hearing impaired and ten normal hearing adolescents. For the control group, there were significant differences in F1 and F2 frequencies among the three vowels as expected. In contrast, the hearing impaired speakers did not show significant F2 frequency differences between /a/ and /Á/. Compared to the vowels produced by the control speakers, the hearing impaired speakers showed a reduction in the range of both F1 (tongue height) and F2 (frontback placement of the tongue). Listeners with normal hearing perceived the vowels produced by hearing impaired speakers with an accuracy of 65% correct for /a/, 32% correct for /i/, and 19% correct for /Á/. These results can be explained by the larger deviations from normal F1/F2 patterns for /i/ and /Á/ than for /a/. One of the most common errors was the confusion of a target vowel with /ø/, which may be explained by the clustering of vowels produced by the hearing impaired speakers towards the center of the F1/F2 space.