Vowel effect on glottal parameters and the magnitude of jaw opening.

This study investigated the relationship among the magnitude of jaw opening, intrinsic fundamental frequency (F0), and glottal parameters in natural speech. Acoustic, jaw opening, and electroglottographic (EGG) signals were simultaneously recorded. The subjects were 10 healthy men with New Zealand English as their native language. Subjects were asked to repeat a standard nonemphasized sentence in which one of the target vowels (/a/, /e/, /i/, /o/, and /u/) was embedded in various contexts. The glottal parameters F0, open quotient (OQ), and speed quotient (SQ) were measured from the EGG signal. Results of a series of one-way repeated-measures analyses of variance (ANOVA) showed a significant vowel effect on the magnitude of jaw opening [F(4, 24) = 25.512, P < .001], F0 [F(4, 28) = 45.415, P < .001] and speed quotient [F(4, 28) = 5.233, P = .003], but not on the open quotient [F(4, 28) = 0.501, P = .735]. The magnitude of jaw opening was found to be inversely related with F0 (r = -0.624, n = 25, P = .0009). These findings showed that the magnitude of jaw opening was related to F0 and that jaw opening might be a control signal for simulation of long-term F0 variation to achieve a higher degree of naturalness in artificial voice.