Intrinsic fundamental frequency of vowels in sentence context.

High vowels have a higher intrinsic fundamental frequency (F0) than low vowels. This phenomenon has been verified in several languages. However, most studies of intrinsic F0 of vowels have used words either in isolation or bearing the main phrasal stress in a carrier sentence. As a first step towards an understanding of how the intrinsic F0 of vowels interacts with intonation in running speech, this study examined F0 of the vowels [i,a,u] in four sentence positions. The four speakers used for this study showed a statistically significant main effect of intrinsic F0 (high vowels had higher F0). Three of the four speakers also showed an interaction between intrinsic F0 and sentence position such that no significant F0 difference was observed in the unaccented, sentence-final position. The interaction was shown not to be due to vowel neutralization or correlated with changes in the glottal waveform shape, as evidenced by measures of the first formant frequency and spectral slope. Comparison with studies of tone languages and speech of the deaf suggests that both the lack of accent and the lower F0 caused the reduction in the intrinsic F0 difference.