Effect of tones on vocal attack time in Cantonese speakers

Vocal attack time (VAT) is the time lag between the growth of the sound pressure signal and the development of physical contact of vocal folds at vocal initiation. It can be derived by a cross-correlation of short-time amplitude changes occurring in the sound pressure and electroglottographic (EGG) signals. Cantonese is a tone language in which tone determines the lexical meaning of the syllable. Such linguistic function of tone has implications for the physiology of tone production. The aim of the present study was to investigate the possible effects of Cantonese tones on VAT. Sound pressure and EGG signals were simultaneously recorded from 59 native Cantonese speakers (31 females and 28 males). The subjects were asked to read aloud 12 disyllabic words comprising homophone pairs of the six Cantonese lexical tones. Results revealed a gender difference in VAT values, with the mean VAT significantly smaller in females than in males. There was also a significant difference in VAT values between the two tone categories, with the mean VAT values of the three level tones (tone 1, 3, and 6) significantly smaller than those of the three contour tones (tone 2, 4, and 5). The findings support the notion that norms and interpretations based on nontone European languages may not be directly applied to tone languages.