Analysis of Normal and Slow Speech Rate on the F0 Contour of Tones in Mandarin Broadcasting Speech

Existing studies have shown that variations in speech rate can affect the acoustic characteristics at segmental levels, such as vowels and consonants, but the suprasegmental characteristics are seldom discussed. This research aims to investigate the influence of speech rate variations on the F0 contour of tones in Mandarin broadcasting speech. Utilizing broadcasting materials from CCTV News, this paper compares the difference in F0 contours between normal and slow rate, employing a linear mixed-effects modeling and growth curve analysis. The results indicate that as the speech rate decreases from normal to slow, the mean F0 of all four tones significantly decreases; the F0 contour of the falling tone (T4) becomes less steep while the corresponding indices of the other three tones (T1~3) exhibit minimal change. The U-shaped contours of all the four tones show no significant alterations; the F0 range of the falling tone (T4) broadens, whereas those of the other three tones remain largely unchanged. In conclusion, the falling tone (T4) is more susceptible to off-target effects at slower speech rates, suggesting that future studies should establish more detailed speech rate gradients and provide specific speech rate values to more accurately explore the impact of speech rate variations on acoustic parameters.