Fundamental frequency peak delay in Mandarin.

Fundamental frequency (F0) peak delay (henceforth peak delay) refers to the phenomenon that an F0 peak sometimes occurs after the syllable it is associated with either lexically or prosodically. Although peak delay has been reported for various languages, the mechanism of its occurrence has so far remained unclear. In Mandarin, peak delay has been found to occur regularly in the rising (R) tone but not in the high (H) tone. The present study investigates the underlying mechanisms of peak delay by examining its relationship with tone, tonal context, and speech rate. An experiment was conducted to test the possibility that peak delay may occur also in the H tone in Mandarin if the H-carrying syllable is sufficiently shortened. Native speakers of Mandarin Chinese recorded three types of sentences each containing a H, a R, or a weakened H tone. The sentences were produced at three speech rates: normal, fast and slow. Analysis of F0 contours and peak alignment revealed that at normal speech rate, peak delay occurred regularly in both the R and weakened H tones but only occasionally in the H tone; at slow speech rate, peak delay continued to occur regularly in the R tone but only occasionally in weakened H and rarely in the H tone; at fast speech rate, peak delay occurred not only regularly in the R and weakened H tones, but also frequently in the H tone. Results of F0 contour alignment analysis indicate that peak delay occurs when there is a sharp F0 rise near the end of a syllable, regardless of the cause of the rise. The finding of this study provides support for the view that, rather than due to actual misalignment between underlying pitch units and segmental units, much of the variability in the shape and alignment of F0 contours in Mandarin is attributable to the interaction of underlying pitch targets with tonal contexts and articulatory constraints.