Invariance of relative F0 change field of Chinese disyllabic words

In automatic voice response systems where a large number of words are inserted into fixed sentences, such as in voiceguided car navigation systems, one of the most important problems is the adjustment of the fundamental frequency (F0) contour of the inserted word to suit the F0 context of the fixed sentence. The effects of intonation and tone on the F0 contours of Chinese words can be described in terms of a word-level F0 range (WF0R) and an F0 change field (F0CF). WF0R in any position of a sentence is a tone-independent general F0 range, whereas F0CF is an F0 range taking the tone combination of words into account. Relative F0CF is regulated in reference to WF0R. If WF0R is used to represent the declination of a sentence, the relative F0CF should be invariant but dependent on the tone combination of a word. This paper examines the invariance of the relative F0CF among individuals. From an analysis of four native speakers’ utterances of 160 words in the initial, middle and final parts of three carrier sentences, conducted over 2 days, we show that: (1) Chinese speakers read words in the same sentence position with stable relative F0 change; (2) the relative F0CFs in the middle position of a sentence are generally the same as those in the initial position, but slightly different from those in the final position; and (3) the relative F0CFs reveal that the effects of tone on F0 contour is individual independent.