Effects of Speaking Rate on the Thai Emphatic Tone

Effects of speaking rate on the production of the Thai emphatic tone were investigated as a function of following tonal contexts. Stimuli consisted of bisyllabic adverbials elicited in a fixed syntactic and prosodic environment. Fundamental frequency (F0) and time-normalized, fitted, third-order polynomial curves were used to compare F0 height and slope characteristics of the tonal contours at each of 11 measurement locations between fast and slow speaking rates. The most salient feature distinguishing the emphatic tone between the two speaking rates is the overall flattening of its F0 slope under the fast speaking rate. Analysis of the preceding carrier syllable revealed that changes in F0 height in the early portion of the emphatic tone is primarily due to perseverative effects of tonal coarticulation rather than to speaking rate itself Despite extensive changes in F0 height and slope, the overall average height of the emphatic tone did not vary depending on speaking rate.