Arthur S. Abramson
Haskins Labs., 270 Crown St., New Haven, CT 06511-6695 and Univ. of Connecticut, Storrs, CT 06269-1145
This is part of a larger effort to test the robustness over speaking styles of acoustic properties that underlie phonological contrasts. So much of the knowledge comes from the study of citation forms that one might wonder whether in running speech the presence of much top-down information and other contextual cues does not lead to the impoverishment of some of the bottom-up phonetic information. A good candidate for possible instability is relative duration as a means of distinguishing phonemes. The Thai language, in both production and perception, uses relative duration to distinguish its ``short'' and ``long'' vowels. In this study vowel durations were measured under three conditions. (1) Eight minimal pairs of words were recorded in carrier sentences by four native speakers at two rates, normal and fast. (2) Casual unrehearsed conversations were recorded by two couples. (3) Many words and short expressions taken from each person's part of a conversation were read aloud by that person. The data show that the quantity distinction in Thai is rather stable. The overlap in the pooled data from running speech largely disappears once certain contextual factors are taken into account. [Work supported by NIH Grant HD-01994 to Haskins Labs.]