ASA 124th Meeting New Orleans 1992 October

4aSP3. A cross-linguistic validation of locus equations: Are there ``phonetic hot spots'' in CV acoustic space?

Harvey M. Sussman

Farhan Ahmed

Katherine Hoemeke

Dept. of Commun. Sci. and Disord., Univ. of Texas, Austin, TX 78712

A previous study [Sussman et al., J. Acoust. Soc. Am. 90, 1309--1325 (1991)] of American English CV coarticulation showed a remarkably linear relationship between onset frequencies of F2 transitions (plotted along the ordinate) in relation to midvowel target frequencies (plotted along the abscissa) in CVC tokens with initial /bdg/ followed by ten medial vowels. Slope and y intercept of regression functions (``locus equations'') fitted to these coordinates systematically varied as a function of stop place. Discriminant analyses, using as predictor variables, slope and y intercept, yielded 100% correct classification of stop place categories. Locus equations provide a systematic lawfulness to coarticulatory variation and a relationally invariant phonetic index for stop place classification. The present study extends the metric to three additional languages---Thai, Cairean Arabic, and Urdu. Resulting scatterplots were extremely linear and varied as a function of stop place. Plotting slope X y intercept yields a derived map of CV phonetic space with which to relationally compare 2, 3, and 4-stop place languages. Within-language stop place contrasts were consistly divergent in CV space. Variability of labial, alveolar/dental, and velar coordinates across five languages showed fairly broad clustering of stop place categories, rather than narrowly focused ``phonetic hot spots.'' The data are discussed in relation to quantal and adaptive dispersion theories. [Work supported by NSF.]