ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

5pSC2. Prediction of obstruent spectra from the slope of preceding and following second formant transitions.

Gary Weismer

Vidya Guhan

Ray D. Kent

Dept. Commun. Disord. and Waisman Ctr., Univ. of Wisconsin-Madison, 1500 Highland Ave., Madison, WI 53705-2280

There is evidence that the slope of second formant (F2) transitions provides an index of the severity of speech mechanism involvement in motor speech disorders [Weismer et al., 1085--1098 (1992)]. From an articulatory perspective, the slope of the F2 transition is an ordinal index of the rate of change in vocal tract configuration. It was hypothesized that, for single words, these F2 slopes would predict quantitative spectral characteristics of adjacent obstruents, under the assumption that the rate of change in vocal tract configuration during a vocalic segment would influence the articulation of a preceding or following obstruent. Quantification of obstruent spectra was achieved by means of spectral moments, which were regressed on F2 transition slopes for a group of normally articulating men and a group with amyotrophic lateral sclerosis, a degenerative motoneuron disease typically associated with dysarthria. Results partially confirmed the hypothesis for both groups of subjects; the findings will be discussed in terms of separate treatment of vocalic and obstruent segments in a model of speech intelligibility. [Work supported by NIH.]