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

1aSC14. On the ``locus equation'' and its relation with the consonant place of articulation.

Sig. Dept. ENST, 46 Rue Barrault, 75634 Paris, France

Bjorn Lindblom

Univ. of Stockholm, S-10691 Stockholm, Sweden

The specification of the consonant place of articulation from the locus equation coefficients [Sussman et al., 1256--1268 (1991)] is subject to discussion. For instance, Fowler [Percept. Psychophys. 55, 597--610 (1994)] claims that these coefficients can vary significantly within homorganic consonants. In order to study the relation between these coefficients and place of articulation, V1CV2 utterances were stimulated using the distinctive region model and three different instants of initiating the second vowel: before the acoustic segment of the consonant, at the beginning of that segment, and, in the third case, after it. The results show that linear locus equations can be acceptably fitted to those conditions, but that their coefficients vary as a function of the second vowel onset. It was noted that the locus equations are sensitive to degree of consonant--vowel coarticulation. Also, when y intercepts were plotted against the associated slopes for a given place and across the simulated timing conditions, highly linear relationships were observed. Thus the coefficients of such ``second-order'' locus equations stay constant for a given place despite variations in temporal and coarticulatory conditions. Hence, for natural speech, such ``second-order'' parameters might be a more stable place correlate than first-order coefficients.