Locus equations were investigated as a potential higher-order metric capable of illustrating relational invariance for place of articulation in voiced initial stop consonants independently of vowel context. Locus equations are straight line regresson fits to data points formed by plotting onsets of F2 transitions along the y-axis and their corresponding midvowel nuclei along the x-axis. Twenty subjects, 10 male and 10 female, produced /b/v/t/, /d/v/t/, and /g/v/t/ tokens for 10 vowel contexts. Each CVC token was repeated in a carrier phrase five times yielding 150 tokens per subject. Formant measures were obtained using the MacSpeech Lab II speech analyis system. Locus equation scatterplots revealed extremely tight clustering of points around the regression line that were consistent across speakers and gender. Derived slope and y-intercept parameters were significantly different across stop place categories. The relative value of F2 onset as it linearly changes in relation to the coarticulatorily produced vowel reflects a stable acoustic correlate capturing relational invariance for stop place. A discriminant analysis using F2onset & vowel as predictors showed 82%, 78%, and 67% classification rates for labial, alveolar, and velar place. Using derived slope and y-intercept values as predictors led to 100% classification into stop place categories.
Cite as: Sussman, H.M. (1991) An investigation of locus equations as a source of relational invariance for stop place categorization. Proc. ESCA Workshop on Phonetics and Phonology of Speaking Styles, paper 050
@inproceedings{sussman91_ppst,
author={Harvey M. Sussman},
title={{An investigation of locus equations as a source of relational invariance for stop place categorization}},
year=1991,
booktitle={Proc. ESCA Workshop on Phonetics and Phonology of Speaking Styles},
pages={paper 050}
}