On the relation between locus equations and subglottal resonances

Abstract

In consonant-vowel transitions, it is well known that the frequency of the second formant at the onset of voicing (F2onset) is linearly correlated with the frequency of the second formant in the middle of the vowel (F2vowel). This correlation, which holds across vowel contexts, is an indication of the amount of coarticulation between the consonant and the vowel, and is characterized by a regression line (locus equation) with a slope and y-intercept that depend upon the consonant place of articulation. Furthermore, for a given place of articulation, slopes and y-intercepts of a collection of locus equations are inversely related. The cause of this inverse relation has not yet been explained. In this presentation it will be shown that the inverse relation implies that the coordinate system of the F2vowel vs. F2onset space is shifted away from the origin, and that the size of the shift is a function of both the place of articulation and of the second and third subglottal resonances. © 2009 Acoustical Society of America.