The acoustic counterpart to coarticulation resistance and aggressiveness in locus equation metrics and vowel dispersion

Abstract

In speech articulation, a segment with high coarticulatory resistance in tongue configurations tends to exhibit greater coarticulatory aggressiveness on neighbouring segments. This study examined whether this articulatory relationship can be acoustically captured through locus equations and the magnitude of vowel dispersion. This question was investigated in CV sequences in English where C varies in the degree of articulatory constraints imposed on the tongue dorsum. The results show a tight relationship between locus equation slopes and vowel dispersion, where coarticulatory resistance and aggressiveness appear to be two sides of the same coin in speech acoustics.

Can locus equations model dialect-specific variation in coarticulation?

“…This study confirms that LEs successfully model C-V effects across a variety of contexts, strongly depending on the place of articulation (Hardcastle & Hewlett 1999;Perillo et al 2015;Bang 2017). Less consistent results were obtained as language-specific effects were evaluated in highly similar dialects.…”

“…Experimentally, a classic method of indirectly assessing the degree of consonant-vowel (C-V) coarticulation is represented by first order locus equations (LEs, henceforth). They also capture articulatory-acoustic relationships, carrying information about places of articulation -see Perillo et al (2015) and Bang (2017), for reviews. Indeed, LEs are regression lines fitting scatterplots of vowel formant frequencies.…”

V-to-V Coarticulation Induced Acoustic and Articulatory Variability of Vowels: The Effect of Pitch-Accent

“…In line with the above, the aim of the present study is (1) to further explore if prominence provokes CR, (2) to further clarify the effect of vowel quality on CR, and (3) to uncover the interrelations of acoustic and articulatory variability of vowels due to carryover V-to-V effects conditioned by pitch-accent. For this purpose, we analyzed V-to-V coarticulatory effects both in the acoustic and the articulatory domains, in real words, but in phonetically well-controlled contexts, in minimally constrained C-context, in the presence/absence of sentence-level accent (+ word stress co-varying with accent) in Hungarian, in a high number of speakers.…”

“…In the acoustic domain, we measured F1 and F2 of the target vowel at the left edge (median of first 10%; F2onset) and in the temporal midpoint (median of middle 10%; F2mid) in Praat [10] automatically, using the Burg algorithm. Building on the locus equation approach, to gauge the degree of coarticulation, first, we fitted linear models on F2mid and F2onset [2], as a function of context and condition, for each vowel separately. Then, we also calculated the difference of F2onsets of coarticulated (asymm) and non-coarticulated (symm) instances (to get data comparable to [7], the articulatory data of [4], and the articulatory data of the present study).…”

“…The extent a segment is susceptible to coarticulation, i.e., the contextual variability it exhibits, is referred to as coarticulatory resistance (CR; greater resistance = less variance) [2]. CR in Vto-V coarticulation may be influenced by several factors.…”