Vowel coarticulation: Landmark statistics measure vowel aggression.

Regression analysis and mutual information have been used to measure the degree of dependence between a consonant and a vowel, and this has been used to identify the invariance of consonant place and to quantify the coarticulatory resistance of consonants [e.g., Fowler (1994). Percept. Psychophys. 55, 597-610]. This paper presents the first application of this approach to measure coarticulatory properties of vowels, using regression analysis and mutual information on articulatory data of CV syllables produced by seven Taiwan Mandarin speakers. The results show that vowel /i/ shares the most information with the preceding consonant among vowels for the tongue body, whereas vowels /a/ and /u/ are not significantly different from each other in that respect. For the lip articulator, the degree of information sharing for vowels is in the progression: /u/ > /i/ > /a/. Based on the CV model theory of gestural coordination (C-V in-phase relation) and the present results, this study proposes that landmark statistics for vowels reflect the degree of vowel aggression and that V-to-C effect is dominant over C-to-V effect in C-V coarticulation.