Syllabifications of the /st/ cluster and vowel-to-vowel coarticulation in English

This paper investigates how different syllable boundaries involving the /st/ cluster in English affect vowelto-vowel (v-to-v) coarticulation. Although several models of coarticulation offer accounts of vowels and consonants in different syllable positions (e.g. Articulatory Phonology (Browman & Goldstein, 1988; 2000) and ‘carrier’ models of coarticulation (e.g. Ohman, 1966)), the effects of syllable structure on v-to-v coarticulation remain poorly understood. Most studies on v-to-v coarticulation only deal with one syllable type, namely open syllables (though see Modarresi, Sussman, Lindblom & Burlingame, 2004). However, notwithstanding the lack of a clear definition of a phonetic syllable, many studies show that syllable onset and coda are different acoustically, articulatorily, typologically and perceptually. Acoustic studies indicate that onset consonants are longer and exhibit stronger cohesion with tautosyllabic vowels than do coda consonants (e.g. Byrd, 1996; Sussman, Bessell, Dalston & Majors, 1997). Articulatory studies show that syllable onset and coda consonants coordinate differently with the vowels, and that gestures for onset consonants are stronger and more distinct than those for coda consonants (e.g. Browman & Goldstein, 1988; Krakow, 1999). Onset consonants are more frequent in the world’s languages, and are more distinguishable than coda consonants in noise (Redford & Diehl, 1999). All this suggests that syllable onset and coda consonants have different coordination with the vowel, which might therefore be expected to affect v-to-v coarticulation. The /st/ cluster in English can be syllabified in three ways: onset /#st/, heterosyllabic /s#t/ and coda /st#/ (where # denotes a syllable boundary). It was hypothesized that the onset /#st/ should allow the least v-to-v coarticulation because onsets are stronger and more stable, followed by the heterosyllabic /s#t/ and the coda /st#/ because coda consonants are the most variable. The /st/ cluster was chosen for investigation because it is homorganic, thus reducing conflicting influences of intervocalic consonants on formant transitions.