L'influenza della durata consonantica sulla coarticolazione della sillaba CV con gradi diversi di prominenza prosodica

In the present work we address the question of a possible causal relationship between degree of anticipatory coarticulation and prosodic strength by examining the variation in segmental duration and degree of anticipatory coarticulation in CV syllables (C = / d /, V = / a / or / i /) that differ in lexical stress (unstressed vs stressed) and in their affiliation to a focused constituent (stressed vs accented). It has been confirmed also for Italian that prominence maximizes the place characteri-stics for consonants and vowels and reduces the mutual coarticulatory influences. As for English, the amount of CV coarticulation has been shown to depend not only on vowel type and on the degree of expansion of the vocalic space, but also on the size of consonantal contact. We hypothesize a relationship between the duration of the consonant and the degree of anticipatory CV coarticulation, and we expect that syllables of progressively longer duration endowed with higher degrees of prosodic prominence (unstressed - stressed - accented) will show a progressively lower degree of anticipatory coarticulation by the vowel on the onset consonant. The results show that while the duration of C (in /a/ context) and V increases systemati-cally according the position of the syllable in the prosodic hierarchy, the degree of coarticu-lation follows a reverse path, i.e. it is highest in unstressed syllables, it lowers in stressed syllables and it is lowest in accented ones. At least for some speakers, syllables at higher levels in the prosodic hierarchy show a covariation of duration and frequency, and the in-crease in duration and in F2 of the consonant may be explained by the increase in the size of the articulatory contact of consonantal occlusion, as hypothesized by Lindblom, Agwuele & Sussman (2009). The reduction in coarticulation that affects prosodically strong syllables, such as lexi-cally stressed syllables and intonationally accented syllables in focused constituents, could be interpreted as a further indication of localized hyperarticulation, which results in stren-gthening syntagmatic contrasts (between contiguous phones, or in praesentia) as well as paradigmatic contrasts (among other phones in the system, or in absentia) and, ultimately, in facilitating phonetic clarity.