How is anticipatory coarticulation of suffixes affected by lexical proficiency?

More and more studies find differences in fine phonetic detail related to the morphological function of words and segments. In the present study, we investigated to what extent these differences arise due to anticipatory coarticulation of inflectional exponents and the amount of long-term practice with individual verbs such as American English "clean", "cleaned", "cleans", "cleaning". Kinematic studies of hand movements show that with greater practice, i.e. regular repetition of a sequence of gestures, upcoming gestures are stronger and smoother anticipated. Consequently, we hypothesized to find stronger anticipatory coarticulation of inflectional exponents during the articulation of the stem vowel in verbs for which speakers acquired a greater lexical proficiency, as their articulatory gestures were better practiced. We observed both, stronger anticipatory coarticulation towards the offset of the gesture and less coarticulation concomittant with more hyperarticulation towards the onset of the gesture. We link these results to findings that morphological function is reflected in fine phonetic detail, challenging traditional models of speech production, which assume a separation of lexical information and the phonetic detail.