Acoustic Representations of Segmental and Metrical Encoding in Speech Production

Abstract

Language has a rhythmic structure, but little is known about the mechanisms that underlie how it is planned. Traditional models of language production assume that metrical and segmental planning occur independently and in parallel (Roelofs & Meyer, 1998). We test this claim in three experiments. In Experiment 1, participants completed an event-description task in which a disyllabic target word shared segmental overlap with a prime that either had matching or non-matching metrical stress. Participants lengthened words that shared segmental and metrical information with recently produced words, which suggests that these features create competition during phonological encoding. In Experiment 2, participants completed a phrase repetition task, and again they lengthened phrases that had segmental and metrical overlap. These findings could either be the result of interference from an abstract representation of meter or interference due to similar acoustic realizations of words. To adjudicate between these possibilities, Experiment 3 included segmentally distinct word pairs with either matching or non-matching stress. Participants again showed lengthening in trials with both segmental and metrical overlap, but no lengthening from metrical overlap alone. These data suggest that the acoustic-phonetic similarity of the initial syllables of the prime and target creates lexical competition that leads to greater lengthening. These results do not support an abstract metrical representation, but are consistent with production models in which segmental and metrical structure are tightly bound in production.