The present paper investigates the influence of opposing lexical forces on speech production using the duration of the stem vowel of regular and irregular verbs as attested in the Buckeye corpus of conversational North-American English. We compared two sets of predictors, reflecting two different approaches to speechproduction, one based on competition between word forms, the other based on principles of discrimination learning. Classical measures in word form competition theories such as word frequency, lexical density, and gang size (types of vocalic alternation) were predictive of stem vowel duration. However, more precise predic-tions were obtained using measures derived from a two-layer network model trained on the Buckeye corpus. Measures representing strong bottom-up support predicted longer vowel durations. Conversely, measures reflecting uncertainty predicted shorter vowel durations, including a measure of the verb’s semantic density. The learning-based model also suggests that it is not a verb’s frequency as such that gives rise to shorter vowel duration, but rather a verb’s collocational diversity. Results are discussed with reference to the Smooth Signal Redundancy Hypothesis and the Paradigmatic Signal Enhancement Hypothesis.
Opposing forces on acoustic duration
