Speech adaptation in conversation: Effects of segment cue-weighting strategy for non-native speakers

Abstract

Research has investigated how speakers make phonetic adaptations by adjusting their speech sounds to either converge to or diverge from their interlocutor’s. Less is known about the dynamic adaptive strategies non-native speakers use to improve intelligibility when interacting with native speakers, particularly how their strategies change over the course of spontaneous conversations. The current study examines phonetic adaptations in English words contrasting tense and lax vowels (e.g., sheep-ship) in unscripted conversations between non-native Japanese English and native English speakers during an engaging computer game task. Japanese speakers have previously been found to rely on temporal cues (vowel length) for tensity distinctions due to their L1 cue-weighting strategy rather than spectral cues (vowel quality) that are predominantly used in English. Acoustic analyses are conducted to examine changes in non-native vowel productions before, during and after the conversation task. We predict that, in an attempt to overcome miscommunication, non-native speakers may initially lengthen the tense vowels to distinguish them from their lax counterparts. As the conversation progresses, non-native speakers may adapt to a more native-like cue-weighting pattern by shifting to spectral distinctions. Results are discussed in terms of adaptations to cue-weighting strategies for intelligibility gains by interlocutors of different linguistic backgrounds.