Phonetic Accommodation during Discourse between Native and Nonnative Speakers

Midam Kim, Ann Bradlow & William Horton, Northwestern University

Phonetic accommodation among adult speakers in a conversation (Giles et al., 1991; Pardo, 2006; Pickering & Garrod, 2006) provides evidence for the claim that linguistic representations of adults might still be flexible, and challenges the idea of a strong limitation on language acquisition or modification after critical periods. However, phonetic accommodation might be constrained by the characteristics of adult speech obtained over their lifetime. For example, speakers might show a larger amount of phonetic convergence when they share the same dialect than when they don't. Also, native and nonnative speakers of a language might show a higher degree of phonetic convergence when the nonnative speaker has a higher proficiency in the target language.

This study explores phonetic accommodation during relatively brief interactions between two native or nonnative speakers of English or Korean (four English native-native interactions / four Korean native-native interactions / four English native-nonnative interactions). We relate phonetic accommodation patterns to the native speakers' dialects, and to nonnative speakers' proficiency (nonnative accentedness) as a means of assessing the extent to which long term linguistic knowledge plays into short term linguistic change.

Adult speakers (18 to 34 years, the average of 23 years) participated in a cooperative picture matching game in either English or Korean. Conversations lasted approximately ten to twenty minutes. To track phonetic accommodation patterns, utterance samples of less than two seconds were taken from relatively early and relatively late in each speaker's part of the conversation. These utterance samples were compared to their partner's in an XAB similarity perception test (where X is one talker's utterance, while A and B are early and late utterances from the partner). A separate set of listeners participated in these similarity judgment tests (native English listeners judged English samples and native Korean listeners judged Korean samples). Patterns of phonetic convergence and divergence is indexed by how frequently listeners select the "late" utterance as sounding more (or less) similar to the target utterance. In another test, nonnative speakers' English samples were rated for degree of accentedness on a scale of one to seven.

Phonetic convergence was observed for native-native conversations (English and Korean), and this was stronger when speakers shared the same or similar dialects. In native-nonnative conversations (target language = English), none of the native speakers converged towards a nonnative partner, while nonnative speakers showed different patterns depending on their proficiency, with greatest convergence for moderately accented nonnatives.

The results suggest that adult speakers can change their speech production patterns in response to their conversation partner even after critical periods for language acquisition. In detail, the data indicates that phonetic accommodation can occur cross-linguistically, and that it may be constrained both by speakers' dialect and by their language proficiency.