Second language speech production: Investigating linguistic correlates of comprehensibility and accentedness for learners at different ability levels

The current project aimed to investigate the potentially different linguistic correlates of comprehensibility (i.e., ease of understanding) and accentedness (i.e., linguistic nativelikeness) in adult second language (L2) learners’ extemporaneous speech production. Timed picture descriptions from 120 beginner, intermediate, and advanced Japanese learners of English were analyzed using native speaker global judgments based on learners’ comprehensibility and accentedness, and then submitted to segmental, prosodic, temporal, lexical, and grammatical analyses. Results showed that comprehensibility was related to all linguistic domains, and accentedness was strongly tied with pronunciation (specifically segmentals) rather than lexical and grammatical domains. In particular, linguistic correlates of L2 comprehensibility and accentedness were found to vary by learners’ proficiency levels. In terms of comprehensibility, optimal rate of speech, appropriate and rich vocabulary use, and adequate and varied prosody were important for beginner to intermediate levels, whereas segmental accuracy, good prosody, and correct grammar featured strongly for intermediate to advanced levels. For accentedness, grammatical complexity was a feature of intermediate to high-level performance, whereas segmental and prosodic variables were essential to accentedness across all levels. These findings suggest that syllabi tailored to learners’ proficiency level (beginner, intermediate, or advanced) and learning goal (comprehensibility or nativelike accent) would be advantageous for the teaching of L2 speaking. As many second language (L2) researchers have pointed out, it is crucial to set realistic goals for adult L2 learners, prioritizing understanding over © Cambridge University Press 2015 0142-7164/15 terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0142716414000502 Downloaded from https://www.cambridge.org/core. IP address: 54.191.40.80, on 04 Aug 2017 at 21:11:37, subject to the Cambridge Core Applied Psycholinguistics 37:2 218 Saito et al.: Reexamining comprehensibility and accent nativelikeness, in order for learners to be able to communicate successfully in academic and business settings (e.g., Derwing & Munro, 2009; Levis, 2005). Consistent with this agenda, recent research has begun to focus on two listenerderived constructs, namely, comprehensibility (ease of understanding) and accentedness (sounding nativelike), examining how different aspects of language (e.g., phonological, lexical, grammatical, and discourse-level factors) contribute to these constructs (e.g., Kang, Rubin, & Pickering, 2010; Munro & Derwing, 1999; Trofimovich & Isaacs, 2012). Building on this work, the current study aimed to examine linguistic correlates of comprehensibility and accentedness for L2 learners at different ability levels (beginner, intermediate, and advanced). Our overall objective was to clarify the relationship between comprehensibility and accentedness at different levels of L2 oral ability and to identify possible pedagogical implications for learners at different levels, and for their teachers, wishing to pursue comprehensible, but not necessarily unaccented, speech as a learning goal.