The Impact of Learner and Acoustic Variables on Foreign Accentedness in L2 English Vowels

초록

Foreign accents are typically slow to change, although the perceived strength of foreign accent is affected by many learner factors (e.g., initial L2 age, age of arrival [AOA] and length of residence [LOR] in L2-speaking environments, amount of L1/L2 use). Furthermore, foreign-accented speech deviates from native acoustic norms across diverse acoustic measurements (e.g., frequencies of the first formant (F1), the second formant (F2), the third formant (F3), and vowel duration). While most research on the perceived strength of foreign accent focuses on either learner variables or acoustic properties, this study investigates the impact of both learner (initial L2 age, AOA, LOR, and full-time equivalent [FTE] years of L2 input) and acoustic variables (F1/F2/F3 distances and vowel duration differences from native acoustic norms) on foreign accentedness in L2 English vowels with L1-Korean-speaking adults living in the U.K. Four native speakers of Standard Southern British English (SSBE) and 28 Korean learners produced 12 bVt English words (e.g., bit, bot). Four different native SSBE listeners assessed the perceived strength of foreign accent on a 7-point Likert scale. The productions of native speakers and Korean learners were subjected to acoustic measurements. The effects of learner and acoustic variables on foreign accentedness were statistically estimated with ordinal mixed-effects regression models. The results from learner variables showed that only the effect of LOR was significant. The results from LOR and four acoustic measures as well as two-way interactions of LOR and each acoustic variable showed that all main effects and LOR were statistically significant; shorter F1, F2, F3 distances and longer vowel durations led to a significantly weaker foreign accentedness. The interaction between F2 distance and LOR and that between duration difference and LOR were also significant, indicating that the impact of F2 distance and duration difference grew stronger with increased LOR. The results suggest that adult L2 learners were perceived as foreign accented as their acoustic measures deviate from native acoustic norms and that adult L2 learners’ foreign accentedness can be reduced as their LOR increases. The study further discusses the implications of the findings for L2 theories of phonological acquisition.

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