Acoustic characteristics of Korean-English bilingual speakers' /l/ and the relationship to their foreign accent ratings.

Purpose: The current study examined acoustic characteristics of English /l/ produced by Korean speakers who speak English as their second language (KE). Comparisons were made to patterns of their Korean /l/ and English /l/ produced by monolingual speakers of American English (AE). Vowel context and word position effects on acoustic differences among the three /l/ sounds were examined in relation to the degree of foreign accentedness of KE speakers. Methods: Korean and English word-initial and-final /l/ in two vowel contexts (high front vs. low back) were produced by 12 KE female adult speakers in a carrier phrase. A comparison group of 10 AE speakers produced English /l/. F1 and F2 values of each /l/ production were extracted at the /l/ midpoint and were compared to each other. Euclidean distances across the productions were also examined in relation to the degrees of foreign accentedness of KE speakers. Results: KE speakers' English /l/ showed significantly lower F2-F1 values than their Korean /l/ across word position and vowel context but significantly higher F2-F1 values than AE speakers' English word-initial /l/. Euclidean distance between KE speakers' English and Korean /l/, and KE and AE speakers' English /l/ correlated significantly with KE speakers' degree of foreign accentedness across word position and vowel context. Conclusion: Results indicate that the influence of Korean on KE speakers' English /l/ productions varied by word position and vowel context, as well as the degree of their foreign accentedness ratings. This finding suggests the context-dependent nature of /l/ productions and highlights the need for considering a speakers' degree of foreign accent when exploring English /l/ patterns of KE speakers.