Dynamic spectral patterns of American English front monophthong vowels produced by Korean-English bilingual speakers and Korean late learners of English

This study investigated how Korean-English bilingual speakers and Korean late learners of English realize dynamic patterns of front monophthong vowels in American English. Twenty subjects read monosyllabic [CVC] words containing the vowels [i, I, Ɛ, æ] in a carrier sentence. F1, F2, and F3 frequency values were measured at 11 points for each speaker by dividing their vowel duration into ten equal segments. The results indicated that, compared to Korean late learners of English (Group NK), the Korean-English bilingual speakers (Group KE) exhibited F1, F2, and F3 transition shapes and overall formant values of the English front vowels that are more similar to those of native speakers of American English (Group NE). It was also found that the movement directions of the vowels [i] and [æ] varied widely across the three groups, those of the vowel [I] were similar across the three groups, and those of the vowel [Ɛ] were similar for Groups NE and KE, but not for Group NK. For the vowel [I], the ranges of the formant movements overlapped for Groups NE and KE, but that of Group NK was quite distinct. For Groups NE and KE, the trajectories of the vowels [Ɛ] and [æ] were not as distinct as the trajectories of [i] and [I], though they did not overlap. The vowels [Ɛ] and [æ] completely overlapped for Group NK. In general, Group KE exhibited more native-like spectral changes of the American English vowels than Group NK, indicating that there is an effect of language experience in learning the dynamic patterns of the vowels. (Ewha Womans University)