Abstract

An Analysis of English and Korean Vowels Produced by Korean ESL Learners:
Focusing on the Acoustic Properties, Speech Intelligibility, and L2-experience


Korea University Graduate School
English Education
Kyunghee Lee

The current study aims to investigate English and Korean vowels produced by Korean ESL(English as a Second Language) learners, focusing on acoustic characteristics, speech intelligibility, and L2-experience. This study mainly consists of three experiments: 1) English vowel production experiment, 2) English vowel intelligibility experiment, 3) Korean vowel production experiment. Twenty-three Korean ESL learners residing in the U.S. participated in the English vowel production experiment, and the participants were divided into two groups according to their length of residence(LOR) and their age of arrival(AOA) in the U.S. They produced ten English vowels, /i/, /?/, /?/, /æ/, /?/, /?r/, /?/, /?/, /?/, /u/, and their productions were analyzed in terms of spectral and temporal acoustic features. Specifically, the vowel formants (F1, F2, F3) and vowel duration were measured and compared to the production of native English speakers. Some acoustic differences between native English speakers and ESL learners were observed, but the differences differed according to vowels.
In the second experiment, four native English-speaking listeners evaluated the intelligibility of the English vowels recorded by the participants of the first experiment. They identified the specific vowels they heard while listening to the recordings. The results of the intelligibility task suggest that intelligibility can be affected by acoustic similarity to the native English speakers’ vowels. Furthermore, certain vowels obtained high intelligibility scores even though they are acoustically quite different from native English speakers’ vowels. The correlation between acoustic features and speech intelligibility showed different results according to the vowel types and participants’ LOR and AOA.
In the third experiment, the Korean vowel production experiment was conducted with four female ESL learners to investigate the effect of L2 learning experience on L1 vowel production. The results showed that the acoustic features of Korean vowels spoken by the ESL learners were different from Korean standard vowel properties. Moreover, they have similar features to English vowels. This implies that the English-learning experience can have an influence on L1 vowel productions, as well as English vowel productions. The findings of this study put forward some educational implications for learners and teachers of ESL.