Efficacy of Teaching English Diphthongs [eΙ]and [oƱ] to Korea EFL Learners

This paper investigated the acquisition of English diphthongs [eI] and [oƱ] by conducting experiments. A total of 28 college students participated in the perception and production tests on [eI] and [oƱ] before and after the training of the target sounds. Overall, the results of the study showed that the participants had more difficulties with the perception and production of [oƱ] than with [eI] both in the pretest and posttest. The most predominant error pattern in perceiving and producing [oƱ] was the deletion of the second element of [oƱ], resulting in vowel reduction. Although the perception and production of [oƱ] was more problematic, [oƱ] showed a more noticeable teaching effect than [eI] due to the ceiling effect of the latter. It was also found that the participants' perception and production abilities of [oƱ] showed a different degree of progress in that the perception of [oƱ] was significantly worse than the production of it even after training. The difficulties in perceiving and producing [oƱ] were further analyzed with respect to the number of syllables in the target words containing [oƱ]. The result revealed that target words with more number of syllables induced more errors both in perception and production across the tests. Further, disyllabic and trisyllbic words were mainly responsible for the participants' poor performance in the perception of [oƱ] -containing words in the posttest, compared with the production of the targets. Based on the findings of the study, implications for effective pronunciation teaching of the diphthongs [eI] and [oƱ] were drawn.