This study aims at investigating the capability of the English department students, Faculty of Humanities, Udayana University in pronouncing diphthongs. Diphthong is a glide from one vowel to another. English is very rich in words containing diphthongs, such as: / aI / in the word try / traI / buy / baI /; / eI /, in the words they / ðeI /, day / deI /, / eə / as in hair / heə /, chair /tʃeə/. Meanwhile, the number of diphthongs in Indonesian and Balinese as the mother tongue of the students is very limited. This difference certainly creates problems for students in pronouncing the English words consisting of diphthongs.
The knowledge of English sounds is taught in the subject of English phonetics and phonemics in the fifth semester. This study examined the ability of new students who have not taken the English Phonetics and Phonemics subject to be compared with the ability of those who have got this subject, so that it can be seen to what extent this course can change student performance in pronouncing diphthongs.
This research is a qualitative descriptive research supported by quantitative data. The population of this study was 50 new students and 50 sixth semester students, taken randomly. The research instrument was a list of English words containing diphthongs and questionnaires. The technique of collecting data was done through recording, and the data were analyzed descriptive qualitatively and presented formally and informally.