First language (L1) vowel systems play an important role in the vowel production of a second language (L2). In this study, the focus is specifically on Javanese and Sundanese-two of the most widely spoken Indonesian local languages. This present study investigated how the Javanese and Sundanese speakers produce ten English vowels. Forty Javanese and Sundanese speakers and ten native English speakers participated in the experiment. According to the Speech Learning Model (SLM), highly advanced Javanese and Sundanese speakers of English should continue have trouble producing vowels that are similar, such as/iː/and/uː/, but should no longer exhibit native-language interference with new L2 vowels, such as/ɪ, ɛ, ʊ, æː, ɑː, ɔː, ʌ, ɝ/. In contrast, the Second Language Linguistic Perception (L2LP) model predicts that the production of new L2 vowels is more difficult than of similar L2 vowelsas long as the L2 acquision process has not been completed. The results show that that the Javanese and Sundanese speakers have more difficulty with the new than with the similar vowels in English, which indicates that the L2 acquisition process has not been completed. Moreover, the members of English tense-lax vowel pairs are poorly contrasted by spectral parameters while the use of duration is relatively adequate.