Stability of the /o/–/u/ Contrast in Yanbian Korean

This study examined whether frequent exposure to Seoul Korean promotes convergence between the vowels /o/ and /u/ among Yanbian Korean speakers, given that the ongoing /ɛ/–/e/ merger in Yanbian Korean has been affected by contact with Seoul Korean (Yu, Cho, & Lee., 2024). The analysis was based on recordings from 20 Yanbian speakers, who were classified by the degree of their exposure to Seoul Korean using a Likert scale. In these recordings, tokens of /u/ were extracted from word-final content morphemes, while those of /o/ were taken from word-final function morphemes. The results showed that exposure to Seoul Korean had minimal influence on the realization of /o/ and /u/. Most speakers maintained a clear distinction between the two vowels in the F1–F2 space, although individual variation in formant values was largely observed. These findings suggest that, unlike the /ɛ/–/e/ merger, the /o/–/u/ contrast in Yanbian Korean remains largely stable despite contact with Seoul Korean and that contact-induced sound change selectively influences phonological contrasts even within the same speaker community.