In this paper I discuss the results of an apparent-time sociophonetic study on the emergence of a tonal distinction in Jejueo, a critically endangered Koreanic language spoken on Jeju Island, South Korea, and the Jeju variety of Korean spoken by younger generations on the island. In developing this project I partly replicated Cho et al.’s (2002) study on Jeju, to determine whether younger generations maintained the VOT distinction that Cho et al. reported in older generations, or whether a tonal distinction was developing. The results of this apparent-time sociophonetic study show that tonogenesis has spread outward from mainland Korea and has entered Jejueo for all speakers, but to varying degrees, based on extralinguistic factors of age, language dominance in Korean or Jejueo, and attitudes toward Jejueo. This study has implications for the literature on language loss and also sound change, as language dominance and attitudes are shown to contribute to phonological attrition of heritage language in a diglossic environment.
