Why Do Back Vowels Shift in Heritage Korean?

For heritage speakers (HSs), expectations of influence from the community’s dominant language are pervasive. An alternative account for heritage language variability is that HSs are demonstrating sociolinguistic competence: HSs may either initiate or carry forward a pattern of variation from the homeland variety. We illustrate the importance of this consideration, querying whether /u/-fronting in Heritage Korean is best interpreted as influence from Toronto English, where /u/-fronting also occurs, or a continuation of an ongoing vowel shift in Homeland (Seoul) Korean that also involves /ɨ/-fronting and /o/-fronting. How can patterns of social embedding untangle this question that is central to better understanding sociolinguistic competence in HSs? For Korean vowels produced in sociolinguistic interviews by Heritage (8 adult immigrants, 8 adult children of immigrants) and 10 Homeland adults, F1 and F2 were measured (13,232 tokens of /o/, 6810 tokens of /u/, and 20,637 tokens of /ɨ/), normalized and subjected to linear regression. Models predict effects of gender, age, orientation toward Korean language and culture, the speaker’s average F2 for the other shifting vowels, and duration. These models highlight HS’s sociolinguistic competence: Heritage speakers share linguistic and social patterns with Homeland Korean speakers that are absent in English. Additionally, heritage speakers lack the effects of factors attested in the English change.