Cross-linguistic voice variations in Korean-English bilinguals

Languages often exhibit distinct pitch ranges and voice qualities. To investigate how bilingual speakers modulate their voice quality and pitch in their two languages, this study examines voice variation in Korean-English bilingual speakers. We recorded 30 Korean-English bilinguals (F = 15, all more dominant in Korean) reading “The North Wind and the Sun” in their two languages, and measured F0, SHR, and two spectral tilt measures (H1*-H2*, H1*-A1*) at 5 ms intervals in all sonorant sounds. The results showed that the bilingual speakers’ two languages were indeed different as reflected in the four measures, with the differences mediated by their English proficiency and gender. Overall, mean F0 and F0 variation were greater in Korean than in English. Interestingly, higher English proficiency correlated with greater F0 variation in English, making it more similar to Korean. Bilingual speakers produced English with stronger subharmonics, suggesting a creakier phonation, than Korean, indicated by higher SHR values. Finally, spectral slope measures showed gender-specific patterns: males exhibited greater values (suggesting breathiness) in Korean while females showed the opposite. These findings suggest that bilingual speakers have distinct voice in their two languages, but their vocal adjustments are influenced by language proficiency and gender of the speakers.