Contrast Maintenance in the Bulgarian and Judeo-Spanish Unstressed Vowels of Heritage Bilinguals

We present an acoustic-phonetic investigation of vowels in the spontaneous speech of heritage speakers of Judeo-Spanish ( /ɛ a ɔ i u/ ) and Bulgarian ( /ɛ a ɔ i ɤ u/ ), alongside monolingual Bulgarians’ vowels. Formant frequencies and duration were analyzed for 9,498 vowel tokens. Linear mixed models revealed no spectral differences between Judeo-Spanish and Bulgarian stressed vowels, pointing to shared targets in the bilinguals’ grammars. Unstressed vowel reduction, which is typical for Bulgarian (realized as nonhigh vowel raising), was found in all three varieties. In Bulgarian it was stronger, as well as categorical, as evidenced by bimodal F1 frequency distributions. Multivariate analysis of variance showed that vowels in the unstressed pairs /a–ɤ/ and /ɔ–u/ were merged in the monolinguals’ speech, while in Judeo-Spanish all contrasts were preserved. A degree of contrast was also maintained in the bilinguals’ Bulgarian, indicating influence of the heritage language on the majority one.