The acoustics of Contemporary Standard Bulgarian vowels: A corpus study

A comprehensive examination of the acoustics of Contemporary Standard Bulgarian vowels is lacking to date, and this article aims to fill that gap. Six acoustic variables—the first three formant frequencies, duration, mean f0, and mean intensity—of 11 615 vowel tokens from 140 speakers were analysed using linear mixed models, multivariate analysis of variance, and linear discriminant analysis. The vowel system, which comprises six phonemes in stressed position, ε a ɔ i ɤ u, was examined from four angles. First, vowels in pretonic syllables were compared to other unstressed vowels, and no spectral or durational differences were found, contrary to an oft-repeated claim that pretonic vowels reduce less. Second, comparisons of stressed and unstressed vowels revealed significant differences in all six variables for the non-high vowels ε a ɔ. No spectral or durational differences were found in i ɤ u, which disproves another received view that high vowels are lowered when unstressed. Third, non-high vowels were compared with their high counterparts; the height contrast was completely neutralized in unstressed a-ɤ and ɔ-u while ε-i remained distinct. Last, the acoustic correlates of vowel contrasts were examined, and it was demonstrated that only F1, F2 frequencies and duration were systematically employed in differentiating vowel phonemes.