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.