Adaptive dispersion theory and phonological vowel reduction in Russian.

Russian exhibits a rich pattern of phonological vowel reduction, by which some vowel contrasts are neutralized in unstressed syllables. Recent work in phonology suggests a mechanism by which phonetic vowel reduction--compression of the overall vowel space due to target undershoot--might lead to patterns like Russian. Presenting acoustic data from 9 speakers of Russian, we use Euclidean distance measures, measures of F1-F0 and F2-F1, and Bayesian classification to provide a basic picture of how the overall vowel space, as well as the distribution of vowels, change as stress is reduced. We are particularly interested in whether contraction of the vowel space in unstressed positions is primarily due to raising, and in whether contrasting pairs of vowels are evenly spaced within and across contexts. Our results provide qualified support for the first hypothesis, but largely do not support the hypothesis of equal spacing, in particular across contexts. Of additional interest, we find that some impressionistically described neutralizations are incomplete.