Positional Neutralization - Linguistics - University of California ...

seven-vowel stressed system /i, e, , a, , o, u/ is reduced to five vowels [i, e, a, o, u] in
unstressed syllables. Most important here is the fact that contrast-enhancing UVR is
argued specifically not to be a product of duration-dependent undershoot of the sort
described above. It is rather a strictly perceptual phenomenon whereby naturally difficult
contrasts are eliminated from positions of lesser phonetic prominence. The main evidence
that this is so is the putative appearance of true corner vowels in contrast-reducing
systems. Thus, in Belorussian and Italian, unstressed /a/ is not raised as dramatically
toward schwa as it is in, for example, Bulgarian.
The immediate problem with contrast-enhancing UVR lies in the typological
predictions it makes. Contrast enhancing reduction is said to take place as a response to
an imperative to eliminate of “perceptually difficult” contrasts from positions in which a
lack of the necessary cues (here, duration) would lessen the likelihood of their correct
parsing by the listener. For this reason, it prefers peripheral vowels, explaining why
Belorussian leaves /a/ as [a], while Bulgarian raises it to schwa. The problem comes in
the definition of what constitutes a perceptually-difficult vowel contrast? Crosswhite
argues that mid vowels are less robust than corner vowels perceptually, and hence prone
to effacement, and this is surely true. But previous accounts of vowel neutralization in
phonetically-driven phonology have given a very different answer to this question.
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