Positional Neutralization - Linguistics - University of California ...

phonetic implementations as a function of the amount of duration assigned by the
phonetics to the syllable in question.
If, on the other hand, the two levels of reduction of unstressed /a/ and /o/ were
actually to be considered phonologically distinct categories with different constellations
of features (or rather, in this case, the features of [a] vs. complete underspecification), we
would expect two completely independent sets of spectral realizations, one corresponding
to an [a], and the other functioning something like schwa in English, truly phonetically
targetless with formant values interpolated from the action of coarticulation with
surrounding segments superimposed on an otherwise neutral vocal tract (see Browman
and Goldstein 1992 for discussion of the need for a target articulation for schwa). In such
a situation, the rise of F1 values toward those characteristic of [a]/[] as permitted by
adequate duration is entirely unexpected and inexplicable. That they should actually
reach those values when given the opportunity is stranger still.
While there is ample evidence demonstrating the difficulty of articulating a low
vowel under a certain durational threshold, which explains a raising trend in shorter
syllables, there is no reason whatsoever to expect a mechanical link between lowering of
schwa toward [a] and small increases of duration. In this experiment the highest recorded
duration for a second pretonic /a, o/ was 61 ms. and yet nonetheless the vowels in the
upper durational range have F1 values more characteristic of the range found for first
103