Positional Neutralization - Linguistics - University of California ...

it is not as high as Bulgarian schwa (for example) is therefore not because it is specified
[+low], but because the pressure of the duration decrease is usually just not extreme
enough to force it to raising the full distance to schwa. In a case such as this, it is not even
clearly meaningful to draw a distinction between “schwa” and “a” , unless we wish to
define an arbitrarily-selected F1 value as the border, beyond which a system ceases to be
contrast-enhancing, and becomes prominence-reducing instead. The fact that the
realization of /a/ is gradiently determined by duration is even worse, of course, since even
such an arbitrarily-selected F1 boundary has no meaning if F1 of the vowel in question is
so loosely targeted as to be essentially a function of another property, such as duration.
The same problem arises for the pretonic syllables of Brazilian Portuguese, which
Crosswhite argues to undergo contrast-enhancing reduction. Nobre and Ingemann (1987)
give experimental results showing the mean F1 of stressed and pretonic /a/ for four
Brazilian Portuguese speakers to differ by nearly 100 Hz (stressed /a/ - 684 Hz, pretonic
/a/ 585 Hz). Flemming (2001) notes of the tense and lax mid vowels that the neutralized
realizations are centralized in the F2 dimension, while in F1 falling in between the
stressed realizations of the tense and lax phones. To this may be added the facts observed
by Major concerning the tendency for the second degree of reduction (raising of non-high
vowels) to apply in pretonic syllables at faster rates of speech.
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