A Phonetically-Based Model of Phonological Vowel Reduction

This paper proposes an analysis of phonological vowel reduction according to which vowel contrasts are subject to neutralization in unstressed syllables because it is more difficult to keep vowels distinct where vowel duration is shorter. Where the durational difference between stressed and unstressed vowels is large enough, it may not be possible to realize the same number of vowel contrasts in stressed and unstressed syllables while keeping the unstressed vowels adequately distinct, in which case it is preferable to reduce the size of the unstressed vowel inventory. The analysis is formulated as a numerical model, extending Liljencrants and Lindblom’s (1972) model of vowel inventories by incorporating aspects of the prosodic and segmental contexts of vowels, and allowing for different vowel inventories in different contexts. The model contributes to our understanding of vowel reduction, providing an explanation for the observation that vowel reduction primarily neutralizes height contrasts, and demonstrates how Liljencrants and Lindblom’s modeling approach can be developed to analyze contextual restrictions on the distribution of speech sounds.