Phonetic reduction, vowel duration, and prosodic structure

Word frequency, phonological neighborhood density, semantic predictability in context, and discourse mention have all been previously found to cause reduction of vowels. Other researchers have suggested that reduction based on these factors is reflective of a unified process in which “redundant” or “predictable” elements are reduced, and that this reduction is largely mediated by prosody. Using a large read corpus, we show that these four factors show different types of reduction effects, and that there are reduction effects of prosody independent of duration, and vice versa, suggesting the existence of multiple processes underlying reduction.