Rebecca Morley (OSU will present a colloquium in Linguistics on Friday March 8th at 3:30 in ILC N400. All are welcome!
Title: Phonological contrast as an evolving function of local predictability
In this talk I conceptualize phoneme identification as the result of a phonological parse that maps acoustic input to a series of discrete abstract structures. As has been proposed for syntactic processing, the phonological parse is built up incrementally as the speech signal is received, and the highest-probability parse available is selected at each point. As the parse proceeds, listener expectations develop regarding future input. If those expectations fail to be met, the phonological parser can be “garden-pathed” just as a syntactic parse would be. The primary difference between the two domains is that the input to the syntactic parser is typically
assumed to consist of already segmented sequences of words, and the induction problem is one of determining the hierarchical groupings among those words. The input to the phonological parser, on the other hand, will be assumed to consist of a stream of continuously
valued acoustic cues, and the induction problem to be literal segmentation: attributing perceived cues to sequentially ordered discrete segments.
This proposal is illustrated through a re-analysis of the well-known, and well-researched, phenomenon of vowel lengthening in American English. I will argue that no actual lengthening
of vowels before voiced obstruents occurs (nor shortening before voiceless obstruents), but that the effect is an epiphenomenon of speaking rate and prosodic lengthening. I take the results of production experiments to argue for an underlying specification of /short/ for English “voiced” obstruents. And I show that the categorical perception results (in which vowel duration is found to be a sufficient cue to “voicing” on word-final obstruents) can be derived from general properties of the proposed phonological parser. The implications for theories of contrast, diagnostics of contrastive features, and theories of sound change will be discussed.