Phonological parsing and lexical retrieval

Abstract

Speech is a natural error-correcting code. The speech signal is full of rich sources of contextual redundancy at many levels of representation including allophonic variation, phonotactics, syllable structure, stress domains, morphology, syntax, semantics and pragmatics. The psycholinguistic literature has tended to concentrate heavily on high level constraints such as semantics and pragmatics and has generally overlooked the usefulness of lower level constraints such as allophonic variation. It has even been said that allophonic variation is a source of confusion or a kind of statistical noise that makes speech recognition that much harder than it already is. In contrast, I argue that aspiration, stop release, flapping, palatalization and other cues that vary systematically with syllabic context can be used to parse syllables and stress domains. These constituents can then constrain the lexical matching process, so that much less search will be required in order to retrieve the correct lexical entry. In this way, syllable structure and stress domains will be proposed as an intermediate level of representation between the phonetic description and the lexicon. My argument is primarily a computational one and will include a discussion of a prototype phonetic parser which has been implemented using simple well- understood parsing mechanisms. No experimental results will be presented.