Syllabic Phase: a Bottom-up Representation of the Temporal Structure of Speech

This paper concerns the perception of syllable structure and the way this process allows us to form structural representations of syllables in memory. It is argued that bottom-up processes are required for the formation of phonological representations of nonwords in short-term memory, and of words in early childhood, where top-down knowledge concerning syllable structure cannot be assumed. A new model is presented using signal processing techniques to show that representations of syllable structure can be developed from acoustic information, without top-down input. The model is motivated by psycholinguistic data and theory, expressed at the level of a putative neural mechanism, and supported by recent neurophysiological and brain imaging data. It describes syllable structure not in terms of events (e.g., syllable boundaries) or phonological frames with discrete slots, but in terms of a continuously varying measure of syllable position: syllabic phase. The validity of the model is demonstrated using a corpus of spoken sentences from the TIMIT database. Implications of the model for theories of phonological memory and developmental dyslexia are discussed. On the basis of recent functional imaging and neurophysiological studies, the neural basis for the proposed mechanism is hypothesized to be in the posterior Superior Temporal Sulcus.