Phonetic perspectives on modelling information in the speech signal

This paper reassesses conventional assumptions about the informativeness of the acoustic speech signal, and shows how recent research on systematic variability in the acoustic signal is consistent with an alternative linguistic model that is more biologically plausible and compatible with recent advances in modelling embodied visual perception and action. Standard assumptions about the information available from the speech signal, especially strengths and limitations of phonological features and phonemes, are reviewed, and compared with an alternative approach based on Firthian prosodic analysis (FPA). FPA places more emphasis than standard models on the linguistic and interactional function of an utterance, de-emphasizes the need to identify phonemes, and uses formalisms that force us to recognize that every perceptual decision is context- and task-dependent. Examples of perceptually-significant phonetic detail that is neglected by standard models are discussed. Similarities between the theoretical approach recommended and current work on perception-action robots are explored.