A Phonetic Model of English Intonation

This thesis proposes a phonetic model of English intonation which is a system for linking the phonological and F0 descriptions of an utterance. It is argued that such a model should take the form of a rigorously defined formal system which does not require any human intuition or expertise to operate. It is also argued that this model should be capable of both analysis (F0 to phonology) and synthesis (phonology to F0). Existing phonetic models are reviewed and it is shown that none meet the specification for the type of formal model required. A new phonetic model is presented that has three levels of description: the F0 level, the intermediate level and the phonological level. The intermediate level uses the three basic elements of rise, fall and connection to model F0 contours. A mathematical equation is specified for each of these elements so that a continuous F0 contour can be created from a sequence of elements. The phonological system uses H and L to describe high and low pitch accents, C to describe connection elements and B to describe the rises that occur at phrase boundaries. A fully specified grammar is described which links the intermediate and F0 levels. A grammar is specified for linking the phonological and intermediate levels, but this is only partly complete due to problems with the phonological level of description. A computer implementation of the model is described. Most of the implementation work concentrated on the relationship between the intermediate level and the F0 level. Results are given showing that the computer analysis system labels F0 contours quite accurately, but is significantly worse than a human labeller. It is shown that the synthesis system produces artificial F0 contours that are very similar to naturally occurring F0 contours. The thesis concludes with some indications of further work and ideas on how the computer implementation of the model could be of practical benefit in speech synthesis and recognition.