A method and system for synthesizing acoustic waveforms in, for example, a text-to-speech system is disclosed which employs the concatenation of a very large number of very small, sub-phoneme, acoustic units. Such sub-phoneme sized audio segments, called wavelets, can be individually spectrally analyzed and labelled as fenones. Fenones are clustered into logically related groups called fenemes. Sequences of fenemes can be matched with individual phonemes, and hence words. In the case of a text-to-speech system, the required phonemes are determined from prior linguistic analysis of the input words in the text. Suitable sequences of fenemes are predicted for each phoneme in its own context using hidden markov modelling techniques. A complete output waveform is constructed by concatenating wavelets to produce a very long sequence thereof, each wavelet corresponding to its respective feneme. The advantages of using a feneme set extracted from a training script read by a single human speaker is that it is possible to generate natural sounding speech, using a finite sized codebook.
Method and system for synthesizing speech