It has a number of innovative features which are designed to obtain the most natural sounding possible synthetic output. These parameter files specify values for formant frequencies and amplitudes, excitation type and fundamental frequency, each at 10ms intervals. Phonological and prosodic processing dependent on a syntactic parse that has been optimised for these particular tasks. Retrieval and conjoining of representations of acoustic syllables to provide the sequence of frames of parameter values for driving the synthesiser. For certain applications the units may be mixed within a particular synthesis task.
Phonological syllables form the basis of higher level processing including prosodic assignment.
In standard mode the system depends on an inventory of around 10,000 normalised, parametrically analysed acoustic syllables segmented from recorded natural speech. Other normalisation procedures are designed to minimise discontinuities which might arise at syllable boundaries during the conjoining procedure. Generating a sentence sized parameter file consists of assembling the appropriate syllable units from the inventory making durational adjustments in line with a calculated rhythmic contour and supplying a complete f0 contour for the entire sentence. The actual acoustic syllable selected later depends on this initial identification of the syllabic structure of particular words, but the outcome is also influenced by subsequent phonological processing. These markers are used in parsing input sentences for subsequent prosodic processing.