Data processing: speech signal processing – linguistics – language – Speech signal processing – Synthesis
Reexamination Certificate
1997-12-11
2001-12-11
Smits, Talivaldis Ivars (Department: 2641)
Data processing: speech signal processing, linguistics, language
Speech signal processing
Synthesis
C704S267000
Reexamination Certificate
active
06330538
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is concerned with speech synthesis, and particularly, though not exclusively, with text-to-speech synthesisers which operate by concatenating segments of stored speech waveforms.
2. Related Art
Various prior art systems have been devised for converting text to synthesized speech. While these systems provide associated techniques to determine the timing and duration of synthesized phonetic units, it is believed that there is room for improvement in this regard.
BRIEF SUMMARY OF THE INVENTION
According to the present invention there is provided a speech synthesiser comprising:
means for supplying a sequence of representations of phonetic units;
means for retrieving stored portions of data to generate waveforms corresponding to the phonetic units;
means for determining durations for the phonetic units: and
means for processing the portions of data to adjust the time durations of the waveforms according to the determined durations;
wherein the determining means is operable to define a constant duration corresponding to a regular beat period and to adjust that duration in dependence on the nature of the phonetic unit and/or its context within the sequence.
Preferably the stored data are themselves digitised speech waveforms (though this is not essential and the invention may also be applied to other types of synthesiser such as formant synthesisers). Thus in a preferred arrangement the synthesiser includes a store containing items of data representing waveforms corresponding to phonetic sub-units, the retrieving means being operable to retrieve, for each phonetic unit, one or more portions of data each corresponding to a sub-unit thereof, and a further store containing for each sub-unit statistical duration data including a maximum value and a minimum value, wherein the determining means is operable to compute for each phonetic unit the sum of the minimum duration values and the sum of the maximum duration values for the constituent sub-unit(s) thereof and to adjust the said constant duration such that it neither falls below the sum of the minimum values nor exceeds the sum of the maximum values.
In the preferred embodiment the phonetic units are syllables and the sub-units are phonemes.
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British Telecommunications public limited company
Nixon & Vanderhye P.C.
Smits Talivaldis Ivars
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