Patent ID: 6081781
Filing Date: 2000-06-27
Classification: G10L

Abstract:
A speech synthesis system which synthesizes a speech in a desired fundamental frequency distinct from the fundamental frequency of an input speech, comprisinga reference codebook prepared by clustering the spectrum envelope of a learning speech data in the same range of the fundamental frequency as the input speech by a statistical technique,a codebook for a different range of the fundamental frequency from the input speech, the codebook being prepared from a learning speech data for the same text as the learning speech data initially mentioned in a manner to exhibit a correspondence to code vectors in the reference codebook,a differential vector codebook comprising differential vectors between corresponding code vectors of the reference codebook and a codebook for a different range,a frequency difference codebook comprising differences of mean values of the fundamental frequency of element vectors in each corresponding class between the reference codebook and the codebook for the different range,quantizing means for vector quantizing the spectrum envelope of the input speech using the reference codebook,differential vector evaluation means for determining a differential vector which corresponds to the quantized code using the diffential vector codebook,means for calculating a stretching rate on the basis of the fundamental frequency of the input speech, the desired fundamental frequency and the frequency difference which corresponds to the quantized code and which is determined from the frequency difference codebook,stretching means for stretching the differential vector in accordance with the stretching rate,means for adding the stretched differential vector and the spectrum envelope of the input speech together,and means for transforming the added spectrum envelope into the time domain.