Pitch-synchronous speech coding by applying multiple analysis to select and align a plurality of types of code vectors

A speech coder for subjecting input speech to linear predictive analysis to construct a speech synthesis filter, reproducing speech on the basis of codevectors read out from a codebook including an adaptive codebook storing codevectors corresponding to a past excitation signal and a noise codebook storing codevectors corresponding to noises and the speech synthesis filter, and coding the input speech on the basis of the reproduced speech and the input speech, wherein

• a pulse codebook storing a plurality of types of codevectors corresponding to pitch waveforms of voiced sounds is provided in a complementary manner to the noise codebook.

A speech coder comprising:

• means for subjecting input speech to linear predictive analysis to construct a speech synthesis filter in the speech coder;
• first searching means in the speech coder for successively cutting off a plurality of codevectors by changing the cutting position from an adaptive codebook storing codevectors corresponding to a past excitation signal, driving the speech synthesis filter using each of the cut codevectors to produce reproduced speech corresponding to the cut codevectors, and searching for the codevector corresponding to the reproduced speech whose distortion from the input speech reaches a minimum, and
• second searching means in the speech coder for successively reading out the codevectors from a noise codebook storing a plurality of types of codevectors corresponding to noises and a pulse codebook storing a plurality of types of codevectors corresponding to pitch waveforms of voiced sounds, producing, on the basis of each of the codevectors read out and the speech synthesis filter, reproduced speech corresponding to the codevector read out, and searching for the codevector corresponding to the reproduced speech whose distortion from the input speech reaches a minimum.

The speech coder for reproducing speech on the basis of codevectors stored in a codebook and coding, on the basis of the reproduced speech and input speech, the input speech, wherein

• there is provided a pulse codebook storing a plurality of types of codevectors corresponding to pitch waveforms of voiced sounds, and
• in producing reproduced speech on the basis of a codevector read out from the pulse codebook, the reproduced speech corresponding to each of a plurality of impulse trains in which impulses are generated at intervals of the pitch cycle of the input speech and the impulse trains differ from each other in their initial positions, the impulse train corresponding to the reproduced speech whose distortion from the input speech reaches a minimum is selected, and the codevector read out from the pulse codebook is caused to have periodicity on the basis of the selected impulse train.

A speech coder for reproducing speech on the basis of codevectors read out from a codebook including an adaptive codebook storing codevectors corresponding to a past reproduction signal and a noise codebook storing codevectors corresponding to noises, and coding, on the basis of the reproduced speech and input speech, the input speech, wherein

• a pulse codebook storing a plurality of types of codevectors corresponding to pitch waveforms of voiced sounds is provided in a complementary manner to the noise codebook.

A speech coder comprising:

• first searching means in the speech coder for successively cutting off a plurality of codevectors by changing the cutting position from an adaptive codebook storing codevectors corresponding to a past reproduction signal, to produce reproduced speech corresponding to each of the cut codevectors, and searching for the codevector corresponding to the reproduced speech whose distortion from the input speech reaches a minimum, and
• second searching means in the speech coder for successively reading out the codevectors from a noise codebook storing a plurality of types of codevectors corresponding to noises and a pulse codebook storing a plurality of types of codevectors corresponding to pitch waveforms of voiced sounds, producing reproduced speech corresponding to each of the codevectors read out, and searching for the codevector corresponding to the reproduced speech whose distortion from the input speech reaches a minimum.