Sprachkodierungssystem

摘要

A speech coding method which can code a speech signal at a bit rate of 8 kb/s or less by a comparatively small amount of calculation to obtain a good sound quality. An autocorrelation of a synthesis signal synthesized from a codevector of an excitation codebook (140) and a linear predictive parameter of an input speech signal is corrected using an autocorrelation of a synthesis signal synthesized from a codevector of an adaptive codebook (120) and a linear predictive parameter and a cross-correlation between the synthesis signal of the codevector of the adaptive codebook (120) and the synthesis signal of the codevector of the excitation codebook (140). A gain codebook (210) is searched using the corrected autocorrelation and a cross-correlation between a signal obtained by subtraction of the synthesis signal of the codevector of the adaptive codebook (120) from the input speech signal and the synthesis signal of the codevector of the excitation codebook (140).