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

摘要

A speech coder using a pitch synchronous innovation code excited linear prediction (PSI-CELP) speech coding system. The speech coder is capable of representing a portion which is not sufficiently represented by an adaptive codebook in a periodic portion of input speech and capable of improving the quality of reproduced speech. The periodicity corresponds to the pitch cycle of input speech by preliminarily reproducing speech from simple impulse trains. The speech coder depending on the particular embodiment includes an adaptive code book, a fixed code book, a noise code book, and a pulse codebook. A pulse code book stores a plurality of types of codevectors corresponding to pitch waveforms of voiced sounds. At the time of coding input speech, the pulse code book is searched.