Method of encoding and decoding speech signals

Abstract

In a speech codec algorithm for low speed transmission, a first linear prediction analysis is performed for an input speech signal and a second linear prediction analysis is performed for a residual signal generated from the first linear prediction analysis. Low-pass-filtering utilizing a cut-off frequency of 2 kHz is employed to generate second linear prediction coefficients. The second linear prediction coefficients are transmitted to a receiver, together with the first linear prediction coefficients. A baseband signal is generated for the first linear prediction coefficients using the second linear prediction coefficients during reproduction of the speech signal, and the speech signal is restored using the baseband signal and the first linear prediction coefficients. Thus, a high-quality restored tone can be provided with a low-cost digital signal processor.