Patent ID: 7024354
Filing Date: 2006-04-04
Classification: G10L

Abstract:
1. A speech decoder for decoding a coded speech signal into a decoded speech signal and for reproducing a speech signal using the decoded speech signal, the decoder comprising: a spectral parameter calculating circuit, responsive to the decoded speech signal, for calculating spectral parameters based on the decoded speech signal; an excitation signal calculating circuit for calculating an excitation signal and for obtaining a level of the excitation signal, on the basis of the decoded speech signal and the spectral parameters; a smoothing circuit responsive to the spectral parameters and the excitation signal, for smoothing at least one of the spectral parameters and the level of the excitation signal, so as to output the spectral parameters and the excitation signal where at least one is subjected to smoothing; and a synthesis filter circuit having a synthesis filter constructed with the spectrum parameters output from the smoothing circuit, and for synthesizing the excitation signal by using the synthesis filter, so as to reproduce the speech signal, wherein the excitation signal calculating circuit, the smoothing circuit, and the synthesis filter circuit operate only in compliance with predetermined conditions.