| 摘要 |
PURPOSE:To reduce deterioration in the quality of a speech even if a parameter in a 2nd noise code book has an error by not using the 2nd noise code book having low priority to update an adaptive code book. CONSTITUTION:Noise parameters stored in a 1st noise code book 120 are set higher in priority than noise parameters stored in the 2nd noise code book 150. The indexes of the adaptive code book 110, the code of a gain outputted from a gain encoding circuit 140, and the index and gains of the noise code book 120 are protected with error correction codes having high correcting ability. Only the indexes and gains of the adaptive code book 110 and noise code book 120 are used to generate driving codes to be stored in the adaptive code book 110 sequentially. |
