MODIFIED CONCEALING DEVICE AND METHOD FOR A SPEECH DECODER

A speech decoder 10 comprises a decoding processing portion 11 and an amplification process control portion 12. Here, the decoding processing potion 11 is a device for decoding a received coded speech signal (bitstream) BS and outputting a decoded speech signal SP. Additionally, the amplification process control portion 12 monitors the state of occurrence of frame errors in the coded speech signal BS, and when the number of successive frame errors exceeds a predetermined reference frame error number, outputs amplification instructions for a predetermined number of frames after the successive frame errors disappear. As a result, instead of codebook data DCB obtained by a decoding process of the decoding processing portion 11, amplified codebook data DACB are supplied to a synthesis filter portion 17, and is written into the codebook decoder 18 of the decoding processing portion 11 as new original codebook data DCBO. Therefore, after successive frame errors, it is possible to decode normally input coded speech signals BS at a power close to the originally intended power, thus enabling the subjective sound quality of the decoded speech SP to be improved.