A frame erasure concealment algorithm based on gain parameter re-estimation for CELP coders

In this paper, we propose a frame concealment algorithm based on reestimating gain parameters for a code-excited linear prediction (CELP) coder. When a frame is detected as being erased, the coding parameters, especially the adaptive codebook gain and fixed codebook gain, of the erased and subsequent frames, are reestimated by a gain-matching procedure. By doing this, we can reduce the abrupt change caused in the decoded excitation signal by a simple scaling down procedure. We have applied this technique to the IS-641 speech coder and found that the proposed algorithm improves the speech quality under various channel conditions compared with the conventional extrapolation-based concealment algorithm.