Statistical block protection coding for DPCM-encoded speech

Blocks of speech-carrying dpcm bits are protected from transmission errors by means of explicit communication of two block statistics–the maximum and the root-mean-square (rms) values of the adjacent-sample differences in the dpcm-quantized speech. At the receiver, the maximum value is used as a cue for error-detection, white the rms value is used for a partial waveform correction procedure that provides intelligible speech at bit error rates as high as 10 percent.