Backward adaptive tree coding of speech at 16 kbps

The authors investigate the performance of eight fully backward adaptive DPCM-based code generators with exhaustive searching to shallow depths. In particular, they compare the performance of fixed (matched and unmatched) autoregressive (AR), fixed (matched and unmatched) moving average (MA), undamped and damped Kalman AR, and undamped and damped gradient MA code generators in DPCM searched to a maximum depth of 5 with incremental single symbol release. SNR, subjective listening test, and spectrogram performance comparisons are employed. The performance gain due to adaptive prediction over unmatched fixed prediction is greater than the gain provided by multipath searching over single path searching