Experimental Comparison of All-Pole, All-Zero, and Pole-Zero Predictors for ADPCM Speech Coding

Simulation results are presented which compare the performance of all-pole, all-zero, and pole-zero predictors in ADPCM at data rates of 16 and 32 kbits/s over both ideal and noisy channels. Separate backward adaptive gradient algorithms are used to adapt the poles and the zeros independently. The performance indicators used are signal-to-quantization noise ratio (SNR), signal-to-prediction error ratio (SPER), segmental SNR (SNRSEG), and subjective listening tests. For speech sources, the all-zero and pole-zero predictors produce SNR and SNRSEG values that are approximately 1-3 dB higher than those generated by the all-pole predictor. Subjective listening tests reveal that an eighth-order all-zero predictor performs as well or better than an allpole predictor for all conditions studied.