A Comparative Study of Various Quantization Schemes for Speech Encoding
Peter Noll · Bell System Technical Journal · 1975
In this paper, the performance limits, as given by the signal-to-noise ratio (s/n), are described for different speech-encoding schemes including adaptive quantization and (linear) adaptive prediction schemes. The comparison is made on the basis of computer simulations using 8-kHz-sampled speech signals of one speaker. Different bit rates (two bits per sample–five bits per sample) have been used. A three-bit-per-sample pcm scheme with a nonadaptive μ100 quantizer leads to an s/n value of approximately 9 dB. A maximum s/n value of approximately 25 dB has been reached using an encoding scheme including both adaptive quantization and adaptive prediction. Entropy coding of the quantizer output symbols leads to an additional gain in s/n of nearly 3 dB.