Noise suppression effect of a linear predictor and a coding scheme for narrow-band speech communications
Yasuhiko Arai, Toshio Yagi · The Journal of the Acoustical Society of America · 1988
The relation between the perceptual noisiness of quantization error and the number of prediction coefficients was experimentally studied. It was revealed that a speech coder (a kind of APC) with ten coefficients shows considerably less noisiness than that one with four coefficients. Though improvement of the segmental SNR was only 1 dB, perceptual noisiness was improved by an equivalent value to a quantizing accuracy of 1.5 bits (approximately 9 dB). Taking this result into consideration, a coder scheme was proposed for special-purpose, narrow-band, wireless communcations. The narrow-band speech coder to be used in very noisy channels having a transmission error rate of 10−2 or 10−1 requires good intelligibility and less perceptual noisiness. It was confirmed that a source coder having eight or ten prediction coefficients and an error correction code for side information would meet the requirements. Even if the residual information fails to be transmitted, the source decoder is capable of synthesizing intelligible speech from only the side information including coefficients.