DocumentCode :
766956
Title :
Predictive Coding of Speech at Low Bit Rates
Author :
Atal, Bishnu S.
Author_Institution :
Bell Labs., Murray Hill, NJ
Volume :
30
Issue :
4
fYear :
1982
fDate :
4/1/1982 12:00:00 AM
Firstpage :
600
Lastpage :
614
Abstract :
Predictive coding is a promising approach for speech coding. In this paper, we review the recent work on adaptive predictive coding of speech signals, with particular emphasis on achieving high speech quality at low bit rates (less than 10 kbits/s). Efficient prediction of the redundant structure in speech signals is obviously important for proper functioning of a predictive coder. It is equally important to ensure that the distortion in the coded speech signal be perceptually small. The subjective loudness of quantization noise depends both on the short-time spectrum of the noise and its relation to the short-time spectrum of the Speech signal. The noise in the formant regions is partially masked by the speech signal itself. This masking of quantization noise by speech signal allows one to use low bit rates while maintaining high speech quality. This paper will present generalizations of predictive coding for minimizing subjective distortion in the reconstructed speech signal at the receiver. The quantizer in predictive coders quantizes its input on a sample-by-sample basis. Such sample-by-sample (instantaneous) quantization creates difficulty in realizing an arbitrary noise spectrum, particularly at low bit rates. We will describe a new class of speech coders in this paper which could be considered to be a generalization of the predictive coder. These new coders not only allow one to realize the precise optimum noise spectrum which is crucial to achieving very low bit rates, but also represent the important first step in bridging the gap between waveform coders and vocoders without suffering from their limitations.
Keywords :
Adaptive coding; Speech coding; Acoustic noise; Adaptive systems; Bit rate; Distortion; Predictive coding; Quantization; Speech coding; Speech enhancement; Time varying systems; Vocoders;
fLanguage :
English
Journal_Title :
Communications, IEEE Transactions on
Publisher :
ieee
ISSN :
0090-6778
Type :
jour
DOI :
10.1109/TCOM.1982.1095501
Filename :
1095501
Link To Document :
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