Proceedings Article10.1109/ICASSP.1976.1170079
Digital coding of speech in sub-bands
R. Crochiere,S. A. Webber,James L. Flanagan +2 more
- 12 Apr 1976
- Vol. 1, pp 233-236
281
TL;DR: A rationale is advanced for digitally coding speech signals in terms of sub-bands of the total spectrum, which provides a means for controlling and reducing quantizing noise in the coding.
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Abstract: A rationale is advanced for digitally coding speech signals in terms of sub-bands of the total spectrum. The approach provides a means for controlling and reducing quantizing noise in the coding. Each sub-band is quantized with an accuracy (bit allocation) based upon perceptual criteria. As a result, the quality of the coded signal is improved over that obtained from a single full-band coding of the total spectrum. In one implementation, the individual sub-bands are low-pass translated before coding. In another, "integer-band" sampling is employed to alias the signal in an advantageous way before coding. Other possibilities extend to complex demodulation of the sub-bands, and to representing the subband signals in terms of envelopes and phase-derivatives. In all techniques, adaptive quantization is used for the coding, and a parsimonious allocation of bits is made across the bands. Computer simulations are made to demonstrate the signal qualities obtained for codings at 16 and 9.6 Kbits/sec.
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Citations
Current perspectives in digital speech
R. Crochiere,J. Flanagan +1 more
TL;DR: This paper briefly outlines some of the basic properties of speech and the techniques of coding that use these properties and point to areas of current research and areas of practical hardware implementation.
20
A comparison of the performance of four low-bit-rate speech waveform coders
TL;DR: A weighted combination of two objective measures, one accounting for noise and the other for bandwidth effects, appears promising as a predictor of the subjective quality ratings.
18
A novel approach for implementing pitch prediction in sub-band coding
R. Crochiere
- 01 Apr 1979
TL;DR: A novel method uses digital linear phase shifters based on a bandpass interpolation scheme to achieve the non-integer delays necessary in the feedback loops of the pitch predictors.
18
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References
•Journal Article
Phase vocoder
J. L. Flanagan,R. M. Golden +1 more
TL;DR: A vocoder technique is described in which speech signals are represented by their short-time phase and amplitude spectra, which leads to an economy in transmission bandwidth and to a means for time compression and expansion of speech signals.
435
Methods for the Calculation and Use of the Articulation Index
TL;DR: Articulation Index (AI) as discussed by the authors is a measure that is indicative of the intelligibility scores that would be obtained for a speech communication system under actual test conditions, and it can be used for evaluation of most speech communication systems.
413
Digital coding of speech waveforms: PCM, DPCM, and DM quantizers
N.S. Jayant
- 01 May 1974
TL;DR: It is pointed out that error waveforms in speech quantization cannot be regarded as additive white noise, in general, and that for finer assessments of speech coders, either relative or absolute, one needs to supplement SNR-based observations with corrections for subjective and perceptual factors.
282
Band width and transmission performance
C. B. Feldman,W. R. Bennett +1 more
TL;DR: The significance of signal hand width and frequency occupancy in relation to other transmission factors such as power, noise, interference, and overall performance for certain specific multiplex systems under assumed operating conditions is discussed.
44