Multiple impulse excitation speech encoder and decoder

Details Multiple impulse excitation speech encoder and decoder Multiple impulse excitation speech encoder and decoder

1999-11-16

2001-04-24

Hudspeth, David (Department: 2641)

Data processing: speech signal processing, linguistics, language

Speech signal processing

For storage or transmission

C704S217000, C704S225000

Reexamination Certificate

active

06223152

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to digital voice coders performing at relatively low voice rates but maintaining high voice quality. In particular, it relates to improved multipulse linear predictive voice coders.
BACKGROUND OF THE INVENTION
The multipulse coder incorporates the linear predictive all-pole filter (LPC filter). The basic function of a multipulse coder is finding a suitable excitation pattern for the LPC all-pole filter which produces an output that closely matches the original speech waveform. The excitation signal is a series of weighted impulses. The weight values and impulse locations are found in a systematic manner. The selection of a weight and location of an excitation impulse is obtained by minimizing an error criterion between the all-pole filter output and the original speech signal. Some multipulse coders incorporate a perceptual weighting filter in the error criterion function. This filter serves to frequency weight the error which in essence allows more error in the formant regions of the speech signal and less in low energy portions of the spectrum. Incorporation of pitch filters improve the performance of multipulse speech coders. This is done by modeling the long term redundancy of the speech signal thereby allowing the excitation signal to account for the pitch related properties of the signal.
SUMMARY OF THE INVENTION
The basic function of the present invention is the finding of a suitable excitation pattern that produces a synthetic speech signal which closely matches the original speech. A location and amplitude of an excitation pulse is selected by minimizing the mean-squared error between the real and synthetic speech signals. The above function is provided by using an excitation pattern containing a multiplicity of weighted pulses at timed positions.
The selection of the location and amplitude of an excitation pulse is obtained by minimizing an error criterion between a synthetic speech signal and the original speech. The error criterion function incorporates a perceptual weighting filter which shapes the error spectrum.


REFERENCES:
patent: 4618982 (1986-10-01), Horvath et al.
patent: 4669120 (1987-05-01), Ono
patent: 4776015 (1988-10-01), Takeda et al.
patent: 4815134 (1989-03-01), Picone et al.
patent: 4845753 (1989-07-01), Yasunaga
patent: 4868867 (1989-09-01), Davidson et al.
patent: 4890327 (1989-12-01), Bertrand et al.
patent: 4980916 (1990-12-01), Zinser
patent: 4991213 (1991-02-01), Wilson
patent: 5001759 (1991-03-01), Fukui
patent: 5027405 (1991-06-01), Ozawa
patent: 5235670 (1993-08-01), Lin et al.
patent: 5265167 (1993-11-01), Akamine et al.
patent: 5307441 (1994-04-01), Tzeng
patent: 5999899 (1999-12-01), Robinson
patent: WO86/02726 (1986-06-01), None
Veeneman et al., “Computationally efficient stochastic coding of speech,” 1990 IEEE 40th Vehicular Technology Conference, May 1990, pp. 331 to 335.*
Proc. ICASSP '82, A New Model of LPC Excitation for Producing Natural-Sounding Speech at Low Bit Rates, B.S. Atal and J.R. Remde, pp. 614-617, Apr., 1982.
Proc. ICASSP '84, Improving Performance of Multi-Pulse Coders at Low Bit Rates, S. Singhal and B.S. Atal, paper 1.3, Mar. 1984.
Proc. ICASSP '84, Efficient Computation and Encoding of the Multiple Excitation for LPC, M. Berouti et al., paper 10.1, Mar., 1984.
Proc. ICASSP '86, Implementation of Multi-Pulse Coder on a Single Chip Floating-Point Signal Processor, H. Alrutz, paper 44.3, Apr., 1986.
Digital Telephony, John Bellamy, pp. 153-154, 1991.

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