Estimation of excitation parameters
First Claim
1. A method of analyzing a digitized speech signal to determine excitation parameters for the digitized speech signal, comprising:
- dividing the digitized speech signal into one or more frequency band signals;
determining a first preliminary excitation parameter using a first method that includes performing a nonlinear operation on at least one of the frequency band signals to produce at least one modified frequency band signal and determining the first preliminary excitation parameter using the at least one modified frequency band signal;
determining at least a second preliminary excitation parameter using at least a second method different from the said first method; and
using the first and at least a second preliminary excitation parameters to determine an excitation parameter for the digitized speech signal.
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Abstract
A method of encoding speech by analyzing a digitized speech signal to determine excitation parameters for the digitized speech signal is disclosed. The method includes dividing the digitized speech signal into at least two frequency bands, determining a first preliminary excitation parameter by performing a nonlinear operation on at least one of the frequency band signals to produce a modified frequency band signal and determining the first preliminary excitation parameter using the modified frequency band signal, determining a second preliminary excitation parameter using a method different from the first method, and using the first and second preliminary excitation parameters to determine an excitation parameter for the digitized speech signal. The method is useful in encoding speech. Speech synthesized using the parameters estimated based on the invention generates high quality speech at various bit rates useful for applications such as satellite voice communication.
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Citations
41 Claims
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1. A method of analyzing a digitized speech signal to determine excitation parameters for the digitized speech signal, comprising:
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dividing the digitized speech signal into one or more frequency band signals; determining a first preliminary excitation parameter using a first method that includes performing a nonlinear operation on at least one of the frequency band signals to produce at least one modified frequency band signal and determining the first preliminary excitation parameter using the at least one modified frequency band signal; determining at least a second preliminary excitation parameter using at least a second method different from the said first method; and using the first and at least a second preliminary excitation parameters to determine an excitation parameter for the digitized speech signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of analyzing a digitized speech signal to determine excitation parameters for the digitized speech signal, comprising the steps of:
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dividing the digitized speech signal into one or more frequency band signals; determining a preliminary excitation parameter using a method that includes performing a nonlinear operation on at least one of the frequency band signals to produce at least one modified frequency band signal and determining the preliminary excitation parameter using the at least one modified frequency band signal; and smoothing the preliminary excitation parameter to produce an excitation parameter. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A method of analyzing a digitized speech signal to determine excitation parameters for the digitized speech signal, comprising the steps of:
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estimating a fundamental frequency for the digitized speech signal; evaluating a voiced/unvoiced function using the estimated fundamental frequency to produce a first preliminary voiced/unvoiced parameter; evaluating the voiced/unvoiced function at least using one other frequency derived from the estimated fundamental frequency to produce at least one other preliminary voiced/unvoiced parameter; and combining the first and at least one other preliminary voiced/unvoiced parameters to produce a voiced/unvoiced parameter. - View Dependent Claims (28, 29, 30, 31)
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32. A method of analyzing a digitized speech signal to determine a fundamental frequency estimate for the digitized speech signal, comprising the steps of:
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determining a predicted fundamental frequency estimate from previous fundamental frequency estimates; determining an initial fundamental frequency estimate; evaluating an error function at the initial fundamental frequency estimate to produce a first error function value; evaluating the error function at at least one other frequency derived from the initial fundamental frequency estimate to produce at least one other error function value; selecting a fundamental frequency estimate using the predicted fundamental frequency estimate, the initial fundamental frequency estimate, the first error function value, and the at least one other error function value. - View Dependent Claims (33, 34, 35, 36)
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37. A system for analyzing a digitized speech signal to determine excitation parameters for the digitized speech signal, comprising:
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means for dividing the digitized speech signal into one or more frequency band signals; means for determining a first preliminary excitation parameter using a first method that includes performing a nonlinear operation on at least one of the frequency band signals to produce at least one modified frequency band signal and determining the first preliminary excitation parameter using the at least one modified frequency band signal; means for determining a second preliminary excitation parameter using a second method that is different from the above said first method; and means for using the first and second preliminary excitation parameters to determine an excitation parameter for the digitized speech signal.
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38. A system for analyzing a digitized speech signal to determine excitation parameters for the digitized speech signal, comprising:
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means for dividing the digitized speech signal into one or more frequency band signals; means for determining a preliminary excitation parameter using a method that includes performing a nonlinear operation on at least one of the frequency band signals to produce at least one modified frequency band signal and determining the preliminary excitation parameter using the at least one modified frequency band signal; and means for smoothing the preliminary excitation parameter to produce an excitation parameter.
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39. A system for analyzing a digitized speech signal to determine modified excitation parameters for the digitized speech signal, comprising:
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means for estimating a fundamental frequency for the digitized speech signal; means for evaluating a voiced/unvoiced function using the estimated fundamental frequency to produce a first preliminary voiced/unvoiced parameter; means for evaluating the voiced/unvoiced function using another frequency derived from the estimated fundamental frequency to produce a second preliminary voiced/unvoiced parameter; and means for combining the first and second preliminary voiced/unvoiced parameters to produce a voiced/unvoiced parameter.
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40. A system for analyzing a digitized speech signal to determine a fundamental frequency estimate for the digitized speech signal, comprising:
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means for determining a predicted fundamental frequency estimate from previous fundamental frequency estimates; means for determining an initial fundamental frequency estimate; means for evaluating an error function at the initial fundamental frequency estimate to produce a first error function value; means for evaluating the error function at at least one other frequency derived from the initial fundamental frequency estimate to produce a second error function value; means for selecting a fundamental frequency estimate using the predicted fundamental frequency estimate, the initial fundamental frequency estimate, the first error function value, and the second error function value.
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41. A method of analyzing a digitized speech signal to determine a voiced/unvoiced function for the digitized speech signal, comprising:
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dividing the digitized speech signal into at least two frequency band signals; determining a first preliminary voiced/unvoiced function for at least two of the frequency band signals using a first method; determining a second preliminary voiced/unvoiced function for at least two of the frequency band signals using a second method which is different from the above said first method; and using the first and second preliminary excitation parameters to determine a voiced/unvoiced function for at least two of the frequency band signals.
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Specification