Combination speech synthesis and recognition apparatus
First Claim
1. An apparatus for synthesizing speech from stored representations and for generating representations of speech for use in speech analysis, including but not limited to speech recognition, such apparatus being reconfigurable between the two functions and comprising:
- A. a lattice filter including elements which are configurable selectively to provide an all-pole transfer function for synthesis and an all-zero transfer function for analysis, the lattice filter being responsive to coefficients supplied thereto;
B. an input converter for converting analog representations of acoustic waveforms to signals suitable for processing by said all-zero lattice filter;
C. an output converter coupled to said all-pole reconfigured lattice filter for coverting the output signals from said filter to analog signals suitable for conversion into acoustic waveforms;
D. an excitation source for supplying to the input of said all-pole filter signals representing vocal tract excitation;
E. a filter coefficient correction means for modifying lattice filter coefficients responsive to a speech signal being analyzed, to generate representations of such speech;
F. means for receiving filter coefficients for speech synthesis;
G. means for selectively interconnecting, for speech synthesis or analysis, the lattice filter, the input converter, the output converter, the excitation source, the filter coefficient correction means and the coefficient receiving means.
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Abstract
A reconfigurable lattice filter is employed to permit the same circuitry to function as a speech synthesizer and as a speech analyzer or recognizer. The lattice filter can be configured both as an all-pole filter (for synthesis) and as an all-zero filter (for analysis), with the choice being determined by the state of an analysis/synthesis signal (i.e., mode control signal) provided thereto. The connections between various elements in the circuitry are controlled by the analysis/synthesis signal, also.
In synthesis mode, partial correlation coefficients are supplied to the filter from a microprocessor. The filter is excited by a one of a number of stored patterns simulating a glottal pulse for voiced sounds and by a pseudo-random noise generator for unvoiced sounds.
In analysis mode, appropriate feedback control paths are enabled so as to provide to the filter coefficients which change in response to changes in the input speech waveform. Coefficient values thus determined are averaged over fixed intervals and successions of such averaged coefficient sets produce representations of words or phrases which can then be used for speech recognition.
33 Citations
14 Claims
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1. An apparatus for synthesizing speech from stored representations and for generating representations of speech for use in speech analysis, including but not limited to speech recognition, such apparatus being reconfigurable between the two functions and comprising:
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A. a lattice filter including elements which are configurable selectively to provide an all-pole transfer function for synthesis and an all-zero transfer function for analysis, the lattice filter being responsive to coefficients supplied thereto; B. an input converter for converting analog representations of acoustic waveforms to signals suitable for processing by said all-zero lattice filter; C. an output converter coupled to said all-pole reconfigured lattice filter for coverting the output signals from said filter to analog signals suitable for conversion into acoustic waveforms; D. an excitation source for supplying to the input of said all-pole filter signals representing vocal tract excitation; E. a filter coefficient correction means for modifying lattice filter coefficients responsive to a speech signal being analyzed, to generate representations of such speech; F. means for receiving filter coefficients for speech synthesis; G. means for selectively interconnecting, for speech synthesis or analysis, the lattice filter, the input converter, the output converter, the excitation source, the filter coefficient correction means and the coefficient receiving means. - View Dependent Claims (5, 6, 13)
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2. An apparatus for synthesizing speech from stored representations and for generating representations of speech for use in speech analysis, including but not limited to speech recognition, such apparatus being reconfigurable between the two functions and comprising:
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A. a lattice filter selectively configurable to have an all-pole transfer function for synthesis and an all-zero transfer function for analysis, the lattice filter being responsive to coefficients supplied thereto; B. an input inverter for converting analog representations of acoustic waveforms to signals suitable for processing by said all-zero lattice filter; C. an output converter coupled to said all-pole reconfigured lattice filter for coverting the output signals from said filter to analog signals suitable for conversion into acoustic waveforms; D. an excitation source for supplying to the input of said all-pole filter signals representing vocal tract excitation; E. a filter coefficient correction means for modifying lattice filter coefficients responsive to a speech signal being analyzed, to generate representations of such speech, and comprising 1. a feedback control means for adapting the response of said lattice filter to signals from said input converter, and 2. a coefficient integrator and storage means coupled to said feedback control means for integrating the output of said feedback control means and storing the results of the integration, said results being a set of coefficients characteristic of the input acoustic waveform; F. means for receiving filter coefficients for speech synthesis; G. means for selectively interconnecting, for speech synthesis or analysis, the lattice filter, the input converter, the output converter, the excitation source, the filter coefficient correction means and the coefficient receiving means. - View Dependent Claims (3, 4, 7, 8, 9, 10, 11, 12, 14)
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Specification