Patent Document ID: 4520499
Application ID: 06392309

Base 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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Claim 13:
13. An apparatus as defined in claim 1 including A. a first controllable scaler for controlling the amplitude of the excitation applied to said lattice filter when the filter is in its all-pole configuration; and B. a second controllable scaler for adjusting the amplitude of the output of said lattice filter, whereby the maximum amplitude of the signal passing through the filter may be maintained substantially at the maximum amplitude of which the filter is capable, thereby to minimize noise, and the amplitude of the output from the output converter may be adjusted to generate the overall energy variations in the speech signal being synthesized.