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Predictive speech signal coding with reduced noise effects

  • US 4,133,976 A
  • Filed: 04/07/1978
  • Issued: 01/09/1979
  • Est. Priority Date: 04/07/1978
  • Status: Expired due to Term
First Claim
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1. A predictive speech signal communication system comprising apparatus (135) for analyzing a speech signal in selected time intervals to generate a set of formant related prediction parameter signals for each interval;

  • circuitry (107,109) jointly responsive to said speech signal and said formant related prediction parameter signals for producing a signal representative of the difference between said speech signal and its predicted value;

    a modifying circuit (137) for modifying said difference representative signal;

    a quantizer (111) responsive to said modified difference signal for generating a quantized signal; and

    a subtracter circuit (113) for forming a quantizing error signal corresponding to the difference between said quantized and unquantized modified difference signal CHARACTERIZED IN THAT said modifying circuit (137) is jointly responsive to said formant related prediction parameter signals, said quantizing error signal and said difference signal to concentrate the quantizing error in the formant portions of said speech signal spectrum whereby the quantizing error is masked by said speech signal formants.

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