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Adaptive noise reduction circuit for a sound reproduction system

  • US 5,412,735 A
  • Filed: 02/27/1992
  • Issued: 05/02/1995
  • Est. Priority Date: 02/27/1992
  • Status: Expired due to Term
First Claim
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1. A noise reduction circuit for a sound reproduction system having a microphone for producing an input signal in response to sound in which a noise component is present, said circuit comprising:

  • an adaptive filter including a variable filter responsive to the input signal for producing a noise-estimating signal and further including a first combining means responsive to the input signal and the noise-estimating signal for producing a composite signal;

    said variable filter having parameters which are varied in response to the composite signal to change the operating characteristics thereof;

    a second filter for filtering the noise-estimating signal to produce a filtered noise-estimating signal;

    means for delaying the input signal to produce a delayed signal; and

    second combining means for combining the delayed signal and the filtered noise-estimating signal to attenuate noise components in the delayed signal and for producing a noise-reduced output signal.

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