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Telephone set with background noise suppression function

  • US 5,748,725 A
  • Filed: 12/20/1994
  • Issued: 05/05/1998
  • Est. Priority Date: 12/29/1993
  • Status: Expired due to Fees
First Claim
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1. A telephone set for suppressing background noise comprising:

  • a speaker for outputting a first voice signal;

    a first microphone provided in the vicinity of said speaker, for generating a first voice band signal;

    a second microphone for generating a second voice band signal including said background noise;

    said noise elimination circuit comprising;

    a level detector for comparing said received voice signal with a predetermined threshold value to output a control signal indicative of whether said received voice signal is equal to or higher than the predetermined threshold level;

    a first adaptive filter for producing a third voice band signal based on said received voice signal and first tap coefficients and for updating said first tap coefficients based on said first voice band signal and an error signal when said control signal indicates that said received voice signal is higher than the threshold value;

    a first subtracter for subtracting said third voice band signal from said first voice band signal to produce said error signal;

    a second adaptive filter for producing said estimated background noise based on said second voice band signal and second tap coefficients and for updating said second tap coefficients when said control signal indicates that said received voice signal is lower than said threshold value; and

    a second subtracter for subtracting said estimated background noise from said received voice signal to produce said first voice signal.

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