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Apparatus for reducing noise in a closed space having divergence detector

  • US 5,809,152 A
  • Filed: 10/10/1996
  • Issued: 09/15/1998
  • Est. Priority Date: 07/11/1991
  • Status: Expired due to Fees
First Claim
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1. A noise-reducing apparatus, comprising:

  • noise detection means for detecting noises generated by propagation of mechanical vibration;

    arithmetic means for calculating a signal to produce secondary sounds of reverse phase to the noises in terms of frequencies of the vibrations;

    secondary sound generating means for generating the secondary sounds based on the signal calculated by the arithmetic means to reduce the noises;

    means for monitoring values of the signal univocally determined by adaptive filter coefficients used by the arithmetic means to calculate the signal; and

    means for automatically interrupting the signal before the generation of the secondary sounds if the noises and the secondary sounds at positions of the noise detection means are predicted to deviate in their reverse phase relationship or if amplitudes of the secondary sounds are predicted to deviate from amplitudes of the noises, as determined by said means for monitoring.

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