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In-ear active noise reduction earphone

  • US 9,792,893 B1
  • Filed: 09/20/2016
  • Issued: 10/17/2017
  • Est. Priority Date: 09/20/2016
  • Status: Active Grant
First Claim
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1. An active noise reduction (ANR) earphone system comprising:

  • a feedback microphone for detecting noise;

    feedback circuitry, responsive to the feedback microphone, for applying a digital filter Kfb to an output of the feedback microphone to produce an antinoise signal;

    an electroacoustic driver for transducing the antinoise signal into acoustic energy;

    a housing supporting the feedback microphone and the driver near the entrance to the ear canal; and

    an ear tip for coupling the housing to the external anatomical structures of a first ear of a user and positioning the housing to provide a consistent acoustic coupling of the feedback microphone and the driver to the ear canal of the first ear;

    wherein the acoustic coupling includes a tube of air defined by the combination of the housing and ear tip, having a length L and effective cross-sectional area A such that the ratio L/A is less than 0.6 mm

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