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Microphone environmental protection device

  • US 9,084,053 B2
  • Filed: 03/12/2013
  • Issued: 07/14/2015
  • Est. Priority Date: 01/11/2013
  • Status: Active Grant
First Claim
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1. An environmental protection device for a microphone having a microphone sensing surface, comprising:

  • a) a chamber enclosing a volume, the chamber comprising a plurality of sides, one of the plurality of sides being formed by an outer surface exposed to an ambient environment, at least part of the outer surface forming a perforated barrier which is perforated by at least one perforation passing through the outer surface from the ambient environment from which sound is to be detected into the chamber;

    b) a gas permeable acoustic vent arranged between the microphone sensing surface and the chamber that restricts water from entering a microphone inlet, the acoustic vent being located such that the sensing surface is outside of any imaginary straight line passing through the chamber from the ambient environment through the perforated barrier to the sensing surface; and

    c) a recessed drain channel located inside the chamber and forming part of the side of the chamber which is opposite the perforated barrier, the drain channel having a depth such that a distance from the perforated barrier to the bottom of the drain channel is greater than 1 mm;

    wherein an acoustic mass of the perforated barrier combined with an acoustic compliance of the chamber forms an acoustic resonator amplifying the sound at the microphone sensing surface by acoustic means around a resonance frequency of between 1 kHz and 8 kHz.

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