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

• Current Assignee: Red Tail Hawk Corporation
• Original Assignee: Red Tail Hawk Corporation
• Inventors: Parkins, John W.
• Primary Examiner(s): Goins, Davetta W
• Assistant Examiner(s): Ojo, Oyesola C
• Application Number:
  US13/796,579
• Publication Number:
  US 20140198932A1
• Time in Patent Office: 854 Days
• Field of Search: 381/189, 381/355, 381/359, 381/360, 381/395, 381/391, 290/6
• US Class Current: 1/1
• CPC Class Codes: H04B 1/385 Transceivers carried on the body, e.g. in helmets
• CPC Class Codes: H04R 1/086 Protective screens, e.g. all weather or wind screens
• CPC Class Codes: H04R 1/1075 Mountings of transducers in earphones or headphones
• CPC Class Codes: H04R 2410/07 Mechanical or electrical reduction of wind noise generated by wind passing a microphone
• CPC Class Codes: Y10S 2/906 Head covering or protector
• CPC Class Codes: Y10S 2/909 Head protector, e.g. helmet, goggles

Abstract

A device for protecting a microphone sensing surface, such as a diaphragm, from the detrimental effects of the ambient environment. The device incorporates a perforated surface to protect the microphone and in conjunction with a chamber volume creates an acoustic resonance in the 1 kHz to 20 kHz spectrum, which improves the microphone signal-to-noise ratio performance. The microphone is acoustically coupled to the chamber volume for sensing pressure of the ambient environment. There is no line of sight to the microphone sensing surface from the ambient environment, so that rain, wind and sand have no direct path to the microphone sensing surface. The perforations of the outer surface are small to prevent objects from contacting the microphone sensing surface via a direct path. Water drains from the chamber volume and does not become trapped if an embodiment of the invention is temporarily submerged so that the microphone returns to normal operation quickly.

Claims

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.

2. The device of claim 1, further comprising a mesh screen covering the at least one perforation.

3. The device of claim 1, in which there is an indirect unobstructed path from the ambient environment to the acoustic vent.

4. The device of claim 1, wherein the microphone is located above at least one of the perforations.

5. The device of claim 1, in which perforated barrier is formed by a plurality of slots passing through the outer surface.

6. The device of claim 1, in which the chamber has a volume of less than 2.32 cubic centimeters.

7. The device of claim 1, further comprising an auxiliary wind screen on an exterior side of the outer surface.

17. The device of claim 1, in which an average depth of the chamber is greater than 1 mm.

19. The device of claim 5, in which the plurality of slots are greater than 0.5 mm in width.

21. The device of claim 1, in which the outer surface is an outer surface of an earcup.

23. The device of claim 1, in which the microphone is at least partially located within the drain channel.

26. The device of claim 1 further comprising a microphone located in the upper region of the chamber.

8. An environmental protection device for a microphone having a microphone sensing surface, comprising:

a chamber enclosing a volume of less than 2.32 cc and an average chamber depth of more than 1 mm, acoustically coupled to the microphone sensing surface,

the chamber comprising a plurality of sides,

one of the plurality of sides being formed by an outer surface exposed to an ambient environment from which sound is to be detected by the microphone, 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 into the chamber; and

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 a 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.

9. The device of claim 8, further comprising a mesh screen covering the at least one perforation.

10. The device of claim 8, further comprising a gas permeable acoustic vent arranged between the microphone sensing surface and the chamber that restricts water from contacting the microphone sensing surface.

11. The device of claim 10, in which there is an indirect unobstructed path from the ambient environment to the gas permeable acoustic vent.

12. The device of claim 8, in which there is an indirect unobstructed path from the ambient environment to the microphone sensing surface.

13. The device of claim 8, further comprising an elastomeric microphone coupler acoustically coupling the chamber to the microphone sensing surface.

14. The device of claim 8, wherein the microphone is located above at least one of the perforations.

15. The device of claim 8, in which the perforated barrier is formed by a plurality of slots passing through the outer surface.

16. The device of claim 8, further comprising an auxiliary wind screen on an exterior side of the outer surface.

18. The device of claim 8, in which an average depth of the chamber is greater than 1 mm.

20. The device of claim 15, in which the plurality of slots are greater than 0.5 mm in width.

22. The device of claim 8, in which the outer surface is an outer surface of an earcup.

24. The device of claim 8, in which the microphone is at least partially located within the drain channel.

25. The device of claim 13, in which the microphone coupler is at least partially located within the drain channel.

27. The device of claim 8 further comprising a microphone located in the upper region of the chamber.