Microphone system having pressure-gradient capsules

• US 20060083390A1
• Filed: 09/30/2005
• Published: 04/20/2006
• Est. Priority Date: 10/01/2004
• Status: Active Grant

• Current Assignee: AKG Acoustics GmbH, Vienna (Samsung Electronics Co. Ltd.)
• Original Assignee: AKG Acoustics GmbH, Vienna (Samsung Electronics Co. Ltd.)
• Inventors: Haindl, Klaus Alois, Kaderavek, Johann
• Granted Patent: US 8,036,412 B2
• Time in Patent Office: Days
• US Class Current: 381/92
• CPC Class Codes: H04R 1/38 in which sound waves act upon both sides of a diaphragm and incorporating acoustic phase-shifting means, e.g. pressure-gradient microphone
• CPC Class Codes: H04R 1/406 microphones

Abstract

A microphone system may include a housing having a housing opening. Pressure-gradient capsules may be provided in the housing. The capsules may include a diaphragm and at least one sound entry opening. One sound entry opening may be connected with a front side of the diaphragm in an acoustically conductive manner and another sound entry opening may be connected with a rear side of the diaphragm in an acoustically conductive manner. The sound entry openings may be located in each of the pressure-gradient capsule on an entry surface. The diaphragms of the pressure-gradient capsules may be oriented substantially parallel to each other. The sound entry opening may be directed into a space, which may be closed in a direction perpendicular to the entry surface. The space may be connected to the housing opening in an acoustically conductive manner. The microphone system may be compact and robust, and it may be suitable for use with hands-free devices.

Claims

1. A microphone system for use with hands-free devices, comprising:

a housing including a housing opening; and

two pressure-gradient capsules disposed in the housing, the capsule including;

a diaphragm having a front side and a rear side;

a first sound entry opening connected with the front side in an acoustically conductive manner; and

a second sound entry opening connected with the rear side in an acoustically conductive manner;

where the first sound entry opening and the second sound entry opening are located on an entry surface of the capsule.

2. The microphone system of claim 1, where the first sound entry opening and the second sound entry opening are directed into a space formed within the housing.

3. The microphone system of claim 2, where the space is configured to be closed in a direction perpendicular to the entry surface and connected with the housing opening in an acoustically conductive manner.

4. The microphone system of claim 1, where the pressure-gradient capsules are aligned parallel to a surface of the diaphragm.

5. The microphone system of claim 1, where the pressure-gradient capsules are angularly aligned with respect to each other.

6. The microphone system of claim 2, where a front surface of one pressure-gradient capsule faces a front surface of the other pressure-gradient capsule where the entry surface is a front surface.

7. The microphone system of claim 6, where the space is formed between front surfaces of the pressure-gradient capsules.

8. The microphone system of claim 2, where front surfaces of the two pressure-gradient capsules face away from each other where the entry surface is a front surface.

9. The microphone system of claim 8, where the front surfaces are directed into the space.

10. The microphone system of claim 1, where the first sound entry opening and the second sound entry opening are disposed opposite to each other.

11. The microphone system of claim 1, where at least one of the pressure-gradient capsules is supported in the housing in a way that the pressure-gradient capsule is capable of being turned with respect to the diaphragm.

12. The microphone system of claim 1, where the two pressure-gradient capsules are arranged in the housing between a housing floor and a closed housing front.

13. The microphone system of claim 12, where the closed housing front is curved and substantially parallel to the housing floor.

14. The microphone system of claim 13, where the housing opening is located in a wall.

15. The microphone system of claim 12, where the housing opening is substantially parallel to the housing front.

16. The microphone system of claim 2, further comprising a sound channel supplied between the space and the housing opening.

17. The microphone system of claim 16, where the sound channel is filled at least in part with flexible material.

18. The microphone system of claim 17, where the flexible material comprises one of foam, fiber and wool.

19. The microphone system of claim 17, where the sound channel comprises at least one of a step or a rib.

20. The microphone system of claim 2, where the space is extended in a direction substantially parallel to the entry surface and the extended portion is about twice as large as a width of the space.

21. The microphone system of claim 2, where the space is extended in a direction substantially parallel to the entry surface and the extended portion is more than twice as large as a width of the space.

22. The microphone system of claim 2, where the space is extended in a direction substantially parallel to the entry surface and the extended portion is about five times as large as a width of the space.

23. The microphone system of claim 2, where the space is extended in a direction substantially parallel to the entry surface and the extended portion is more than five times as large as a width of the space.

24. The microphone system of claim 2, where the space is extended in a direction parallel to the entry surface and the extended portion is about ten times as large as a width of the space.

25. The microphone system of claim 2, where the space is extended in a direction parallel to the entry surface and the extended portion is more than ten times as large as a width of the space.

26. The microphone system of claim 1, where the first sound entry opening is subdivided.

27. The microphone system of claim 26, where the second sound entry opening is subdivided.

28. A microphone system, comprising:

a first pressure-gradient capsule operable to generate a first audio signal;

a second pressure-gradient capsule operable to generate a second audio signal where the first and second pressure-gradient capsules are disposed to produce directional characteristics of the first audio signal and the second audio signal; and

a sound signal processing unit including;

a controller operable to receive and analyze the first and second audio signals from the first and second pressure-gradient capsules; and

an adaptive filter operable to filter the first audio signal and the second audio signal in response to a control signal supplied from the controller.

29. The microphone system of claim 28, where the sound signal processing unit further comprises:

an analog-to-digital converter placed between the first and second pressure-gradient capsules and the controller; and

a digital-to-analog converter placed subsequent to the adaptive filter.

30. The microphone system of claim 28, where the controller determines a filter coefficient based on analysis of the first and second audio signals.

31. The microphone system of claim 30, where the adaptive filter operates with the filter coefficient.

32. The microphone system of claim 31, where the adaptive filter generates a feedback control signal and provides it to the controller.

33. The microphone system of claim 28, where the first capsule is directed to a driver of a vehicle and a second capsule is directed to a passenger of the vehicle.

34. A microphone system, comprising:

means for generating a first audio signal and a second audio signal where the first audio signal and the second audio signal have different directional characteristics;

control means for receiving the first and second audio signals and analyzing them;

filter means for suppressing an interfering signal and equalizing a desired signal in response to a control signal provided from the control means where the first and second audio signals include at least one of the interfering signal or the desired signal.

35. The microphone system of claim 34, where the control means operates to determine properties of the filter means where the properties include a filter coefficient.

36. The microphone system of claim 34, where the filter means operates to format the first and second audio signals in response to a working environment of the microphone system.

37. A method for processing a signal from a microphone system, comprising:

generating a first audio signal at a first pressure-gradient capsule;

generating a second audio signal at a second pressure-gradient capsule;

converting the first audio signal and the second audio signal in a digital format;

analyzing the first audio signal and the second audio signal at a control unit; and

filtering the first audio signal and the second audio signal at an adaptive filter.

38. The method of claim 37, further comprising generating a control signal based on analysis of the first audio signal and the second audio signal.

39. The method of claim 37, further comprising identifying a speech signal and an interfering signal among the first audio signal and the second audio signal.

40. The method of claim 39, where filtering the first audio signal comprises suppressing the interfering signal.

41. The method of claim 39, where filtering the first audio signal comprises equalizing the speech signal.

42. The method of claim 39, where filtering the first audio signal comprises detecting the speech signal from a desired direction and suppressing the interfering signal from all other directions.

43. The method of claim 37, further comprising estimating a value of an interfering signal where the interfering signal is contained in a speech signal.

44. The method of claim 43, further comprising adjusting properties of the adaptive filter based on the estimated value of the interfering signal.