Adjustable microphone boom with acoustic valve

• US 6,768,804 B1
• Filed: 11/15/2001
• Issued: 07/27/2004
• Est. Priority Date: 11/15/2001
• Status: Expired due to Fees

• Current Assignee: Plantronics, Inc.
• Original Assignee: Plantronics, Inc.
• Inventors: Isvan, Osman K.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Ensey, Brian
• Application Number:
  US09/999,049
• Time in Patent Office: 985 Days
• Field of Search: 381/355, 381/356, 381/357, 381/358, 381/359, 381/360, 381/361, 381/362, 381/363, 381/364, 381/365, 381/366, 381/376, 381/313, 381/338, 381/375, 381/382, 181/20, 181/22, 181/126, 181/128
• US Class Current: 381/376
• CPC Class Codes: H04R 1/083 Special constructions of mouthpieces
• CPC Class Codes: H04R 1/1016 Earpieces of the intra-aural type
• CPC Class Codes: H04R 1/1058 Manufacture or assembly
• CPC Class Codes: H04R 2201/107 Monophonic and stereophonic headphones with microphone for two-way hands free communication

Abstract

A sound sensing apparatus such as a communication headset uses a microphone and an acoustic valve controlled by a movable boom to operate in at least a compact and an extended-boom mode, with the valve variously coupling the microphone to different openings on the boom or the main body functioning as the acoustic sensing point.

Claims

1. An apparatus for receiving acoustic signals from a desired acoustic source and generating transmit signals, the apparatus comprising:

a microphone;

an acoustic valve, coupled to the microphone; and

a boom, movably coupled to the acoustic valve and adapted to be positioned in at least a first position or a second position, and further having at least a first opening and a second opening, the acoustic valve acoustically coupling the first opening to the microphone when the boom is in the first position and acoustically coupling the second opening to the microphone when the boom is in the second position.

2. The apparatus of claim 1, wherein:

the microphone is adapted to receive acoustic signals through an acoustic sensing point, the acoustic sensing point being located at the first opening of the boom when the boom is in the first position and at the second opening of the boom when the boom is in the second position.

3. The apparatus of claim 1, wherein:

the first opening is closer to the desired acoustic source than the second opening when the boom is in the first position and the second opening is closer to the desired acoustic source than the first opening when the boom is in the second position.

4. The apparatus of claim 1, wherein the acoustic valve comprises:

a valve core; and

a valve cap, rotatably coupled to the valve core about a valve axis.

5. The apparatus of claim 4, wherein:

the valve core is a pivot ball; and

the valve cap is a pivot socket.

6. The apparatus of claim 4, wherein:

the valve core is a cylindrical hub; and

the valve cap is a cylindrical cap.

7. The apparatus of claim 4, wherein:

the valve core encloses a link tube, acoustically coupled to the microphone at one end, and adapted to be acoustically coupled at an opposite end to the first opening when the boom is in the first position, and to the second opening when the boom is in the second position.

8. The apparatus of claim 4, wherein:

the valve core encloses at least a first link tube and a second link tube, the first link tube being acoustically coupled at one end to the microphone and at an opposite end to the first opening when the boom is in the first position, and the second link tube being acoustically coupled at one end to the microphone and at an opposite end to the second opening when the boom is in the second position.

9. The apparatus of claim 8, wherein:

the valve core further encloses the microphone; and

the first and the second link tubes are on opposite sides of the microphone'"'"'s diaphragm.

10. The apparatus of claim 1, wherein the boom pivots about the acoustic valve.

11. The apparatus of claim 1, further comprising:

a first acoustic channel, adapted to acoustically couple the first opening to the microphone when the boom is in the first position; and

a second acoustic channel, adapted to acoustically couple the second opening to the microphone when the boom is in the second position.

12. The apparatus of claim 11, wherein the first acoustic channel comprises a first sound tube extending substantially axially in line with the boom from the acoustic valve to the first opening.

13. The apparatus of claim 1, wherein the first opening and the second opening are disposed on the boom on opposite sides of the acoustic valve.

14. The apparatus of claim 1, further comprising:

a secondary boom, slidably coupled to the boom and terminating in a third opening at its distal end, the secondary boom being adapted to adjust to at least a first sliding position relative to the boom, and further adapted to dispose the third opening closer to the desired acoustic source than the first opening of the boom when the boom is in the first position and the secondary boom is in the first sliding position, wherein the third opening is acoustically coupled to the microphone.

15. The apparatus of claim 1, wherein:

the microphone is adapted to be acoustically coupled with an acoustic sensing point located at a distal end of the boom via the first opening when the boom is in the first position and via the second opening when the boom is in the second position.

16. The apparatus of claim 1, wherein the microphone converts acoustic signals into electrical signals, the apparatus further comprising:

a transmit controller for adjusting a transmit gain applied to the electrical signals based on the boom'"'"'s position.

17. The apparatus of claim 16, wherein the transmit controller further comprises:

a switch that causes the transmit controller to modify the transmit gain, the switch being activated when the boom is in at least one of the first and second positions.

18. The apparatus of claim 1, further comprising:

a control device for adjusting the microphone'"'"'s sensitivity based on the boom'"'"'s position.

19. The apparatus of claim 18, wherein:

the microphone is an electret condenser microphone; and

the control device adjusts a supply voltage associated with the microphone.

20. The apparatus of claim 18, wherein:

the microphone is an electret condenser microphone; and

the control device adjusts a bias resistance associated with the microphone.

21. The apparatus of claim 1, wherein:

the microphone is a directional microphone of capacitive type that generates transmit signals in proportion to pressure differences between a first side and a second side of the microphone'"'"'s diaphragm; and

the microphone'"'"'s diaphragm is acoustically coupled on the first side to one of the first and second openings, and on the second side to at least one sealed cavity, of which volume the microphone'"'"'s sensitivity to acoustic signals received on the first side of the diaphragm depends, the volume of the at least one sealed cavity being adjusted in response to position of the boom.

22. The apparatus of claim 1, wherein:

the microphone is a directional microphone of capacitive type that generates transmit signals in proportion to pressure differences between a first side and a second side of the microphone'"'"'s diaphragm; and

the microphone'"'"'s diaphragm is acoustically coupled to the first opening on the first side and to a first set of one or more sealed cavities on the second side when the boom is in the first position, and acoustically coupled to the second opening on the second side and to a second set of one or more sealed cavities on the first side when the boom is in the second position, the microphone'"'"'s sensitivity to acoustic signals on one side of the microphone being a function of volumes of sealed acoustic cavities to which the microphone'"'"'s diaphragm is acoustically coupled on another side.

23. The apparatus of claim 1, further comprising:

a first acoustic channel acoustically coupling the microphone to the first opening when the boom is in the first position, and a second acoustic channel acoustically coupling the microphone to the second opening when the boom is in the second position, wherein the first acoustic channel has a first transmission loss and the second acoustic channel has a second transmission loss.

24. The apparatus of claim 23 wherein:

the first acoustic channel comprises a first sound tube with a first geometrical shape providing a first acoustic impedance coupling ratio to the microphone, and the second acoustic channel comprises a second sound tube with a second geometrical shape providing a second acoustic impedance coupling ratio to the microphone, the first and the second transmission losses being a function of the respective impedance coupling ratios.

25. The apparatus of claim 23 wherein:

the first acoustic channel comprises a first sound tube encased in a first material and the second acoustic channel comprises a second sound tube encased in a second material, the associated transmission losses being a function of the respective encasing materials of the first and second acoustic channels.

26. The apparatus of claim 1, wherein:

the first opening is located at a first distance from the desired acoustic source when the boom is in the first position and the second opening is located at a second distance from the desired acoustic source when the boom is in the second position, the first distance shorter than the second distance.

27. The apparatus of claim 26, wherein the microphone converts acoustic signals into electrical signals, the apparatus further comprising:

a transmit controller that applies a first transmit gain to the electrical signals in response to the boom being in the first position, and a second transmit gain to the electrical signals in response to the boom being in the second position, wherein the first transmit gain is smaller than the second transmit gain.

28. The apparatus of claim 26, further comprising:

a control device that provides the microphone with a first level of sensitivity in response to the boom being in the first position, and a second level of sensitivity in response to the boom being in the second position, wherein the first level of sensitivity is smaller than the second level of sensitivity.

29. The apparatus of claim 26, wherein:

the microphone is a directional microphone of capacitive type and is disposed adjacent to one or more acoustic cavities enclosed in the apparatus, the microphone'"'"'s sensitivity to acoustic signals on one side of the microphone being a function of the volumes of all sealed acoustic cavities to which the microphone is acoustically coupled on an opposite side; and

the microphone is acoustically coupled to a first set of one or more sealed acoustic cavities when the boom is in the first position and to a second set of one or more sealed acoustic cavities when the boom is in the second position, the first set of sealed acoustic cavities having smaller total volume than the second set of scaled acoustic cavities.

30. The apparatus of claim 26, further comprising:

a first acoustic channel acoustically coupling the microphone to the first opening and a second acoustic channel acoustically coupling the microphone to the second opening, wherein the first acoustic channel is associated with a first transmission loss and the second acoustic channel is associated with a second transmission loss, the first transmission loss being greater than the second transmission loss.

31. The apparatus of claim 30, wherein the first acoustic channel includes an acoustic energy attenuator element.

32. The apparatus of claim 30, wherein the first acoustic channel comprises a tapered sound tube, of which the cross sectional area increases with distance from the second opening.

33. The apparatus of claim 32, wherein the tapered sound tube is of a reversed exponential horn shape.

34. The apparatus of claim 30, wherein the second acoustic channel comprises an exponential horn shaped sound tube, the cross sectional area of which decreases with distance from the first opening.

35. The apparatus of claim 1, wherein the apparatus is a communications headset.

36. The apparatus of claim 1, wherein the apparatus is a mobile phone.

37. The apparatus of claim 1, wherein the apparatus is a sound recorder.

38. The apparatus of claim 1, wherein the apparatus is a video camera.

39. An apparatus for receiving acoustic signals from a desired acoustic source and generating transmit signals, the apparatus comprising:

a main body enclosing a microphone and having at least a first opening; and

a boom, movably coupled to the main body and adapted to be positioned in at least a first position or a second position, and further having at least a second opening, wherein the microphone is adapted to be acoustically coupled with the first opening when the boom is in the first position and acoustically coupled with the second opening when the boom is in the second position.

40. The apparatus of claim 39, wherein:

the first opening is closer to the desired acoustic source than the second opening when the boom is in the first position and the second opening is closer to the desired acoustic source than the first opening when the boom is in the second position.

41. An apparatus for receiving acoustic signals from a desired acoustic source and generating transmit signals, the apparatus comprising:

a main body enclosing a microphone;

a boom, movably coupled to the main body and adapted to be positioned in at least a first position or a second position;

a first acoustic channel, adapted to acoustically couple the microphone to a first opening for receiving acoustic signals when the boom is in the first position; and

a second acoustic channel, adapted to acoustically couple the microphone to a second opening for receiving acoustic signals when the boom is in the second position.

42. The apparatus of claim 41, wherein:

the first opening is as least as close to the desired acoustic source as is the second opening when the boom is in the first position and the second opening is at least as close to the desired acoustic source as is the first opening when the boom is in the second position.

43. The apparatus of claim 41, further comprising:

an acoustic valve, coupled to the microphone and adapted to acoustically couple the microphone to the first opening via the first acoustic channel when the boom is in the first position, and acoustically couple the microphone to the second opening via the second acoustic channel when the boom is in the second position.

44. The apparatus of claim 43, wherein the acoustic valve comprises:

a pivoting ball; and

a pivoting socket, rotatably coupled to the valve core about a valve axis.

45. The apparatus of claim 43, wherein the acoustic valve comprises:

a cylindrical hub; and

a cylindrical cap, rotatably coupled to the valve core about a valve axis.

46. The apparatus of claim 43 wherein the first opening and the second opening are disposed on the boom on opposite sides of the acoustic valve.

47. The apparatus of claim 43 wherein the first acoustic channel is extendable.

48. The apparatus of claim 41, wherein the second acoustic channel forms a portion of the first acoustic channel when the boom is in the first position.

49. The apparatus of claim 48, wherein the second acoustic channel is fixed relative to the microphone when the boom is in both the first and the second positions.

50. The apparatus of claim 48, wherein the first opening coincides with the second opening.