Microphone array with rear venting
View Patent ↗Microphone arrays (MAs) are described that position and vent microphones so that performance of a noise suppression system coupled to the microphone array is enhanced. The MA includes at least two physical microphones to receive acoustic signals. The physical microphones make use of a common rear vent (actual or virtual) that samples a common pressure source. The MA includes a physical directional microphone configuration and a virtual directional microphone configuration. By making the input to the rear vents of the microphones (actual or virtual) as similar as possible, the real-world filter to be modeled becomes much simpler to model using an adaptive filter.
1. A device comprising:
a headset including a housing;
a loudspeaker connected to the housing;
a first microphone connected to a first side of the housing, the housing having a first front vent opening configured to provide the first microphone with access to speech, the first microphone having a first rear port configured to receive a first pressure in response to a source signal;
a second microphone connected to a second side of the housing, the housing having a second front vent opening configured to provide the second microphone with access to speech, the second microphone having a second rear port configured to receive a second pressure in response to the source signal, the first pressure being substantially equal to the second pressure;
a shared-vent configuration positioned in an interior region of the housing and including a vent cavity that forms a common rear port of the first microphone and the second microphone, the vent cavity having a volume that is small relative to a wavelength of acoustic signals received by the first and second microphones; and
an adaptive filter configured to receive a first signal from the first microphone and a second signal from the second microphone.
2. The device of claim 1 , wherein the first microphone and the second microphone sample a common pressure of the vent cavity.
3. The device of claim 2 , wherein the first microphone and the second microphone have an equivalent response to the common pressure.
4. The device of claim 1 , comprising a first orifice in a third side of the housing, the first orifice connecting the vent cavity to an external environment.
5. The device of claim 4 , comprising a second orifice in a fourth side of the housing, the second orifice connecting the vent cavity to the external environment.
6. The device of claim 1 , wherein a first rear port of the first microphone and a second rear port of the second microphone are connected to the vent cavity.
7. The device of claim 6 , wherein a first rear port delay of the first microphone is approximately equal to a second rear port delay of the second microphone.
8. The device of claim 6 , wherein a first input to the first rear port is substantially similar to a second input to the second rear port.
9. The device of claim 6 , wherein a first delay of the first rear port is approximately equal to a second delay of the second rear port.
10. The device of claim 6 , wherein a first front port of the first microphone and a second front port of the second microphone vent outside the vent cavity.
11. The device of claim 10 , wherein a pressure of the second front port is approximately proportional to a pressure of the first front port multiplied by a difference in amplitude of noise between the first and the second microphone multiplied by a delay between the first and the second microphones.
12. The device of claim 10 , wherein a pressure of the first rear port is approximately proportional to a pressure of the first front port multiplied by a difference in amplitude of noise between the first and the second microphone multiplied by a delay between the first front port and the common rear port.
13. The device of claim 1 , wherein a first noise response and a first speech response of the first microphone overlaps with a second noise response and a second speech response of the second microphone.
14. The device of claim 1 , wherein a first noise response of the first microphone and a second noise response of the second microphone are substantially similar.
15. The device of claim 1 , wherein a first speech response of the first microphone and a second speech response of the second microphone are substantially dissimilar.
16. The device of claim 1 , wherein the second microphone is positioned approximately orthogonally to the first microphone.
17. The device of claim 1 , wherein the second microphone is positioned approximately opposite to the first microphone.
18. The device of claim 1 , wherein the first microphone and the second microphone are directional microphones.
19. The device of claim 1 , wherein the headset is portable and attaches to a region of a human head.
20. The device of claim 1 , wherein the first microphone and the second microphone receive acoustic signals including acoustic speech and acoustic noise.
21. The device of claim 20 , wherein a source that generates the acoustic speech is a mouth of a human wearing the headset.
22. The device of claim 1 , comprising a processing component coupled to the first microphone and the second microphone.
23. The device of claim 22 , comprising a voice activity detector coupled to the processing component, the voice activity detector generating voice activity signals.
24. The device of claim 22 , comprising an adaptive noise removal application coupled to the processing component, the adaptive noise removal application receiving signals from the first and second microphones and generating the output signals.
25. The device of claim 22 , comprising a communication channel coupled to the processing component, the communication channel comprising at least one of a wireless channel, a wired channel, and a hybrid wireless/wired channel.
26. The device of claim 25 , comprising a communication device coupled to the headset using the communication channel, the communication device comprising one or more of cellular telephones, satellite telephones, portable telephones, wireline telephones, Internet telephones, wireless transceivers, wireless communication radios, personal digital assistants, and personal computers.
27. A device comprising:
a housing that is portable and attaches to a region of a human head;
a loudspeaker connected to the housing;
a first microphone connected to the housing, the housing having a first front vent opening configured to provide the first microphone with access to speech, the first microphone having a first rear port configured to receive a first pressure in response to a source signal;
a second microphone connected to the housing, the housing having a second front vent opening configured to provide the second microphone with access to speech, the second microphone having a second rear port configured to receive a second pressure in response to the source signal, the first pressure being substantially equal to the second pressure;
a shared-vent configuration positioned in an interior region of the housing and including a vent cavity positioned behind the first microphone and the second microphone, the vent cavity having a volume that is small relative to a wavelength of acoustic signals received by the first and second microphones; and
an adaptive filter configured to receive a first signal from the first microphone and a second signal from the second microphone.
28. The device of claim 27 , wherein a first rear port of the first microphone and a second rear port of the second microphone are connected to the vent cavity and the vent cavity forms a common rear port of the first microphone and the second microphone.
29. The device of claim 28 , wherein the first rear port and the second rear port sample a common pressure of the vent cavity.
30. The device of claim 28 , wherein a first rear port delay of the first microphone is approximately equal to a second rear port delay of the second microphone.
31. The device of claim 28 , wherein a first delay of the first rear port is approximately equal to a second delay of the second rear port.
32. The device of claim 28 , wherein a first front port of the first microphone and a second front port of the second microphone vent outside the vent cavity.
33. The device of claim 32 , wherein a pressure of the second front port is approximately proportional to a pressure of the first front port multiplied by a difference in amplitude of noise between the first and the second microphone multiplied by a delay between the first and the second microphones.
34. The device of claim 32 , wherein a pressure of the first rear port is approximately proportional to a pressure of the first front port multiplied by a difference in amplitude of noise between the first and the second microphone multiplied by a delay between the first front port and the common rear port.
35. The device of claim 28 , comprising a first orifice in the housing, the first orifice connecting the vent cavity to an external environment.
36. The device of claim 35 , comprising a second orifice in the housing, the second orifice connecting the vent cavity to the external environment.
37. The device of claim 28 , wherein a first noise response of the first microphone and a second noise response of the second microphone are substantially similar.
38. The device of claim 28 , wherein a first speech response of the first microphone and a second speech response of the second microphone are substantially dissimilar.
39. The device of claim 27 , comprising a processing component coupled to the first microphone and the second microphone.
40. The device of claim 39 , comprising an adaptive noise removal application coupled to the processing component, the adaptive noise removal application receiving signals from the first and second microphones and generating the output signals.
41. The device of claim 39 , comprising:
a communication channel coupled to the processing component, the communication channel comprising at least one of a wireless channel, a wired channel, and a hybrid wireless/wired channel; and
a communication device coupled to the processing component via the communication channel, the communication device comprising one or more of cellular telephones, satellite telephones, portable telephones, wireline telephones, Internet telephones, wireless transceivers, wireless communication radios, personal digital assistants, and personal computers.
42. A device comprising:
a headset comprising a housing that attaches to a human head;
a first microphone connected to a first side of the housing, the housing having a first front vent opening configured to provide the first microphone with access to speech, the first microphone having a first rear port configured to receive a first pressure in response to a source signal;
a second microphone connected to a second side of the housing, the housing having a second front vent opening configured to provide the second microphone with access to speech, the second microphone having a second rear port configured to receive a second pressure in response to the source signal, the first pressure being substantially equal to the second pressure;
a shared-vent configuration positioned in an interior region of the housing and including a vent cavity that is connected with a first rear port of the first microphone and a second rear port of the second microphone, the vent cavity having a volume that is small relative to a wavelength of acoustic signals received by the first and second microphones; and
an adaptive filter configured to receive a first signal from the first microphone and a second signal from the second microphone.
43. The device of claim 42 , comprising a processing component coupled to the first microphone and the second microphone.
44. The device of claim 43 , comprising an adaptive noise removal application coupled to the processing component, the adaptive noise removal application receiving signals from the first and second microphones and generating the output signals.
45. The device of claim 43 , comprising:
a communication channel coupled to the processing component, the communication channel comprising at least one of a wireless channel, a wired channel, and a hybrid wireless/wired channel; and
a communication device coupled to the processing component via the communication channel, the communication device comprising one or more of cellular telephones, satellite telephones, portable telephones, wireline telephones, Internet telephones, wireless transceivers, wireless communication radios, personal digital assistants, and personal computers.
46. The device of claim 1 , wherein the volume of the vent cavity is approximately 0.0006 cubic inches.
47. The device of claim 27 , wherein the volume of the vent cavity is approximately 0.0006 cubic inches.
48. The device of claim 42 , wherein the volume of the vent cavity is approximately 0.0006 cubic inches.