System and method for calibration of an acoustic system

• US 20050254662A1
• Filed: 05/14/2004
• Published: 11/17/2005
• Est. Priority Date: 05/14/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Johnston, James David, Atkinson, Robert G., Van Flandern, Michael W., Olynyk, Kirk O., Blank, William Tom, Schofield, Kevin M.
• Granted Patent: US 7,630,501 B2
• Time in Patent Office: Days
• US Class Current: 381/58
• CPC Class Codes: H04R 2227/003 Digital PA systems using, e.g. LAN or internet
• CPC Class Codes: H04S 7/301 Automatic calibration of stereophonic sound system, e.g. with test microphone

Abstract

The present invention is directed to a method and system for automatic calibration of an acoustic system. The acoustic system may include a source A/V device, calibration computing device, and multiple rendering devices. The calibration system may include a calibration component attached to each rendering device and a source calibration module. The calibration component on each rendering device includes a microphone. The source calibration module includes distance and optional angle calculation tools for automatically determining a distance between the rendering device and a specified reference point upon return of the test signal from the calibration component.

Claims

1. A calibration system for automatically calibrating an acoustic system, the acoustic system including a source A/V device, calibration computing device and at least one rendering device, the calibration system comprising:

a calibration component attached to at least one selected rendering device; and

a source calibration module operable from the calibration computing device, the source calibration module including distance calculation tools for automatically determining a distance between the selected rendering device and a specified reference point upon receiving information from the rendering device calibration component.

2. The calibration system of claim 1, wherein the selected rendering device comprises a speaker and the calibration component comprises a microphone.

3. The calibration system of claim 2, wherein the source calibration module comprises input processing tools for receiving and processing a test signal from each microphone.

4. The calibration system of claim 3, wherein the calibration module comprises a coordinate determination module for determining coordinates in at least one plane of each selected rendering device relative to a fixed origin.

5. The calibration system of claim 4, wherein the calibration module comprises a speaker selection module for selecting a test signal generating speaker.

6. The calibration system of claim 5, further comprising means for causing the selected test signal generating speaker to generate the test signal at a precise time.

7. The calibration system of claim 1, wherein the information comprises a test signal, the test signal comprising a bandwidth limited, flat frequency spectrum signal facilitating distinction between the test signal and background noise.

8. The calibration system of claim 1, wherein the information comprises a test signal, the test signal providing a sharp autocorrelation or autoconvolution peak enabling precise localization of events in time.

9. The calibration system of claim 1, wherein the information comprises a test signal and the calibration system implements a correlation method for performing matched filtering in the frequency domain, rejecting out-of-band noise, and decorrelating in-band noise signals.

10. The calibration system of claim 1, wherein the information comprises a test signal and the test signal comprises a flat bandwidth limited signal with a sharp autocorrelation or autoconvolution peak and performs matched filtering in the frequency domain.

11. The calibration system of claim 10, wherein the flat frequency response and autocorrelation properties of the signal are used to capture the frequency and phase response of a speaker system and at least one room containing the speaker system.

12. The calibration system of claim 11, wherein the calibration system partially corrects the captured properties of the speaker system and at least one room based on the captured phase and frequency response.

13. The calibration system of claim 1, wherein the calibration computing device comprises synchronization tools for synchronizing the calibration computing device and the at least one rendering device.

14. The calibration system of claim 1, wherein the calibration component comprises two microphones attached to at least one rendering device.

15. The calibration system of claim 14, wherein the two microphones are vertically aligned.

16. The calibration system of claim 14, wherein the two microphones are horizontally aligned.

17. The calibration system of claim 1, further comprising a room communication device connected over a network with the at least one rendering device.

18. A method for calibrating an acoustic system comprising:

receiving a test signal at a microphone attached to a rendering device;

transmitting information from the microphone to a calibration computing device; and

automatically calculating, at the calibration computing device, a distance between the rendering device and a fixed reference point based on a travel time of the received test signal.

19. The method of claim 18, further comprising using the calibration computing device to select a test signal generating speaker for rendering a test signal at a precise time.

20. The method of claim 18, further comprising receiving the test signal at multiple microphones attached to multiple rendering devices and recording each reception time.

21. The method of claim 19, further comprising transmitting the received test signal and each reception time from the multiple rendering devices to the calibration computing device.

22. The method of claim 21, further comprising receiving the transmitted test signal and each reception time with input processing tools of the calibration computing device.

23. The method of claim 22, further comprising time stamping each test signal received by the input processing tools.

24. The method of claim 23, further comprising automatically calculating, at the calibration computing device, a distance between each of the multiple rendering devices and the selected test signal generating speaker.

25. The method of claim 24, further comprising automatically calculating at the calibration computing device each angle between each rendering device.

26. The method of claim 24, further comprising determining coordinates of each selected rendering device relative to a fixed origin.

27. The method of claim 18, further comprising synchronizing the source A/V device, and the rendering device.

28. The method of claim 20, further comprising synchronizing the source A/V device with the multiple rendering devices.

29. The method of claim 18, further comprising determining coordinates of a sound source.

30. The method of claim 29, further comprising remotely constructing a room pointing vector using two generated sounds.

31. The method of claim 30, further comprising locating an intersection between the vector and a list of target devices.

32. The method of claim 31, further comprising controlling an identified device using the intersection.

33. The method of claim 18, further comprising measuring acoustic room response.

34. The method of claim 33, further comprising determining appropriate corrections to an audio stream based on room response.

35. The method of claim 34, further comprising allowing the corrected audio stream to be rendered by the rendering device.

36. A computer readable medium storing the computer executable instructions for performing the method of claim 18.

37. A method for calibrating an acoustic system including at least a source A/V device and a first and a second rendering device, the method comprising:

generating a test signal from the first rendering device at a selected time;

receiving the test signal at the second rendering device at a reception time;

transmitting information pertaining to the received test signal from the second rendering device to the calibration computing device; and

calculating a distance between the second rendering device and the first rendering device based on the selected time and the reception time.

38. The method of claim 37, further comprising using the calibration computing device to select the first rendering device for playing the test signal at the selected time.

39. The method of claim 37, further comprising receiving the test signal at multiple microphones attached to multiple rendering devices and recording each reception time.

40. The method of claim 39, further comprising transmitting the received test signal and each reception time from the multiple rendering devices to the calibration computing device.

41. The method of claim 39, further comprising receiving the transmitted test signal and each reception time with input processing tools of the calibration computing device.

42. The method of claim 41, further comprising time stamping each test signal received by the input processing tools.

43. The method of claim 42, further comprising automatically calculating, at the calibration computing device, a distance between each of the multiple rendering devices and the selected test signal playing speaker.

44. The method of claim 43, further comprising automatically calculating at the calibration computing device each angle between each rendering device.

45. The method of claim 43, further comprising determining coordinates of each selected rendering device relative to a fixed origin.

46. The method of claim 37, further comprising synchronizing the source A/V device with each rendering device.

47. A computer readable medium storing the computer executable instructions for performing the method of claim 37.

48. A calibration module operated by a computing device for automatically calibrating an acoustic system, the acoustic system including at least one rendering device having an attached microphone, the calibration module comprising:

input processing tools for receiving information from the microphone;

distance calculation tools for automatically determining a distance between the rendering device attached to the microphone and a specified reference point based on the information from the microphone.

49. The calibration module of claim 48, wherein the selected rendering device comprises a speaker.

50. The calibration system of claim 49, wherein the calibration module comprises a speaker selection module for selecting a test signal generating speaker.

51. The calibration module of claim 50, further comprising means for causing the selected speaker to play a test signal at a precise time.

52. The calibration module of claim 48, further comprising a coordinate determination module for determining coordinates of each rendering device relative to a fixed origin.

53. The calibration module of claim 48, wherein the calibration computing device comprises synchronization tools for synchronizing the source A/V device and the at least one rendering device.

54. The calibration module of claim 49, wherein the input processing tools further comprise means for receiving a test signal from multiple microphones attached to the rendering device.

55. A method for calibrating an acoustic system through transmission of a test signal, the method comprising:

transmitting the test signal to a rendering device, the test signal comprising a flat frequency band facilitating distinction between the test signal and background noise and a sharp correlation peak enabling precise measurement;

receiving the test signal at a microphone attached to the rendering device; and

automatically calculating a distance between the rendering device and a fixed reference point based on a travel time of the received test signal.

56. A method for automatically calibrating a surround-sound system including a plurality of speakers with a calibration system including a calibration computing device and a calibration module within at least one selected speaker, the method comprising:

detecting connection of the plurality of speakers with the calibration computing device;

assuming a speaker configuration with the calibration computing device;

playing a test signal from at least one speaker at a precise time;

receiving the test signal at least at one calibration module;

calculating a distance based upon a time of receipt of the test signal; and

checking the assumed speaker configuration based upon the calculated distance.

57. The method of claim 56, further comprising repeating the test signal generation, receiving, and calculating steps for each of the plurality of speakers.

58. The method of claim 56, further comprising determining the location of each of the plurality of speakers based upon the calculations.

59. The method of claim 57, further comprising locating a preferred listening position and adjusting a delay of each speaker to allow a test signal generated from each speaker to reach the preferred listening position simultaneously.

60. A calibration method for calibrating a sound system having at least one rendering device, the calibration method comprising:

generating a calibration pulse from each rendering device, said calibration pulse having a sharp autocorrelation or autoconvolution peak and a bandwidth commensurate with the rendering device;

calculating any of time delay, gain, and frequency response characteristics of the sound system from a recorded calibration pulse; and

creating an inverse filter based on any of the time delay, gain and frequency response characteristics for reversing at least one of frequency errors and phase errors of the sound system.

61. The method of claim 60, further comprising using a wideband probe signal to obtain a bandwidth for the calibration pulse.

62. The method of claim 60, further comprising equalizing the acoustic performance of each rendering device including its surroundings utilizing the inverse filter.