Method of Performing Measurements By Means of an Audio System Comprising Passive Loudspeakers

• US 20090003613A1
• Filed: 12/18/2006
• Published: 01/01/2009
• Est. Priority Date: 12/16/2005
• Status: Active Grant

• Current Assignee: Music Group IP Limited (Music Group Services US Incorporated)
• Original Assignee: TC Electronic A/S
• Inventors: Christensen, Knud Bank
• Granted Patent: US 8,270,620 B2
• Time in Patent Office: Days
• US Class Current: 381/58
• CPC Class Codes: H04R 2205/024 Positioning of loudspeaker enclosures for spatial sound reproduction
• CPC Class Codes: H04R 2400/01 Transducers used as a loudspeaker to generate sound aswell as a microphone to detect sound
• CPC Class Codes: H04S 7/301 Automatic calibration of stereophonic sound system, e.g. with test microphone

Abstract

The present invention relates to a method of performing measurements by means of an audio system comprising passive loudspeakers, whereby said measurements loudspeakers for producing sound and at least one of said loudspeakers for measuring said sound. The present invention further relates to an audio system comprising N passive loudspeakers, wherein said audio system further comprises an output stage where each output acts as a combined output channel and a measurement input.

Claims

1. Method of performing measurements by means of an audio system comprising passive loudspeakers, whereby said measurements are performed by using at least one of said loudspeakers for producing sound and at least one of said loudspeakers for measuring said sound.

3. Method of performing measurements according to claim 1, whereby said measurements comprises impulse responses.

4. Method of performing measurements according to claim 1, whereby said measurements comprises speaker-room-speaker responses.

5. Method of performing measurements according to claim 1, whereby said audio system comprises N passive loudspeakers, and said measurements are performed between pairs of said loudspeakers, N being at least two.

6. Method of performing measurements according to claim 1, whereby said method comprises analysing said measurements for determining spatial information.

8. Method of performing measurements according to claim 6, whereby said spatial information comprises information about the relative location of said passive loudspeakers.

10. Method of performing measurements according to claim 6, whereby said spatial information comprises an acoustical image of the surroundings of said audio system.

12. Method of performing measurements according to claim 6, whereby said spatial information comprises an estimated optimal listening position.

15. Method of performing measurements according to claim 1, whereby said method comprises analysing said measurements for determining room response information.

17. Method of performing measurements according to claim 1, whereby said method comprises analysing said measurements to determine a set of loudspeaker coloration responses.

18. Method of performing measurements according to claim 17, whereby said loudspeaker coloration responses comprise representations of the frequency response of said loudspeakers and how said loudspeakers acoustically couple to their surroundings.

19. Method of performing measurements according to claim 17, whereby said loudspeaker coloration responses comprise least-squares average coloration log-magnitude responses of said loudspeakers.

26. Method of performing measurements according to claim 5, whereby N is at least 3, and said measurements comprise measuring N·

(N−

1) speaker-room-speaker responses, where each of said N loudspeakers are used for producing sound in N−

1 measurements, and each of said N loudspeakers are used for measuring said sound in N−

1 measurements.

27. Method of performing measurements according to claim 6, whereby said spatial information is determined by calculating cross correlation functions between said produced sound and said measured sound.

28. Method of performing measurements according to claim 1, whereby distances between loudspeakers are determined on the basis of an analysis of cross correlation functions for absolute maxima and multiplying with the speed for sound through air.

31. Method of performing measurements according to claim 17, whereby said loudspeaker coloration responses are determined by analysing an equation system based on said measurements.

32. Method of performing measurements according to claim 17, whereby said loudspeaker coloration responses are determined by solving an equation system comprising speaker-room-speaker responses.

34. Method of performing measurements according to claim 5, whereby a loudspeaker coloration response is determined for each of said N loudspeakers by solving an equation system comprising N·

(N−

1) speaker-room-speaker responses.

35. Method of performing measurements according to claim 31, whereby said equation system is linear.

36. Method of performing measurements according to claim 4, whereby said speaker-room-speaker responses are log-magnitude responses.

37. Method of performing measurements according to claim 4, whereby said speaker-room-speaker responses are log-frequency responses or pairs of log-magnitude responses and group-delay responses.

38. Method of performing measurements according to claim 4, whereby said speaker-room-speaker responses are impulse responses.

39. Method of performing measurements according to claim 17, whereby an equalization target response for a loudspeaker is established on the basis of said loudspeaker coloration responses.

40. Method of performing measurements according to claim 39, whereby said equalization target response is established by subtracting a loudspeaker coloration response from a system target response.

41. Method of performing measurements according to claim 39, whereby said equalization target response is filtered.

44. Method of performing measurements according to claim 10, whereby room modes of said surroundings are determined from said measurements.

46. Method of performing measurements according to claim 44, whereby an equalization target response is established on the basis of said room modes.

47. Method of performing measurements according to claim 44, whereby an equalization target response is established on the basis of both a loudspeaker coloration response and said room modes.

48. Method of performing measurements according to claims 39, whereby said equalization target response is implemented in an audio system comprising N passive loudspeakers for enabling room corrected operation of said audio system in said surroundings.

49. Method of performing measurements according to claim 39, whereby said equalization target response is implemented in an audio system comprising N passive loudspeakers for improving the tonal balance of said audio system in said surroundings.

52. Method of performing measurements according to claim 1, whereby said measurements and/or determining information is repeated several times and averaged information is determined.

54. Method of performing measurements according to claim 1, whereby said measurements are performed several times, average measurement results calculated, and said determining information is based thereon, thereby determining averaged information.

57. Method of performing measurements according to claim 1, whereby said sound comprises music.

58. Method of performing measurements according to claim 1, whereby said sound comprises maximum length sequence MLS signals.

60. Method of performing measurements according to claim 1, whereby one loudspeaker produces sound and at least two loudspeakers measure said sound simultaneously.

61. Method of performing measurements according to claim 1, whereby at least two loudspeakers produce different sound and at least one loudspeaker measures said sound.

62. Method of performing measurements according to claim 1, whereby said loudspeakers produce and measure sound simultaneously.

64. Method of performing measurements according to claim 4, whereby said speaker-room-speaker responses are measured for a frequency range of substantially 5 Hz to substantially 500 Hz.

68. Method of performing measurements according to claim 1, whereby a set of equalization target responses for improving the tonal balance of an audio system in a room, said audio system comprising at least N passive loudspeakers, N being at least two, is established by performing the steps of:

determining, for P combinations of loudspeaker pairs in said audio system, the speaker-room-speaker response for a test signal provided to a loudspeaker of said loudspeaker pair and captured by the other loudspeaker of said loudspeaker pair, said other loudspeaker operating as a microphone, P being equal to or larger than N,

establishing N equalization target responses on the basis of said P speaker-room-speaker responses, said N equalization target responses corresponding to said N loudspeaker channels of said audio system.

2. (canceled)

7. (canceled)

9. (canceled)

11. (canceled)

13. (canceled)

14. (canceled)

16. (canceled)

20. (canceled)

21. (canceled)

22. (canceled)

23. (canceled)

24. (canceled)

25. (canceled)

29. (canceled)

30. (canceled)

33. (canceled)

42. (canceled)

43. (canceled)

45. (canceled)

50. (canceled)

51. (canceled)

53. (canceled)

55. (canceled)

56. (canceled)

59. (canceled)

63. (canceled)

65. (canceled)

66. (canceled)

67. (canceled)

69. Method of determining relative locations of at least two passive loudspeakers, comprising the steps of

producing sound by said loudspeakers and measuring said sound by said loudspeakers,

calculating cross-correlation functions of pairs of produced sound and measured sound,

analysing said cross-correlation functions to determine relative distances between pairs of said loudspeakers, and

analysing said relative distances to determine said relative locations.

70. (canceled)

71. (canceled)

72. (canceled)

73. Method of determining a set of loudspeaker coloration responses for at least one out of N passive loudspeakers, whereby said loudspeaker coloration responses are determined by analysing measurements performed by using at least one of said loudspeakers for producing test sound and at least one of said loudspeakers for measuring said test sound.

74. Method of determining a set of loudspeaker coloration responses according to claim 73, whereby said loudspeaker coloration responses comprise representations of the frequency response of said loudspeakers and how said loudspeakers acoustically couple to their surroundings.

75. Method of determining a set of loudspeaker coloration responses according to claim 73, whereby an equalization target response for a loudspeaker is established on the basis of said loudspeaker coloration responses.

113. Method of determining a set of loudspeaker coloration responses according to claim 73, whereby said loudspeaker coloration responses are determined by analysing an equation system based on said measurements.

76. (canceled)

77. Audio system comprising N passive loudspeakers, wherein said audio system further comprises an output stage where each output acts as a combined output channel and a measurement input, wherein said audio system comprises means for performing measurements by using at least one of said loudspeakers as a microphone, wherein said measurements comprise impulse responses, and wherein said measurements comprise speaker-room-speaker responses

81. Audio system according to claim 77, wherein said output stage comprises a measurement controller, and wherein said measurement controller comprises means for determining spatial information on the basis of said measurements.

83. Audio system according to claim 81, wherein said spatial information comprises information about the relative location of said passive loudspeakers.

86. Audio system according to claim 81, wherein said spatial information comprises an estimated optimal listening position.

88. Audio system according to claim 77, wherein said output stage comprises a measurement controller, and wherein said measurement controller comprises means for determining room response information on the basis of said measurements.

89. Audio system according to claim 88, wherein said room response information comprises loudspeaker coloration responses.

90. Audio system according to claim 77, wherein said output stage comprises a measurement controller, wherein said measurement controller comprises a room correction controller and wherein said room correction controller comprises means for establishing equalization target responses on the basis of said loudspeaker coloration responses.

94. Audio system according to claim 77, wherein said audio system comprises a room correctable audio system.

95. Audio system according to claims 77, wherein said output stage comprises a room correcting output stage.

96. Audio system according to claim 77, wherein said output stage comprises an equalizer and wherein said measurement controller cooperates with said equalizer in implementing said equalization target responses in said audio system.

98. Audio system according to claim 77, wherein said output stage comprises a power amplifier and wherein said power amplifier (PWA) comprises means for measuring signals from loudspeakers used as microphones.

104. Audio system according to claim 77, wherein said output stage comprises a measurement controller, and wherein said measurement controller comprises means for performing cross correlation between output signals and input signals of said audio system.

107. Audio system according to claim 77, wherein said output stage comprises means for determining loudspeaker coloration responses on the basis of speaker-room-speaker responses measured between pairs of said loudspeakers.

108. Audio system according to claim 89, wherein said output stage comprises means for establishing equalization target responses on the basis of said loudspeaker coloration responses.

111. Audio system according to claim 77, wherein said output stage comprises a measurement controller, and wherein said measurement controller is implemented in a measurement module as an add-on to a common audio amplifier system.

112. Audio system according to claim 77, wherein said output stage comprises a measurement controller comprising a room correcting controller which is implemented in a room correcting module as an add-on to a common audio amplifier system.

78. (canceled)

79. (canceled)

80. (canceled)

82. (canceled)

84. (canceled)

85. (canceled)

87. (canceled)

91. (canceled)

92. (canceled)

93. (canceled)

97. (canceled)

99. (canceled)

100. (canceled)

101. (canceled)

102. (canceled)

103. (canceled)

105. (canceled)

106. (canceled)

109. (canceled)

110. (canceled)