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  1. Acoustics
  2. AKG Acoustics
  3. Audio feedback
  4. Audio level compression
  5. Audio quality measurement
  6. Audio-Technica
  7. Balanced audio connector
  8. Beyerdynamic
  9. Blumlein Pair
  10. Capacitor
  11. Carbon microphone
  12. Clipping
  13. Contact microphone
  14. Crosstalk measurement
  15. DB
  16. Decibel
  17. Directional microphone
  18. Dynamic range
  19. Earthworks
  20. Electret microphone
  21. Electrical impedance
  22. Electro-Voice
  23. Equal-loudness contour
  24. Frequency response
  25. Georg Neumann
  26. Harmonic distortion
  27. Headroom
  28. ITU-R 468 noise weighting
  29. Jecklin Disk
  30. Laser microphone
  31. Lavalier microphone
  32. Loudspeaker
  33. M-Audio
  34. Microphone
  35. Microphone array
  36. Microphone practice
  37. Microphone stand
  38. Microphonics
  39. Nevaton
  40. Noise
  41. Noise health effects
  42. Nominal impedance
  43. NOS stereo technique
  44. ORTF stereo technique
  45. Parabolic microphone
  46. Peak signal-to-noise ratio
  47. Phantom power
  48. Pop filter
  49. Positive feedback
  50. Rode
  51. Ribbon microphone
  52. Schoeps
  53. Sennheiser
  54. Shock mount
  55. Shure
  56. Shure SM58
  57. Signal-to-noise ratio
  58. Soundfield microphone
  59. Sound level meter
  60. Sound pressure
  61. Sound pressure level
  62. Total harmonic distortion
  63. U 47
  64. Wireless microphone
  65. XLR connector



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Soundfield microphone

From Wikipedia, the free encyclopedia


The Soundfield microphone is an audio microphone comprised of four closely spaced subcardioid (unidirectional) microphone capsules positioned in a tetrahedron. It was invented by Michael Gerzon and Peter Craven, and is a part of, but not exclusive to, Ambisonics, a surround sound technology.

A Soundfield microphone kit, consisting of the microphone and a signal processor, produces two distinct sets of audio signals.

The first set, the A-format, is produced by the Soundfield microphone itself and consists of the four signals from the microphone capsules. These four signals are not intended to be used without further processing. The A-Format is then normally transformed into the second set of audio signals, the B-format. This process is described in references 1 and 2. Depending on the mic, this transformation is performed in either hardware or software.

The B-format is the standard audio format produced by a Soundfield kit. It consists of the following four signals:

  • W - a pressure signal (mono) corresponding to the output from an omni-directional microphone
  • X - the front-to-back directional information, a forward-pointing velocity or "figure-of-eight" microphone
  • Y - the side-to-side directional information, a leftward-pointing figure-of-eight microphone
  • Z - the up-to-down directional information, an upward-pointing figure-of-eight microphone

By combining these signals in various proportions, it is possible to derive any number of first-order microphones, pointing in any direction. For example, a forward-facing cardioid is produced by\sqrt2 W + X. Examples of software that perform these calculations are the Visual Virtual Microphone and Soundfield Research Surround Zone plugin.


  1. Michael A. Gerzon (1975). "The Design of Precisely Coincident Microphone Arrays for Stereo and Surround Sound". 50th Convention of the Audio Engineering Society: Preprint L-20.
  2. Peter G. Craven and Michael A. Gerzon. "Coincident Microphone Simulation Covering Three Dimensional Space and Yielding Various Directional Outputs". US patent 4042779.

External links

  • SoundField Limited, a soundfield mic manufacturer
  • AGM Digital Arts GmbH, a soundfield mic manufacturer
  • Core Sound, a soundfield mic manufacturer
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