Advertisement

Spherical Microphone Arrays for 3D Sound Recording

  • Jens Meyer
  • Gary W. Elko

Abstract

With the recent widespread availability of inexpensive DVD players and home theater systems, surround sound has become a mainstream consumer technology. The basic recording techniques for live sound events have not changed to accommodate this new dimension of sound field playback. More advanced analysis of sound fields and forensic capture of spatial sound also require new microphone array systems. This chapter describes a new spherical microphone array that performs an orthonormal decomposition of the sound pressure field. Sufficient order decomposition into these eigenbeams can produce much higher spatial resolution than traditional recording systems, thereby enabling more accurate sound field capture. A general mathematical framework based on these eigenbeams forms the basis of a scalable representation that enables one to easily compute and analyze the spatial distribution of live or recorded sound fields. A 24 element spherical microphone array composed of pressure microphones mounted on the surface of a rigid spherical baffle was constructed. Experimental results from a real-time implementation show that a theory based on spherical harmonic eigenbeams matches measured results.

Keywords

Microphone Array Beamforming Spherical 3D Sound Recording 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. [1]
    R. H. DuHamel, “Pattern synthesis for antenna arrays on circular, elliptical and spherical surfaces,” Tech. Rep. 16, Electrical Engineering Research Laboratory, University of Illinois, Urbana, 1952.Google Scholar
  2. [2]
    M. Hoffman, “Conventions for the analysis of spherical arrays,” IEEE Trans. Antennas Propagat., vol. 11, pp. 390–393, Jul. 1963.Google Scholar
  3. [3]
    A. K. Chan, A. Ishimaru, and R. A. Sigelmann, “Equally spaced spherical arrays,” Radio Science, vol. 3, No. 5, May 1968.Google Scholar
  4. [4]
    B. Preetham Kumar and G. R. Branner, “The far-field of a spherical array of point dipoles,” IEEE Trans. Antennas Propagat., vol. 42, pp. 473–477, Apr. 1994.Google Scholar
  5. [5]
    P. G. Craven and M. A. Gerzon, “Coincident microphone simulation covering three dimensional space and yielding various directional outputs,” US Patent 4,042,779, Jul. 1975.Google Scholar
  6. [6]
    R. K. Furness, “Ambisonics-an overview,” in Proc. of the AES8th international conference, Washington, 1990.Google Scholar
  7. [7]
    G. W. Elko and A.-T. Nguyen Pong, “A steerable and variable first-order differential microphone array,” in Proc. of IEEE ICASSP, Munich, 1997.Google Scholar
  8. [8]
    J. Daniel, Representation de champs acoustique, application a la transmission et a la reproduction de scene sonores complexes dans un contexte multimedia, PhD thesis, University Paris 6, 2000.Google Scholar
  9. [9]
    J. Meyer and G. W. Elko, “A highly scalable spherical microphone array based on an orthonormal decomposition of the soundfield,” in Proc. of IEEE ICASSP, Orlando, 2002.Google Scholar
  10. [10]
    T. D. Abhayapala and D. B. Ward, “Theory and design of high order sound field microphones using spherical microphone array,” in Proc. of IEEE ICASSP, Orlando, 2002.Google Scholar
  11. [11]
    A. Laborie, R. Bruno and S. Montoya, “A new comprehensive approach of surround sound recording,” in Proc. of the 114th AES Convention, Amsterdam, 2003.Google Scholar
  12. [12]
    P. M. Morse and K. U. Ingard, Theoretical Acoustics, McGraw-Hill, New York, 1968.Google Scholar
  13. [13]
    E. G. Williams, Fourier Acoustics, Academic Press, San Diego, 1999.Google Scholar
  14. [14]
    J. J. Bowman, T. B. A. Senior, and P. E. Uslenghi, Electromagnetic and Acoustic Scattering by Simple Shapes, Hemisphere Publishing Corporation, New York, 1987Google Scholar
  15. [15]
    A. C. Ludwig, “Spherical wave theory,” in The handbook of antenna design, vol. 1, chap. 2.1, Peregrinus, New York, 1983Google Scholar
  16. [16]
    E. N. Gilbert and S. P. Morgan, “Optimum design of antenna arrays subject to random variations,” Bell Syst. Tech. J., 34, pp. 637–663, May 1955.Google Scholar
  17. [17]
    G. W. Elko, “Superdirectional Microphone Arrays,” in Acoustic Signal Processing for Telecommunication, S. L. Gay and J. Benesty, Eds., Boston, MA: Kluwer Academic, 2000.Google Scholar
  18. [18]
    H. Cox, R. M. Zeskind, and T. Kooij, “Practical supergain,” IEEE Trans. ASSP 34, pp. 393–398, 1986.Google Scholar
  19. [19]
    G. H. Golub and C. F. van Loan, Matrix computations, The Johns Hopkins University Press, Baltimore and New York, 1996.Google Scholar

Copyright information

© Kluwer Academic Publishers 2004

Authors and Affiliations

  • Jens Meyer
    • 1
  • Gary W. Elko
    • 2
  1. 1.Mh acousticsUSA
  2. 2.Avaya LabsAvaya

Personalised recommendations