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Summary: NON-SPHERICAL MICROPHONE ARRAY STRUCTURES FOR 3D BEAMFORMING AND
SPHERICAL HARMONIC ANALYSIS
Thushara D. Abhayapala and Aastha Gupta
Applied Signal Processing Group
Department of Information Engineering, RSISE, CECS
The Australian National University
Email: {Thushara.Abhayapala, Aastha.Gupta}.anu.edu.au
ABSTRACT
Decomposition of a soundfield into spherical harmonics is a funda-
mental problem in acoustic signal processing. This paper shows how
to design non-spherical microphone array structures in 3D space to
decompose a soundfield into spherical harmonic components. We
use the mode limiting property of the Bessel functions and zeros of
the associated Legendre functions together with orthoganality of the
exponential functions over circles to construct an array of parallel
circles of microphones. The result provides flexible design guide-
lines to construct 3D arrays than traditional spherical arrays. A sim-
ple beamforming example is given to verify the result.
Index Terms-- Spherical array of microphones, spherical har-
monics, circular array, beamforming, soundfield
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