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Spherical harmonic analysis of wavefields using multiple circular sensor arrays

Summary: Spherical harmonic analysis of wavefields
using multiple circular sensor arrays
Thushara D. Abhayapala, Senior Member, IEEE and Aastha Gupta Student Member, IEEE
Spherical harmonic decomposition of wavefields is not only an active problem in acoustic signal processing
but also a useful tool in a plethora of applications such as 3D beamforming, direction of arrival estimation, and
spatial sound recording. This paper presents a novel array structure consisting of a set of parallel circular arrays of
sensors to decompose a wavefield into spherical harmonic components. The new structure presented here provides an
alternative design to the traditional spherical microphone arrays with increased flexibility on sensor locations. We use
the underlying structure of the wave propagation together with the properties of the associated Legendre functions
and the spherical Bessel functions to develop a systematic approach to place circular arrays and construct a hybrid
array. As an illustration, we design a fifth order spherical harmonic decomposition array using 57 microphones to
operate over a frequency band of an octave and compare it with a spherical array. We use computer simulations to
show the performance of the array in a beamforming example.
Index Terms
Spherical array of microphones, spherical harmonics, circular array, beamforming, spatial soundfield, wavefield,
wavefield decomposition, acoustic scene analysis
Some parts of the preliminary work related to the current manuscript has been appeared in Proc. of the International Workshop on Acoustic
Echo and Noise Control (IWAENC08).
Authors are with the Applied Signal Processing Group, Department of Information Engineering, RSISE, CECS, The Australian National


Source: Abhayapala, Thushara D. - Department of Information Engineering, Australian National University


Collections: Computer Technologies and Information Sciences