Regularization for improving the deconvolution in real-time near-field acoustic holography

Near-field acoustic holography is a measuring process for locating and characterizing stationary sound sources from measurements made by a microphone array in the near-field of the acoustic source plane. A technique called real-time near-field acoustic holography (RT-NAH) has been introduced to exte...

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Bibliographic Details
Published inThe Journal of the Acoustical Society of America Vol. 129; no. 6; p. 3777
Main Authors Paillasseur, Sébastien, Thomas, Jean-Hugh, Pascal, Jean-Claude
Format Journal Article
LanguageEnglish
Published United States 01.06.2011
Subjects
Acoustics - instrumentation
Computer Simulation
Fourier Analysis
Holography - instrumentation
Models, Theoretical
Motion
Numerical Analysis, Computer-Assisted
Pressure
Signal Processing, Computer-Assisted
Sound
Sound Spectrography
Time Factors
Transducers
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Summary:Near-field acoustic holography is a measuring process for locating and characterizing stationary sound sources from measurements made by a microphone array in the near-field of the acoustic source plane. A technique called real-time near-field acoustic holography (RT-NAH) has been introduced to extend this method in the case of nonstationary sources. This technique is based on a formulation which describes the propagation of time-dependent sound pressure signals on a forward plane using a convolution product with an impulse response in the time-wavenumber domain. Thus the backward propagation of the pressure field is obtained by deconvolution. Taking the evanescent waves into account in RT-NAH improves the spatial resolution of the solution but makes the deconvolution problem "ill-posed" and often yields inappropriate solutions. The purpose of this paper is to focus on solving this deconvolution problem. Two deconvolution methods are compared: one uses a singular value decomposition and a standard Tikhonov regularization and the other one is based on optimum Wiener filtering. A simulation involving monopoles driven by nonstationary signals demonstrates, by means of objective indicators, the accuracy of the time-dependent reconstructed sound field. The results highlight the advantage of using regularization and particularly in the presence of measurement noise.
ISSN:1520-8524
DOI:10.1121/1.3586790