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Beamforming and other methods for denoising microphone array data

Abstract : Measured acoustic data can be contaminated by noise. This typically happens when microphones are mounted in a wind tunnel wall or on the fuselage of an aircraft, where hydrodynamic pressure fluctuations of the Turbulent Boundary Layer (TBL) can mask the acoustic pressures of interest. For measurements done with an array of microphones, methods exist for denoising the acoustic data. Use is made of the fact that the noise is usually concentrated in the diagonal of the Cross-Spectral Matrix, because of the short spatial coherence of TBL noise. This paper reviews several existing denoising methods and considers the use of Conventional Beamforming, Source Power Integration and CLEAN-SC for this purpose. A comparison between the methods is made using synthesized array data. A source power [Pa 2 ] a source amplitude B auto-spectrum [Pa 2 ] C CSM [Pa 2 ] mn C cross-spectrum [Pa 2 ] c PFA vector of latent factors [Pa] c speed of sound [m/s] D dirty matrix [Pa 2 ] d CSM diagonal [Pa 2 ] F cost function [Pa 2 ] g steering vector n g steering vector component h source component I number of iterations i imaginary unit () i iteration index J number of averages j snapshot index K number of sources , kl source index L PFA mixing matrix M Mach number of main flow , mn microphone index N number of microphones NI number of integration areas n noise vector [Pa] p benchmark pressure vector [Pa] 0 r reference distance [m] 1 r stretched distance [m], Eq. (4) s signal vector [Pa] () st acoustic signal [Pa] t time [s] U unitary matrix with eigenvectors of C U main flow speed [m/s] ⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯ U convection speed in TBL [m/s] w beamforming weight vector n w weight vector component x microphone location [m] ,, x y z cartesian coordinates [m] α PFA vector defining diagonal matrix 2  2 1 M −  loop gain  number of PFA latent factors  diagonal matrix with eigenvalues of C [Pa 2 ]  SLRD relaxation parameter  integration area index  noise multiplier () t  noise signal [Pa] 2 0  accuracy constant in Eq. (29)  scaling factor  angular frequency [rad/s]  source location [m] ,,    source coordinates [m]
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Submitted on : Wednesday, June 5, 2019 - 9:12:47 AM
Last modification on : Wednesday, July 8, 2020 - 12:42:27 PM

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  • HAL Id : hal-02147804, version 1
  • ARXIV : 1906.02965

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Pieter Sijtsma, Alice Dinsenmeyer, Jérôme Antoni, Quentin Leclere. Beamforming and other methods for denoising microphone array data. 2019 AIAA/CEAS Aeroacoustics conference, May 2019, Delft, Netherlands. ⟨hal-02147804⟩

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