This paper examines the application of Nearfield Acoustical Holography based on the Helmholtz Equation Least-Squares (HELS) method for visualization of the sound-pressure field in the passenger compartment of a vehicle with hard interior surfaces. In the HELS method, sound pressure is determined by an expansion of a set of orthogonal basis functions that are solutions to the Helmholtz equation. Coefficients associated with these basis functions were determined by a collocation method with errors minimized by the least-squares method. The number of expansion terms in the method was optimized to ensure a convergence of the solution anywhere in the interior region of the vehicle, including the boundary surfaces. The reconstructed sound pressures were compared with benchmark sound pressures calculated by the boundary element method (BEM). Results demonstrated that the HELS method permitted reconstruction of the sound-pressure field with much greater computational efficiency than the BEM procedure. Accuracy of reconstruction was relatively insensitive to the choice of the locations for input data. For hard interior surfaces, a small box-shaped surface on which input data were collected was shown to be sufficient to provide good reconstruction results. Such a configuration could be implemented relatively easily in practice. Reconstruction of sound-pressure fields at resonance frequencies of the vehicle interior cavity was also validated.
Visualization of vehicle interior sound field using Nearfield Acoustical Holography based on the Helmholtz-Equation Least-Squares (HELS) method
Darstellung des Schallfeldes im Fahrzeuginneren mittels akustischer Nahfeld-Holographie auf Basis der Helmholtz-Gleichung und der Methode der kleinsten Quadrate
Noise Control Engineering Journal ; 53 , 4 ; 145-154
2005
10 Seiten, 17 Quellen
Article (Journal)
English
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