scholarly journals Investigation on holographic reconstruction of sound field using wave superposition approach

2004 ◽  
Vol 53 (8) ◽  
pp. 2607
Author(s):  
Yu Fei ◽  
Chen Xin-Zhao ◽  
Li Wei-Bing ◽  
Chen Jian
Keyword(s):  
Sound Field ◽  
Wave Superposition ◽  
Holographic Reconstruction

A sound field visualization system based on the wave superposition algorithm

2008 ◽  
Vol 222 (8) ◽  
pp. 1403-1412 ◽  
Author(s):  
J Q Li ◽  
J Chen ◽  
C Yang ◽  
G M Dong
Keyword(s):  
Numerical Simulations ◽  
Tikhonov Regularization ◽  
Sound Field ◽  
Point Sources ◽  
Experimental Results ◽  
Visualization System ◽  
Field Reconstruction ◽  
Wave Superposition ◽  
Sound Field Reconstruction ◽  
Regularization Strategy

Sound field visualization is a helpful design and analysis tool for the study of sound radiation and dispersion problems. It can help to comprehend deeply about noise transmission mechanism, monitor environment noise, evaluate sound quality, and even diagnose the machinery faults based on mechanical noise. The well-known near-field acoustic holography is an accurate sound field visualization technique. However, this technique has disadvantages such as strict measurement requirements and the need of an enormous number of microphones, which limits its extended applications. In order to visualize the sound field with a small number of microphones for measurements, the regeneration method of the radiated field by using the wave superposition algorithm is attempted in this study. It is based on the principle of equivalent source: the sound field radiated by an arbitrarily shaped radiator is substituted by the distributed point sources (monopole or dipole) constrained inside the actual source surface. For suppressing the adverse effect of measurement noise, the Tikhonov regularization strategy is adopted to work together with the wave superposition algorithm to give an accurate solution. Numerical simulations were performed based on a two-pulse-ball model to evaluate the accuracy of the combined algorithm of the wave superposition and the Tikhonov regularization strategy. In addition, an integrated sound field visualization system is designed and implemented. The functions include acoustic signal acquisition and processing, sound field reconstruction, and results visualization. The performance of the presented system was tested by experiments in a semi-anechoic chamber by using two sound boxes to simulate the sound sources. As concerning practical measurement microphones, there exist phase mismatches between the channels. Results will go wrong if the sound field reconstruction is performed directly with these uncalibrated measurement data. Therefore, a calibration procedure is applied to eliminate them. Experimental results indicate that the phase mismatches between the channels after calibration decay to 0.1°. Both the numerical simulations and experimental results accurately reconstructed the exterior sound field of the models. It is shown that the wave superposition algorithm together with the Tikhonov regularization strategy can exactly reconstruct the exterior sound field of radiators, which makes a base to its applications in practice. This sound field visualization system will make an operator's experimental work much easier.

Research on the reconstruction of the vibro-acoustic field generated by the complicated sources using the modified wave superposition algorithm

2008 ◽  
Vol 223 (2) ◽  
pp. 353-361 ◽  
Author(s):  
H B Zhang ◽  
W K Jiang ◽  
Z Y Huang ◽  
Q Wan
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Accurate Result ◽  
Sound Field ◽  
Acoustic Holography ◽  
Object Boundary ◽  
Independent Components ◽  
Sound Fields ◽  
Wave Superposition ◽  
Inverse Procedure

The nearfield acoustic holography (NAH) method based on the wave superposition algorithm (WSA) assumes that the sound field is induced by a series of simple sources inside the vibrational object boundary. The sound field can be reconstructed after the strength of virtual sources is determined in an inverse procedure. The theory, numerical simulation, and application of WSA-based NAH is often concerned with the simple sources. In practice, the vibrational objects are more complicated and sometimes should even be treated as multiple separated objects. The reconstruction of a sound field by using conventional WSA-based NAH directly is not satisfactory. In the presented modified WSA-based NAH, complicated vibrational objects are separated into several parts and looked at as independent components. Whole sound fields are generated by all these components. The comparisons between conventional and modified WSA-based NAH are carried out through numerical simulations. It shows that the more accurate result is obtained by applying the modified WSA-based NAH to the complicated objects. An experiment of a compressor with complicated structures is conducted to illustrate the validity of modified WSA-based NAH.

Study of a sound field separation technique based on a single holographic surface and wave superposition method

2009 ◽  
Vol 223 (8) ◽  
pp. 1827-1836
Author(s):  
W Q Jia ◽  
J Chen ◽  
C Yang ◽  
Z Y Wang
Keyword(s):  
Sound Pressure ◽  
Regularization Parameter ◽  
Sound Field ◽  
Mirror Image ◽  
Separation Technique ◽  
Tikhonov Regularization Method ◽  
Superposition Method ◽  
Wave Superposition ◽  
Measurement Surface ◽  
Field Separation

In order to overcome the limitation of traditional near-field acoustical holography (NAH), that the sound field on one side of the holographic surface must be free, a sound field separation technique based on single holographic surface and wave superposition method (WSM) is proposed. According to the WSM, the field on and near the measurement surface may be approximated by the field produced by virtual source points placed on a surface inside the structure. The source strengths are evaluated by applying boundary conditions on the measurement surface. Here, the ‘pseudo’ sound pressure of the reconstruction surface is first obtained based on the principle of sound field mirror image and WSM, then the sound pressure of the target sound source acting on the holographic surface is separated by the sound pressures of the holographic surface and the reconstruction surface, and the sound field separation is realized. The technique requires the inversion of the Green's function matrix, which may be ill-conditioned. The Tikhonov regularization method is used to invert it, and the value of the regularization parameter is determined by the L-curve criteria. Through the numerical simulation and experiment, the results show the validity and efficiency of this technique.

An Indirect Boundary Element Method for Computing Sound Field

2012 ◽  
Vol 476-478 ◽  
pp. 1173-1177
Author(s):  
Sheng Yao Gao ◽  
De Shi Wang
Keyword(s):  
Integral Equation ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Acoustic Field ◽  
Boundary Surface ◽  
Sound Field ◽  
Boundary Integral ◽  
Superposition Method ◽  
Wave Superposition ◽  
Element Method

Computing sound field from an arbitrary radiator is of interest in acoustics, with many significant applications, one that includes the design of classical projectors and the noise prediction of underwater vehicle. To overcome the non-uniqueness of solution at eigenfrequencies in the boundary integral equation method for structural acoustic radiation, wave superposition method is introduced to study the acoustics. In this paper, the theoretical backgrounds to the direct boundary element method and the wave superposition method are presented. The wave superposition method does not solve the Kirchoff-Helmholtz integral equation directly. In the approach a lumped parameter model is estabiled from spatially averaged quantities, and the numerical method is implemented by using the acoustic field from a series of virtual sources which are collocated near the boundary surface to replace the acoustic field of the radiator. Then the sound field over the of a pulsating sphere is calculated. Finally, comparison between the analytical and numerical results is given, and the speed of solution is investigated. The results show that the agreement between the results from the above numerical methods is excellent. The wave superposition method requires fewer elements and hence is faster, which do not need as high a mesh density as traditionally associated with BEM.

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