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Nearfield acoustic holography based on the equivalent source method

On the basis of the nearfield acoustic holography (NAH) based on the distributed source boundary point method (DSBPM), a novel NAH based on the equivalent source method (ESM) is proposed. The theoretical model of the proposed method is established at first. And then, the error sensitivity and the reconstruction problems of a multi-source acoustic field and a semi-free acoustic field are analyzed, and the corresponding treatment methods are proposed. Subsequently, an experiment on a speaker is investigated to validate the feasibility and correctness of the method. In the method, no discretization is needed on the boundary of the vibrating body. The acoustic field is predicted directly by a set of weighted equivalent sources located inside the vibrating body. Therefore, the variable interpolation, the treatments of singular integrals and non-uniqueness of solutions in the characteristic wave number are avoided. Additionally, the method is adapted to arbitrary-shaped source, so it is really a meshless method. Furthermore, there are such merits as the simple principle, the high calculation efficiency and precision. It is valuabe for the NAH to be applied in the practical engineering field.