Research On Closed-Space Near-Field Acoustic Holography Technology Based On Equivalent Source Method

Near-field acoustic holographic technology(NAH)predicts and reconstructs the radiated acoustic field through sound field information near the target sound source to identify the sound source and analyze the sound field characteristics.Since the inner sound field in the enclosed space is a strong reverberation field containing the direct sound radiated by the target sound source and the reflected sound of the boundary,it is difficult for the traditional near-field sound holographic technology to complete the tasks of the identification of the target sound source,the reconstruction and prediction of the sound field in the enclosed space.This paper analyzes and studies the NAH technology from the three aspects of free field sound field reconstruction,non-free field sound field prediction and sound field separation.The main research contents are as follows:The radiated acoustic field of the simple aluminum plate was studied and analyzed by numerical simulation tools and combined with experiments,the effectiveness of THEAH technology based on the equivalent source method(ESM)was verified,and the effects of different regularization parameter selection methods,holographic surface arrangement and equivalent source plane fallback distance on the sound field reconstruction accuracy were analyzed.Numerical simulation results show that although the GCV method takes the longest time,it has the strongest anti-interference ability.Aiming at the problem of sound field prediction in enclosed space,a theoretical model of sound field prediction method in closed space based on equivalent source method is established,and the performance of ESM-based closed space sound field prediction algorithm under different boundary conditions is analyzed,and the simulation results show that the algorithm can accurately reconstruct the sound field,which proves the effectiveness and applicability of the algorithm.Aiming at the sound field separation problem of non-free field,a theoretical model of single-layer sound field separation based on the equivalent source method is established.The correctness of the method is verified by numerical simulation tools,and the effect of the interference source intensity and the separation distance of the holographic surface on the restoration error is analyzed.Impact.In addition,a simulation study of the radiated sound field of a point sound source in a closed space is carried out,and the influence of the holographic surface arrangement on the restoration error is analyzed.Improve the acoustic cavity modal characteristics of the holographic surface.Finally,the effectiveness of the separation algorithm in closed space is verified by experiments.