Study Of Sound Source Identification Based On Wideband Acoustic Holography

Near field acoustic holography is an effective tool for noise source identification.The near-field acoustic holography based on the equivalent source method has been widely studied and applied because it is not affected by the shape of the actual sound source,but the method is only suitable for the reconstruction of low frequency acoustic field due to the influence of array aperture.Based on the equivalent source method and sparse regularization,wideband acoustic holography can accurately reconstruct the medium and high frequency acoustic field with a small number of sampling points,which has high application value.In this paper,wideband acoustic holography is studied and the algorithm is improved according to the actual demand,aiming at expanding the application range of wideband acoustic holography and applying it to the noise source identification of reducer.The main contents of this paper are as follows:The acoustic transfer matrix is constructed by deducing the equivalent source integral equation,and then Tikhonov regularization and wideband acoustic holography(WBH)are introduced to solve the inverse problem respectively.The sound field reconstruction performance of the two methods is compared by numerical simulation,and the influence of the initial source intensity on the reconstruction results of WBH is analyzed.The results show that WBH has a good reconstruction accuracy in middle and high frequency bands,but it is difficult to identify coherent sound sources with lower frequencies,and the intensity of the initial source has a significant influence on the reconstruction results of wideband acoustic holography.Based on the above,the method of wideband acoustic holography is improved in stationary sound field,and the application scope of wideband acoustic holography is expanded.An improved Wideband acoustic holography algorithm(mWBH)is proposed by changing the iterative conditions and the initial source intensity of the algorithm to solve the problem that the wideband acoustic holography technology is difficult to identify the low frequency coherent sound source.In terms of sound field reconstruction method for spatial continuous sound source,the compressed singular value equivalent source method(CVESM)based on generalized inverse is proposed by combining the compressed singular value equivalent source method and the generalized inverse of matrix.Finally,the validity and correctness of mWBH and CVESM are verified by experiments.Then,wideband acoustic holography is applied to cyclic stationary acoustic field,and a cyclic stationary acoustic field reconstruction method based on wideband acoustic holography(CY-mWBH)is proposed combining with the cyclic stationary near-field acoustic holography theory based on wave superposition method(WSA-based CYNAH).Through numerical simulation,it is found that CY-mWBH has strong anti-noise ability and higher analysis frequency than WSA-based CYNAH.Finally,the improved wideband acoustic holography under stationary sound field and cyclic stationary sound field is applied to the sound source identification of gear reducer.In the stationary sound field,CVESM is used to identify the noise source of the gear reducer.In the cyclic stationary sound field,CY-mWBH was used to compare the distribution of the cyclic power spectrum density of the gear reducer under the conditions of no load and full load.The results show that wideband acoustic holography can effectively identify the noise source of gear reducer.