Research On Sound Field Reconstruction Interpolation Method Of Joint Equivalent Sound Source And Near Field Acoustic Holography

With the rapid development of the national economy,people have put forward higher requirements for the acoustic environment comfort,and sound pollution control has become an urgent problem to be solved.Accurate reconstruction of the sound field is the key to sound pollution control,the core of sound field visualization,and an important reverse science problem in acoustic research.To this end,this paper proposes a sound field reconstruction interpolation method combining the equivalent sound source method(ESM)and near-field acoustic holography(NAH).Based on the mathematical model of near-field reconstruction of acoustic holography,the problems of low accuracy of sound field reconstruction and difficulty in solving ill-posed equation caused by insufficient sound pressure information are effectively solved by means of equivalent sound source and improved Newton interpolation algorithm.The fast solution of ill-posed equation and efficient reconstruction of sound pressure field in holographic plane are realized without increasing the number of microphones.The method is verified by numerical simulation and experimental results.In addition,the topic was funded by the National Natural Science Foundation of China(61671262,61871647).The main research contents are as follows:(1)Based on the definition of near-field acoustic holographic sound field reconstruction mechanism,reconstruction mathematical model and key factors,the core problems affecting the sound pressure reconstruction accuracy of acoustic holographic surface are discussed in detail,and the key influencing factors and related parameters are determined.The sound source equivalent principle,the equivalent source plane arrangement and the equivalent source number of the equivalent sound source are established,and the relationship between the equivalent source surface and the holographic sound pressure surface is established.(2)In-depth study of Newton's interpolation method,and an improved Newton interpolation algorithm is proposed for the interpolation accuracy and speed problem.The position angle of the array element is measured as a variable,and the adjacent point interpolation is used to effectively increase the usefulness on the measurement surface.The sound pressure value realizes the sound pressure interpolation on the non-measurement point of the measuring surface.(3)On the basis of the above research,an interpolation method of sound field reconstruction combining the equivalent sound source method and the near-field acoustic holography(ESM-NAH)is proposed.The relationship between the sound pressure of the holographic surface and the reconstructed surface is established by the equivalent sound source.The effective sound pressure information on the measured surface is increased by the improved Newton interpolation,the effective sound pressure amplitude of the near-field reconstruction of the acoustic holography is increased,the reconstruction accuracy is enhanced,and the reconstruction accuracy is improved.The speed of solving the ill posed sound pressure equation is increased.(4)Numerical simulation of ESM-NAH sound field reconstruction.A lot of numerical analysis is carried out for the key factors and the selection of relevant parameters of the method and the core algorithm.The influencing factors in the process of holographic surface,equivalent source surface and improved Newton interpolation are given,the relevant reasonable parameters are determined,and the method and algorithm are verified numerically with single and double sound sources.(5)Measurement experiment of ESM-NAH sound field reconstruction.In order to further clarify the validity and reliability of the method,the holographic sound field reconstruction experiment was carried out in the laboratory.Taking the single and double sound sources in the numerical analysis as the measurement object,the key algorithms and influencing factors such as the improved Newton interpolation algorithm and the principle of equivalent source,the number and position,and the distance between the holographic surface and the measurement surface are measured and studied.Compared with the numerical results,the validity of the theory and application of this method is verified.The practicability of the method is verified by the holographic reconstruction experiment of the noise field of the dehumidifier.