Non-conformal measurement near field acoustic holography sound field rebuilding method

Abstract

The invention relates to a non-conformal measurement near field acoustic holography sound field rebuilding method, and relates to the technical field of acoustics. The method includes the steps that spherical wave function q(x,y) in a common wave superposition method (see the formula in the description) is replaced by a compound ray wave function with principal value directivity, by means of the method, when the holographic plane and a sound source shape are under the non-conformal condition, namely a planar array, a spherical array, a cylindrical surface array and other regular shape arrays are adopted in a holographic measurement plane, and a sound source is in an any shape, a system matrix is still in the good state of main diagonal domination, magnitude equivalence and approximate symmetry, numerical value inversion can be directly conducted on the system matrix efficiently and accurately, approximate solutions of ill-posedness problems can be obtained without using a regularization method or using the regularization method less, some variables of virtual equivalent sources are analyzed and prolongated to a complex space from a traditional real space, appropriate virtual damp is added, and therefore unique solution is obtained in the full wave number field.

Description

Technical field [0001] The invention relates to the technical field of acoustics, in particular to a non-conformal near-field acoustic holographic reconstruction technology. Background technique [0002] Because NAH (Nearfield acoustic holography, NAH for short) can reconstruct the entire sound field, theoretically, the acoustic information at any point in the sound field can be easily obtained. This is the feedback control strategy used in any single-point or multi-point (observation point) test in the past. Are incomparable. However, to meet the real-time requirements, it is necessary to start with the rapid measurement of complex sound pressure (sound intensity) or vibration velocity on the holographic surface and the fast algorithm of sound field reconstruction, in order to minimize the time lag between sound field reconstruction and the control system. It truly becomes an effective means for real-time monitoring of the sound field and closed-loop feedback control. [0003] T...

AI Technical Summary

Problems solved by technology

However, there is still a big gap between the above algorithms and the ideal sound field space transformation algorithm, and there are more or less different defects: such as the planar, cylindrical and spherical Fourier space transformation algorithm and the SONAH of the planar, cylindrical and spherical surface, etc. , they are only suitable for sound sources with regular shapes such as planes, cylinders, and spheres. For the sound field inversion of sound sources with irregular shapes, these methods can at best obtain the complex sound pressure and vibration velocity on the reconstruction surface with a similar regular shape. , but the vibration details (vibration velocity, etc.) The characteristic of ill-posed problems is that the system matrix may be "ill-conditioned" (larger condition number)

The biggest flaw is that it is only suitable for sound field reconstruction on regular-shaped sound source surfaces such as planes, cylinders, and spheres.

The biggest flaw is: there is a "conformal" problem, regularization processing is required, and the calculation accuracy and efficiency are not high

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