Unsteady-state free-field reduction method using single-sided sound pressure and mass point vibration velocity measurement

Abstract

The invention discloses an unsteady-state free-field reduction method using single-sided sound pressure and mass point vibration velocity measurement. Two-dimensional spatial Fourier transform is carried out on a time-domain sound pressure and time-domain mass point velocity that are measured directly on a measurement plane H to obtain sound pressure and mass point vibration velocity time-domain wavenumber spectrums on the plane H; and with the sound pressure and mass point vibration velocity time-domain wavenumber spectrums on the plane H, known sound pressure and mass point vibration velocities, a time-domain impulse response function between the sound pressures, and a surface reflection coefficient of a target sound source, a free-field reduction formula is derived and a time-varying sound pressure signal radiated on the plane H under the free field condition of the target sound source is reduced in real time. According to the disclosed method, only with one measurement plane, the input amount does not need to be obtained by approximate calculation and the reduction formula is calculation of the forward convolution sum; no unrolling and inversion processing is needed; and the influence of the unsteady-state scattered sound field is eliminated in real time. The method can be applied to field analysis of the time-varying radiation characteristic and vibration characteristic ofthe target sound source in an actual sound field environment.

Description

technical field [0001] The invention relates to the technical field of noise in physics specialty, in particular to an unsteady-state free-field reduction method using single-plane sound pressure and particle vibration velocity measurement. Background technique [0002] The actual sound field environment is a non-free field, which includes not only the radiated sound of the target sound source, but also the interference sound from the other side of the measurement surface and the scattered sound generated by the interference sound on the surface of the target sound source. In addition to the sound field produced by the interfering sound that can affect the sound field radiated by the target sound source, the scattered sound can also affect the accurate measurement of the radiated sound field of the target sound source. eliminated from the results. [0003] So far, scholars at home and abroad have proposed a variety of free-field restoration methods: Hald et al. proposed a f...

AI Technical Summary

Problems solved by technology

In this unsteady-state reduction method, the relationship between the time-domain sound pressure radiated by the target sound source in the free field and the mixed time-domain sound pressure on the double measurement surfaces cannot be directly established. It is necessary to separate the unsteady-state sound field first, and then to Unless the sound field is scattered in a steady state, real-time restoration cannot be achieved; this restoration method still requires complex iterative unconvolution calculations, and its process is an ill-conditioned inverse problem, which requires Tikhonov regularization and singular value decomposition to obtain a suitable solution, resulting in the reduction method calculation The amount is large, and the restoration accuracy largely depends on the reasonable selection of regularization parameters; the distance between the two measurement surfaces also affects the restoration accuracy

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