Resolution enhanced statistically optimal cylindrical near-field acoustic holography based on equivalent source method

The spatial resolution of near-field acoustic holography based on the equivalent source method (ESM) is closely related to the number of measurement points, the higher the number of measurement points, the higher the resolution. However, the number of measurement points in the actual measurement cannot be increased infinitely. To solve the contradiction between the resolution and the number of measurement points, this paper proposes an equivalent source density interpolation method (ESDIM). First, the equivalent source intensity is obtained using the sound pressure measured by the array element and the Green function, and the equivalent source intensity density is obtained based on the equivalent source intensity and grid area. Second, the Hermite interpolation function was used to obtain the interpolated equivalent source intensity density. However, as the number of interpolated grids increased, the resolution, computation, and running time of ESDIM increased, and the number of subdivided grids per unit grid was 9-25 in this study. Finally, the sound field was reconstructed based on the obtained interpolated equivalent source intensity and Green transfer function, and the reconstruction accuracies of ESDIM and ESM were compared and analyzed. The simulation and experimental data processing results showed that the resolution of the equivalent source intensity density interpolation method was higher than that of the equivalent source method.

show abstract

“…To evaluate the effects of ESDIM and ESM methods, the reconstruction error is defined as follows [1,28]:…”

Section: Simulation Methodologymentioning

confidence: 99%

“…Near-field acoustic holography (NAH) [1][2][3][4] reconstructs the acoustic quantities at the source surface and at any point in the entire three-dimensional sound field by measuring the complex acoustic pressure or vibration velocity on the near-field because of its large measuring surface and high density of sensors.…”

Section: Introductionmentioning

confidence: 99%

Application of equivalent source intensity density interpolation in near-field acoustic holography

Gao

Yang

et al. 2023

Meas. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…After 40 years of development, various NAH algorithms based on diferent EWFs have been established, for example, discrete Fourier transform-based NAH (DFT-based NAH) [5][6][7], inverse boundary element method (IBEM) [8][9][10], equivalent source method (ESM) [11][12][13][14], statistically optimized NAH (SONAH) [15][16][17], Helmholtz equation least squares (HELS) [18][19][20][21], and so on. Teoretically, DFTbased NAH implicitly expands the sound feld by a set of EWFs such as plane, cylindrical, or spherical wave functions, while the spatial spectra can be considered as the weighting coefcients.…”

Section: Introductionmentioning

confidence: 99%

Statistically Optimized Near-Field Acoustic Holography Using Prolate Spheroidal Wave Functions

Zhang,

Lou,

et al. 2023

Shock and Vibration

View full text Add to dashboard Cite

Near-field acoustic holography (NAH) is an effective tool for realizing accurate sound field reconstruction in three-dimensional space on the prerequisite that appropriate elementary wave functions are selected or constructed to match the characteristics of the sound sources. However, for elongated sources, common wave functions, i.e., plane, cylindrical, or spherical waves, sometimes do not perform well during the sound field projections. To solve this problem, statistically optimized near-field acoustical holography combined with prolate spheroidal wave functions is proposed. In the approach, the sound field is expanded by a series of prolate spheroidal wave functions, whose wavefronts can be set nearly conformal to the elongated sources. Based on these wave functions, fewer expansion terms are required to model the sound field, and the need for regularization can be reduced during the inverse solving process. Therefore, the accuracy of the reconstruction results can be further improved. Numerical simulations are conducted by two types of elongated source models, namely, spatially separated and extended. The results show that the proposed method can effectively reconstruct the sound pressures of elongated sources and perform robustly across a wide frequency range. Simultaneously, a designed experiment is carried out in an anechoic chamber, which demonstrates the feasibility of the proposed method.

show abstract

Sound field separation technique for nonplanar sources based on field prediction by using statistically optimized near-field acoustic holography

Cheng

Song

et al. 2023

Meas. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

For the sound field of cylindrical or compact sources, the current sound field separation technique (FST) based on statistically optimized near-field acoustic holography (SONAH) uses the planar wave to separate and has not studied the effects of different wave functions. However, the non-conformal problem between the hologram surface and the sound sources will have the risk of accuracy reduction. To solve this problem, a FST for nonplanar sources based on SONAH is proposed. First, according to the characteristic that field prediction of near-field acoustic holography will make errors attenuate, by moving the reconstruction surface to the prediction area, noise immunity of FST is effectively improved in a noisy environment. Subsequently, combining the shape of the sound source, the appropriate conformal wave function is determined and then substituted into the improved method in the first step to separate the free-field sound pressure. Finally, the simulations and the experiments of loudspeakers and a cylindrical experiment platform further proves the effectiveness of the proposed method, which can improve adaptability and reliability of FST in nonplanar sound sources in mechanical systems.

show abstract

Resolution enhanced statistically optimal cylindrical near-field acoustic holography based on equivalent source method

Cited by 3 publications

References 35 publications

Application of equivalent source intensity density interpolation in near-field acoustic holography

Application of equivalent source intensity density interpolation in near-field acoustic holography

Statistically Optimized Near-Field Acoustic Holography Using Prolate Spheroidal Wave Functions

Sound field separation technique for nonplanar sources based on field prediction by using statistically optimized near-field acoustic holography

Contact Info

Product

Resources

About