Simulation and experimental investigations for the patch near-field acoustical holography

Abstract

In order to reconstruct the sound field, the fast Fourier transform (FFT)-based near-field acoustical holography (NAH) demands that the measurement surface must extend to a region where the sound pressure decreases to a low level. This method is unfit for reconstructing the partial sound field in which the measurement aperture size is limited either by physical necessity or as a way of reducing the measurement cost. Statistically optimal NAH (SONAH) performs plane-to-plane calculations directly in the spatial domain, avoids all errors occurred in the FFT-based NAH and significantly increases the accuracy of the reconstruction of the partial sound field. In the present work, combined with the different regularization methods, SONAH is performed for reconstructing the partial sound field. The errors over the central and the peripheral sections of the reconstruction area are researched separately. Simulations and experiments show that SONAH is successful in reconstructing the partial sound field and the errors over the central sections are smaller than that over the peripheral sections. Experiments demonstrate that Tikhonov regularization in conjunction with Engl's criterion is suitable for the reconstruction of the practical sound field.

Uncertainty of array-based measurement of radiated and absorbed sound intensity

“…NAH [7] requires that the sound pressure tends to zero at the extremes of the measurement surface, in order to limit the truncation errors [8]. An accurate reconstruction of the sound field can be obtained with a large holographic plane that requires a large microphone array or multiple positioning of a small array in order to cover a large area with different measurements.…”