Speaker
Description
When available, the spherical wave decomposition (SWD) of a sound source can be used to reconstruct the acoustic field radiated by this source. SWD coefficients are usually determined by fitting distributed pressure measurements taken around the source using a regularized least-squares inversion. The performance of this method critically depends on the adequate tuning of the SWD truncation order, and of the regularization parameter. The smoothness of the radiated field causes high order SWD coefficients to decay. Based on these considerations, early studies on sound radiation proposed truncating the SWD at order kd (the kd rule), where k is the acoustic wavelength and d is the extent of the source. However, in the case of complex radiation phenomena, defining the extent of the source is difficult. Furthermore, at higher frequency, the kd rule yields excessively high truncation orders.In this study, we propose a cross-validation-based framework in order to optimally define the SWD estimation parameters. Numerical simulations show that the regularization parameter can be sought for prior to the SWD truncation order, saving computational time. The optimal truncation orders obtained using both simulated and experimental data show good agreement with the kd rule at lower frequency, and comply with the order limitation of the array used for the measurements at higher frequency.