Prediction of sound pressure fields by Picard-iterative BEM based on holographic interferometry

Holographic interferometry offers amplitude data with a high spatial resolution which can be used as vibration boundary condition for calculating the corresponding sound pressure field. When investigating objects with arbitrary 3D-shape this requires contour measuring, performing holographic interferometry for three axes of freedom, combining contour and vibration data into a boundary element (BE) model, and then solving the discretized Helmholtz-Kirchhoff integral equation for the surface sound pressure. The latter is done by means of the Picard-iterative boundary element method (PIBEM), which does not need matrix operations at all and such is capable of also treating large BE models arising from small bending wavelengths at high vibration frequencies. An experimental verification of this method by microphone measurements in an anechoic chamber is presented for a cylindrical object