Reconstruction and prediction of semi-free field in the distributed source boundary point method based nearfield acoustic holography

In the semi-free field, the actual field pressure is composed of two parts:the direct pressure and the reflected pressure. Pressure is a scalar quantity, so it is difficult to distill the direct pressure from the field pressure. Consequently, the general formulas cannot be used to reconstruct sound source and predict acoustic field directly. To take the reflected part of the field pressure into consideration, a new holographic reconstruction and prediction model of semi-free field based on the distributed source boundary point method (DSBPM) are established. Subsequently, an example is investigated to demonstrate its feasibility and correctness. The results show that, the problem on how to deal with the reflected pressures existed on the hologram surface can be solved effectively and the application scope of acoustic holography technique is extended. Since the DSBPM is used to realize the nearfield acoustic holography, the calculation speed, the calculation precision, and the calculation stability of the reconstruction and prediction are improved.