半自由声场的全息重建和预测技术研究

在半自由声场中,实际测量声压为直达声压和反射声压的叠加,而声压为标量,很难直接将其中直达声压成分分离出来,因而不能简单地用常规的方法来直接进行声源重建和声场预测。在充分地考虑到反射声压的情况下,建立了半自由声场环境下反射面为刚性和非刚性时的声场全息重建和预测理论模型,并通过实例验证了此模型的可行性和正确性。结果表明:此方法有效地解决了半自由声场中进行声场全息重建和预测时所存在的声压反射问题,从而扩充了声全息重建和预测技术的应用范围;采用分布源边界点法作为全息变换算法,提高了声全息重建和预测的速度、精度和稳定性。

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.