【摘要】 由于长空间的特殊空间尺寸,基于传统室内声学理论所假设的扩散声场分布规律和混响规律在长空间不完全适用.基于几何声学的虚源法可以对长空间的声场的传播进行研究.然而,虚源法建模忽略了长空间中声线在边界多次反射产生的干涉效应.在虚源法的基础上,通过对虚源之间的相干求和,考虑了多次反射形成的无限个虚源之间的干涉效应,并且将各不相同的边界阻抗率加入到模型中,实现了一种预测矩形长空间中声场的传播的复虚源模型.实验所用长空间的墙壁分别是密度板和吸声材料,以模拟不同的阻抗边界.实验采用衰减系数逾量描述数值模拟和实际测量的结果.实验证明了所提理论模型的有效性,所提理论模型的预测结果可以较好地模拟出不同边界长空间声场的衰减趋势,反映出不同频率的声波在长空间中的传播趋势,比基于声线法的软件ODEON的结果更接近实验结果.更多还原

【Abstract】 The sound field in long enclosures is not diffuse as assumed by the classical theory of room acoustics,because one dimension of the long enclosures is much greater than the other two. The image source method is the most commonly used approach for predicting the sound field of long enclosures. However,the image source method is unlikely to be satisfactory for using in predicting intricate patterns of interference due to contributions from each image source. A theoretical model has been developed for the prediction of sound propagation in a rectangular long enclosure. The model is based on the image-source method,and the effect of interference among the infinite number of image sources generated by multiple reflections is incorporated by coherently summing the contributions from the image sources. The various impedances of the boundaries are considered in the model. The term excess attenuation (EA) is used for the presentation of numerical and experimental results. Experiments were carried out to validate the proposed theoretical model,where the enclosure walls are lined with different kinds of sound absorption material to simulate different impedance boundaries. It is shown that the developed model agrees better with the experimental data than that of the ODEON software,and the trends in the behavior of sound attenuation along the enclosure at different frequency have been correctly predicted.更多还原