一种预测扩散声场在非规则形状刚性壁面附近干涉图样的方法

扩散声场会在反射边界附近形成干涉图样,研究方法包括平面波模型、简正模态分析、渐进模态分析等,但仅适用于尺度远大于声波波长的矩形声腔。提出一种预测扩散声场在非规则刚性壁面结构附近形成的干涉图样的数值方法,表明结构附近“受挡”声压的互谱矩阵取决于:(1)假定该结构在自由空间中振动辐射声音时其表面法向振速到表面及场点声压的边界元系数矩阵;(2)假定结构置于自由空间中且表面刚性时,点声源辐射声波入射到结构表面上产生的散射声场的边界元系数矩阵;(3)扩散声场均方声压。仿真表明,该途径预测的干涉图样与理论值完全吻合。该预测方法还可用于混响环境下声源附近直达声压均方值的空间分布估计,为混响环境下设备的声源定位提供帮助。 

One method predicting the interference pattern of a nonregular shaped rigid surface in a diffuse sound field

The existing methods predicting the interference patterns near the reflecting surfaces in a diffuse sound field, such as plane-wave model,eigenmode analysis,and asymptotic mode analysis are only applicable to the rectangular acoustic cavity whose reflecting surfaces are very large compared to an acoustic wavelength.One method predicting the interference patterns near the nonregular-shaped rigid structure in a diffuse sound field is given here,which shows that the cross-spectrum matrix of the“blocked”sound pressure can be written in terms of: (1) the BEM coefficient matrices from the normal velocity on the structural surface to the sound pressure at the structural surface and field points when this structure is as a radiator in the infinite space, (2) the BEM coefficient matrix of the scattering sound field caused by the incidence of sound waves radiated from a series of monopole sources upon the structural surface,supposing this structure is placed in the free field with the rigid surface,and (3) the spatial averaged mean-square value of the sound pressure within the diffuse sound field.The numerical research of a structure of three-wall and right-angle corner in a diffuse sound field is implemented,which shows that the numerical results of the interference pattern are in accord with the theoretical ones completely.This method can also be applied to predict the spatial distribution of mean-square direct sound pressure near a sound source in the reverberant environment,helpful to the sound source identification of the equipment in the reverberant environment.