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 theblockedsound 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.