Prediction of the Random-Incidence Scattering Coefficient Using a FDTD Scheme

This paper is focused on the evaluation of the scattering coefficient of sound diffusers which are based on the incoherency of diffusely reflected sound. A new approach for predicting the scattering coefficient is proposed; the method is based on a finite difference time domain (FDTD) scheme. Two established scattering coefficient measurement methods, proposed by Mommertz and Vorlander [1], are simulated; these correspond to measurements in a reverberant chamber, and free field. The results are also compared to those obtained in a previous paper [2], wherein it was demonstrated that FDTD schemes can be used to predict polar responses. These free field polar responses are used to find the correlation scattering coefficient, which in turn is used to validate the free field case. In modelling the reverberant chamber method, 2D simulations have been used to reduce computation time; hence it is necessary to derive a diffuse field formulation for a 2D reverberation chamber, which is presented. In this case, 1: 5 scale experimental data is used for validation.