A New Model for Room Acoustic Prediction and Auralization

The development of two room acoustic prediction models and auralization methods are described. The first prediction model is a combination of two well known algorithms with some extensions; the image source model and ray-tracing. The second model consists of an entirely new algorithm based on a unified treatment of diffuse and specular reflection, and addresses many of the drawbacks of previously reported models. The new model applies approximate cone-tracing where diffuse reflection is handled by split-up of cones striking diffusing surfaces. The algorithm utilizes properties of diffuse reflection to avoid the very long calculation times associated with a "brute force" implementation of cone split-up. To further decrease the computational power required, reflection growth extrapolation is applied to enable to the use of a low number of secondary cones. The algorithm adapts dynamically to the acoustical properties of a given environment and assigns most processing power to where it is needed, i.e. to the early part of the echogram and to strong reflections.<p /> The properties of the new algorithm makes it especially well suited to create audible simulations - auralization - since it creates millions of weak diffuse reflections and thereby a smooth reverberation. To facilitate binaural post-processing of the high number of reflections generated, reflection decimation, based on the limitations of human hearing is applied