An adaptive beam tracing method for room acoustics prediction

Abstract

A new adaptive beam-tracing algorithm was developed and implemented into a computer model to predict the propagation of sound in enclosed spaces. Unlike previous beam-tracing methods, the model predicts a near perfect geometrical representation of a propagating sound field by adaptively tailoring it to the shape of the reflecting surfaces. Using this adaptive approach, problems such as gaps and overlaps between beams, and the ambiguity of reflection direction when a beam hits more than one surface can be eliminated. In addition, the beam tracing can start with only a small number of beams. Child beams are generated automatically upon each reflection to adapt to the complexity of the room. This method runs faster than traditional beam and ray-tracing methods in the early part and faster than the image method in the later part of the reverberation process. Diffuse reflections are handled by a radiant exchange process and combined with the specular reflections to calculate the impulse response of a room. This model is applied to several spaces with representative workspace shapes and fittings and the result is compared with traditional prediction methods. The suitability of using diffuse reflections to model the effect of factory fittings is investigated.