Real-Time Simulation of Sound Source Occlusion

Sound source occlusion occurs when the direct path from a sound source to a listener is blocked by an intervening object. Currently, a variety of methods exist for modeling sound source occlusion. These include finite element and boundary element methods, as well as methods based on time-domain models of edge diffraction. At present, the high computational requirements of these methods precludes their use in real-time environments. In the case of real-time geometric room acoustic methods (e.g. the image method, ray tracing), the model of sound propagation employed makes it difficult to incorporate wave-related effects such as occlusion. As a result, these methods generally do not incorporate sound source occlusion. The lack of a suitable sound source occlusion method means that developers of real-time virtual environments (such as computer games) have generally either ignored this phenomenon or used rudimentary and perceptually implausible approximations. A potential solution to this problem is the use of shadow algorithms from computer graphics. These algorithms can provide a way to efficiently simulate sound source occlusion in real-time and in a physically plausible manner. Two simulation prototypes are presented, one for fixed-position sound sources and another for moving sound sources.