The sound particle simulation technique - an efficient prediction method for room acoustical parameters of concert halls
This paper mainly presents recent improvements in ray tracing algorithms. The Sound Particle Simulation Method (SPSM) and the Mirror Image Source Method (MISM) are well known room acoustical methods of numerical sound field simulation, especially of concert halls. All important room acoustical parameters can principally be predicted by both methods. It is shown, however, by a thorough analysis of probabilities, that the caluclation time of the MISM is much longer than that of the SPSM, so that the MISM is not able to complete with the SPSM. In contrast to the similar "Ray Tracing Technique", especially as far as detection is concerned, which is based on a particle model, the SPSM is a real Monte Carlo method, i.e. a statistical method. Some recent proposals for the reduction of the calculation time of this efficient algorithm are discussed. To these belong following methods: - to improve the time-consuming "point on wall" test - to distinguish "inner" and "outer" walls - to check "forb idden" wall combinations - grouping walls, i.e. introduce sub-structures of the room.