(An) efficient image model algorithm for the prediction of room acoustics

Abstract

In this study, a computer simulation technique is developed for the prediction of the acoustical characteristics of a room. The developed simulation technique is based on the image model technique where the propagation of sound waves in a room is simplified by the propagation of the sound rays. There have been some deficiencies in the existing image model algorithms, such as too long time of computation and the requirement of large size core memory. In order to improve the computational efficiency, a new algorithm is proposed in this study. The required size of core memory is reduced by introducing a coordinate transformation method, and the computation time is reduced by neglecting computations for the infeasible combinations of reflecting walls. Also a method of compensating simulation error is proposed because the simulation of impulse response is limited to the finite time duration. Eyring``s reverberation formula derived from the diffuse field approximation, is used for the correction of the simulation error. With these modifications, a new computer simulation system is developed. The inputs for the developed simulation system are the geometry of room, the locations of sources and receiver, and absorption coefficients of surfaces. The results of simulation are the sound ray paths from sources to receiver, which can be reduced to the impulse response, the reverberant energy decay, and the useful/detrimental energy ratio. The developed simulation technique shows a better computational efficiency than the other existing image model algorithms. The computation time is greatly reduced when the computation is executed up to the higher order reflections. When the computation is performed for the problem of multiple sources, the reduction of computation time is greater. An experimental investigation which compares the measured data with the simulated values, is performed for the verification of the accuracy of simulation. The results show that the developed simula...