Is it worth applying sound particle scattering methods to sound propagation in factory halls?—Results and comparisons of some simulations

Abstract

Sound particle simulation, a version of ray tracing, is meanwhile a well-established method in room acoustics. In usual closed rooms, sound propagation is dominated by multiple reflections. In factory halls, the problem arises that a lot of inner sound scattering obstacles (machines, etc.) may practically not be registered in detail. A principal deficiency of ray tracing is the impossibility of taking diffraction into account. Often only a mean level decay per distance is of interest. Therefore, it is a well-founded and -tested semi-analytical approach of using only a mean scattering surface area per volume q=S/(4V) and combining that with a simple mirror image source method for rectangular rooms (German guideline VDI 3760). With the sound particle method, this multiple scattering is directly simulated in a Monte Carlo manner. This has several advantages: rooms of arbitrary form, diffuse reflecting surfaces, and inhomogeneous distributions of scattering bodies may be simulated. Meanwhile, on modern PCs, computation times lie in the range of only a few minutes. A disadvantage is the much higher effort of defining the (often uncertain!) input data. Some recent results of simulations of typical setups in factory halls (not computable by common methods) are presented and compared.