Influence of sound source directivity on finite element simulation of small-room acoustics

Abstract

Numerical simulation is a flexible and effective method for room acoustic design. Full-range simulation of room acoustics requires a combination of different numerical methods, in which wave acoustic methods (WAM) and geometric acoustic methods (GAM) are used for the low and high frequency region, respectively. In the general low-frequency WAM simulation, a sound source is often assumed to be a point source or loudspeakers are usually approximated by circular planar pistons. However, compared to a large room, the critical frequency between WAM and GAM should be higher in acoustic simulation of small rooms because of relative size between the wavelength and the room, and thus, the above simplifications of actual sound sources, typically loudspeakers, may lead to errors in terms of directivity in the frequency range that the WAM is applied for. Further errors in the desired room impulse responses or other room acoustic parameters caused by directivity errors needs quantitative analysis, and then evaluation can be made on whether it is necessary to consider a more accurate sound source directivity in the WAM simulation of small room acoustics.