Directional source modeling in wave-based room acoustics simulation

Wave-based modeling in room acoustics and virtualisation applications constitutes an alternative to geometric or ray-based approaches; finite difference time domain (FDTD) methods, defined over regular grids, are an excellent match to parallel architectures. Acoustic sources are typically included as monopoles or collections of monopoles, realised, in an FDTD setting, as a forcing of a single grid point. This paper is concerned with more general representations of multipole point sources, based on spatially bandlimited approximations to the Dirac delta function in 3D. As such, it becomes possible to incorporate, in a flexible manner, multipole sources without regard to direction or alignment with an underlying grid. Numerical results are presented in the case of the acoustic monopole, dipole and quadrupole.