Outdoor Sound Propagation Based on Adaptive FDTD-PE

In outdoor scenes, the inhomogeneity of the atmosphere and the ground effect have a great impact on sound propagation, but these two effects are usually ignored in previous methods. We propose an adaptive FDTD-PE method to simulate sound propagation in 3D scenes taking into account atmospheric inhomogeneity and the ground effect to produce more realistic sound propagation results. In the simulation, the ground is considered as a porous medium with a certain thickness. The scene is categorized into a number of two-dimensional vertical ground planes in the three-dimensional cylindrical coordinate system. These planes are decomposed into the near-source complex regions and the far-source regions, which are solved by the FDTD solver and the parabolic equation (PE) solver, respectively. Furthermore, a novel encoding method was designed to process sound pressure data. In the far-source regions, the one-way sound propagation is only affected by the ground and atmosphere inhomogeneity, so we encode sound pressure data through function fitting. Finally, an efficient sound rendering method with this encoding representation is developed to perform auralization in the frequency-domain. We validated our method in various outdoor scenes, and the results indicate that our method can realistically simulate outdoor sound propagation, with quite higher speed and lower storage.