Acoustic radiosity simulation with custom bidirectional reflectance distribution implementation in three dimensions

Geometrical acoustics methods provide efficient techniques to estimate sound propagation properties in virtual spaces. Advances based on acoustic radiance transfer principles facilitate the simulation of environments with complex scattering distributions via the implementation of bidirectional reflectance distribution functions (BRDF). Though significant work has been developed in the optimization of such methods, the effects of complex BRDF implementation have seldom been studied. In this article, two scattering distribution modeling approaches are compared, based on random incidence and bidirectional scattering coefficients, respectively. Their implementation in an acoustic radiosity (AR) simulation tool is discussed. The simulation of a single façade shows that random-incidence modeling in the radiosity tool aligns with state-of-the-art ray-tracing (RT) simulation. Bidirectional scattering approach results of retro-reflective surface simulations are closest to a reference wave-based simulation output, meaning they capture more of the spatial details of the scattering distribution. The simulation of a street canyon scene further highlights how the choice of scattering modeling leads to significant differences in the energy time curve. The results evidence minor artifacts due to the AR and RT implementations. Major computational performance metrics are also assessed.