Simulation of acoustic environments for binaural reproduction using a combination of geometrical acoustics and Boundary Element Method

Auralization of a space requires measured or simulated data covering the full audible frequency spectrum. For numerical simulation, this is extremely challenging, since that bandwidth covers many octaves in which the wavelength changes from being large with respect to features of the space to being comparatively much smaller. Hence, the most efficient way of describing acoustic propagation changes from wave descriptions at low frequencies to geometric ray and sound-beam energy descriptions at high frequencies. These differences are reflected in the disparate classes of algorithms that are applied. Geometric propagation assumptions yield efficient algorithms, but the maximum accuracy they can achieve is limited at low frequencies in particular. Methods that directly model wave effects are more accurate but have a computational cost that scales with problem size and frequency, thereby limiting them to small or low frequency scenarios. Hence, it is often necessary to operate two algorithms in parallel to handle the complete bandwidth. Here, we utilize Boundary Element Method as the low frequency method in such a scheme. Using the SEACEN Round Robin scenarios as case studies, this paper will discuss challenges including: representing source directivity; choosing suitable boundary condition data; encoding BEM results for binaural presentation.