A framework for auralization of boundary element method simulations including source and receiver directivity.

The Boundary Element Method (BEM) is a proven numerical prediction tool for computation of room acoustic transfer functions, as are required for auralization of a virtual space. In this paper, it is validated against case studies drawn from the "Ground Truth for Room Acoustical Simulation" database within a framework that includes source and receiver directivity. These aspects are often neglected but are respectively important to include for auralisation applications because source directivity is known to affect how a room is excited and because the human auditory system is sensitive to directional cues. The framework uses weighted-sums of spherical harmonic functions to represent both the source directivity to be simulated and the pressure field predicted in the vicinity of the receiver location, the coefficients of the former being fitted to measured directivity and those of the latter computed directly from the boundary data by evaluating a boundary integral. Three validation cases are presented, one of which includes a binaural receiver. The computed results match measurements closely for the two cases conducted in anechoic conditions but show some significant differences for the third room scenario; here, it is likely that uncertainty in boundary material data limited modelling accuracy.