Speaker
Description
Raytracing is an established method for computing the late-time part of room impulse responses, but it has the drawback that only very crude Monte Carlo models of boundary scattering and diffraction are possible to include without it losing its attractive computational cost scaling. This happens because higher-resolution models of these processes output multiple child rays for every parent ray received, making the number of rays grow with reflection order. An emerging solution is so-called ‘Surface-Based’ Geometrical Acoustics. Here the distribution of rays arriving at a boundary is mapped onto a predefined set of spatial elements and angular interpolation functions, producing a vector of coefficients. Re-radiation of subsequent reflections is then a matrix multiplication, with the steady state solution being solvable via a Neumann series. Since rays only ever propagate one reflection order before being collected, diffraction and scattering process that cause them to multiply can be included without issue. In the paper an approach to efficiently represent edge diffraction in such algorithms is presented. In involves discretising the sound energy arriving and departing an edge via angle and representing the diffraction via a matrix multiplication relating these coefficients. Indicative results are shown demonstrating the approach.