NURBS and Mesh geometry in Room Acoustic Ray-tracing Simulation

Room Acoustic Simulation models have been in use for some time now, they are capable of simulating the impulse response of a room, as well as estimate objective parameters. Various benchmarks have been done to evaluate their accuracy in reproducing the impulse response of existing musical spaces. When it comes to simulating sound reflection of curved surfaces, most simulation models depend on the discretization of these surfaces into smaller planar segments. This simplification can be particularly problematic when it comes to the complex curved forms that are now being used in a wide range of acoustic environments, especially in concert and opera halls. The advent of advanced computational geometry, in particular the use of Non-Uniform Rational Basis Splines or NURBS, give us the possibility to better represent ”free-form” complex and curved geometry. This presents the opportunity to significantly improve raytracing simulation models. This paper conducts a comparison of simulations done with and without the use of NURBS for concert halls with curved reflective ceilings. Various ceiling configurations and simulation parameters are compared in order to understand the potential of this new possibility.