Perceptually plausible room acoustics simulation including diffuse reflections

Abstract

Immersive and convincing acoustics in virtual reality applications require computationally efficient methods. The fast and perceptually plausible room acoustics simulator [RAZR, see Wendt et al., JAES, 62, 11 (2014)] approaches this demand by drastic simplifications with respect to physical accuracy while still accomplishing perceptual plausibility. RAZR is based on a hybrid approach where early reflections are calculated as image sources for a shoebox-room approximation up to a low order, and the later reverberation is generated by a binaurally extended feedback-delay-network (FDN). Although it was demonstrated that a good perceptual agreement with real non-shoebox rooms is achieved, the shoebox-room simplification might cause limitations for rooms which strongly diverge from this assumption. Here the perception of temporal smearing of early diffuse reflections, effectively simulating effects of scattering and multiple reflections caused by geometric disturbances at walls and by objects in the room, was systematically assessed. A single parameter was introduced to quantify deviations from an empty shoebox room. It was demonstrated that perceptually plausible results can be obtained for auralized natural stimuli and for the binaural impulse responses themselves. It is shown how parameters in RAZR are derived from room geometry and surface materials or from measured BRIRs or frequency-dependent reverberation times.