Edge Diffraction and Surface Scattering in Concert Halls: Physical and Perceptual Aspects
Rendell R. Torres, Nicolas de Rycker and Mendel Kleiner
In auralization of room sound fields, most conventional approaches base their computations on geometrical-acoustics assumptions, which fail at lower frequencies (or for scattering from small facets) due to the neglect of edge diffraction and to coarse approximations of surface scattering, e.g., approximations based on Lambert-scattering models. This paper investigates the physical and subjective effects of three main approaches to modeling surface scattering for inclusion in transient room impulse responses for auralization, as the impulse response is the temporal characteristic of the roomfs acoustical quality. These scattering models include the following: Lambert surface scattering from rough surfaces, edge-diffraction, and boss surface-scattering. In particular, a parametric approach to modeling edge-diffraction is developed and compared with the high-accuracy model; the parametric approach uses four output parameters to collectively model the physical behavior of edge diffraction and retains the phase effects that reproduce the basic first-order scattering behavior from finite facets.
Key words: auralization, scattering, diffraction, edge diffraction, perceptual modeling, physical modeling