The inclusion of diffraction effects in room acoustical modeling.

Abstract

This paper will give a brief overview of some alternatives for including diffraction effects in computational room acoustics. Geometrical acoustics is the basis for most computer modeling methods in room acoustics, and both deterministic and stochastic approaches are used. The image source method and the beam tracing method dominate for the former, and ray tracing for the latter. Deterministic methods are used for sequences of specular reflections, and diffraction effects are straightforward to include in such methods. Paths that involve at least one diffuse reflection are usually handled by ray tracing and recent work has suggested how to implement diffraction in ray tracing. The inclusion of diffraction effects might offer more accurate modeling, most notably for free‐hanging reflectors, orchestra pits, balcony edges, etc. The boundary condition issue will be discussed since diffraction solutions that are useful in room acoustics exist only for ideally rigid surfaces. Underlying approximations in some formulations will be mentioned, and computational aspects will be described, including the huge number of diffraction paths that are generated in a room, with a corresponding huge range of amplitudes. Special attention will be given to singularity issues and an attempt at an outlook for the near future will be offered.