Computation of edge diffraction for more accurate room acoustics auralization.

Abstract

Inaccuracies in computation and auralization of room impulse responses are related in part to inadequate modeling of edge diffraction, i.e., the scattering from edges of finite surfaces. A validated time-domain model (based on analytical extensions to the Biot-Tolstoy-Medwin technique) is thus employed here to compute early room impulse responses with edge diffraction. Furthermore, the computations are extended to include combinations of specular and diffracted paths in the example problem of a stage-house. These combinations constitute a significant component of the total nonspecular scattering and also help to identify edge diffraction in measured impulse responses. The computed impulse responses are then convolved with anechoic signals with a variety of time-frequency characteristics. Initial listening tests with varying orders and combinations of diffraction suggest that (1) depending on the input signal, the diffraction contributions can be clearly audible even in nonshadow zones for this conservative open geometry and (2) second-order diffraction to nonshadowed receivers can often be neglected. Finally, a practical implementation for binaural simulation is proposed, based on the singular behavior of edge diffraction along the least-time path for a given source-edge-receiver orientation. This study thus provides a first major step toward computing edge diffraction for more accurate room acoustics auralization.