A method for extracting an average scattering coefficient for room acoustic modeling

Abstract

This work introduces frequency-dependent Average Scattering Coefficients (ASCs) to quantify the room-averaged degree of scattering per mean free path that results from sound wave interactions with objects, elements, and impedance discontinuities. In this work, the sound field of a room is decomposed into two components: (1) specular reflections from boundary surfaces and (2) non-specular component by the room's interiors and elements. Time-dependent coherence coefficients extracted from impulse responses of furnished rooms and their empty averages are used to derive ASCs, which can be used to facilitate the transition from a specular to a non-specular component in room acoustical modeling. This study extracts ASCs in rooms with varying amounts, distributions, and absorptions of interior elements, and different source and receiver positions based on a wave-based solver. Moreover, ASCs are measured in a real furnished room and utilized to reconstruct the measured sound field with a hybrid model. The specular component is calculated from the empty room case, while the non-specular component is modeled with a stochastic technique. Results from the hybrid models show strong agreement with ground truth regarding early decay time, reverberation time, the degree of scattering, and the level of diffuseness, demonstrating the potential of ASCs for high-frequency room acoustic modeling with reduced computational resources.