Computationally-efficient and perceptually-motivated rendering of diffuse reflections in room acoustics simulation

TL;DR

This paper introduces a computationally-efficient, perceptually-motivated method for simulating diffuse reflections in room acoustics, enhancing realism in real-time applications by coupling non-specular reflections with diffuse reverberation models.

Contribution

It proposes a digital-filter approach that efficiently models diffuse reflections and couples them with a diffuse reverberation model using a spatially rendered feedback delay network.

Findings

Perceptually comparable to real room recordings

Efficient enough for real-time applications

Improves realism of room acoustics simulation

Abstract

Geometrical acoustics is well suited for simulating room reverberation in interactive real-time applications. While the image source model (ISM) is exceptionally fast, the restriction to specular reflections impacts its perceptual plausibility. To account for diffuse late reverberation, hybrid approaches have been proposed, e.g., using a feedback delay network (FDN) in combination with the ISM. Here, a computationally-efficient, digital-filter approach is suggested to account for effects of non-specular reflections in the ISM and to couple scattered sound into a diffuse reverberation model using a spatially rendered FDN. Depending on the scattering coefficient of a room boundary, energy of each image source is split into a specular and a scattered part which is added to the diffuse sound field. Temporal effects as observed for an infinite ideal diffuse (Lambertian) reflector are simulated using cascaded all-pass filters. Effects of scattering and multiple (inter-) reflections caused by larger geometric disturbances at walls and by objects in the room are accounted for in a highly simplified manner. Using a single parameter to quantify deviations from an empty shoebox room, each reflection is temporally smeared using cascaded all-pass filters. The proposed method was perceptually evaluated against dummy head recordings of real rooms.