Interactive and aliasing-free acoustic modeling of reflections and diffractions in architectural environments

Abstract

A primary challenge in geometrical acoustic modeling is computation of reverberation paths from sound sources fast enough for real-time auralization. This paper describes an aliasing-free beam tracing algorithm based on precomputed spatial subdivision and beam tree data structures that enables real-time acoustic modeling and auralization for sound sources in interactive applications. The proposed method traces convex polyhedral beams from the location of each sound source and receiver through a precomputed spatial subdivision data structure, constructing a beam tree representing the regions of space reachable by potential sequences of transmissions, diffractions, and specular reflections at surfaces of a 3D polygonal model. By computing beam trees asynchronously (off-line), our system can generate reverberation paths between sources and receivers at interactive rates and spatialize audio signals in real-time as sources and receivers move under interactive user control. Unlike previous geometrical acoustic modeling work, our beam tracing method: (1) supports evaluation of early reverberated paths at interactive rates, (2) scales well for large, densely occluded architectural environments, and (3) computes paths of diffraction without aliasing using the uniform theory of diffraction. This system is being used to develop interactive applications in which a user experiences a virtual environment immersively via simultaneous auralization and visualization.