We present a novel approach for wave-based sound propagation suitable for large, open spaces spanning hundreds of meters, with a small memory footprint. The scene is decomposed into disjoint rigid objects. The free-field acoustic behavior of each object is captured by a compact per-object transfer function relating the amplitudes of a set of incoming equivalent sources to outgoing equivalent sources. Pairwise acoustic interactions between objects are computed analytically to yield compact inter-object transfer functions. The global sound field accounting for all orders of interaction is computed using these transfer functions. The runtime system uses fast summation over the outgoing equivalent source amplitudes for all objects to auralize the sound field for a moving listener in real time. We demonstrate realistic acoustic effects such as diffraction, low-passed sound behind obstructions, focusing, scattering, high-order reflections, and echoes on a variety of scenes.

Abstract-We present an interactive algorithm to compute sound propagation paths for transmission, specular reflection and edge diffraction in complex scenes. Our formulation uses an adaptive frustum representation that is automatically sub-divided to accurately compute intersections with the scene primitives. We describe a simple and fast algorithm to approximate the visible surface for each frustum and generate new frusta based on specular reflection and edge diffraction. Our approach is applicable to all triangulated models and we demonstrate its performance on architectural and outdoor models with tens or hundreds of thousands of triangles and moving objects. In practice, our algorithm can perform geometric sound propagation in complex scenes at 4-20 frames per second on a multi-core PC.

We present a new approach for simulating real-time sound propagation in complex, virtual scenes with dynamic sources and objects. Our approach combines the efficiency of interactive ray tracing with the accuracy of tracing a volumetric representation. We use a four-sided convex frustum and perform clipping and intersection tests using ray packet tracing. A simple and efficient formulation is used to compute secondary frusta and perform hierarchical traversal. We demonstrate the performance of our algorithm in an interactive system for complex environments and architectural models with tens or hundreds of thousands of triangles. Our algorithm can perform real-time simulation and rendering on a high-end PC.

We present a novel method for tuning geometric acoustic simulations based on ray tracing. Our formulation computes sound propagation paths from source to receiver and exploits the independence of visibility tests and validation tests to dynamically guide the simulation to high accuracy and performance. Our method makes no assumptions of scene layout and can account for moving sources, receivers, and geometry. We combine our guidance algorithm with a fast GPU sound propagation system for interactive simulation. Our implementation efficiently computes early specular paths and first order diffraction with a multiview tracing algorithm. We couple our propagation simulation with an audio output system supporting a high order interpolation scheme that accounts for attenuation, cross fading, and delay. The resulting system can render acoustic spaces composed of thousands of triangles interactively.

We present an efficient technique to compute the potentially visible set (PVS) of triangles in a complex 3D scene from a viewpoint. The algorithm computes a conservative PVS at object space accuracy. Our approach traces a high number of small, volumetric frusta and computes blockers for each frustum using simple intersection tests. In practice, the algorithm can compute the PVS of CAD and scanned models composed of millions of triangles at interactive rates on a multi-core PC. We also use the visibility algorithm to accurately compute the reflection paths from a point sound source. The resulting sound propagation algorithm is 10− 20X faster than prior accurate geometric acoustic methods.