This video demonstrates the GSound sound propagation library in action. GSound is a ray tracing sound propagation and rendering library that is designed to be lightweight, flexible, and fast enough to be used in games and other real-time systems.
All video was captured and rendered in real time on a 2.16 GHz Core Duo laptop.
For more information, please see:
http://gamma.cs.unc.edu/GSOUND
Follow up work was published in the proceedings of ACM SIGGRAPH 2014:
High-Order Diffraction and Diffuse Reflections for Interactive Sound Propagation in Large Environments
Carl Schissler, Ravish Mehra, Dinesh Manocha.
http://gamma.cs.unc.edu/HIGHDIFF/