The beam tracing method of Funkhouser has been implemented to calculate the reverberation paths in planar faceted environments, such as rooms. For a given sound source, the reflection paths are calculated for each ear, utilizing also generic head related transfer functions for an ear. To make the method real-time, the reflection paths up to order N are precalculated for every pair of source/receiver positions. Real-time display of reverberation as a user walks around a virtual environment is then possible through table lookup.

Since increasing the order N of reverberations is computationally expensive, we tested the effect of order of reverberation on the perception of room size. Using a reference room of 5-by-5 meters, we asked users to compare the quality of sound versus 6-by-6, 10-by-15, and 15-by-15 meter rooms for 0, 1, 2, 4, and 8 orders of reverberation. It was found that 8 orders of reverberation were generally adequate to distinguish the larger rooms from the reference room. For the 5-by-5 versus 15-by-15 comparison, even one order of reverberation was sufficient to make the discrimination. However, the 5-by-5 and 6-by-6 rooms were difficult to discriminate.

Publications

1. Newton, B., Acoustic Perception of Room Size Using Beam Traced Reflection Paths, M.S. Thesis, School of Computing, University of Utah, 2005.