Adaptive pyramid tracing: a new technique for room acoustics

A numerical code for the prediction of 3D sound propagation is presented. I t is mainly suited for indoor environments, and uses a variation of the Pyr amid Tracing Method, which we called Adaptive Pyramid Tracing. Energy carri ers are three-sided pyramidal beams, which are adaptively split at each ref lection according to impinged geometry. To avoid an exponential growth of t he number of pyramids with the number of reflections, beams that have local ly lower energy are absorbed by adjacent ones, in order to reduce their num ber without affecting the overall energy balance. Sound sources can be disc retized with a user-defined number of pyramids and may have an arbitrary di rectivity pattern. Compared to a classical pyramid tracing the algorithm av oids receiver detection errors, energy losses, and consequently it does not require an (additive or multiplicative) correction factor to adjust the re sults. The code has been validated with numerical tests in order to verify both stability and agreement with current analytical methods, and finally w ith data measured in a real environment. (C) 2000 Elsevier Science Ltd. All rights reserved.