Validation of computer models for predicting noise levels in factory buildings

Two computer programs written in Fortran for predicting sound propagation (SP) in factories are investigated. These are based on a simple image method and on a ray-tracing technique proposed by Ondet-Barbry [12]. For both programs, predicted results are compared with measured results in four full-size enclosures some being nominally empty and others fitted with machinery. Theoretical developments of the two prediction methods and the relevant theories of SP in enclosures are reviewed.

The correlation between the predicted and measured results is discussed. Good agreement between the ray-tracing predictions with actual measurements was noted, as found by Ondet-Barbry [12] and Hodgson [15] when they made similar comparisons. However, the ray-tracing method involves fairly long times in preparation. By contrast, the simple image method involves short times but gives less accurate results.