Computer Prediction of Insertion Loss Due to a Single Barrier in a Non-Diffuse Empty Enclosed Space

Abstract

This paper describes the development of an efficient barrier model for the prediction of sound distribution in non-diffuse empty enclosed spaces. Diffraction is modelled using an extended version of the Ondet and Barbry computer model, RAYCUB, which is a proven model used to predict sound distribution in empty and fitted non-diffuse enclosed spaces. As RAYCUB is based on geometric acoustics, it is not possible to directly model diffraction around a barrier.

Diffraction around barriers is known to cause only localised, frequency dependent effects on sound distribution in acoustically complex environments such as factories. It was intended that a barrier model should impose a minimum of additional computation time on the factory noise prediction program. Three methods of approximating barriers were developed, all based upon a simplified implementation of the geometric theory of diffraction.

The barrier models were tested in two configurations of an empty test space. The model REDIR gave more accurate results than the original RAYCUB model, especially at lower frequencies.