Combined beam tracing and Biot transfer-matrix model for predicting sound fields in enclosed spaces

Abstract

Numerous methods exist for predicting sound fields in enclosed spaces such as rooms, aircraft cabins, and the sea. These are generally energetic approaches which ignore phase and associated wave effects, and which describe sound reflection from surfaces by the energy absorption coefficient. Many, such as ray tracing, require long calculation times. In the work reported here, a new model is presented which is computationally efficient, includes phase, and decribes surface reflection by the angularly varying surface impedance. It is a triangular-beam-tracing algorithm, combined with a Biot-theory transfer-matrix model for laterally homogeneous, multilayer, poroelastic surfaces. The Biot model has been validated in the case of plates, porous materials, and seabeds. The combined approach is being validated in comparison with predictions by analytic and numerical approaches, and with experiment. The model is being used to study the effect of surface extended reaction on enclosed sound fields.

Accurately Representing the Sound Field in Industrial Halls Using the Ray-Tracing Technique

“…Recently, Dance and Shield 20 have suggested that it is possible to more accurately predict the sound propagation in an empty factory using sound pressure to predict the sound pressure levels in a room rather than to model only the energy in the room. Hodgson et al 21 recently wrote a model which can calculate the precise phase change on reflection from a room surface to help improve the accuracy of prediction. These refinements to various mathematical models may provide predictions with a high degree of consistency and reliability.…”