Angular distribution of incident sound energy for estimating the sound transmission loss of multilayered panels

Abstract

The sound transmission coefficient in the diffuse field depends on the angular distribution of the incident sound energy. Although the field incidence formula has suggested that instead of the random incidence formula, the determination of the limit angle near the grazing incidence is very empirical and various limit angles have been defined by many researchers until now. This angle is especially important when dealing with the sound transmission loss of multilayered panel systems. In order to find the angular energy distribution of the incident sound in the actual test situation, a numerical simulation by using ray tracing is performed for the bounding surfaces of a sphere and a reverberation chamber. The results show that the sound energy distribution of the incidence angle on a bounding surface may be approximated to the Gaussian distribution. Sound transmission losses are predicted by utilizing the concept of the Gaussian distribution of the incidence energy for various single and multilayered panels and they agree very well with experimental results.