Revision of Sabine's reverberation theory by following a different approach of Eyring's theory

Abstract

The room acoustic theory was established based on Sabine’s reverberation theory. However, in Sabine's theory, the reverberation time does not become zero even if the absolute absorption condition is satisfied. This is considered to be a contradiction of Sabine’s theory, and Eyring revised the reverberation theory to resolve this contradiction. In this study, the theoretical framework for a consistent reverberation theory is first presented. By using this framework, it is shown that Eyring's theory has a contradiction between the sound energy density in the steady state and the energy decay from the steady state, which is absent in Sabine's theory. Based on the proposed theoretical framework, Sabine’s reverberation theory is revised by following a different approach of Eyring's theory. The reverberation time obtained using the revised theory is shorter than that obtained using Sabine's theory and longer than that obtained using Eyring's theory. Finally, computer simulations using the ray-tracing method are performed to verify the revised theory. The average sound pressure levels and reverberation times obtained using the computer simulations are in better agreement with the values calculated using the revised theory compared to those calculated using Sabine's and Eyring's theories.