Comparison of isotropy estimators for the analysis of reverberation rooms

Reverberation-room measurements of absorption coefficients are subject to high uncertainties and irreproducibility across different laboratories. One reason is the lack of a sufficiently isotropic sound field both in steady-state and during the sound field decay. Recently, two different methods - based on the decomposition of the sound field into plane waves - have been proposed for the estimation and analysis of the sound field isotropy in reverberation rooms [1]–[5]. This study compares the two methods based on numerically calculated plane wave sound fields as well as experimental results obtained from array measurements in a reverberation room in different configurations. The room configurations comprise the room occupied with an absorber sample, with and without hanging panel diffusers, and additionally the empty room without diffusers. Both methods are compared regarding their suitability in the analysis of reverberation rooms and the required angular resolution for the plane wave decomposition.