An optimization method for reverberation room design

The ISO 354:2003 standard relating to sound absorption measurement in reverberation rooms is currently under revision to improve the reproducibility of the measurement procedure. Round robin tests conducted across various reverberation rooms indeed revealed significant disparities between sound absorption measurements of the same sample. One of the reasons is that, at low frequencies, the sound field in a single laboratory cannot be considered fully diffuse. However, the average sound field across different laboratories may be considered diffuse if the interaction between the finite sample and the diffuse field is duly accounted for. In this work, a method is developed for optimizing reverberation room design such that measured absorption values are as close as possible to ensemble average diffuse values at low-frequency. The reverberation room is modeled using the finite element method and standardized measurements of an absorptive sample are simulated. The distance between resulting absorption coefficients and diffuse target values is minimized in an optimization procedure having the geometrical characteristics of the model as input parameters. The results may contribute to the revision of the ISO 354 by delivering useful insight for the construction of new reverberation rooms and the improvement of existing ones.