Investigation into the relationship between standing audience density and absorption.

Predicting acoustics of occupied performance venues is problematic due to difficulties in the selection of accurate audience absorption coefficients. The absorption due to a small group of people measured in a reverberation chamber cannot be accurately transferred to larger audiences due to differences between area to edge ratio. Analysis of data from an FDTD acoustic model of a reverberation chamber with an audience modelled as columns distributed at different densities with various perimeter to area ratios, allows derived absorption coefficients to be transferable to larger audience sizes. For densely-packed audiences, diffraction results in low frequencies having linear correlation between audience size and total absorption. There is less increase in total absorption per person at higher frequencies. Comparable real-world measurements confirm these findings, allowing the verified absorption coefficients to be applied to an acoustic model of a performance venue to inspect audience effects on absorption for typical configurations.