Predicting theater chair absorption from reverberation chamber measurements

Abstract

The sound absorption of small samples consisting of up to 18 upholstered theater chairs was measured in a reverberation chamber and these results were related to the effect of larger samples of the same chairs in auditoria. The sound absorption coefficients of the chairs, measured in a reverberation chamber, were found to be linearly related to the ratios of perimeter to area of the samples of chairs. Extrapolating these reverberation chamber measurements to smaller perimeter to area ratios, characteristic of seating blocks in auditoria, produced good agreement with measurements of the same seats in the auditoria. This procedure is proposed as a more accurate approach to predicting the absorbing characteristics of upholstered theater chairs in auditoria. Three other more approximate approaches were also considered including the use of screens to eliminate edge absorption, average sample size corrections, and the use of average absorption coefficients for all types of chairs. The merits of each approach are discussed and data are given for average sample size corrections.