Use of Mean Squared Pressure along a Reverberant Room Diagonal for Sound Power Measurement

Abstract

The mean of the squared pressure along part of a room diagonal is frequently used to determine the sound power using the reverberant room technique. The spatial pressure along a room diagonal has been evaluated experimentally and theoretically for a source located in the corner of a 300-m3 and a 150-m3 reverberant room. For frequencies between 100 and 2000 Hz, the average number of maxima in the mean squared pressure 〈p2〉 is given by N=4L/πλ, where L is the length along the diagonal and is independent of absorption, room size, and stationary diffusers. The variation of 〈p2〉 at a maxima is given by 〈p2〉=An cos(πkx/4), where the An possesses a gamma probability distribution that depends on absorption. It is shown that the value of the mean of 〈p2〉 for white noise with a 6-Hz bandwidth depends on the traverse length selected and is independent of damping while the standard deviation is improved by adding damping. Experimental results substantiate this conclusion.