Sound power from sources near reverberation chamber boundaries

Abstract

Lower sound power values have been obtained when using the reverberation room method of source power output than those measured in free field (anechoic room) [1]. This difference could be partly due to source position and orientation within the reverberation chamber. Previous investigations, for point monopole, dipole, quadrupole and a vibrating beam source [2–6], have shown that the radiated sound power when averaged over all possible source positions (including orientations for directional sources) within the reverberation chamber, including positions near the chamber boundaries, is equal to the required free field value. As the sound power is usually measured for only a few source positions above the floor of the reverberation chamber, this can lead to a different value for sound power. This paper is a theoretical and experimental attempt to quantify the effect of source positions near reverberation chamber boundaries on the measured source power. A correction factor is proposed here, which accounts for the effect of the chamber boundaries (floor, walls and ceiling).