Noise reduction and sound radiation efficiency of the rectangular enclosure-Structure-borne sound-

Abstract

Statistical energy analysis is used to predict the noise reduction and the sound radiation efficiency of the rectangular enclosure, when the enclosure are excited by the shaker. Under conditions that the various loss fact0r (especially coupling loss factor) for the enclosure are known, and the enclosure and its wall are excited with the multimodal reverberant vibration, the above equations for the noise reduction and the radiation efficiency can be obtained theoretically. It is shown that by our assumption of the reciving room being the free space or the anechoic room, the external sound pressure near the panel can be obtained from the sum of the resonant sound radiation power and the non-resonant sound transmission power of the panel. The ratio of the non-resonant sound transmission power from the test panel to the sound radiation power from the same area of the infinite rigid panel(such as the piston)having the same velocity with the test panel is obtained. Thus the sum of the second radiation efficiency and the above ratio, that is, the apparent sound radiation efficy is introduced. For the noise reduction and the apparent radiation efficiency including the non-resonant transmission power, experimental results are compared with theoretical predictions with generally good agreement.