Christopher M. Hobbs Ali R. Kolaini
Natl. Ctr. for Phys. Acoust., Univ. of Mississippi, University, MS 38677
Results of a laboratory experiment to characterize the sound propagation through a bubble screen are described. A bubble screen of various void fractions was positioned in the middle of an anechoic water tank. The cloud was driven using a broadband source and the acoustic pressure was measured on both sides of the layer. The results have revealed that there is significant attenuation near the resonance frequency of the bubbles contained within the screen. When the source frequency is near that of one of the ``collective-oscillation'' frequencies of the screen, sound pressure amplification may occur. In this paper the new findings corresponding to the collective mode amplification, high-frequency attenuation, as a function of the screen's physical properties are discussed. [Work supported by ONR.]