An Experimental Study of Sound Transmission from Air Into Bubbly Water,

摘要

Sound transmission from air into water in the long wavelength limit is enhanced by the presence of large concentrations of small bubbles. Simple acoustic theory shows that considerable enhancement can take place because the bubbles lower the acoustic impedance of the water and thus decrease the impedance mismatch between air and water. However, impedance matching cannot totally account for the very large increases in acoustic pressure that have been observed in laboratory experiments in a simple hydroacoustic tank (not acoustically damped). In these experiments, sound pressures measured near the apex of a conical shaped bubbly region (apex at its bottom) have been found to be as much as two orders of magnitude greater, at certain frequencies, than pressures measured at the same place in the tank in the absence of bubbles.