PENETRATION OF SONIC BOOM ENERGY INTO THE OCEAN: AN EXPERIMENTAL SIMULATION
HYDROSPACE RESEARCH CORP ROCKVILLE MD
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Penetration of sound into a body of water from a simulated airborne sonic boom was measured in an acoustically scaled experiment. Dynamite caps were used to produce spherically spreading N-waves which impinged upon the water. Microphones at the water surface and hydrophones at various shallow depths were used to measure the exponentially attenuating penetration of the airborne pressure field into the water, under total reflection conditions. Agreement between the scaled experimental measurements and predictions based on existing theory was generally good. Application of the theory to the case of actual sonic booms impinging upon the ocean, and comparisons with measurements of typical deep-ocean ambient noise, indicate that underwater sonic boom noise will be discernible only at very low frequencies and at shallow depths. Pressure fluctuation spectrum levels due to surface waves will be higher than levels due to sonic booms.