New Method for Determining Acoustic Properties of the Seabed from the Ambient Noise Field in the Ocean

摘要

It is shown that by measuring the noise power distribution in the vertical, the critical grazing angle of the ocean bottom (alpha C) can be determined and hence the compressional sound speed in the bottom sediment deduced. The ambient noise vertical directionality was measured at six sites using specially designed vertical line-array sonobuoys. The critical grazing angle and the sound speed in the bottom were estimated from the noise data for all six areas. Similar data from independent seismic surveys are available for one of the sites. For this area the independent estimate of alpha C (28 deg) compares closely with the result obtained from the noise technique (26.2 deg).