Ambient Sea Noise in the Deep and Shallow Ocean

Abstract
Ambient sea noise was measured simultaneously with 2 identical hydrophones in the frequency range 22-715 Hz. One was located on a shallow bank in about 30 f (fathoms) of water, the other at a depth of about 900 f, both near the ocean bottom. Windspeed measurements were taken simultaneously. Autocorrelations of the ambient-noise levels and windspeed, as well as cross correlations between hydrophones and between the individual hydrophone levels and windspeed, are presented. At low frequency, the shallow hydrophone ambient noise shows greater correlation with windspeed than the deep one. At higher frequencies, the correlation with windspeed is similar for both receivers. The sea noise at the deep hydrophone was found to be greater than at the shallow one. This difference is a maximum at about 50 Hz, decreasing at both lower and higher frequency.