Experimental and Theoretical Studies of the Seismo-Acoustic Noise Field at Very Low Frequencies.

Abstract : While the first ambient-noise spectra were published in 19481 it was the growing interest in passive sonar systems in the 1960's that stimulated research into this aspect of underwater acoustics. The first published results relating to low-frequency ambient noise appeared in a paper by Wenz2, describing data in the range 50 Hz to 10 kHz. The noise sources reported included turbulence, wave motion, earthquakes, biological activity and shipping. Other contributions appearing in that period deal with wind and wave-generated noise3-5, underwater volcanism6,7 and relevant to this report a large rise in noise levels at frequencies below 4 Hz 81,9