Statistical properties of underwater acoustic ambient noise fields

This paper presents new results characterizing the statistical properties of under-water acoustic ambient noise fields. The acoustic output of a single hydrophone in the 75-200 Hz. band is analyzed to obtain quantitative measures of the noise power fluctuations as a function of frequency and time. This analysis demonstrates the nonstationarity of the noise power in .78 Hz bands. In addition, the correlation between the noise power fluctuations in .78 Hz. bands is shown as a function of time and frequency separation of the bands. The fluctuations appear to consist of a slow broad-band power increase and a smaller amplitude fluctuation process which has small correlation across frequency and time.