Analysis technique for classifying wind‐ and ship‐generated noise characteristics

An analysis technique is described that permits the classification of ambient noise sources (wind generated and shipping) without the need for information concerning the environment or shipping in the area of interest. Wind‐generated and ship‐generated ambient noise, or a combination of the two, can be classified by finding the zero‐axis crossing time of the autocorrelation function versus frequency of the long‐term (greater than two weeks) ambient noise time series for a given geographic area. Results obtained from the zero‐axis crossing times of the autocorrelation function of ambient noise level versus time (measured by omnidirectional hydrophones and processed through 1/3‐octave filters) are bounded by two distinct zero‐axis crossing times. Analysis of data from four widely separated geographic areas produces the same bounds, which suggests that they may be independent of area. In the region of the spectra where 1/3‐octave bands were highly correlated with wind speed, the decorrelation time (i.e., zer...