Breaking wave noise measurements at frequencies below 400 Hz

A sea surface noise experiment was conducted in shallow water (200 m) near San Clemente Island in March/April 1995 using a vertical array deployed from the RP/FLIP. Measurements of the time-frequency structure of the noise generated from individual breaking waves were obtained using the endfire beam of a vertical array along with optical measurements of the locations, sizes, and lifetimes of those breaking waves. Strong acoustic bursts in time coincidence with the larger breaking wave events were observed. There is no apparent correlation between the smaller breaking wave occurrences and low-level acoustic noise at the sea surface in this frequency band. These acoustic measurements were the first at-sea measurements capable of spatially resolving the individual breaking wave contributions at frequencies below 400 Hz where collective bubble oscillations are believed to be the dominate sound generation mechanism.