A MODEL OF THE SOUND GENERATED BY BREAKING WAVES

The sound produced from a single bubble, oscillating at its breathing mode frequency, and the bubble size distribution are used to model the sound produced by breaking waves. The data of Medwin and Daniel [J. Acoust. Soc. Am. 88, 408-412 (1990)] is used to evaluate the performance of the model. The model generates a damped sinusoidal pulse for every bubble formed, as calculated from the bubble size distribution. If the range from the receiver to the breaker is known then the only unknown parameters are epsilon, the initial fractional amplitude of the bubble oscillation, and L, the dipole moment arm. It is found that if the product epsilon x L is independent of the bubble radius the model reproduces the shape and magnitude of their measured sound spectrum accurately. The success of this simple model implies that the inverse problem (calculation of the bubble size distribution from the sound power spectrum) may be solved without the need to explicitly identify individual bubble pulses in the acoustic time series.