Effect of monomolecular films on the underlying ocean ambient‐noise field

A series of at‐sea tests has unequivocally established that the presence of a monomolecular film on the sea surface results in a pronounced reduction of ambient noise beneath the film. This reduction was observed to begin around 2 kHz, continue to at least 20 kHz, and was evident to some degree throughout sea states 1 1/2 to 6. A predictive model is developed that is generally consistent with the film’s observed behavior, and several possible mechanisms are speculated through which the film could affect the underlying ambient‐noise field.