Spatial Ambient Noise Inversion Using a Single Hydrophone

We formulate a new approach to extract environmental information from a single omnidirectional hydrophone receiver that passively senses ambient noise. Recorded samples essentially hold information about the ocean itself as the pressure waveforms at the noise source and receiver are different due to distortions induced by the underwater acoustic channel. Our scenario of interest is warm shallow waters, where the ambient soundscape is dominated by snapping shrimp noise at medium-to-high frequencies. By taking only the direct arrival and surface reflection into account, we show that the hydrophone's depth can be deduced passively by using an autocorrelation function (ACF) derived from the ambient noise process. Moreover, the ACF can be exploited further to derive the snap distribution as a function of range from the hydrophone receiver, which in turn offers key advantages in environmental monitoring of warm shallow waters.