Narrow-band spectra of sound backscattering were investigated in a series of experiments. Two types of scattering spectra are distinguished. In the first case, side-lobes are observed at a certain distance from the carrier frequency. This effect is caused by Bragg scattering on surface waves. In the second case, a smooth broadening of the spectrum around the carrier frequency is observed. In this case, the reverberation spectrum is interpreted using the phenomenological model of sound scattering at subsurface inhomogeneities. These inhomogeneities are moving along circular tracks under the action of wind waves currents, which velocities are rather smaller than the phase velocities of surface waves.
$^1$Institute of Applied Physics RAS
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