Here the object is to estimate the effect of scattering by randomly rough seabed and surface waves on attenuation of low‐frequency sound waves in shallow water. The experiment was pursued with CW signals (100 and 230 Hz) in Barents Sea. The transmission loss and interference pattern of a sound field were measured within 100 km of the acoustic sources. Mesoscale relief of the bottom with spatial resolution 10 m and wind parameters were recorded as well. The experimental results (the average sound intensity) were compared with theoretical ones calculated with and without taking into account seabed and surface roughness. The calculation was carried out on the base of modal theory of sound scattering by rough boundaries in a waveguide. It was demonstrated that the random roughness substantially affects the transmission loss for long distances. In this paper the method is suggested for bottom parameter estimation using the statistical attributes of sound field in shallow water with random rough boundaries as well. [The work was supported by Russian Foundation of Basic Research (Grant 96‐02‐17194).]