Abstracts of some doctoral dissertations in poland

The basic properties of the sea noise in the South Baltic have been discussed: the spectral density, the statistical characteristics, the directivity, and the dependence on the wind. The theoretical model of the anisotropy of the noise field in the South Baltic has been developed. It has been found that the sea noise level in the Baltic is higher than in the ocean at the same wind velocity. In the author's opinion the acoustical properties of the bottom, the traffic of ships and the large amount of gas bubbles are responsible for this increase. In the spectrum of the sea noise (80-10 000 Hz) there are two main components: one, which is independent on the metereological circumstances and the other one, which is dependent on the wind velocity. The distribution of the probability density of the sea noise often differs from the normal distribution (in 30-50 % of cases) and depends on the place of the measurements and the frequency.