Abstract: Artificial intelligence systems have been more and more used for the purposes of classification and identification. Recently, a lot of attention has been devoted to the exploration of such techniques in combination with the passive acoustic signals of vessels in the sea environment. Although some of the research imply optimistic results it seems necessary to apply the results of investigations regarding the sound propagation in the sea. This paper suggests was of improving the quality of neural classification by narrowing broadband frequency band to some specific narrow bands.