The invention is a method and system for screening materials with a tube-shaped screen. The tube that has at least one section with a plurality of screen openings, which are placed in the wall of the tube, and that form a screen frame which defines at least the length and the cross section of the tube, and a screen mesh, that is tensioned on the screen frame, to form at least a part of the wall of the tube-shaped screen. The system further includes at least one ultrasonic converter and at least one feed-line sound conductor placed between the ultrasonic converter and the tube, with the tube being configured, to be subjected to ultrasonic excitation so that the amplitude of the ultrasonic excitation transferred to the tube has a component in a direction perpendicular to, and a component in a direction parallel to, the central axis of the screen.