Sound Transmission Loss of a Ship Structural Panel

Abstract

This report is concerned with sound transmission through a panel constructing ship structure. There are two courses of sound transmission of panel. The one is out of plane vibration of panel, the other is in plane vibration. We show that the principal element of the transmission is caused by out of plane vibration. We formulate a coupled vibration of panel-sound medium interaction by using both boundary conditions, making use of the B.E.M. for panel and sound medium. As a numerical example, we calculate the sound transmission loss through a circular panel in an infinite rigid baffle. We discuss the relation between transmission loss and panel stiffiness and material. We clarify that the tendency of transmission depends on the frequency of the incident sound. For a low frequency vibration, the dominant element of transmission is by panel flexural vibration mode, so that the transmission loss increases with flexural rigidity of panel. For a high frequency range, property of transmission can be explained by the mass law.