Shipboard Noise and Vibration Sources

Noise, whether habitability or underwater radiated, is most often dominated by the acoustic levels associated with propulsion sources. This includes the prime mover(s) and propulsors. Next items of concern are the auxiliary equipment. High vibrations exist at their attachment point to the ship’s structure. Furthermore, this equipment is often well distributed throughout the length and width of the vessel. Vibrations induced by this equipment and traveling through and along the vessel structure are called “structureborne noise.” The other significant path starts as high noise levels in machinery spaces. This noise impinges on the surrounding ship structure, which has a measurable vibration response. This vibration, as it is distributed along over the vessel, is considered “secondary structureborne noise”. The remaining path of concern is airborne transmission from one compartment to the next or from an airborne noise source to an on-deck station. It is critical to understand both these noise and vibration components. This allows one to rank sources of importance by their frequency-weighted acoustic levels.