Control of radiated noise from a ship's cabin floor using a floating floor

In order to develop the noise control design for a ship's cabin, a series of acoustic tests were carried out in a large scale noise test facilities with two reverberation rooms and deckhouse mock-up. From the tests, it was found that the combined noise level of a cabin was dominated by the radiated noise from the floor structure, which is a combination of a stiffened steel deck and deck covering. In this paper, the dynamic characteristics of floor structure are firstly identified through the structure-borne noise transmission test in the deckhouse mock-up. Based on the result, multi-layer floating floor systems were applied on the steel deck to reduce the radiated noise from the floor structure. Before the application, numerical simulations using assumed modes and structure-borne noise transmission tests are carried out for the floating floor itself to extract the optimum structure. Finally, the considered floating floor systems were applied in the cabin of deckhouse mock-up and the cabin noise reductions are compared. Through a series of numerical simulations and structure-borne noise transmission tests, it is found that the cabin noise reduction of a multi-layer floating floor can be greatly improved over the entire frequency range if the visco-elastic deck covering is installed between the steel deck and the mineral wool of floating floor. (C) 2009 Institute of Noise Control Engineering.