Insertion loss prediction of floating floors used in ship cabins

In this paper, vibration reduction in ship cabins by using floating floor is studied. Two theoretical models are developed and predicted insertion losses of floating floors are compared to experimental results, where measurements are done in the mock-up built for simulating typical ship cabins. The floating floor consists of upper board and mineral wool, which is in turn laid on the deck plate. The first model (M-S-Plate Model) is that upper plate and mineral wool are assumed as a one-dimensional mass-spring system lying on the simply supported elastic floor. The second model (Wave Model) is that mineral wool is assumed as elastic medium, in which longitudinal wave propagates. The comparisons show that M-S-Plate model is in good agreement with experimental results, while mass-spring model on the rigid floor behaves very poorly in the low frequency ranges, particularly near the natural frequency associated with mass-spring system. On the other hand, the wave model significantly underestimates the insertion loss. It is found that including elastic behavior of the deck plate is essential in improving accuracy of the insertion loss prediction for low frequency range below 100-200 Hz. (C) 2007 Elsevier Ltd. All rights reserved.