Floating lining system has been employed to reduce noise level in cabins. However, the noise reduction level is approximately 10dB (A) and it is not satisfactory. Therefore, more effective system is desired to be realized. This paper presents the reason why the conventional systems have poor effects and shows the techniques to improve the effects. The present system is consist of a box made of four lining walls and a ceiling set on a floating floor, and the box has no connecting points to the steel structure except a few rubber pieces. Experiments with the presented system were carried out by using a scale model. Employing the new system, the vibration level on the lining could be the same level as the floating floor and the vibration level of the lining is more than 10dB lower than the conventional system in wide frequency ranges.
