Abstract
In this paper we describe the experimental study of the contribution ratio between transmission sound and solid borned sound against interior noise level when the ventilating equipment for Shinkansen only operates. From the test resulst, the contribution ratio of transmission noise against interior noise level is much smaller than that of solid borned noise that includes the fluid noise caused by the flowing air in the duct under the floor. We obtained the instruction that decreasing solid boned noise and fluid noise by means of elastic support and expanding the cross sectional area of the duct would be effective measures for decreasing interor noise level.
