SOUND DEADENING METHOD AND SOUND DEADENING STRUCTURE FOR ELEVATED STRUCTURE

摘要

PROBLEM TO BE SOLVED: To provide a sound deadening technique for an elevated structure than can deaden a sound radiated from a lower surface of the elevated structure owing to vibration of a floor slab.;SOLUTION: As a vehicle 4 etc., travels on an elevated structure 2, a floor slab 3 of the elevated structure 2 vibrates and a low-frequency sound +L in a band due to natural vibration of the floor slab 3 is radiated downward from a lower surface 20 of the elevated structure 2. At this time, part of the low-frequency sound +L radiated from the lower surface 20 of the elevated structure 2 is made to enter an internal space 10 of a helmholtz resonator 1 through a flat plane 14 of the helmholtz resonator 1 in contact with the lower surface 20 of the elevated structure 2. Then the phase is inverted at a sound output opening part 15 of the helmholtz resonator 1, and a low-frequency sound -L having the opposite phase is radiated downward from the sound output opening part 15 of the helmholtz resonator 1. Consequently, radiation efficiency of a sound wave radiated from the elevated structure 2 is reduced.;SELECTED DRAWING: Figure 1;COPYRIGHT: (C)2017,JPO&INPIT