床衝撃音に関する基礎研究 : 衝撃源と床振動の関係

This report discussed about the relation between the vibrations of impact sources and of floor, and the impact sound. It pointed out the matters to be attended to predict the impact sound level from the floor vibration.
The main result was as follows.
1) When the plywood floor was impacted with a tappiing machine, the signal of vibration acceleration of the joist was approximated with half sine wave, but that of the floor be tween joists could not. This suggested that the linear theory did not be used for the vibration power level of the floor between joists, though the higher acceleration level was showed on the floor between joists than that on a joist. The important unsolved subject was left on the prediction of impact sound level.
2) It was known that the carpet was effective in impact sound for a light weight impact source. One of methods for analysis on the effectiveness of overlay was induced from the wave of the impact force. But the decrease of the peek level of signal did not coincide with the decrease of the vibration acceleration level at tatami compared with that of cut pile carpet. Therefore the effect of oyerlay on the floor should be considered on the stand point of the vibration acceleration level of the subfloor.
3) When the second floor was impacted, the vibration transmitted to the elements of construction. The possibility of the sound generated with these elements is present. But this report shows that the sound which effects on the impact sound might be only the sound of the celling on the first floor.