Sound proof device



PROBLEM TO BE SOLVED: To provide a sound proof device that can reduce noise in which directivity changes.SOLUTION: When noise Wpasses through a piercing 8a of a noise reduction part 8, the noise Wbecomes a plane wave to advance toward a sound absorption part 9. As a result, even when directivity of the noise Wwith respect to a sound proof device 7 varies with along with a movement of a sound source S, the noise Wadvances to the sound proof device 7 with an almost fixed directivity orthogonal to the piercing 8a of the noise reduction part 8. When the noise Wpasses through the noise reduction part 8, viscosity resistance when the noise Wpasses through the piercing 8a attenuates energy of the noise W, and then, the noise Wreduces. When the noise Wpassing through the noise reduction part 8 advances toward the sound absorption part 9, the noise Wis absorbed by the sound absorption part 9. When the noise Wpassing through the noise reduction part 8 enter a closed space C, a noise reduction part 10 is configured to generate a sound wave Wof an inverse phase in the same amplitude as the noise Win the closed space C, and the sound wave Wand noise Ware overlapped in the closed space C so as to cancel out the th noise W, which in turn the noise Wreduces.SELECTED DRAWING: Figure 2
【課題】指向性が変化する騒音を低減することができる防音装置を提供する。 【解決手段】騒音低減部8の穿孔8aを騒音W 1 が通過すると、騒音W 1 が平面波となって吸音部9に向かって進む。その結果、音源Sの移動とともに防音装置7に対する騒音W 1 の指向性が刻々と変化しても、騒音低減部8の穿孔8aに対して直交する略一定の指向性で騒音W 1 が防音装置7に進む。騒音低減部8に騒音W 1 が通過するとこの騒音W 1 が穿孔8aを通過するときの粘性抵抗によって騒音W 1 のエネルギーが減衰し騒音W 1 が低減する。騒音低減部8を通過する騒音W 1 が吸音部9に向かって進入すると、この騒音W 1 が吸音部9によって吸収される。騒音低減部8を通過する騒音W 1 が閉空間Cに進入すると、騒音W 1 と同振幅で逆位相の音波W 2 を騒音低減部10が閉空間Cに発生し、騒音W 1 を打ち消すように音波W 2 と騒音W 1 とが閉空間Cで重ね合わされて騒音W 1 が低減する。 【選択図】図2




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