| 摘要 |
PROBLEM TO BE SOLVED: To provide an active silencing device capable of being installed while securing a passage for vehicle traffic and reducing a noise with a wide frequency band generated by tunnel construction.SOLUTION: A fixed type low-frequency band speaker 15a is installed at an outer shell side in a tunnel 8. Then, a truck 25 mounted with a reference microphone 17, a high-frequency band speaker 15b and an error microphone 19 is moved so that the high-frequency band speaker 15b is positioned at an opening section 13, surrounded by low-frequency band speakers 15a, which is a central section of the tunnel 8. Blasting work of the natural ground 1 is subsequently conducted while reducing a noise by operating an active silencing device 21. When a construction vehicle travels in the tunnel 8, the truck 25 is kept in a place out of construction traffic. |
