| 摘要 |
PROBLEM TO BE SOLVED: To provide a sound reduction device having high additionally installing property to an existing sound insulating wall, and capable of switching to a passive form from an active form. SOLUTION: This sound reduction device is placed on the head top part of the sound insulating wall 100, and has a casing 20 having housing parts 21 and 22 on an upper surface for respectively housing an active sound reduction cell 10 or a sound absorbing material 80 having the function for actively reducing a diffraction sound pressure component of arrival noise on the sound source side of the noise and the opposite side of the sound source side, and is characterized in that the casing 20 has a recessed part 23 fitted to the head top part of the sound insulating wall 100 on the bottom surface, the active sound reduction cell 10 or the sound absorbing material 80 is housed in the housing parts 21 and 22. COPYRIGHT: (C)2004,JPO
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