| 摘要 |
PROBLEM TO BE SOLVED: To reduce noise by driving a secondary sound source on the basis of the response of an an along filter. SOLUTION: This sound isolation wall for reducing road noise comprises a plurality of sound reduction devices (UT) arranged side by side along the direction of extension of a wall (7). The sound reduction device comprises a reference microphone (1); a control circuit (9) for receiving output of the reference microphone; and the secondary sound source (5) to be driven on the basis of output of the control circuit. The control circuit has the analog filter (10) which responds to output of the reference microphone. The analog filter has filter characteristics which correct characteristics, which drives the secondary sound source in such a way as to reduce sound from a primary sound source in front of the wall at a top part of the wall immediately close to the sound reduction device, in such a way as to reduce both sound from the side of the front surface of the sound reduction device and sound from the secondary sound source of other left and right sound reduction devices at a prescribed location behind the wall. The filter characteristics form an area of a sound reduction effect between -8dB and -6dB behind the wall. COPYRIGHT: (C)2007,JPO&INPIT
|
