| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a standing-wave noise reduction technique for reducing, by using an active noise cancelling unit, standing-wave noise which occurs indoor due to noise caused by an outdoor noise source. <P>SOLUTION: A principal frequency of large volume noise is calculated by using, as a base position, a position of the large volume noise calculated from a rough plane distribution measurement of the noise volume in a room. A plane sound volume distribution is calculated through sound volume measurement at measurement grid points which are set by using the base position as an origin and a unit length being a quarter or less of the principal frequency. A measurement point showing the maximum sound volume is calculated from the plane sound volume distribution as the maximum sound volume point. A loudspeaker emitting a noise cancelling control sound is arranged at the large sound volume point. Further, a measurement grid point which shows a sound volume not less than the average sound volume at the measurement grid points and close to the maximum sound volume is calculated as a specific sound volume point. A noise detection microphone is arranged at the specific sound volume point. <P>COPYRIGHT: (C)2013,JPO&INPIT |
