| 摘要 |
PROBLEM TO BE SOLVED: To provide a monitoring method, a monitoring device and a security device to reduce manufacturing costs, and to detect only a sound with a target frequency by deciding an area to be monitored. SOLUTION: This monitoring method is performed by setting an arrangement interval matched with the frequency of a sound to be monitored by arraying a plurality of microphones in a direction crossing an axis extended to a monitor target direction, and deciding a monitor target direction based on the delay sum of sounds detected by the microphones, and monitoring the generation of a sound with a specific frequency in the specific area to be monitored. COPYRIGHT: (C)2005,JPO&NCIPI
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