| 摘要 |
PROBLEM TO BE SOLVED: To surely determine the generation of abnormal sounds, using a comparatively simple signal processing. SOLUTION: A separation part 122 separates a sound collection signal, collected by a sound collection sensor 11, into a plurality of frequency bands. A channel determination part 123 measures the signal for each frequency band for a prescribed period, calculates the reference value for each frequency band, determines a permissible range for each frequency band on the basis of the reference value for each frequency band, compares the signal for each frequency band separated by the separation means with the corresponding permissible range, and determines the generation of abnormal sound, when at least the signal of at least one of the frequency bands exceeds the permissible range. Because the processing is performed not by frequency analysis or waveform analysis, but by only signal level determination of the plurality of frequency bands, the signal processing is comparatively simple and a low-cost signal processing chip may be utilized. Furthermore, because the reference value is calculated for each frequency band at each installation location, the permissible range matching with the surrounding environment is determined. COPYRIGHT: (C)2008,JPO&INPIT
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