| 摘要 |
PURPOSE:To contrive to reduce the cost of an apparatus and to make it possible to easily carry out the judgement of a state, by a method wherein a power spectrum obtained by subjecting an acoustic signal to frequency analysis is converted to smooth power spectrum distribution and abnormality is detected from the magnitude of the absolute value of deviation with a known power spectrum. CONSTITUTION:A power spectrum asked from the output of a microphone 1 provided in an accommodation container generates fluctuation therein because of the variation in the frequency of blower sound in the accommodation container. Therefore, when power capstrum 4 is asked to be returned to a power spectrum 6 through a lifter 5, a fluctuation component is eliminated and an almost constant pattern is obtained always. Herein, by once storing this pattern as a standard acoustic pattern 7, the power spectrum 6 is asked from data collected periodically hereinafter through a similar order and the difference with the standard acoustic pattern 7 to carry out the display of deviation at a position 8. When abnormality is generated acoustically, the deviation with the standard acoustic pattern 7 is made large as shown by the dotted line 11 within curve display 9 and the generation of abnormality can be judged clearly. |
