Patent ID: 8831233

Claim:
A monitoring apparatus, comprising: an acquisition unit configured to acquire an environmental sound in measurement points within a space in which one or more machines to be measured are present to produce an environmental sound signal; an analysis unit configured to perform frequency analysis by sampling the environmental sound signal, to extract characteristic frequency components of the machines, each of the characteristic frequency components being a frequency component with the highest sound pressure level in frequency components included in operating sounds of the machines; a calculation unit configured to calculate a first value of metrics in the measurement points based on the sound pressure levels of the characteristic frequency components, the metrics indicating at least one index for determining difference of sound quality; a storage to store contour data items generated by connecting a second value of the metrics in the measurement points, the second values being pre-calculated according to an operational state of the machines; and a determination unit configured to determine whether or not there is a first measurement point in which the first value and the second value match, if there is the first measurement point and change of the first value is less than a threshold value, determine that the operational state of the machines is normal, if there is no first measurement point or the change is not less than the threshold value, determine that the operational state of at least one of the machines is abnormal, and if the first value stays constant for a certain period, determine that at least one of a user and the machines is abnormal in status.