Monitoring system and method

A monitoring system, comprising:

• a vibrating module configured to vibrate a target object;
• an acoustic emission sensor configured to sense an acoustic emission signal generated by a deformation of the target object with liquid as sensing medium;
• and
• a processing device connected to the acoustic emission sensor and comprising a transducer connected to the vibrating module, and configured to receive the acoustic emission signal and perform:
• dividing the acoustic emission signal into a plurality of signal segments, wherein the plurality of signal segments have a same time length;
• performing a time-frequency transformation on the plurality of signal segments to generate a plurality of power spectrums of the plurality of signal segments;
• performing an average calculation on the plurality of power spectrums to generate a power spectral density;
• and
• adjusting or maintaining an operation parameter of the vibrating module according to a comparison result between a difference value and a default difference value, and outputting, by the transducer, a vibrating signal corresponding to the operation parameter to the vibrating module to vibrate the target object, wherein the difference value is a difference between a maximum value of the power spectral density and a set value, wherein the processing device is configured to adjust the operation parameter of the vibrating module when the difference value between the maximum value and the set value is not smaller than the default difference value, and maintain the operation parameter of the vibrating module when the difference value between the maximum value and the set value is smaller than the default difference value.