Abstract The need to create monitoring systems to equip the technological machinery of automated production determines the relevance of searching for parameters of acoustic signals that carry information about the course of treatment processes. The study of acoustic signals in various types of material processing allowed the identification of general features of changes in their spectral composition associated with variations in the power density of energy impact on processed material. The results of experimental work on various technological equipment, including blade processing and processing with concentrated energy flows, are presented in this work. It is shown that changes in the quality of processing in the form of increased tool wear, the concentration of erosion products during WEDM (wire electrical discharge machining), focal plane displacement during laser processing, etc., lead to a natural change in the ratio of acoustic signal amplitudes in the low frequency and high frequency ranges. This property can be used in monitoring systems for automatic equipment. Keywords: monitoring; diagnostics; acoustic emission; cutting process; tool wear; concentrated energy flows; signal spectrum; amplitude ratio