Relevance and objectives. Compression cuffs are widely used in tonometry. Along with creating excess pressure, they are able to form oscillations used to determine blood pressure values. The process of converting arterial pulse waves into oscillations depends on the anatomical features of the tissues under the cuff. Their mass characteristics help smooth out the frequency components of the oscillations perceived by the pressure sensor. The article is devoted to determining the amplitude-frequency characteristics of the pulse waves formed by the hydrocuff during decompression. It has been established that the high sensitivity of the hydrocuff tonometer makes it possible to detect and isolate high-frequency spectral characteristics in the signals of the hydrocuff pressure sensor. This allows, when implementing identification procedures, to obtain transfer functions that take into account the anatomical features of patients. It is proposed to use the hydrocuff technology for the process of oscillation formation. The study of the signals taken from the pressure sensor was performed on the basis of the analysis of the amplitude-frequency characteristics of the oscillations obtained during decompression and the passage of pulse waves through the walls of the brachial artery, musculoskeletal tissues of the shoulder, and the cuff to the pressure sensor. During the research, it was found that the oscillations contain a high-frequency signal spectrum in the range from 100 to 400 Hz. When using liquid as a working medium, transmission coefficient of the frequency spectrum increases by 17 times. At the same time, the phase distortion coefficient decreases by 4 times. #CSOC1120.