were analyzed, among others, by [PERSON] and [PERSON] in their publications. During their research, they tested vibration signals in three orthogonal axes. The distribution of vibrations acting in different directions was perceived subjectively by individuals at varying levels of intensity. In addition, attention should also be paid to the fact that, in the case of automotive vehicles, the elements of the propulsion system of the vehicle itself, as well as from other vehicle components, can also be sources of vibration for a vehicle in addition to road unevenness [13; 14]. The influence of vibrations on humans depends mainly on vibration amplitudes and frequencies. Research and observations have confirmed that vibrations can cause a number of adverse effects in humans. Effects related to the impact of vibrations on humans were presented and discussed, among others, in [PERSON]'s publication [15]. The effects of vibrations on humans can vary considerably, depending on organism predisposition and immunity [16]. However, under no circumstances can they be ignored. That is why actions are taken to prevent this adverse impact and ensure the highest possible comfort for vehicle users [17; 18]. Various vehicle vibrations measurement and evaluation methods are applied [19; 20]. Industry safety standards for various groups of vehicles have been created to protect vehicle users against the effects of exposure to vibrations. These safety requirements also underwent analysis and evaluation [21; 22] as we continue to gain a greater understanding of how to protect users more effectively against the unwelcome consequences of using mechanical tools, machines, and vehicles. When designing vehicles, their bodies, and equipment, manufacturers follow guidelines included in the relevant standards. Compliance with the adopted guidelines is essential due to the necessity of obtaining positive vehicle homologation before entry into sale. This also refers to vehicle seats, which have to fulfill the requirements of existing standards concerning the influence of vibrations on human bodies. The scope of these requirements is laid down in ISO standard 2631-1 [23]. Noticeable discomfort that is the result of low-frequency oscillations can be a consequence of pitch and fore-and-aft acceleration in the plane of the seat. Therefore, in this case, vibrations occur in the pitch and fore-and-aft axes, and there are pitch and fore-and-aft oscillations in an occupant's body. As stated in [24], the feeling of discomfort at such oscillations depends not only on the frequency and acceleration values, but also on the way a passenger's back is supported. The backrest of a passenger seat can increase discomfort at frequencies higher than 0.63 Hz. Based on vibration measurements, one can predict to a large extent how a passenger subsequently feels, making it possible to evaluate travel comfort. Modeling methods are used at the stages of designing and development of vehicle prototypes, and they allow for the optimization of designs at these early stages [25; 26; 27; 28; 29]. In the area of vehicle suspension, work is also underway on new issues [30; 31; 32]. However, during the service lives of vehicles, the assessment of vehicle elements responsible for vibration damping is practically limited to inspecting the conditions of shock absorbers. This takes place, for example, during periodic technical inspections. The possibilities for evaluating the functionality of various vehicle components are becoming broader. Kinematic excitation can be used to analyze types of damage to shock absorbers. A vibration analysis with the application of the short-time Fourier transform method was employed by [PERSON] et al. [33] to assess the volume of oil inside a shock absorber. The shock absorber's damping characteristics change over time, and they are influenced by all components of the shock absorbers [34]. That is why periodic testing of their condition is essential.