The noise generated by hydraulic drive units cannot be sufficiently reduced only by basic approaches to individual components. Its intensity depends on the pump mounting method, mechanical structure and piping system layout. Therefore, the noise behavior of hydraulic drive units is strongly dependent on the entire system. Noise source localization will be performed using acoustic cameras. Experimental modal analysis was used to identify the vibrations of the main noise sources. Natural frequencies and mode shapes of the mechanical structures of hydraulic drive units were determined. Based on the FEM models, a sensitivity analysis will be performed to determine which model parameters have the greatest influence on natural frequencies, especially those responsible for noise generation in hydraulic drives. The methodology described in this paper has been used in many applications and its implementation leads to a significant reduction in the noise of hydraulic drive units.