It is presented a theoretical and experimental study about noise attenuation device in hydraulic power steering systems. Due to the noise reduction from other vehicle sources, as engine, hydraulic system noise contribution has become more relevant. The hydraulic power steering system major noise source is the pump, contributing with its own operating noise, and also by pressure pulsation in pipeline, which in turns excite another sources. The operating principle of attenuation system is the destructive superposition of pressure waves, and for the phenomenon occurrence, the waves must be 180° out of phase. Delay between the waves is obtained through system parameter settings, geometric and physic. So it was performed system modeling, focusing in the pipeline in order to characterize the system components, and also the model validation was done through comparison between model and test data obtained with commercial system.