---

In the present study, the effect of the porous medium in natural-gas pressure regulators, on the operation and reduce the intensity of the sound produced, is studied. First, it was studied experimentally. Experiments apply for the porous medium 20 ppi (pores per inch) and 10 ppi and non-porous system. To check the validity of the results, experiments were evaluated in four different pressure upstream 20, 10, 5, and 2.5 MPa on the critical pressure ratio. Afterward, for evaluation of the flow parameters on the performance of regulators and the sound intensity level, numerical simulation of fluid flow was performed. The results show that the use of porous media for 10 ppi and 20 ppi, flow coefficient decrease, respectively 7% and 15%, and sound intensity level decrease, respectively 25 and 30 dB. The amount of porosity does not have much effect on the sound intensity. On the other hand, the results of the fluid flow simulation show that placing the porous medium in the flow direction reducing the turbulent intensity and regulating the flow. As well, it decreases the sound intensity by decreasing the maximum velocity and the vortex power.