In this paper, reflection waves by the first interface of porous medium having rigid frame is considered. The method presented in this work is based on a temporal model of the direct problem in which a simplified expression of the reflection coefficient at the Darcy’s regime (low frequency range) is established using equivalent fluid model, this expression depends only on the porosity and the viscous permeability (or the flow resistivity) of the medium. The simulated reflected wave is obtained in time domain by convolution between the reflected operator and the incident field. Experimental results are given for samples of air-saturated plastic foams and compared with theoretical predictions.