The work reported in this paper deals with the measurement of the insertion loss IL of a wedge-shaped heap of limestone chips on the ground outdoors. Measurements were carried out to investigate about the potential use of these stocked granular materials as noise barriers. Since the measurements revealed it is worth considering this opportunity, a semi-empirical model was implemented for the calculation of the IL for the observed situation. This model stems from a theoretical model for the diffraction by the straight edge of an hard-wedge of infinite extent. Modifications were applied to the original model in order to take into account the finite acoustic impedance of both the surface of the wedge and the ground. The predicted and the measured values of the insertion loss appear to be in an acceptable agreement.