Effect of porous media properties on the sound propagation and transmission losses through such materials and consequently on the noise reduction facto has been studied with the application to diesel particulate filters. Many types of porous diesel particulate filters with different properties and specifications are studied and compared to verify their ability in transmission losses and noise reduction on the exhaust pipe system. It is found that the engineering geometry of diesel particulate filter and porous media properties such as channel width, porous porosity, wall thickness, number of channels and the pressure drop through the porous media has a significant effect on the transmission losses.