The results of an attempt to increase energy dissipation by making the plate permeable are presented in Fig. 14. The comparison of the results for the impermeable and permeable plates, reveals that the efficiency of the structure is not enhanced and the local turbulence is not intensified by the porosity. On the contrary, although the transmission is almost the same, energy dissipation is lower in the case of the porous plate revealing that the rather big voids in the attached plate and its small thickness contribute positively to the transmission of wave energy. However, it is believed that the structure will operate more efficiently in the case of a permeable plate if the porosity is reduced and the length is increased The last two parameters contribute significantly in the dissipation of energy and will be considered systematically in a subsequent study.