N Abstract—So alyzed in this hen the rigid d cked absorptiv und waves will encer, usually a veral condition cknesses, and en studied in t en compared encer with app d outlet region hieved by appl pendence of th thicknesses o ss section (con ckness of ab proves. In this sorptive silence ipse, square, a en presented. sorptive mater terials) as line d 30 mm for g ect of substanc istivity and de ck...