A die assembly for providing a gypsum ceiling tile having improved acoustic absorption properties includes a punch plate having punches which form perforations through a plasterboard tile and indentors which form indentations in the tile. The punches and indentors are arranged in elongate strips to produce fissure-like perforations and indentations. A stripper plate having apertures corresponding to the punches and indentors and a die plate having apertures corresponding to the punches sandwich the tile, and the punch plate is applied to the tile.