Abstract: A durable light weight, high temperature acoustic CMC liner system. A thin ceramic matrix composite skin, also referred to as a facesheet, forms an outer layer of a cell in the CMC liner system, forming the boundary with the flow of hot gases in the exhaust. A backplate forms the opposite boundary for the cell. The truss structure is formed between the backplate and the facesheet and provides the cell with strength. When the CMC system replaces the metal liner, the backplate thickness is increased so that it is about the thickness of the liner system that it replaces. The truss structure extends between the backplate and the facesheet, forming channels or volumetric spaces. These channels or volumetric spaces are filled with high temperature air permeable acoustic materials that attenuate sound propagated by cooling air in the acoustic range.