Abstract: An acoustic absorber for a gas turbine engine includes a back sheet, a face sheet spaced apart from the back sheet and defining a plurality of perforations, and a core layer positioned between the back sheet and the face sheet and comprising a plurality of cells. The core layer comprises an outer wall extending between the back sheet and the face sheet to define an outer boundary of at least one cell of the plurality of cells and an inner wall positioned within the outer boundary to divide the at least one cell of the plurality of cells into an outer damping volume and an inner damping volume, the inner damping volume being at least partially surrounded by the outer damping volume.