Anechoic termination for acoustic plane wave suppression

An acoustic dampener for a duct carrying an acoustic signal, the acoustic dampener comprising a plurality of laminar surfaces stacked on top of one another and separated from one another, thereby creating a stack, wherein the plurality of laminar surfaces include a front laminar surface and a back laminar surface, a hole arranged in each of the plurality of laminar surfaces, and in the front laminar surface wherein the hole has dimensions enabling a duct carrying an acoustic signal, to be connected to the acoustic dampener and clamping means for clamping together the front laminar surface, the stack of plurality of laminar surfaces and the back laminar surface to create an acoustic dampener.