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, the stack having a closed back end, wherein the plurality of laminar surfaces includes a front laminar surface and a back laminar surface, wherein a periphery side of the stack is exposed to an open atmosphere or to a closed box with particular sizes;
• 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
• a clamp for clamping together the front laminar surface, the stack of plurality of laminar surfaces and the back laminar surface to create an acoustic dampener,
• wherein the plurality of laminar surfaces are separated from one another by air gaps of between 0.1 mm to 0.2 mm.