The world of microperforated panels (MPP) for sound absorption has started to occupy the thoughts of acousticians over the past 10 years. Sontech started commercial production of Acustimet 15 years ago
The delicately cut holes in the 0,1-0,4mm range is creating the absorption without using any absorbant fibers or foams. There are up to 100 000 holes per sqm.
It has been used in the creation of narrowband MPP absorbers which can be tuned by hole size and the dimensions of hole distance and air gap behind the panel.