MICRO-PERFORATED ABSORBER - TRANSPARENCE AND ROOM ACOUSTICS

The trends of room and building environment designs valuing acoustical solutions for space and energy saving, as well as health and environmental friendly sound absorbers are increasing. Transparent/translucent absorbers, such as perforated glass, plastic panel, foil, and honeycomb-structures are merely some suitable choices for these demands. The absorption performance of the micro-perforated (slotted) transparent/translucent material/structure is limited, due to their special characteristics. The vibration of the foil will for example counteract the friction of the air drop with the internal surface of the hole and deteriorates the low frequency absorption performance of the structure. Astutely designed thicker and rigid perforated (slotted) panels will have lower or middle frequency absorptions, but reflects more sound waves at higher frequencies , causing the degrade of absorption coefficient in the high frequency ranges. The affects to the absorption of the parameters of micro perforation (slot) on the “rigid” panel (foil) absorber, like thickness, hole radius, hole distance, air gap depth, has been extensively considered. In this paper the discussion will be focused on the effects of other phenomenon like the vibration of the panels, the existence and the size of the grids in the air gap behind the front panel and multi-layered structures. The performance of absorber structures will be optimized. Some applications of transparent/translucent will also be introduced.