Transparent sound absorption—More than 25 years of applications

Abstract

Optically transparent micro-perforated sound absorbers were introduced more than 25 years ago. One of the first projects carried out was the German Parliament (Bundestag). another project carried out recently is the Canadian Parliament. At first, in the German Parliament, acrylic glas boxes with a sub-millimeter micro-perforations have been developed an applied. Later, on other micro-perforated sheets, such as thin polycarbonate or PVC sheets, have been applied in various projects around the world such as in Ottawa. This contribution concentrates on optically transparent sound absorbers. Fully transparent absorbers can be installed in front of glass facades, under glas roofs and whenever no optical distrubances are wanted. From pandemic times, also transparent screens and other applications are well known. A short review of the applications of various different materials with transparent microperforated sound absorbers is presented. Finally, sound absorption data for different setups are presented.