Micro-perforated sound absorbers in stretched materials

The theory of micro-perforated panel sound-absorbing constructions has been introduced by D.-Y. Maa in 1975. Since then many variations of micro-perforated sound absorbing devices and materials have been introduced. Materials that have been used to be micro-perforated have been metal, wood, plastics and many others. In 2001 a nearly invisible micro-perforation has been introduced to the stretched material making it highly sound absorptive. In this contribution measured sound absorption coefficients of various set-ups with micro-perforated stretched foils and different other acoustic materials will be presented. Finally applications will be shown.