Enhancement of bass frequency absorption in fabric based roll-banner absorbers.

Enhancement of bass frequency absorption in fabric based roll-banner absorbers. In most cases fabric absorbers show inadequate bass frequency absorption. However, the absorption capability of a textile absorber can be increased significantly below 250 Hz by installing the fabric in front of an enclosed air volume, similar to a membrane absorber. The technical and architectural approach on how to increase the bass frequency absorption is shown on the basis of a series of measurements, carried out according to ISO 354 at the reverberation chamber of the Centre for building physics (ZFB) of the Technical University Stuttgart. The measurements show a significant increase of the low frequency absorption below 250 Hz if a fabric with optimal specific flow resistance is used as a cover for a wooden enclosure. Different absorber setups have been measured and will be compared to one another. But also the practical integration of these absorbers roller banners into building projects will be discussed on the basis of projects completed within the last years.