In cooperation with Bayer MaterialScience AG, SilenceSolutions GmbH, a Cologne-based maker of professional acoustic partition systems, has developed a range of designs for effective sound insulation and noise absorption in open-plan and group offices which can reduce noise by 20 dB (A) and more. They are based on "Ruhemodul Office" absorber walls comprising a multi-layer system of flexible polyurethane foam - developed in cooperation with Bayer MaterialScience - enclosed in a perforated metal cassette. "To control office acoustics as effectively as possible, we concentrated on the frequency range of the human voice, which is found to be especially loud at between 200 and 600 Hz," explains Frank Zickmantel, Development Manager at SilenceSolutions.
Noticing that open-plan offices are characterized by cacophony of noise resulting from sound reflections from smooth surfaces and mini-echoes, the company developed a sophisticated layer system comprising different polyurethane foams that slow the progress of sound waves by different amounts. Due to the variation of this resistance - known as impedance - the distance that the sound has to travel through the overall structure is much longer than in a homogeneous absorber layer. This enables the efficient sound absorption of even low frequencies using standard absorber thicknesses. "The different impedance values can be achieved by varying the density, flow resistance, tensile strength, compressive strength and cell structure of the polyurethane foam," explains Manfred Naujoks, an expert in flexible polyurethane foam at Bayer MaterialScience. The multi-layer design complies with all official regulations, including, for example, the provision of a highly effective fire-protective coating. Before the sound waves enter this multi-layer system, they must first pass through the holes of the metallic outer layer, which itself generates considerable attenuation.