Peace and quiet in open-plan offices

Efficient noise protection with a multi-layer system of polyurethane foam

SilenceSolutions and Bayer MaterialScience optimize noise absorption

Leverkusen – Open-plan and group offices are designed to foster teamwork and communication between employees. Service companies, such as banks, insurance companies and call centers, are particularly keen to employ open-space solutions with large windows that let in plenty of daylight, with the aim of creating a pleasant working atmosphere. However, many employees are disturbed by the high noise levels generated by these solutions, particularly when they have to perform complex tasks or listen carefully to conversations. As every employee can’t help but pick up on the noise the others are making, it is difficult to concentrate on a single conversation. In cooperation with Bayer MaterialScience AG, SilenceSolutions GmbH in Cologne has developed a range of designs for effective sound insulation and noise absorption in offices, which can be adapted to the respective situation and, being used as a sound shield, 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 enclosed in a perforated metal cassette. The foam layers were developed specifically for this application in close cooperation with Bayer MaterialScience.

Cacophony of noise

The high noise level in open-plan offices is generated first and foremost by noise reflecting off smooth surfaces, such as windows, partition walls and plasterboard ceilings, and being unable to leave the room. In sound-reflecting environments like these, this problem is compounded by the generation of “mini echoes”, which make it more difficult to understand what is being said. As a result, employees automatically begin to speak louder themselves (Lombard effect), which exacerbates the situation still further. The result is a cacophony of noise that can impair concentration and thus cut productivity significantly.

“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. Sound absorption with porous absorbers is particularly effective when the sound waves are attenuated at the velocity maximum, which is found one-quarter of the sound wavelength away from the wall or window. To achieve maximum absorption, the absorber layer applied must have a similar thickness. “However, the velocity maximum for this frequency range is around half a meter or more away from the wall, which is practically impossible to implement as a construction depth for absorbers inside buildings,” continues Zickmantel. “That’s why commercial absorber systems often provide insufficient protection against the sound of voices.”

Multi-layer system designed for the efficient absorption of voice frequencies

The company mastered this challenge by developing a sophisticated layer system comprising different polyurethane foams that slow the progress of sound waves by different amounts. Thanks 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.

The outer design of the “Ruhemodul Office” absorber walls can be as diverse as their interior is functional. Not only can the cassettes be given a single- or multi-layer coating in all RAL colors, they can also be covered with other materials, such as fabric, to achieve interesting tactile effects. Rooms can also be designed in accordance with the principles of the Feng Shui philosophy. In addition to these modules for surface mounting, SilenceSolutions also offers ceiling height or free-standing absorbers that can be positioned individually in the room or combined with glass segments to create a T-shaped arrangement. These absorbers can be re-arranged or even relocated when moving offices, just like a piece of furniture, thus enabling a mobile, user-friendly solution.

About Bayer MaterialScience:
With 2007 sales of EUR 10.4 billion, Bayer MaterialScience is among the world’s largest polymer companies. Business activities are focused on the manufacture of high-tech polymer materials and the development of innovative solutions for products used in many areas of daily life. The main segments served are the automotive, electrical and electronics, construction and the sports and leisure industries. At the end of 2007, Bayer MaterialScience had 30 production sites and employed approximately 15,400 people around the globe. Bayer MaterialScience is a Bayer Group company.

About SilenceSolutions:
SilenceSolutions GmbH specializes in the development and manufacture of professional acoustic partition systems. The company offers a complete package, including project development and surface optimization for new and existing buildings. It also has an acoustic department that conducts acoustic surveys and uses metrological analyses to provide customers with a highly cost-effective solution.

More information can be found at www.bayermaterialscience.de and www.silencesolutions.de.