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"Drum Sound" performance of laminate floor coverings - measurement, loudness assessment, and influence of attenuating underlays

: Plinke, B.; Schlüter, F.

European Laminates Conference and Workshop 2004. Conference proceedings : 19 - 22 April 2004, Berlin, Germany
Vienna: Technical Conference Management KEG, 2004
European Laminates Conference and Workshop <2004, Berlin>
Conference Paper
Fraunhofer WKI ()

During the recent years the radiation of walking noise ("drum sound") of laminate floor coverings has become an important product property for marketing. Producers of floors are optimizing their products using attached underlays to attenuate drum sound, and the EPLF developed a measurement and evaluation procedure in cooperation with research institutes: A modified tapping machine is operating on the sample area laid in a test room with concrete floor and sufficient sound absorption. The stationary sound signal is recorded and post-processed using the Zwicker loudness analysis. The result is an overall loudness value (in Sone) and a diagram of specific loudness where the frequency components of the sound can be assessed.
Today, very different types of underlay attachements for drum sound attenuation are in use. The range of materials comprises duroplastic or thermoplastic coatings, more or less stiff thermoplastic mats, recycled plastics, rubber mats, and soft fibre boards. Experiences from measurements for many floor and underlay products carried out at WKI show that the materials can perform very differently. But this is not only due to the type of underlay of floor material. Drum sound attenuation is a combined effect of laminate properties, thickness and stiffness of the underlay and the laying method. The difference of overall loudness values between "silent" and "loud" products can be up to 25 Sone. Typical for laminate floorings are a lower frequency peak (400...1000 Hz) - probably caused by resonance effects between the areas mass of the laminate flooring and the stiffness and thickness of the underlay - and another peak at 2000...3000 Hz corresponding to a "rattling" sound from the hard covering. Some products with underlays show a good attenuation of "rattling" sound components, others a shift of the low-frequency components in the spectra.
The technical development of material combinations with improved performance is going on. There is still a need for modelling the process of drum sound generation and radiation so that further improvements can be expected.