When assessing the sound insulation quality of buildings constructions, policy makers and investors typically demand for single number ratings and sound insulation classes that allow for easy ranking of building products. Converting the full frequency content of a precisely measured or calculated structure into a single number, which takes into account all aspects of the insulation performance in a balanced way, is a challenging task. The recently proposed draft standard 717 proposes to take into account also frequencies below 100 Hz. This makes the single value rating even more complicated, since the transmission spectra R (dB) of walls can be qualitatively very different above and below 100 Hz, and even more, since, particularly at low frequencies, human hearing depends not only on frequency but also on the absolute sound level. This article presents a comparison between masonry and light-weight walls with different R value, in terms of the perception of loudness of typical living room, traffic noise and machinery noise transmitted through the walls. The effect of temporal and spectral features of the presented stimuli on loudness perception is analyzed.

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The goal of this contribution is the identification of the interaction of the typical swelling behaviour of viscoelastic fluids and the viscosity of the investigated rubber blends in the context of an extrusion process. By adaptation the fitness equation of the used genetic algorithm it is possible to study the influence of the die swell on viscous properties. With this knowledge a more realistic simulation of the die swell phenomenon and its influence on the resulting profile geometry is possible.

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In diesem Beitrag wird über eine Parameteridentifikation für die Bestimmung der viskosen Eigenschaften von Kautschukmischungen berichtet. Bisher wurde die Kopplung der Zustandsgrößen durch die Anwendung von Korrekturverfahren berücksichtigt. Mit Hilfe eines Iterationsverfahrens werden die Materialparameter nun direkt ermittelt. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)