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Active sound insulation of wall and enclosure openings

: Bay, K.; Leistner, P.

European Acoustics Association -EAA-; Acoustical Society of Finland; Technical Research Centre of Finland -VTT-, Espoo:
Euronoise 2006. Proceedings of the 6th European Conference on Noise Control. CD-ROM : Advanced solutions for noise control, 30 May - 1 June 2006, Tampere, Finland
Helsinki: Acoustical Society of Finland, 2006
SS15-200, pp.1-6
European Conference on Noise Control (Euronoise) <6, 2006, Tampere>
Conference Paper
Fraunhofer IBP ()

Building and enclosure walls and/or wall construction units contain openings for ventilation and exhaust. In some cases the admission of fresh air or heat dissipation requires a conditioning of air and additional fans for sufficient transportation rates. With demands for noise control the openings reduce the sound-insulating effect of the wall construction units substantially. In order to prevent the direct acoustic break out and to create areas for damping means in the sound transmission path at the same time, the openings are connected with labyrinth systems in shape of consecutive bends and changes in cross-section, for example. The labyrinth distance reached by this is usually clearly larger than the actual wall thickness. Since also aerodynamic requirements are to be fulfilled and hidden cavities in wall construction units represent ideal dirt and dust catcher, these aspects must be treated together with the acoustic optimization. One shortcoming of all these passive means is their poor performance at low frequencies. This gives rise to the employment of active resonator systems which can add substantial attenuation especially at the low frequencies and require only short installation distances. Experimental data, acoustic computation possibilities for labyrinth systems and their linkage with the respective wall construction unit are presented.