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2004
Conference Paper
Titel
Water installations in buildings - a system of vibro-acoustic sources
Abstract
The prognosis of sound emission by building services is a current topic of European standardization, see e.g. prEN 12354-5 and prEN 14366. Although their sound level is comparatively low, water installations are particularly annoying sources of noise. In case of pipes or other sanitary installations sound is mostly caused by running water. The water-borne sound is converted into struc-ture-borne sound and transmitted into the building via wall-mounted pipe clamps. Apart from the acoustical properties of the source the sound transmission also depends on the interaction between the source and the excited building element. Therefore, suitable prediction models have to comprise both aspects. This paper is especially focused on the mutual interaction between two point sources and the excitation of different types of plates, respectively. The mass of the plates, the attachment of the sources and the source characteristics have been varied. According to the results of experiments and computations the transmission of structure-borne sound into building elements can frequently be de-scribed by a simple electromechanical model. Simultaneous excitation by two or more coupled point sources, however, can cause interference effects. In this case the vibration level of the element can be either higher (by at most 3 dB) or lower than for incoherent excitation. If the distance between the sources is small compared to the length of bending waves, interference strongly affects the acoustical behaviour. For distances which are large compared to the wavelength, the influence of interference can mostly be neglected.
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