Simplified evaluation of flanking transmission based on the mean mass and mean area of flanking elements

Abstract

Calculation of the flanking transmission of airborne sound energy in a building according to CEN proposals is rather complicated for the average construction engineer. One should aim at simplifying such calculation methods wherever possible with respect to the relatively simple building construction. This principle has been adopted in the draft of the EN standard CEN/ TC126/WG2, which presents the simplified method for establishing flanking transmission in the case of impact sound transmission. In this paper it is shown that this principle may also be applied to calculation of airborne sound transmission. The known relationship between the weighted sound reduction index R w and the junction velocity level difference D vij (or the junction transmission index K ij ) in relation to the surface mass of the separating and flanking elements enables a simplified method for determining the flanking transmission in a building. The relevant calculations have been conducted on the basis of the CEN prediction model (CEN/TC126/WG2 N111 Draft-ENxyz, Building acoustics — estimation of acoustic performance of buildings from the performance products, part 1: airborne sound insulation between rooms. 1993; Gerretsen, E., Calculation of airborne and impact sound insulation between dwellings. Applied Acoustics, 19 (1986) 245–264) and the method used in Poland (Gösele, K. Berechnung der Luftschalldämmung in Massivbauten unter Berücksichtigung der Schall-Längsleitung. Bauphysik, 3 (1984) 79–84, Bauphysik, 4 (1984) 121–126; Szudrowicz, B., Podstawy Kształtowania izolacyjności a Kustycznej pomieszczén w budyn Kach mieszkalnych. Edition ITB; Warsaw, 1992 (in Polish)).