Influence of low frequency bands on airborne and impact sound insulation single numbers for typical Portuguese buildings

Abstract

This paper presents an analysis of in situ measurements for airborne and impact sound insulation performed in typical buildings in Portugal. The direct partition element separating rooms consists of different types of walls or floors. The buildings have concrete frame structures and the partitions are, in the main, heavy walls or floors. A number of group of lightweight walls were studied.The next revision of ISO 717 provides for the inclusion of low frequency bands in the calculation of the sound insulation descriptors and so the aim of this work is to ascertain the influence of the low frequency band measurements on the descriptor results for typical buildings in Portugal. The descriptors (single numbers) for airborne sound insulation DnT,w, DnT,w+C, DnT,w+C50–5000, DnT,w+Ctr and DnT,w+Ctr,50–5000 were calculated and analysed. The impact sound insulation descriptors calculated and studied are L′nT,w, L′nT,w+CI and L′nT,w+CI,50–2500. Additional calculations were performed to determine the uncertainty of the descriptors analysed.The airborne sound insulation tests were performed according to NP EN ISO 140-4 in one-third octave bands from 50Hz to 5000Hz. The impact sound insulation tests followed the procedure set out in NP EN ISO 140-7 with measurements in one-third octave bands from 50Hz to 5000Hz.