Misunderstandings about airborne sound insulation quality estimated in-situ with different descriptors

Abstract

Last investigations about legal airborne sound insulation requirements for dwellings show two main descriptors applying in European countries: the apparent sound reduction index R'w as well standardized sound level difference DnT,w. In order to facilitate in deep comparison of different legal requirements, relation between R'w and DnT,w should be known. For these findings case study from in situ measurements the same wall construction was carried out. Both descriptors R'w and DnT,w of the similar walls erected in different rooms were estimated simultaneously. As investigation object was selected multilayer wall made from expanded-clay concrete 350 cm total thickness. A different dimension of the test rooms was specially selected. For increasing sensitivity of comparison standardized single number ratings were calculated till 0,1 under suggested procedure. Obtained results conform known relation and that in common available dwellings (DnT,w -R'w ) value differences are between -1; +3. Obtained data shows possible advantages of applying DnT,w in legal requirements against R'w and give different items for discussions. For example, as enforcement of requirements field measurements on separating walls between flats in new buildings are applicable. It is mainly carried out a short time prior to handing over the construction works, when the inner partitions not erected else and rooms under test often have a greater volume as well better DnT, w value.