Airborne sound insulation of façades and the criteria for the interior sound pressure level in dormitories in Brazil

In Brazil, the ABNT NBR 15575-4:2021 standard specifies the criteria for airborne sound insulation of façades in buildings in terms of the parameter D2m,nT,w. These criteria were established in reference to the interior sound pressure level limit in dormitories set by ABNT NBR 10152:2017, which specifies that LAeq must be below 35 dB. This study investigates whether meeting the required façade sound insulation ensures that the interior sound pressure level is within the prescribed limit. The results show that this is not the case. One reason investigated is that the ABNT NBR 15575-4:2021 criteria consider a standardization to a reference reverberation time of 0.5 s. However, it is shown that even applying the same standardization to the interior sound pressure level, the criteria of ABNT NBR 10152:2017 would not be met yet. The other reason investigated was the noise profile considered to obtain the parameter D2m,nT,w. In Brazil, the primary source of incident noise on façades is road traffic. When the spectrum adaption term Ctr is taken into consideration, the results are much closer to what would be expected considering the interior sound pressure levels obtained.