The position of the intruments for the sound insulation measurement of building facades: From ISO 140-5 to ISO 16283-3

The international standard ISO 140-5 for the measurement of the sound insulation of building façades will be replaced by the new standard ISO 16283-3 soon. Together with solving a few limits of the existing standard, the review is going to introduce the procedures for measurements at low frequencies. This paper investigates the uncertainties related to the position of the instruments in sound insulation measurements of building façades. The positions proposed by the international standard ISO 140-5 are compared with those proposed in other standards and with the draft standard ISO 16283-3. The limits of measurement of the sound pressure level in front of the façade are investigated by comparing different placements both of the external source and the receiver. This shows that the average among different measurements is necessary in order to reduce the effect of interferences. The average of the sound pressure levels in different microphone positions is easier than the average obtained by movements of the loudspeaker. Later, different placements of the receiver inside the rooms are compared. In particular, corner and center room positions are assessed and their energy-average values according to the ISO 16283-1 are considered. Finally, the uncertainties related to equipment positions are discussed and suggestions to improve the future ISO 16283-3 are reported.