ISO 140 (Sound Insulation Measurement)

ISO 140 was the former international standard series for measuring sound insulation of building elements and between rooms. It has been largely replaced by ISO 10140 (laboratory measurements) and ISO 16283 (field measurements) but remains widely referenced in existing building codes and older literature. ISO 140-3 covered laboratory airborne sound insulation, ISO 140-6 covered laboratory impact sound insulation, and ISO 140-4 and -7 covered the corresponding field measurements. The measurement principle involves generating a known sound level in a source room and measuring the level in an adjacent receiving room, with corrections for the receiving room’s absorption. Results are expressed as transmission loss (R) or standardized level difference (DnT) in third-octave bands. Modern standards ISO 10140 and ISO 16283 provide updated procedures with improved uncertainty management and flanking considerations.