ISO 717 (Single-Number Ratings)

ISO 717 defines the procedures for calculating single-number ratings from frequency-dependent sound insulation measurement data. Part 1 (2020) covers airborne sound insulation (Rw, DnT,w, R’w) and Part 2 (2020) covers impact sound insulation (Ln,w, L’nT,w). The rating method involves shifting a reference curve in 1 dB steps until the sum of unfavorable deviations (measured values below the shifted reference) does not exceed 32 dB. Spectrum adaptation terms C and Ctr account for different noise spectra: C for A-weighted pink noise (general living noise) and Ctr for A-weighted urban traffic noise (emphasizing low frequencies). The combined rating Rw + Ctr is increasingly specified for facades exposed to traffic noise. ISO 717 ratings enable straightforward specification and comparison of building element performance, and are referenced by building codes worldwide including EN 12354, DIN 4109, and many national regulations.