This International Standard assigns sound insulation values to all transparent, translucent and opaque glass products that are intended to be used in glazed assemblies in buildings, and which exhibit properties of acoustic protection, either as a prime intention or as a supplementary characteristic. It outlines the procedure by which glass products can be rated according to their acoustic performance, which enables assessment of compliance with the acoustic requirements of buildings. Rigorous technical analysis of measurement data remains an option, but this International Standard is intended to enable the derivation of simpler indices of performance, which can be adopted with confidence by non-specialists. By adopting the principles of this International Standard, the formulation of acoustic requirements in building codes and of product specifications to satisfy particular needs for glazing is simplified. It is recognized that the acoustic test procedures of ISO 140-1 and ISO 140-3 relate fully only to glass panes and their combinations. Although the same principles should be followed as closely as possible, it is inevitable that some compromises are necessary, because of the bulkier construction of other glazing types. Guidelines on how to adapt these to include glass blocks, bricks, structural glazing, channel-shaped glass and pavers are given in Clause 4. NOTE With regard to the performance variation in windows, all the considerations of this International Standard relate to glass alone. Incorporation of glass into windows can cause changes in acoustic performance, owing to other influences, including frame design, frame material, mounting method and air tightness. Measurements of the sound insulation of complete windows (glass and frame) can be undertaken to resolve such issues.