Insulating glass units installed as windows and doors insulate noise to a significant extent. The noise insulation index of an insulating glass unit depends on the number of the glass panes in the unit and thickness of the glass panes. Double thickness of a glass pane will improve noise insulation by 4 dB. The result can also be improved by using different glass panes, different thicknesses and cavities with different width. To achieve better results, instead of a standard glass pane laminated glass panes made of several glass panes may be used in the insulating glass unit, whereas there is a special interim film installed between the glass panes. The most common interim film is polyvinyl butyral or PVB-film, which is installed between the glass panes by means of heat and big pressure. Also resin-laminated glasses (CIP process) are manufactured. In these units there is resin between the glass panes. Resin is spilled between two glass panes and afterwards the glass pane is treated with chemical additives or UV-rays. Laminated glass panes increase the noise insulation index even further (for instance Pilkington Audioscreen). To achieve noise insulation efficiency of the insulating glass units with glass panes of different thicknesses, the thicknesses must differ from one another by at least 30% (for instance 10+6 mm or 6+4 mm). At the same time it is not important which glass pane type is installed inside or outside in the insulating glass unit, the result will anyhow be the same.