To control and reduce the noise intrusion through the glazing there are several conditions that can be used separately or in combination:
increase the glazing mass, that is, use thicker glass panes;
make the glazing composition asymmetrical, that is combine glazing of glass panes with a thickness difference of about 40%, for example, 6mm + 4mm, or 8mm + 6mm, etc.; bigger glass thickness difference in insulating unit requires the thinner glass to be thermally treated (toughened or heat strengthened), to prevent its breakage under climatic loads;
use laminated glass or special acoustic laminated glass;
use secondary glazing or double skin to create a closed air cavity of about 200mm;
and above all, make sure there are no gaps in the closed window. Your old window can get significantly better at noise cutting just by adjustment of hinges and replacement of old gasket seals.
