Soundproofing for windows in living spaces

My crystal ball says the window sashes are very large and/or heavy or have a low height... Depending on the fitting/sash size/weight, for example, opening restrictors must be installed to reduce the opening angle in order to prevent damage (danger to life and limb) and/or malfunctions. Details can be found in the manufacturer guidelines of the fitting manufacturers. There is no standard for how much a window sash is to be tilted or how far the sash must protrude or how much air must pass through.

But this has nothing to do with sound insulation... open windows, even if only slightly tilted, have (almost) no sound insulation.