Oh and an extra question...if i decide to add a layer of gypsum board to the door ( once i finish strengthening them )....is there a big difference whether i screw them directly to the door or if i use the same number of screws but leave some really minimum gap between gypsium board and doors ? Would that gap be enough to reduce the sound further since there would be no direct contact and sound would have to change the frequency it travels through ( wood - air - gypsium is harder to travel then wood and gypsium ). Or maybe greenglue would be even better ? I am not even sure, does greenglue work as a normal glue soo you dont have to use screws, or is it just like silicone you use in the kitchen ? Not even sure i can buy greenglue in my country, but it sure would be nice, its very cheap and if the reviews are to be belived, it is a mirracle !