I am trying to soundproofing my bedroom, from outside noise.
my bedroom is inside a apartments building that looks like the following image (img_1)
where hundreds of people lives in there.
I googled soundproofing and got these sites
although I didn't find a complete tutorial. By "complete", I mean a sequence of tutorials starting with 6 bare concrete walls that looks like the following image (img_2)
How much I can modify the space? I am allowed to drill on the wall/celling/floor I am not allowed to ged rid of them nor break them apart.