Apartments are wonderful if you don't care for yard work or like to be able to pick up and move at will. A problem with apartments, however, is that they are rarely soundproof. Either you can hear everything your neighbors are doing, or you find that they knock on the walls or ceiling (your floor) every time you accidentally make a loud noise. You can lessen this problem with a little soundproofing. Here are some tips you can use.
The first step to soundproofing an apartment is to furnish it fully. An empty apartment will allow sounds to echo. Put down an area rug, even over an existing wall-to-wall carpet. Use large upholstered furniture items, and hang to lessen the amount of noise that comes from your apartment.
On walls of your apartment that you share with a neighbor, fill the wall with bookshelves full of books. This will deaden a considerable amount of noise.
Get permission: If you need further sound proofing, you will need to do a bit of minor construction, which will require your property owner's permission.
Add furring strips to your walls on top of the existing drywall and then apply a vinyl barrier or vinyl barrier foam composite designed to stop sound transmission. This is not the most attractive thing to have on your walls, but it isn't necessarily ugly either.
If you have ceiling tiles, you can replace them with acoustical tiles. If you have high ceilings, you may want to add acoustical ceiling tiles.
To soundproof the floor, you need to pick up your carpets and install a layer of vinyl foam composite, foam side down on the floor. Reinstall the carpet on top of it.