hi I am asking this for my father,
How do you soundproof walls? if the walls are already built. is there a way to?
well since the walls are already built youd have to put Styrofoam or another sort of isolating material on the outside, if you search google you might find some more information about sound proofing and what you can do about it...
placing a layer of "egg crate" foam around the entire room would give a bit of a sound barrier- shag carpeting the entire room may also help- although it may get expensive- and look kind of odd.