I have an apartment with two roommates and one of them is directly across the wall. He complains about every little sound and I am looking for a way that isn't permanent, that I can sound proof my wall and door. I have a window that is next to his and the wall itself is a big problem. What ways can I soundproof this so he cant hear my voice when I talk late at night? like I said it cant be permanent because I am in an apartment.