It might help, but it won't be great.
Any gaps will just let the sound through.
... think of it like playing a really loud stereo in your bedroom with the window closed. Then open the window just a few inches and see how much louder it gets outside.
In an old rehearsal room of ours we used 4" thick foam padding on all the walls, and then sleeping bags over that. Even the door was about 4" thick and had to be squeezed shut ... the neighbors still complained.