Temporary Soundproof Barrier

Since you will need air tight assembly, I am not aware of a portable soundproof barrier. It is hard enough trying to soundproof a wall, ceiling, and floor using permanant type of construction to an already existing building. Question, are you a owner or renter?

I have never used this product but you might want to check out this and click on the "DesignWall Interior Panels". Goodluck in your seerch.

http://www.homasote.com/products.html

I've heard lead sheets work well but the edges need to be sealed tight. If you are renting, I feel for you. Been there and if the neighbors are unreasonable, the next best thing would be to move.