Does anyone know of any bi-fol,d interior doors and installation method which offer some measure of sound insulation? My missus wants to knock down the wall between front and back rooms downstairs to create a bigger living area but I'd like to make sure first that when necessary we can go back to two separate areas, for example when one of us wants to watch TV in the front room and the other wants to work on the computer in the back room. Might even come in handy when we have a row, so we've got two places to go!