Noise Prevention

It is impossible to prevent noise coming through a party wall. This is because the noise travels through adjoining walls, floor and ceiling as well as the shared wall. And once it gets into the fabric of the house nothing can stop it.
Far more can be achieved from the other side. The resiting of hi-fi equipment or TV to the far side of the room will achieve much more than spending a lot of money on insulation.
Another way to prevent noise from leaving a room is to fix insulating board, cork or polystyrene sheet to the walk, but this will not stop noise coming in.
On floors, a thick carpet and underlay will prevent most noise from travelling to the room below.
On windows, normal double glazing has little effect on noise from outside. The space between panes needs to be increased to about 4in or 6in (100-150mm). And the weight of glass for the secondary glazing must be heavier so that the two sheets do not vibrate in sympathy.