Acoustic foam is a sound absorber and is for making a good listening environment within a room, it will dampen sound slightly and help to a small degreee with soundproofing however to soundproof a room you will need much more than foam
As many recording studios and rehersal rooms are acoustically treated with foam we have had many enquiries asking for our foam to soundproof a room particularly with the arrival of a drum kit into a house or garage.
the only way really to tackle this is to make a room within a room often with multiple layers of varied density composites Rockwool and plasterboard being the most common in domestic usage I have also seen reconstituted chipfoam sheets used in automotive applications this is the same material as is used in many new carpet underlays.
A room within a room (RWAR) is one method of isolating sound and stopping it from transmitting to the outside world where it may be undesirable.
Most vibration / sound transfer from a room to the outside occurs through mechanical means. The vibration passes directly through the brick, woodwork and other solid structural elements. When it meets with an element such as a wall, ceiling, floor or window, which acts as a sounding board, the vibration is amplified and heard in the second space. A mechanical transmission is much faster, more efficient and may be more readily amplified than an airborne transmission of the same initial strength.
The use of acoustic foam and other absorbent means is less effective against this transmitted vibration. The user is advised to break the connection between the room that contains the noise source and the outside world. This is called acoustic de-coupling. Ideal de-coupling involves eliminating vibration transfer in both solid materials and in the air, so air-flow into the room is often controlled. This has safety implications, for example proper ventilation must be assured and gas heaters cannot be used inside de-coupled space.