We recently renovated our new basement and the media room is almost complete. With a size of about 18' x 16' with one angled wall, our space was restricted for such options like staggered studs or double wall construction. The staggered studs require a 2x6 base with 2x4 studs and doing this along all 4 walls meant a reduction in space where inches make a difference between function and slightly less function (e.g. door relocations b/c a wall opening needed an extra 2-4" to fit, slightly shallow headroom on the angled wall b/c of the lost inches in distance from the wider build, etc.).
If we had a bit more space, i would have constructed a design for the walls in this fashion. Compared to a double walled room, it is cheaper.
However, with a good quality wall batting for sound insulation, you can achieve excellent results in sound reduction into other rooms. This material can be found any any Home Depot or Rona store. Drywall the ceiling (drop ceilings had a large tendency to rattle something nasty) and put acoustic batting between all floor joists as well.
Before any walls are sealed in with drywall, give then a good shake and see if anything is loose. Tighten up the shaky walls and build them solid.
Yes, a door is an absolute must for the media room, but an external door is not 100% necessary. Any 'solid' door will do. The hollow core doors commonly used for interiors are useless in this capacity, but you can buy reasonably priced solid wood doors that are very effective. Adding the weather stripping and door sweeps will help to contain air pressure and sound energy.
Lastly, i recommend putting in a good plush carpet with some beefy furniture pieces.
With our system at about 80% in that room, the sound in the next door games room and in the upstairs family room immediately above the media room, sound levels are well within easy tolerances for having conversations.
When i get around to it, i will post pictures of our latest and massive venture along with some numbers of SPL inside the media room and then around the adjacent areas.
If you are looking for dead silence or close to it outside of this area, some more serious design ideas will need to be followed.
