I have a finished theater in which I have terrible sound transmission throughout the rest of my house. I cannot watch a movie at a reasonable level without my wife complaining in the living room and at high levels my 2nd story windows rattle. I am trying to eliminate it as much as possible without removing my ceiling. I want to keep it because I have created arches and shelves that I would then have to destroy.

By doing a second layer of drywall and GG I will also be eliminating the can lights but I do have a bump down for the air ducts and pipes that I want to leave one layer because it is so low. I am thinking that since the bump down is not attached to the joists above that it would help. I am also going to blow in insulation to help with the sound.

I have on order right now some Auralex Subdudes and some corner bass traps that I hope to help in taming the bass.

My question is am I wasting my time by leaving the bump down at just one layer of drywall? Should I seriously consider destroying my arches and shelves in order to install a hat channel reducing my theater height to 7`4" or less?

Any and all help would be much appreciated. I know this is a common question on the forums but I have not got an answer regarding my circumstances.

Containing bass is difficult. One of the key steps is decoupling the room from the rest of the house. The windows are likely shaking because of the mechanical forces traveling from the room to the rest of the house. A second layer of drywall will help some, but I don't think will kill the mechanical transmission of the sound waves.

Any suggestions other than ripping out the ceiling. I am getting subdudes for my towers and sub. I have Def Tech BP7000sc and a supercube and am hoping that the subdudes help alot.

Headphones when the wife is around?:(

Bass traps will help the acoustics within the room but wont help in containing the sound from escaping unfortunately

The ceiling is not your only problem - walls, door and HVAC are also to be considered

goto www.soundproofingcompany.com and read the articles in the library section ... that will give you some insight as to what is necessary and/or what you will be willing to do to achieve your goals

Unfortunately I've been exactly where you are and I'm sorry to report there is no easy answer.
If I might be so bold as to refer you to something I already posted related to your plight:
http://www.avsforum.com/avs-vb/showthread.php?t=1041677

Good luck.

Thank you for all your help. I think I am able to understand that either I spend another 8-10 grand on renovating my existing theater or start all over with a new addition to the house because constantly listening to my over 35,000 equipment purchases at very low levels is unacceptable. It was fine when we had no kids and we watched together but now we have two kids. If I renovate I wont increase my houses value but if I add I will. So now I need to figure out what I would like to do. I still will wait for the Auralex items to see what they do for me.

As previously stated, for real low frequency isolation you need decoupling in 4 walls and a ceiling. Adding GG and drywall in my opinion, won't get what you're looking for.

Also previously stated was the fact that the bass traps won't do anything. Low frequency waves that are able to get into your walls/ ceiling won't be even a little deterred by bass traps. That's not what they're designed to do. The traps reduce echo of soundwaves that don't have sufficient energy to enter the walls and leave the room.

I wish there were a better answer for you.

http://www.soundproofingcompany.com/index.php?/library/articles/elements_of_room_construction

http://www.soundproofingcompany.com/index.php?/library/articles/room_within_a_room

If you are a DIYer it shouldn't be 8-10 grand to do over your room.

I would think you could rip out your drywall, install clips and channel (you only lose 1/2 inch), Add Stagered studs on top of your existing wall framing or use clips on the walls. Rework any HVAC that communicatees with the rest of the house. Eliminate any recessed lighting. Back butter your outlets and switch boxes with putty pads. Install double layers of 5/8 drywall with GG. Use a heavy air tight door. For a reasonable sized room you should be able to get all the materials for 3-4K.