i'm sure this gets asked everyday and i'm sure all of the hardcore members get tired of hearing it
Not at all. What I get tired of, is people we try to help, who get snotty.
Ok, here is the deal. There is ONLY two ways to increase SOUND TRANSMISSION LOSS. PERIOD. Mass, and decoupled MASS. The best bang for the buck is a TWO LEAF, MASS -AIR- MASS . Same as a regular residential wall. However, the difference between a standard wall, with one layer of drywall for each leaf of mass, and a highly proficient sound isolation wall, is decoupled mass. This means, ONE leaf needs to be decoupled from the framework via a device such as RESILIANT CHANNEL, Risc clips and hatchannel, OR staggered stud construction OR a DOUBLE WALL.
However, this applies not only to the walls, but to the floor and ceiling as well. This implies vigorous and expensive construstion. And it is. In your case, I see two implicit limitations. Its not your space, and it is UPSTAIRS. This is why you can do little to improve the actual mass OR decoupling of the interior leaf. First off, the existing floor acts as a drum head, since it is a membrane itself. This floor, structurally ties to the whole house and there is NOTHING you can do about it except this.
"De-couple" your monitors from the floor!!! Even sitting on a desk, table, or what have you, they will structurally transmit to every connection point in the house. Put your monitors on a couple of layers of mouse pads, or some rigid fiberglass, or some rubber pucks. Something that will absorb the vibration, and keep it from transmitting to the next layer of structure below it.
Same with any guitar amps, or anything that is a source of sound. Decouple it from the floor.
The second thing is HVAC ducts. Are there any HVAC supply or return grills in this space? If so, no doubt they provide a perfect flanking path for sound to other rooms. When recording, or creating sound in this space, cover them with something. Or take the grills off and stuff a small pillow in the ducts. Not the best solution, but hey, what else can ya do
Maybe make a framed and hinged trap door that you can fasten over the grills, and open it when you need the HVAC. Be creative
Next, buy a roll of foam weatherstripping and seal the door. TIGHTLY Use good heavy stuff, maybe the rubber strip type with an aluminum backer that has holes for nailing to the door jamb. Airborn sound can leak through the tinyest of holes and cracks. Then get a threshold for the floor. A solid wood one, and one of those rubber strips for the door at the bottom to seal against the threshold.
Another thing for the floor is a throw rug or two if its a wood floor or linoleum. That will help with impact noise from your feet tapping. Ha!
As far a REAL isolation measures, for airborn sound, unless you can add more drywall to the existing drywall, I don't see much you can do in that regard. Maybe replace the existing door, if it is a hollow core. You can find inexpensive SOLID CORE doors at salvage yards. This will help, as doors are the weakest link, and hollow core doors with NO threshold are the worst. The point is this.
Given what you have, you MUST, seal all holes to the best you can. Isolate sound sources from inducing vibration to the structure. And block all flanking paths for airborn noise. Well, thats about all you can do. Good luck. BTW, your slanting ceiling is a good thing, if your monitoring position is placed correctly in relationship to it. It also helps with standing waves between ceiling and floor. As to treatment in the room, your best bet is to spend you next equipment purchase money for Owens Corning 703 Rigid Fiberglass panels instead. It will be a better investment than a new mic!!!
fitZ
