Finally I have to put up one of these.
Before you post please make certain you do the following:
IF YOU FAIL TO DO THIS I WILL NOT RESPOND
Use the search feature to look for threads that may contain the answer to your question. There is a wide variety of projects represented in this forum -- everything from relatively low-budget residential rehearsal rooms to full-scale, professional recording studios. If your searches return too many results, try multiple terms with "Search for all terms" enabled.
If those efforts do not lead you to the answers you need, you are welcome to post your questions on the forum. If you do so:
Edit your profile to include your location. This is very important, because this is a worldwide resource, and as such, material costs and availability vary widely. For example, masonry is cheaper than gypsum in some parts of the globe, whereas it's the exact opposite in other regions. We're not asking for your address or credit card number, just a country will do.
Start your post with an overview of your goals and where you are in the process... Research? Planning? Construction already underway? Finished, and wanna know why it doesn't work?
HOW LOUD are you, and how picky/loud are your neighbors? How close? This is subjective, so you will need to buy something like the Radio Shack Sound Level Meter
Trust me, if you're recording/mixing music you should be using this ALWAYS, so it's not a waste of money. For music at typical mix levels, you want to use "C" weighting, slow. The human ear has no way of "measuring" ABSOLUTE sound levels; it just adapts to what's there, and calls that "normal" - so if you keep raising the volume, pretty soon you're mixing at 110 dB, ruining your hearing and neighbor "atta-boy" points, etc - the SPL meter helps you keep levels constant and safe.
For all other tests, the authorities virtually ALWAYS use A weighting, and (I think) slow response. So for compliance, use "A" weighting measurements.
Include as much detail as possible about the existing construction. Having details about anatomy of your existing floor, walls, and ceiling is critical. In your searches of the forum, you'll likely find examples of the kinds of details that are needed, and you'll see that the quality and timeliness of the advice given are affected by the level of detail provided.
Please don't tell us you want to float your floor if you are building on an upper level - this is almost always impractical, and ALWAYS will require a LOCAL ENGINEER to verify that it will be safe.
Remember that acoustics is THREE DIMENSIONAL, not two - when you give dimensions, we need Length, Width, Height, plus any NON-parallel features of the room.
Include drawings of what you're describing if at all possible. They do not need to be professional or perfectly to scale, but they do need to account for the necessary details. Cropping your drawing will allow you to make the important parts larger and more legible without increasing the overall size. See next...
Please resize as necessary to keep graphics BETWEEN 700 and 750 pixels wide - otherwise it's either too small for details or it forces people to scroll sideways to read every line of text.
If you link to any images OFF this site, please make sure THOSE pictures aren't oversized either - it causes the SAME PROBLEM.