Practical Sound Proofing

[Fret]

I'm not quit sure how to ask this so I’ll ask it a couple ways. I am trying to sound resist my studio. I will be finishing my basement so basically new construction. The basement is mostly underground and external sound transmission is not much of a concern. The main concern is my wife’s sanity and the baby on the way.

My area consists of two concert walls and two framed walls. One of the wood walls will be free standing (One side studio the other just basement so therefore not too much of a concern). The other wall though is the side of an open staircase and therefore quit a bit more concern.

So I guess the question is what kind of/how many “layers” would be necessary to bring the sound down in the rest of the house to a reasonable level? Reasonable level being a baby sleeping in a non-adjacent room and someone else on the phone or just trying to exist.

The other side of the question is how does STC transfer into the real world of sound? For example if you have a standard insulated wall with sheet rock on both sides how much sound is transferred through the wall? If you add a layer of sheet block how loud is it now? What does it take to bring a drum set down to the aforementioned reasonable level?

Thank you for your help

 

[Folkcafe]

The biggest key for isolating the percusive sound of drums is going to be mass. The construction has to be tightly sealed and needs sufficient density. Having said that, the question is going to be, how much space do you have to work with and what % are you willing to give up to isolate it. Also there is the cost thing.

The best isolated drum practice room I've seen is a friend of mines. When he built his house he added a cellar room with no structure above it (kind of like a bomb shelter). It has an expensive lead filled door to enter it. It worked so well you can't hear him playing in the house.

I would suggest building a room that is isolated (not connected to) the floor above. For mass I suggest Walls and ceiling layers of at least double 5/8" drywall. Then screw 1x3 strapping to the walls. Attach 2" ridgid fiberglass insulation (3 lb density)using 3" roofing nails into the strapping. Cover the fiberglass with a common and cheap 1/2" "sound stop" board. Finally cover this with Homasote boards covered in acousticly transparent fabric. For the outside walls use 3 to 4 layers of sound stop covered by plain Homasote wall boards. For the ceilings it is a bit harder because of gravity. Go with double layers of drywall and lay drywall, soundstop and ridig fiberglass outside on the top of the structure.

This odd home brewed collections of materials will net a decent NRC across the spectrum. Use double doors for the entrance (1st door opening out, 2nd opening in). Get insulated metal outside doors with good seals. Make panels out of Homasote boards covered in cloth and cover both sides of both doors.

I used these materials in my studio to great effect. My room is less isolated than what would be needed for drums (less mechanical isolation) but the amount of sound absorption this combination of materials provided is amazing.

I got this idea of combining materials of vaious NRC rating at differing frequencies. I found a good book that deals with acoustics and construction. It had a very extensive table of NRC ratings of very common materials. I then began contacting manufacturers requesting NRC data. Going in, it was one very big acoustics experiment. One that had a happy ending.

It doesn't have to be super expensive to work. It just has to be well thought out and tightly constructed. Be sure to seal every crack and joint with silicone caulk. It will cost a fair amount of money to get it done. There are no shortcut to this one. If your doing the labor yourself, it will save you some.

Congrats to you and your wife.

Don Goguen