How much Studiofoam® do I need to "soundproof" my room?

How much Studiofoam do I need to stop bothering ___________? (Fill in the blank: neighbors, spouse, children, co-workers, etc.)

AND

How much Studiofoam do I need to stop hearing ___________? (Fill in the blank: neighbors, spouse, children, co-workers, airport, highway, barking dog, etc.)

These are the single most common questions we encounter here at Auralex. Unfortunately for many folks seeking an inexpensive cure to their sound woes, acoustical foam is not it. Acoustical foam (and fiberglass and acoustical blankets and mattresses and curtains, and so on) is an acoustical absorber. Foam is ideal for improving the sound in the room but does little to stop sound from leaking into or out of a room.

Absorption and isolation are two separate phenomena. Therefore info about that here. Imagine firing a strong stream of water at a large sponge. The sponge itself would become saturated with water, but if you stand on the other side, you will notice the stream coming through the other side – an absorber at work. If on the other hand, you fire the same hose at a brick wall, most of the water will reflect off, and very little, if any, will go through – an effective barrier.

Good sound isolation results from two main details: density and air gaps (or, more specifically, decoupling of structures). Density is in the form of materials such as drywall, chipboard, plywood, soundboard, vinyl barrier products (SheetBlok), lead, etc. Air gaps between existing and new walls should, if possible, be at least 2 inches wide. (But even air gaps as small as ½inch will serve the purpose of decoupling the structures.) The combination of density and air gaps will provide varying amounts of isolation depending mostly on the quality of workmanship.

If you are bothering someone with your sound – or if someone is bothering you with theirs, here is a list of suggestions in order from cheapest and easiest to most expensive and difficult.

Move. This may sound crazy but often is the least expensive option. Save yourself the hassle of construction, earplugs, or whatever, and move out of that apartment or condo if the neighbors never seem to sleep at a reasonable hour. (Sometimes all it takes is a friendly conversation to reason with seemingly inconsiderate folks.) If you are bothering someone sleeping upstairs, perhaps there’s a different room in your home that is further from the bedroom where you could fit your gear? In acoustical engineering, we are often asked what the best method to quiet a noisy piece of equipment is. Our first answer is always: ”By locating it as far away as possible from people who may be bothered by it.”
Strike a deal with your neighbors/roommates involving rehearsal times, frequency, etc. If moving is unreasonable for whatever reason (cost, hassle, rent-control, etc.), talk to the offenders or offenders to find out if some sort of agreement can be reached. The band downstairs rehearses once a week till 2 a.m. Perhaps you could crash with a friend that night? If you are the offender, find out when the best time to practice might be for your neighbors. Having been in a few bands, I have found that as long as the practice is over by about 10 p.m., no one ever seems to complain. (This may not be the case in apartments with ”paper-thin” walls.)
Buy a really good set of headphones – for everyone if necessary. I was in a band that practiced exclusively through headphones plugged into a headphone amp. A few things were noticeable right away:Improving the construction of the room is the only real option left at this point. For detailed explanations of cost-effective methods for building well-isolated rooms, please read our document Acoustics 101. Information on building walls, ceilings, floors, doors, and windows is all provided free of charge. Many of the tips are based on the ”room-within-a-room” concepts. However, even if you can only add a few layers to the wall, I would encourage you to read through Acoustics 101 thoroughly as you may find there are some very cheap fixes you’ve overlooked.

Everyone was able to hear everyone else.
The drums didn’t give me a headache. Closed headphones tend to block out 20 to 30 dB of outside sound. Talk about hearing protection.
Using in-ear monitors on-stage is a similar concept. Perhaps you could set up that rehearsal space with the monitor system instead of the mains. If you need to practice your stage show, rent a few nights at a dedicated rehearsal hall. Every major marketplace has at least one.
As you can see the above suggestions have nothing to do with ”soundproofing.” They are suggestions that will save you time and money. Exhaust them first. If none are an option, I continue.

Improving the construction of the room is the only real option left at this point. For detailed explanations of cost-effective methods for building well-isolated rooms, please read our document Acoustics 101. Information on building walls, ceilings, floors, doors, and windows is all provided free of charge. Many of the tips are based on the ”room-within-a-room” concepts. However, even if you can only add a few layers to the wall, I would encourage you to read through Acoustics 101 thoroughly as you may find there are some very cheap fixes you’ve overlooked.