Hi Erik. Please read the
forum rules for posting (click here). You seem to be missing a couple of things!
my professor is very intrigued by the intermediary spaces created from the double walls that do not touch
That's the very basis of how studios are isolated successfully at low cost. Without that, the only other choices are extremely massive walls, as in very thick concrete, multi-leaf walls that are not very effective in low frequencies, meaning that a large amount of space would be taken up by each wall to compensate for that, or currently unknown alien technology...
have a look at my floor plans and give me some suggestions.
Both of your options would work, but it looks like the second one would have better sight lines: There is good visibility between all rooms, with very little or no hidden areas, assuming careful placement of glass.
On the other hand, the upper one makes better use of space, and has a much larger live room, so that's also good. It also eliminates that nasty curved wall in the live room, which would give you lots of trouble with the acoustics, and would need some interesting treatment. So from that point of view, the top one is better. The CR is also a bit bigger, and would be better shaped if you wanted to use the room for mixing 5.1 or other multi-channel formats. But I would not chop off the rear corners like that: those are very valuable for bass trapping.
In both cases, I would double check the room geometry (speaker / listening position / room relationship) to make sure it is optimal: it doesn't look like it, from the views you show.
1) What is the reason the double walls are not parallel at the doors, but rather adjacent which creates these interesting spaces?
Sometimes it just works out better that way, form purely structural or architectural points of view, but isn't really needed from the acoustic point of view. John himself explains why he often did that in the past, but doesn't do it so much now:
http://www.johnlsayers.com/phpBB2/viewt ... 15&start=4
2) Are double walls always needed?
If you want good isolation at reasonable cost, then yes. ("isolation" is sometimes incorrectly called "soundproofing". There's no such thing as true "soundproofing", and in any case, the word itslef means different things to different people, so most acousticians use "isolation" to refer to methods for preventing sound from getting from "A" to "B").
I know for sound insulation reasoning they are extremely useful in home situations,
Not just home situations: Any situation where you need good isolation at low cost.
but my building is freestanding and includes rehearsal studios, publishing offices, public tours, etc...
Great! Then only isolate the rooms that need it, and build the other ones conventionally. So your offices, lobby, bathrooms, etc. would be done normally, and the actual studio would be done with two-leaf MSM isolation. Meaning the control room, live room, isolation booth, and rehearsal room. Those can be grouped together in one area, so you'd only need one "outer leaf" isolation wall around all of them, then build each of the rooms individually as free-standing single-leaf room that does not touch any other room, and nor does it touch the outer leaf in any place. That would simplify the overall design and construction, and reduce costs.
So, I have started adding double walls but have stopped because I am not sure where they should go.
As above: Imagine the "studio" part of that floor as being an isolated section, cut off from the rest of the rooms on that floor by a single-leaf isolation wall. The wall itself might be made up from several layers of building materials to get to the required mass and other properties, but they would all be in direct contact with one another, with no air gaps between them. That would be your "outer leaf" that surrounds all of the rooms that need isolation. All rooms where "noisy" things would be happening, or very quite things would be happening.
The within that shell you would build each room as a self-contained stand-alone structure that does not touch any of the other rooms, nor does it touch the outer-leaf. Not any any point. Not even a single nail, screw, pipe, or piece of wire. Each room is built as a single leaf that is fully "decoupled" from all other rooms, mechanically. Here too, that leaf might be made up from several layers of building materials (EG. drywall, OSB, plywood, etc.) to get the right characteristics, but all of those layers would be in direct contact, with no air gaps between them. The only air gap for each room, is the one between it and the outer leaf, or between it and the adjacent room.
This type of construction is often called "fully decoupled two-leaf MSM isolation". It is based on a principle of physics known as "Mass-Spring-Mass", hence the "MSM" part of the name. The rest is self-evident: there are two leaves, and they are fully decoupled from each other, and that's how the isolation is obtained. The equations of physics that deal with Mass-Spring-Mass systems is applied to the walls, in order to determine how much mass is needed on each leaf, and how big the air gap needs to be, and how much damping is needed, to meet the design criteria for the wall, in terms of what frequencies it must isolate, and how well it must isolated them.
Also, Why double sets of sliding doors?
One door in each leaf! Since each room is built as a "2-leaf" system with respect to all other rooms, you need one door for the inner leaf of the room, and another door in the outer-loaf, and of course that "outer leaf" is either the inner leaf of another room, or it is indeed the actual outer-leaf that envelopes all of the rooms. Either way, you need two doors.
I really like the idea of non-parallel adjacent walls which create quite interesting shapes in between.
I wouldn't worry about those shapes at all: they will never be seen after the studio is complete. They would all be totally hidden from view, inside the cavities between the walls. Nobody would ever notice! They only place you'd ever see then, is on the plans and drawings...
Non-parallel walls inside a room are a different thing, of course, and can be useful acoustically, if they are designed with specific purposes in mind. For example, in a live room they can eliminate flutter echo between opposite walls, provided that the angle is greater than 12°, and they can also modify the modal behavior of the room, making it more complex, which can be good for some issues. They can also be used to control reflections, which is very commonly done in control rooms, especially ones that follow the RFZ, CID, or NER control room design concepts, as well as for the older but now obsolete LEDE design concept.
But having the walls of a room non-parallel does not mean that the MSM system also has to be non-parallel. As I mentioned before, sometimes it ends up that way (which implies wasted space), but there is no acoustical need for that to happen. It's fine to keep the MSM walls parallel, which minimizes lost space, and also makes the calculations simpler. You can angle them if you want, and there are some minor benefits from doing that, but as John says, it isn't necessary.
You might find this paper interesting:
https://app.box.com/shared/jcaoavdc8g It's very old (from 1973) but lays out the principles behind MSM construction. They use slightly different terminology, but you'll get the idea easily.
- Stuart -
