New drum/music room - Seeking advice

Hi Guys, I'm from Australia, I've just had my new home built with my wife and fortunately she has let me dedicate one of the rooms to be my music haven!. The dimensions of this room are 3.3M x 3.7M x 2.7M high flat ceiling (Not including measurements of additional Alcove 1.8x.8m on the south east corner) The room has a thick pile carpet covering the whole floor I have sound proofed the southern and eastern internal walls (wasn't able to do the other rooms as the plasterers got to the house before the supersiver said they would! agh!) I'm contemplating building a internal wall liner to soundproof external walls to avoid neighbour complaints. I have created two acoustic panels that are 75mm thick, 1350mm X 580mm and am hangign them on the east wall evenly spaced out behind my drum kit. Accompanying this a .9m high by 2.4m wide acoustic foam layer up against the wall. So as you can see I've begun my sound treatment project and I really don't know what sort of sound treatment I should be doing before I overkill the room. I don't know how to analyse the sound nor do I know where to go from here. I'm contemplating a fake wall on the north and west wall which would essentially be a 75mm thick frame against the walls filled with rockwool and covered in cotton sheeting; however, I'm not sure if this will kill the room? I may need to use plyboard or something? My drums as you can see int he diagram are going to be placed on the far right side just infront of all the treatment facing left. I'll be using 8 microphones to pretty much mic up each tom/snare/kick and 2 overheads assuming with a XY configuration. I've read about bass traps but I'm not sure how much I should try to do? Floor to celing every corner? Once again am I going to kill my room? I've spent over 3 hours reading articles but I still feel like I'm not at an educated level to make my own judgement calls. Any help would be greatly appreciated. Regards Chris Firgaira

Hi Chris. Please read the forum rules... there's something you forgot ... :) Comments on your post:

I have sound proofed the southern and eastern internal walls (wasn't able to do the other rooms as the plasterers got to the house before the supersiver said they would! agh!)

What do you mean by "soundproofed"? How did you accomplish that, in terms of the construction that you did? Please explain that in a bit more detail, so we can understand the steps you have already taken. But if you only did two walls of the room, then you didn't actually "soundproof" it at all (the more correct technical term is "isolate", rather than "soundproof" which isn't even possible). Isolating a room acoustically requires, ummm, well. isolating the room! :) If you only did two walls, then you are missing the other 4, which still need doing. So the room isn't isolated at all right now. Think of it like an aquarium: Sound acts kind of like water in some respects. It is impossible to build an aquarium by only putting glass on two sides of it. You need glass in all six sides if you want it to hold water. Same with your room: it won't "hold sound" until you isolate all size sides to the same level, including doors, windows, HVAC and electrical system. Your isolation is only ever as good as the weakest part: Think what happens when you open the door, and you should get the idea. When the door is open, that empty hole is the weak point, and all the sound "escapes" through it, no matter how well the rest of the room is isolated. All of the work done isolating 1, 2, 3, 4, or 5 sides of a room is useless until the 6th side is also done.

I'm contemplating building a internal wall liner to soundproof external walls to avoid neighbour complaints.

You may or may not be able to do that, depending on how the existing walls are built. You'll think I'm nuts for saying this, and it isn't intuitive at first glance, but is absolutely true: Adding another wall might make your isolation WORSE than it is already. Yup. True. If you already have a two-leaf MSM system, then adding another wall would make it into a three-leaf (or even worse, a 4-leaf system!) That could potentially wreck your low frequency isolation, and "low frequency" is where things like kick drums, snares and toms live... If you explain exactly how those existing walls are built, then we can explain to you how to fix the problem, and isolate the room correctly.

I have created two acoustic panels that are 75mm thick, 1350mm X 580mm and am hangign them on the east wall evenly spaced out behind my drum kit.

How are they made? What kind of insulation? How far from the wall?

So as you can see I've begun my sound treatment project and I really don't know what sort of sound treatment I should be doing before I overkill the room. I don't know how to analyse the sound nor do I know where to go from here.

What are you trying to accomplish? Is this just a rehearsal space, or are you also going to record in there?

I'm contemplating a fake wall on the north and west wall which would essentially be a 75mm thick frame against the walls filled with rockwool and covered in cotton sheeting;

That wouldn't be a wall! It would be an acoustic panel, and 75mm isn't very much. What density rock wool did you use for that?

however, I'm not sure if this will kill the room? I may need to use plyboard or something?

That would make a membrane trap, which is a tuned resonant device. You may or may not need one of those, but if you do then you will have to tune it to the correct frequency. If you don't tune it, then the chances are it will treat thigs that don't need treating, and NOT treat the things that do need it, so once again you might end up making things worse.

I'll be using 8 microphones to pretty much mic up each tom/snare/kick and 2 overheads assuming with a XY configuration.

OK, so you ARE going to record in there, and you are going to be close micing everything, with two overheads. XY might not be the best for such a small room, as you'd be getting too much of the room sound and not enough of the drums. Maybe. MS would probably be even worse. Personally, I kinda like the Recorderman technique for small rooms and live events: it gets the mics in close, and takes care of phasing issues automatically. You might want to try that.

I've read about bass traps but I'm not sure how much I should try to do? Floor to celing every corner? Once again am I going to kill my room?

Not if you do it right! Yes, you will need bass trapping: it is a small room, and you are going to be putting out large amounts of low frequency energy. You can cover them with plastic sheeting to keep the highs in the room, or you could build slot walls.

I've spent over 3 hours reading articles but I still feel like I'm not at an educated level to make my own judgement calls.

It takes a bit more than that. Probably something like 3 years, and even then it just gets you to grasping the basics... :)

Not including measurements of additional Alcove 1.8x.8m on the south east corner)

Ooops! That's a different acoustic space!!! Kind of changes things. Is it part of the room., or isolated from the room? More questions: What is above you, and how is it built? What is below you, and how is that built? What is on the floor currently? Personally, I would start by defining your isolation needs, in terms of real numbers, as well as how much isolation you already have (in terms of real numbers), plus how quiet you need to be (in terms of real numbers), where the latter is most likely defined by your local municipality, so call them and ask for a copy of the noise ordinance (or whatever they call it), and check the legal limits on how much noise you can make. You might be shocked by how low that number is... With those number sin hand, THEN and ONLY THEN can you calculate how much isolation you need, following which you can choose the type of construction needed to get that amount of isolation and that fits your budget. That, in turn, will dictate the interior dimensions of your inner-leaf, which will dictate your room ratio and modal behavior. Based on that you can plan the initial treatment (which might or might not involve 75mm panels of "something"). Once all that is built and in place, you can then measure the acoustic response of the room, using something like REW, which will tell you what additional treatment you need to add. Repeat the last two steps as necessary. That's the correct way to go about designing and building a studio. In any event, the tiny amount of treatment you have so far is inadequate for treating such a small room, and is certainly not doing anything at all to control the modal issues, or the lows. It might be helping for the cymbals and hi-hat, but absolutely is not doing anything useful for the rest of the kit.

The room has a thick pile carpet covering the whole floor

:ahh: Let me guess: Right now, your room sounds rather dull, kind of boomy, and a bit unpleasant? The cymbals sound dead, the snare sounds "honky", and the toms sound loud? If so, your first order of business is to get rid of that carpet, and get down to an acoustically good surface, such as bare concrete (hopefully!). You can then either leave that as is, or maybe lay laminate flooring on it, and perhaps put a small throw rug of come kind right under the kit. that will allow you to treat the ceiling correctly, so you can get a nice neutral drum sound in there. - Stuart -

Thanks for the detailed response. I posted this thread in my lunch break, my apolagies for the structure and detail issues!. To note, I did try to attach the master plans of my home with some additional highlighting of the room dimensions including the alcove. I will respond once I have enough detailed information to further assist you in assisting me! Thanks so much Chris

But if you only did two walls of the room, then you didn't actually "soundproof" it at all (the more correct technical term is "isolate", rather than "soundproof" which isn't even possible). Isolating a room acoustically requires, ummm, well. isolating the room! :) If you only did two walls, then you are missing the other 4, which still need doing. So the room isn't isolated at all right now.

Thanks mate you are correct. Now as far as how these walls East, Southern and Ceiling they have been filled with 32kg/m3 75mm rockwool bradford-soundscreen insulation batts supposably reducing 75% noise but I'm not sure at which frequencies!.

If you explain exactly how those existing walls are built, then we can explain to you how to fix the problem, and isolate the room correctly.

These walls were put together by the builders. My north facing wall (per the screenshot) is 3.7 Metres wide by 2.7M high. This wall is comprised of an external brick wall (1brick wide) with the woodern frame work almost touching filled with standard glasswool insulation 50mm thick but very fluffy and light, there is then Drywall. Summary: Single brick -> Woodern frame -> Drywall. Is this classified as just a single leaf or two leaf system? The western wall is simply a hollow cavity woodern frame with drywall on both sides. My ceiling is simply drywall with the same rockwool 75mm sitting on top covering the whole roof except for where the 75mm slats are. If you could advise on sound isolation techniques first that would be greatly appreciated! I've contemplated getting blown in rockwool insulation but I'm not sure what to think of that, it will cost me around $600 I think for the moment I'll need to focus on my sound isolation component as I really need to nail that first prior to sound treatment. As you advised, I have checked with my council guidelines about noise regulations and have found that 8PM and after I cannot produce noise that causes 45decibels (by the time it reaches neighbouring properties). I have a house directly behind me 10metres away from my drum room If you could advise what sound isolation techniques I have available that would be awesome (And whether my prior idea of an acoustic membrane would suffice) or whether I would achieve a 3 leaf issue? Thanks Chris

Now as far as how these walls East, Southern and Ceiling they have been filled with 32kg/m3 75mm rockwool bradford-soundscreen insulation batts supposably reducing 75% noise but I'm not sure at which frequencies!.

That figure is actually meaningless marketing hype. Whoever gave you that information does not have a clue (or does have a clue, but wants to sell you stuff anyway!) Rockwool does not stop sound moving through a wall any more than a sponge can stop water flowing from a tap! Pure garbage. It is IMPOSSIBLE to stop sound (ie "soundproof" a room) with any reasonable thickness of rockwool (or of any other type of insulation, for that matter). The issue is that insulation is part of a system. Rockwool alone cannot isolate, but when used correctly as part of a correctly designed wall it helps to improve the isolation considerably. OK, let me explain. Back to basics: Sound is just vibrations moving through a medium of some kind, to get from point "A" to point "B". In order to stop sound getting from point "A" to point "B"., there are only four ways of doing it: 1) You can put an infinite vacuum in the way (ie, take all the "medium" away and leave nothing at all, not even air: outer space). That one is pretty hard to do on planet earth, obviously! 2) Your second option is to put an infinite amount of mass in the way, so heavy that the sound waves cannot make it vibrate. 3) Your third option is to put an infinitely stiff (rigid) barrier in the way, so stiff that sound cannot make it vibrate. Also hard to do. 4) You can put a tuned filter in the way, and use the sound itself to stop itself. That's it. There are no more options. Sound obeys the laws of physics, that work everywhere in the known universe. There is nothing else that will stop sound getting from point "A" to point "B". There are no magic materials (despite what some manufacturers and web sites try to tell you). OK, to the "vacuum" idea is impractical. Not gonna happen in a studio. That leaves "mass" "stiffness" and "tuned filter". Mass works, but you need a LOT of it in order to stop loud sounds. Theoretically, you need an infinite amount of mass to stop an infinitely loud sound, which is why we say around here that there is no such things as "soundproofing". There is no conceivable barrier that can stop a sufficiently loud sound. So "mass" is an option, if you have lots of money to buy lots of mass. That leaves "stiffness" and "tuned filter". Stiffness means that you build a barrier so rigid that no amount of sound can make it move. Once again, feasible to a certain extent, but really hard to do. All common materials are flexible to some extent, at least enough that sound waves can make them vibrate and thus transmit sound. Even concrete. OK, that leaves us with "tuned filter". It turns out that his method is actually doable at a reasonable cost! So what is a "tuned filter barrier", well, most people would call that a "wall". All walls stop sound to some extend, due to their mass and to their stiffness (rigidity), but also due to the way the parts vibrate. If they all vibrate together, in sympathy, then the wall transfers sound from one side to the other perfectly. It turns out that all objects in the universe have a natural frequency that they WANT to vibrate at, and that is called the "resonant frequency". It is different for each object, and depends on things like density and dimensions. OK, so if a sound wave hits a wall whose resonant frequency is the same as that of sound, then the wall vibrates perfectly, and in fact is invisible to that sound: it's like the wall wasn't even there. For all other frequencies, the wall still vibrates and transmits sound, but to a lesser extent. And it turns out that at some frequencies, the wall will not transmit sound very well at all, since internally the vibrations are all screwing around with each other, and not letting each other through (kind of: not exactly like that, but it helps to think in those terms). In fact, the wall acts like a filter for those frequencies, and practically stops the sound from getting through. So what if you could make a wall that filters ALL the frequencies that people can hear, and only lets through frequencies that we CANNOT hear? Yup, it turns out that it is possible to do that. You just have t design the wall so that its resonant frequency is way below the lowest frequency that humans can hear. The laws of physics are on our side here, and it is actually not hard to design such a wall. It's the exact same principal as a weight hanging from a spring, and bouncing up and down: it's really hard to make it bounce at any speed other than it's natural resonant speed. So what do you have to do to make such a wall? Very simple: It must have two separate "leaves" with a damped air gap in between. That's all. Very simple. The "leaves" have to have a fair amount of mass in them, and things like plywood, drywall, MDF, and OSB work very well there. The more mass, the better. So for example, you have two leaves of drywall with an air gap between them. Air is a spring (at least, for sound waves it is). So you have two leaves of Mass on either side of a Spring. So you have Mass-Spring-Mass. OR "MSM" Sometimes also called "Mass-Air-Mass" or MAM. An MSM wall is a tuned system, where the leaves of mass on each side (drywall) and the spring between them (air) work together to stop sound getting through. There's one other thing you need in there: to make the wall an even better isolator, you need to take energy out of the spring, and just like on your car, you do that with a shock absorber, which is more correctly known as a "damper", since it "damps" the motion of the spring. It turns out that a really good damper for air is (wait for it!....) Rockwool! :shot: (All that explanation to get to the point! Whew!) Great! But what does all that mean in practice? It means that you have to build a wall right if you want it to isolate. Drywall by itself is not good at isolating. Air by itself is even worse at isolating. And rockwool by itself is pretty bad too. But put them together correctly, and you have an amazingly good isolator. So how do you "put them together correctly"? First, you have to put each piece of drywall (each "leaf" or each "M") on its own stud frame, NOT on the same frame. If you put them on teh same frame (like a normal house wall), then the frame itself defeats the whole thing, and tit wont work. So you need two frames, instead of one. Then you need to put the rockwool in the gap between the frames, and put the drywall on each side. That's it! It ain't hard at all! Two frames, one leaf of drywall on each, and rockwool in the cavity. MSM. Tuned filter. Great isolation.... IF you do it right! Remember I said you have to tune the wall to a frequency BELOW what humans can hear? Very important! If you tune it too high, it won't isolate all sounds, just some of them. So how do you "tune" a wall? There are basically only two parameters in the equation: How much mass you put on each leaf, and how big you make the gap between the leaves. That's it. If you put more mass on each leaf (such as adding an extra layer of drywall, for example), then that forces the wall to resonate at a lower frequency, and that is GOOD. You WANT it to resonate low. Also, as you make the gap bigger, that too forces the resonance down lower. So the key is this: put lots of mass on each side of your wall, and a big gap in between. Done deal! For most cases, two layers of 5/8" drywall on each side of an 8" air gap will give you damn good isolation, several thousand times better (literally) than using the same materials in any other way. There are some key issue here: for this to work, you MUST make sure that there is NOTHING that connects across the gap. Not even a single nail that got put in wrong, and makes a bridge between the two leaves. And bridge (called a "flanking path") destroys the whole system, and you are back to just having a normal wall. Another issue is that each leaf must be sealed air-tight (remember air is your spring! You don't want the spring leaking out!). And the final issue is that you have to do the entire room, not just one or two sides. OK, so now you can see why it is garbage to say that "Rockwool reduces 75% of sound". Trash! It does NOT. If it is used correctly inside the wall, as part of a properly designed and carefully built MSM system, then it is fantastic, and will increase the isolation of that wall by somewhere between 6 dB and 16 dB. That's very good. A reduction of 6 dB is, indeed, very close to 75%! So yes, putting rockwool in the wall IN THE CORRECT MANNER can indeed give you 75% reduction in sound power transmission. But you CANNOT just shove some rockwool in the wall and expect that it will increase your isolation by 75%! Nope. It simply does not work like that. Whoever told you that it does work like that is either lying, doesn't have a clue, or deliberately misleading you. So, back to your room.... You are NOT going to like to hear this, but it is the sad truth: what you have done so far is basically useless, and needs to be undone. It will not work, plain and simple. As sound isolation, it is worthless. Whoever told you it will work is.... OK, well you already know that part. Put it this way: He is not your friend. He has made you waste a lot of time and money, and now yo will have to spend even more time and money to undo what he told you to do, and then do it right.

This wall is comprised of an external brick wall (1brick wide) with the woodern frame work almost touching filled with standard glasswool insulation 50mm thick but very fluffy and light, there is then Drywall. Summary: Single brick -> Woodern frame -> Drywall. Is this classified as just a single leaf or two leaf system?

If the wooden frame is totally separate, not touching the brick at all, no nails, screws, bits of mortar, bracing, brackets, or anything else bridging the gap, then it is a two-leaf. Assuming that the drywall is 12 mm and not fire rated, the resonant frequency of that wall is about 64 Hz, so it does not isolate at all below 90 hz, and only starts isolating reasonably at 128 Hz. That wall is practically transparent to kick drums, some toms, some snares, part of range of the bass guitar, and the bottom couple of octaves on the keyboard. That's assuming that the brick was sealed correctly, and wall is airtight, no leaks. If not, the situation is even worse. Even if it is built perfectly, it still will not isolate your room since I'm betting it is firmly attached to the ceiling and to the walls at each end of the room. If so, it is a tuned system, but not an MSM wall. Rather, it is a panel trap. Probably not what you wanted!

The western wall is simply a hollow cavity woodern frame with drywall on both sides.

That's pretty worthless for isolation! STC of maybe 25 or so, with lots of luck.

My ceiling is simply drywall with the same rockwool 75mm sitting on top covering the whole roof

If the drywall is not decoupled from the joists, then you have the same issue: poor isolation.

except for where the 75mm slats are.

Slat??? What slats?

If you could advise on sound isolation techniques first that would be greatly appreciated!

No problem! That's what this forum is here for! But I think you are not going to want to hear what we have to tell you. The news is not happy news...

I've contemplated getting blown in rockwool insulation but I'm not sure what to think of that, it will cost me around $600

Forget it. No use at all, unless the entire MSM system is correctly built.

I think for the moment I'll need to focus on my sound isolation component as I really need to nail that first prior to sound treatment.

OK great! You have set a goal: isolate the room properly.

As you advised, I have checked with my council guidelines about noise regulations and have found that 8PM and after I cannot produce noise that causes 45decibels (by the time it reaches neighbouring properties). I have a house directly behind me 10metres away from my drum room

Excellent! You have a number. 45 dB sounds about right, and is ridiculously low. It sounds about right because that's a typical for many, many municipalities, but ridiculously low because that's probably about the ambient noise level of your neighborhood at 3 AM on a Sunday! But at least we know what we are dealing with. OK, the bad news is this: Your drum kit can put out about 115 dB when played loud. You need to get that down to 45 dB at your property line. That's a difference of 70 dB, so that is your goal. You need a total of 70 dB reduction in sound level before it hits your property line. That's a BIG deal! You cannot do it with a bit of rockwool shoved in the wall cavity. To put that in perspective, you need to reduce the sound power level by 100 million percent. And that is the literally correct number. The decibel scale is exponential; each time you go up ten points, you MULTIPLY the sound power by ten. So a reduction of 20 db (what your average house wall does) is a power reduction of 1000 percent. 30 dB is ten thousand percent less power. 40 dB is 100,000 percent. 50 dB is one million percent less. 60 dB is a reduction of ten million percent, and 70 dB is a reduction of one hundred million percent: As you can see, that supposed "75% reduction" promised by your rockwool friend falls just a little short of one hundred million percent. "75% reduction in sound" looks wonderful on paper, but means zilch in reality. Great marketing hype! Lousy acoustics. OK, now for the good news: the existing structure is already doing at least something for you, and so is the air between you and your neighbors: we need to know how much. So beg, borrow or buy a sound level meter if you don0t already have one, get someone to beat the hell out of your drums as loud as the possibly can, measure that level in the room, close all the doors and windows and measure the levels along your property line, at several points that are close to your neighbors. That will give you a real figure of how much isolation you are already getting from your existing structure, and will help to figure out what needs to be done in addition to get you the a reduction of on hundred million percent. You can't guess here: you need to base your construction on real numbers, solid science, and proven construction techniques.

If you could advise what sound isolation techniques I have available that would be awesome (And whether my prior idea of an acoustic membrane would suffice)

Membranes have their uses in acoustics, but not for this. To get the high level of isolation you need for your drums, there is only one viable solution: Fully decoupled "room-in-room" MSM system, all around (four walls plus ceiling). There are some publications that will give you an idea of the types of construction you can use to get high levels of isolation. The oft-quoted classic is IR-761 "Gypsum Board Walls: Transmission Loss Data" from the National Research Council of Canada. It is available on-line for free download, but I don't have the link right now. You can probably Google it. IR-586 is interesting too, and so is BRN-217. RR-169 is great for floors. But the sad part here is that you already have finished walls around your room that are flanking, not decoupled, and not designed as MSM systems. You simply cannot get the kind of isolation levels you need by adding stuff to those... I hope I'm not discouraging you too much here. The news isn't good, but there are solutions. - Stuart -