Designing my future home studio

[PLG-88]

Thanks gullfo,

That's kinda what I'm doing at the moment and I don't like it. But this is probably to only/best compromise.
I'm will stick with the two (smaller) rooms approach for now as that seems to be the best choice considering all options.

[PLG-88]

Hello everyone,

It’s been a while, but we finally managed to obtain a plot where we can build our (hopefully near future) home. The plot is just over 500m2 and there is enough room for a studio. It’s been quite a journey to come this far so I’m excited to be able to start my definitive design for the studio. The construction of the house itself is going to be phase 1 and the realization of the studio will probably be phase 2. But if everything is going smoothly, we might do phase 1 and 2 in one go.

The initial principles that I’ve stated in my opening post are still relevant, although a few details might have been changed. One thing is still relevant: The studio will exist of a control room and a ‘live’ room.

Obviously there is a lot to consider designing this studio, sound isolation (and legal issues), measurements, acoustics, power, etc. I thought maybe it would be helpful and clear if I started trying to pinpoint the sound isolation requirements first. This is what I’ve been able to come with so far:

SOUND ISOLATION REQUIREMENTS

Regulations
This is directly a quite complicated topic. In The Netherlands there is regulation on maximum allowed sound volume in a specific area on a central government level and there are rules on a local (municipality) level. The only problem is, most of these rules apply to roads/railways/airports, industry, businesses, shops, establishments, etc. When it comes to civil matters (neighbours) the local law says this:

Article 4.6 ‘Other sound disturbance’, paragraph 1 from the ‘general local ordinance’:
“It is prohibited to operate appliances or sound devices outside an establishment in such a way or to perform actions that cause noise nuisance to a local resident or to the surrounding area.”

Now this a very general and broad rule that comes down to: ‘don’t disturb your neighbours’. But since there are no quantifiable/measurable limits provided with this specific article, there is a lot of room for interpretation and subjectiveness. What I do know is that this article is not limitless exhaustible: When a situation would ultimately end up in a legal dispute about sound disturbance, a judge would always look to what is ‘reasonable’?

But what is reasonable is obviously a very tricky question. Homes/houses are considered as ‘sound sensitive buildings’. When it comes to urban planning or local ‘code’ in the Netherlands, there is distinction between ‘a quiet residential area’ and a more ‘city centre’ type of situation. In the city centre you might expect restaurants, bars, nightlife, etc. so sound regulations in these areas are a little less strict compared to the quiet residential areas. Our plot is going to be in the latter type of situation. The sound regulations in this type of neighbourhood are a little stricter. Everything comes down to what we call: “a good urban planning”. But again, no specific values are given that substantiates “good urban planning”.

In forementioned ‘general local ordinance’ are only specific values included for ‘unamplified music’. When it comes to amplified music we need to look at a general government decree: the ‘Quality Living Environment Decree’. In article 5.65 ‘Standard values and limit values for noise-sensitive areas within indoor and adjacent noise-sensitive buildings’, are standard values and limits included that local governments should included in their local ‘environmental plan’. These are the values given in this article: (table 5.65.1 and table 5.65.2).

These values are standard values that local governments could use in their local building code or environmental plan. They could deviate from these values if they have good reason for it and if they substantiate this deviation properly. In the local environmental plan our local government/municipality included these values:

As I’ve mentioned earlier: these values are not legal limits when it comes to sound disturbances in civil matters: they are applicable on businesses, establishments, industry, infrastructure, etc. But they might give a good framework to answer our earlier questions “what are reasonable sound limits that qualify as disturbance and what is good urban planning”?

Another important thing is that when it comes to sound that is recognizable as music, the given values are 10 dB stricter. As it is in the nature of a music recording studio to produce music, I have to apply this 10 dB penalty on the forementioned values.

The above values are divided into two categories: sound ‘on’ and sound ‘in’ sensitive buildings. Our neightbourhood is going to be a new plan and all the buildings/houses in this plan have to commit to building code that require at least Rw= 20 dB. This is the minimal required sound isolation level for houses, if the allowed ‘activities’ in the neighbourhood are louder, this required level of sounds isolation needs to be higher to bridge that gap. This means that the sound on a sensitive building in a new residential area is always normative as building code requires an external partition construction to provide enough sound isolation to cover the difference.

The urban plan allows residents to build near their property line. So for safety, I’m going to handle the above values as if the neighbouring home was on the property line.

That means that if I commit to the maximum values in table 22.3.1 Value for noise on a noise-sensitive building, and apply the 10 dB ‘music penalty’ and apply this on my property line, I might have a ‘reasonable’ legal framework for determining the maximum allowed sound values in case there will be future discussion/problems concerning sound disturbance.

Environmental background Noise
Obviously it could be the case that on windy days, the environmental noise to be quite a bit higher than 30 dB (A). But again, in specific situations (a quiet summer night for example) it could be very quiet as well. Since the environmental noise is very dependent on weather circumstances, I’ve tried to find out if there is a general estimate for this matter. It turns out that there are ‘soundmaps’ in our country. The lowest value a certain area can be assigned to is <45 dB. Our area is assigned the second lowest value: 46-50 dB environmental noise. This is because of a road (speed limit 80km/hr) nearby that apparently raises the value for environmental noise a bit. I don’t have access to a dB meter that can measure accurately under 40 dB, so I don’t think it’s very valuable/achievable to try and measure the background noise on our future plot as it can be quite silent. Not to mention changing and unpredictable weather circumstances. One thing will probably help raising background/environmental noise: a lot of trees are going to be planted on and around our properties. These trees have to be maintained and these are not allowed to be cut down.

Whether the maximum sound isolation values on the property line will be completely masked by background noise is to be seen and hard to predict accurately at this point. But this would matter on a quiet/windless summer night when the neighbours will be sleeping with their windows open. And even than that would be legally discussable since they could also choose to close their windows if any noise would disturb them. In any other case I do think that maximum 30 dB(A) would easily be masked by environmental sounds or be blocked by the sound isolation characteristics of their home.

Conclusion
Considering all legal and environmental aspects and given that fact the most of my time in the studio will be late in the evening, I need to sound isolate my studio in such a way that I won't go over a long-time average rating level LAr,LT of 40 - 10 =30 dB (a) on my property line.

This is it for now: in the upcoming post I will included a schematical overview of the plot with the intended location of the home studio and also the distances to neighbouring plots/houses. And I will try to determine the needed sound isolation of my studio.

Hopefully the above is a correct interpretation for now. If anyone has tips, advise, comments or additions on the above: I’m happy and open for receiving them in order to better my design of this studio. Thanks for reading.

[Soundman2020]

It’s been a while, but we finally managed to obtain a plot where we can build our (hopefully near future) home. The plot is just over 500m2 and there is enough room for a studio.

Great! Congratulations! 500m2 sounds nice. For both a house and a studio, there should be enough room. But check your building regulations, to make sure there are no limits on how much of that 500m2 can be built, and how much has to be left open, as garden. Some places have a percentage of the total (where I live, you can only build 60% of the total). In other places, it might be a fixed number of m2, regardless of the total plot area. There might also be restrictions on how close you can build to the property line. Where I live, you can build up to the property line on one side, provided that you don't exceed a certain total, and the neighbors don't object. Etc.

Check on all of those to find out just how much total area you can build up, then decide on how much will be the house, and how much will be the studio.

The studio will exist of a control room and a ‘live’ room.

Great! So a basic two-room studio, with the live room aimed mainly at drum practice and general recording?

Obviously there is a lot to consider designing this studio, sound isolation (and legal issues), measurements, acoustics, power, etc. I thought maybe it would be helpful and clear if I started trying to pinpoint the sound isolation requirements first. This is what I’ve been able to come with so far:

It sounds like you have some pretty tough noise regulations! 30 dB A basically means that if you are just talking to someone in your backyard, it would have to be whispering: typical speech levels are around 60 to 70 dB A. Loud speech is even higher.

So, since you want to isolate for drums (the loudest instrument in a typical band), that's not going to be easy. Since you have a blank slate to start with, I'd suggest a few things that might help to maximize isolation. In no specific order (just what came to mind):

• Position the studio on your land so that it is as far as possible from all the boundaries. In other words, don't put it right up against a boundary. Keep it roughly in the middle of the plot. That maximizes the distance to your neighbors, which increases natural isolation for the inverse square law. Basically, that says that each time you double the distance between the sound source and receiver, you get a drop of 6 dB in intensity. So assume a level of 35 dB A at your boundaries, and work back from there to the studio walls to find out what the level needs to be 1m outside the walls.
  
• Position the house to shield the studio in the most important direction. Maybe consider doing an "L" or "U" shaped house to shield two or even three sides of the studio.
  
• Consider doing isolated foundations, where the house and the studio are on separate foundations, separated by a few inches of dirt. If you really want to go as much as possible for very high isolation, consider doing an "isolated slab" for the studio, where the studio outer wall sits on one foundation, and the inner wall sits on a separate slab which is not connected to the outer foundation, mechanically.
  
• Building materials: I'm not sure what typical building materials are commonly used in the Netherlands, but I'd suggest using something like bricks or concrete blocks for the studio walls (at least for the outer leaf), to get as much mass as possible in them. Trying to do this with typical stud framing and OSB is probably not going to give you the isolation levels you need.
  
• Windows: Don't put any windows in the studio, if you can avoid it. Windows are a weak point, as they are hard to isolate to high levels. If you really MUST have windows, then make them small and use very thick acoustic-laminated glass on each leaf, with a large air gap. That's expensive.
  
• Doors: Design the studio so the door does not face towards an important direction (ie, not right at the bedroom window of your closest neighbor!) Doors are hard to isolate to high levels. Try to have just one door into the entire studio, but that might not be allowed by your local building code. Some places require at least two access doors, in the event of an emergency (fire, earthquake, etc.). The door(s) will probably be your toughest issue, so plan those carefully from the start.
  
• Roof: The studio outside roof must have the same mass (surface density) as the outside walls, which is usually a problem for typical home studios. Look into something called "beam and block" roofing. Basically a series of pre-formed concrete beams that span across he studio, from outside wall to outside wall, then are filled in with many individually concrete blocks. That will give you the mass you need. Typical wood trusses with decking and tiles is not going to do it., for very high isolation. Google "beam and block roof" to see how that works.
  
• HVAC: This is also going to be a bit complicated. I'd suggest placing the fresh air inlet and stale air exhaust vents facing away from most important directions. Ideally in between the house and the studio, if possible.

There's a few other things that can help too, but those are the major ones. If you can do all of the above, and your contractors work VERY carefully, then you should be able to get maybe 60 dB or so of isolation from the studio construction itself, plus the extra "free isolation" from the distance to the neighbors. In total, you might be approaching 80 dB of reduction. Considering that drums played hard can get into the 120 dB range, that might be enough to get it down to imperceptible levels at your boundary lines.

A couple of other things: your legal levels are stated dB A, which favors you greatly! dB A is much less sensitive to low frequencies than dB C, and a lot of the energy put out by drums is in the low frequencies. There's also the issue that human hearing is less sensitive to low frequencies than it is to mids (Google "equal loudness curves" and "Flecher-Munson curves" to see how that works). Both of these work in your favor. So overall, it should be possible to do what you want. I'm not going to say that it will be easy, and it certainly won't be cheap, but it is at least feasible, if you plan carefully, and then build carefully.

- Stuart -

[PLG-88]

Source of the post So, since you want to isolate for drums (the loudest instrument in a typical band), that's not going to be easy. Since you have a blank slate to start with, I'd suggest a few things that might help to maximize isolation. In no specific order (just what came to mind):

Hello Stuart and thank you very much for your informative and extensive reply. I've read your post and I'm afraid that some of your recommendations will pose a challenge. But maybe it might be a little early to go into those challenges for now. If you don't mind, what I'd like to do as a next step is to figure out how much sound isolation I'm going to need in order to measure LAr,NT<30dB(A) on the property line.

I think we need a few things to do so:
1. Studio Location Location of the nearest studio wall to my property line = 1,5m (I wish I could have more distance between the studio and the property line, but unfortunately that will not be possible. I will explain in a later post with a drawing of the overview of my plot and urban planning rules on where I'm able to build on the plot. You've already mentioned some limitations of building on the plot in the beginning of your post. But there are more rules that limit me in my freedom to positioning the studio on my plot.)

2. Maximum sound source SPL inside How loud is an acoustic drumset and in which frequency band are the dominant volumes?
I found this paper: https://www.researchgate.net/publication/255725228_Acoustics_Measurements_of_Drum_Sets_in_Laboratory
Groove number four is the loudest groove from the six being played. If I pick that groove and translate that to dB/octave I get something like this:

63Hz=86dB*
125Hz=107dB
250Hz=106dB
500Hz=106dB
1000Hz=102dB
2000Hz=103dB
4000Hz=106dB

These are not peak levels, but RMS-levels. Also, I believe these values are in dB (unweighted), but I'm not sure. *The 63Hz band is not mentioned in the researchpaper (the lowest band is 100Hz), but I've extrapolated that value by continuing the downward trend in the lower frequencies.

Obviously there are different drummers, music styles and playing styles that could change the values above. So to adjust/accommodate for those variables I think it is wise to add +3dB to every measured value to have a more safe estimate for the volume of the drums. That would turn out to something like this:

63Hz=89dB
125Hz=110dB
250Hz=109dB
500Hz=109dB
1000Hz=105dB
2000Hz=106dB
4000Hz=109dB

The peak values would obviously be louder, but since the allowed LAr,NT<30dB(A) is also an average over a time periode and not peak volume, I think these values are suitable for figuring out the needed sound isolation. Allowed peak-values in table 22.3.1 from my previous post are 20dB louder (so allowed peak LAmax= 50dB(A)).

3. Allowed Noise outside the studio Now this is where I struggle. Maybe you could help me with this one.
Since the studio is going to be very close (1,5m) to my property line, I'm going to assume for a moment that I won't get a lot of help/reduction as a result of geometric expansion of the sound. So the outside of the studio has to measure LAr,NT<30dB(A). Now my thoughts would be that I have to have split up the LAr,NT<30dB(A) into separate octave bands that will ultimately sum back to LAr,NT<30dB(A). Some frequencies will have more energy than others, and the dominating frequencies should be isolated more in order to end up LAr,NT<30dB(A). I found a few correction or reference curves that might help splitting up the 30dB(A) into separate octave bands. The following image comes from "NSG - Richtlijn muziekspectra in horecabedrijven" (translation: NSG - Guideline for music spectrums in catering establishments/nightclubs). (LINK: https://nsg.nl/file/CE34_LY/) The table is in Dutch but I think the words used here look a lot like the English equivalents, if there is any trouble I'm happy to translate.

I think that something between the 'Dance' and 'House" spectrum is quite a fitting reference curve with an acoustic drumset as the sound source. This also kind of fits with the measured distribution of volume in the aforementioned research paper.
So I guess I have to inverse calculate the different max. allowed values for each octave band with the 'Dance' or 'House' spectrum as a distribution between the different values on each band that together will sum to LAr,NT<30dB(A)?

If I have those individual values than the differences between those values and the sound source values is the sound isolation for every octave band needed?

I'm not sure about step 3. If you or another forum user could help me that, that would be very much appreciated.
Thanks again!