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Building Soundproofing


jozzafunk
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I’m helping out some friends that have a worship space - They recently converted the big rear room into a yoga studio / devotional music space which gets loud - There used to be a big shrine type arrangement blocking the rear windows but that has moved and the neighbours are complaining.

 

we need to build some plugs to go into the 2 large window cavities.  They can be 200mm deep ( not ideal ) but this also will make them more manageable.  The plan is 3 plugs - 1200mm wide by 1200 high that fit in each window space .   I’m looking for advice on the composition   Currently looking at ( with materials to hand ) From inside room to window. 18mm ply to 70mm Audex foam Then airgap then foam then another layer ply, to make them 200mm deep,  and boxing around outside to hold together.  Do folk think this is best layering for sound proofing? Was considering long thin slots in front ply to help act as traps / diffusers.  Any opinions on whether slots would compromise proofing over benefits it may provide?


thanks for your time and help 
 

will also be building baffles and getting some carpet but the plugs are needed asap 

 

there is a pretty limited budget but some handy folk there

 

JAS

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Do the plugs need to be removable? i.e. Do they still need them to be windows sometimes or do they need to be accessible as a means of egress? 

 

If you just need to seal up the window bucks and they are semi-permanent (can be uninstalled but are meant to be left in place for the long term) I'd fill up the window with an insulation that has a high NRC value – like Owens Corning 703 or Rockwool Safe 'n' Sound. I'd then put in the opening a basic wood frame and attach a piece of drywall. Then I'd caulk the seams with silicon, tape the joints and paint.

 

There are 2 ways sounds transmit, through mechanical coupling – sound vibrates wall, vibrations move through structure, structure vibrates air on the other side – and air gaps/leaks.
 

So the above method fills up the hole (window) with a ton of material that is resistant to the mechanical vibration, and sealing the hole seals the air leaks.

The other thing to consider, is if you have a lot of low frequency sound problems you'll need really thick and or heavy walls to slow that sound from leaking out.

Other sound transmission suggestions is to add another layer of drywall to the inside of the room sandwiching a layer of greenglue, staggering the seams over the original wall seams and calking the joints – but that can get expensive fast. 

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Forgive me as I become pedantic for a moment -- and then, hopefully helpful. Not disagreeing with anyone else, just adding to the info pool:

 

"Soundproofing" is a term this is often misunderstood and even more often misused, although applied here it's closer to its real meaning. "Soundproof" is similar to the term "waterproof." Few things are absolutely waterproof as it depends upon so many qualifying factors, be it amount of immersion, pressure, exposure duration, etc.

 

What we're talking about here is sound attenuation, and not unlike the more appropriate analogy "water resistance" it's a matter of degrees.

 

Sound reflection, sound absorption, and sound dispersion are an entirely different matter (although still related) that deals with how frequencies bounce around within a room and interact with each other. Quite often, when someone asks about "soundproofing" these internal acoustic characteristics are actually what the person is talking about -- however, not is this case.

 

To attenuate low frequencies the two prime principles are mass and decoupling -- ideally, both. For high frequencies it's blocking air flow. All the frequencies in between those extremes are on a continually sliding scale. 

 

In a case like this it's often low frequencies that tend to make its way through structures, the frequency range of offense rising appreciably through windows (lacking the mass). Yes, you need to have mass in your church to help solve this issue (ohh -- bad pun alert... too late!).

 

Decoupling is requiring the offending frequencies to pass through one surface with a given type of attenuation and then through another surface with a different one. Think: thick wall / air space / another thick wall.

 

So here: thick panel / air space / thick panel -- sealed from any air flow.

 

Maybe this helps.

 

 

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Thank you both. Yes helping to affirm current plan - clarify couple things

11 hours ago, John Blankenship said:

Forgive me as I become pedantic for a moment -- and then, hopefully helpful. Not disagreeing with anyone else, just adding to the info pool:

 

"Soundproofing" is a term this is often misunderstood and even more often misused, although applied here it's closer to its real meaning. "Soundproof" is similar to the term "waterproof." Few things are absolutely waterproof as it depends upon so many qualifying factors, be it amount of immersion, pressure, exposure duration, etc.

 

What we're talking about here is sound attenuation, and not unlike the more appropriate analogy "water resistance" it's a matter of degrees.

 

Sound reflection, sound absorption, and sound dispersion are an entirely different matter (although still related) that deals with how frequencies bounce around within a room and interact with each other. Quite often, when someone asks about "soundproofing" these internal acoustic characteristics are actually what the person is talking about -- however, not is this case.

 

To attenuate low frequencies the two prime principles are mass and decoupling -- ideally, both. For high frequencies it's blocking air flow. All the frequencies in between those extremes are on a continually sliding scale. 

 

In a case like this it's often low frequencies that tend to make its way through structures, the frequency range of offense rising appreciably through windows (lacking the mass). Yes, you need to have mass in your church to help solve this issue (ohh -- bad pun alert... too late!).

 

Decoupling is requiring the offending frequencies to pass through one surface with a given type of attenuation and then through another surface with a different one. Think: thick wall / air space / another thick wall.

 

So here: thick panel / air space / thick panel -- sealed from any air flow.

 

Maybe this helps.

 

 

Thanks John. Yes diffusion and trapping is stage 2.  This is rough design I did - scale is bit out

F31B86DB-8571-4C7D-8D6B-389422D09EA5.jpeg

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Joel,

 

Do you know for sure you need bass traps? They're for diminishing standing waves in specific frequencies or ranges. You left out what is one of the most critical aspects of the drawing -- the dimensions: length, width, height, and also the variation of the angled wall.  Is the box-shaped foyer open? If so, then those dimensions matter, too. Once you have a plot of the room, it'll become clearer how to proceed with interior acoustics -- a whole different thing than the sound transmission issue this thread addressed. Naturally, being in the room and plotting it thoroughly with proper gear is by far the best approach, but it's still good to have specific measurements on paper, to know what you may be dealing with standing-wave-wise.

 

Other than two speakers on stands, your diagram doesn't address how sound reinforcement will be handled -- that figures into the equation. Many smaller speakers can distribute sound more evenly and require less sound volume from the main ones which might be part of the culprit where the neighbor's issue is concerned.

 

 

 

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And to be "Mr. Extra Pedantic Clarifying Captain Obvious" here; the sound proofing and trapping that JB is talking about above (and as he mentioned) is mostly pertaining to doing things within the space itself, such as placing mics to record, and/or mixing in there.

As he also mentioned - this is doing little to nothing to prevent low frequencies from leaking into the exterior of said room.

Plugging the windows may provide *SOME* help in terms of mids and highs... depending on how loud the speakers are, some of this may still leak...

 

Decoupling the room, and achieving 'sound isolation" involves some construction work. Recording studios (yes, those dinosaurs that were highly popular before people started making records in their bedrooms) were constructed with the principle of a "room within a room". This means not only having air between a double wall, but also detaching the floor from the ground, meaning  the inner floor often floating on pucks. 

 

Also - Google "Green Glue" and you might find some info relevant to all of this, 

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On 6/20/2020 at 2:49 PM, John Blankenship said:

Joel,

 

Do you know for sure you need bass traps? They're for diminishing standing waves in specific frequencies or ranges. You left out what is one of the most critical aspects of the drawing -- the dimensions: length, width, height, and also the variation of the angled wall.  Is the box-shaped foyer open? If so, then those dimensions matter, too. Once you have a plot of the room, it'll become clearer how to proceed with interior acoustics -- a whole different thing than the sound transmission issue this thread addressed. Naturally, being in the room and plotting it thoroughly with proper gear is by far the best approach, but it's still good to have specific measurements on paper, to know what you may be dealing with standing-wave-wise.

 

Other than two speakers on stands, your diagram doesn't address how sound reinforcement will be handled -- that figures into the equation. Many smaller speakers can distribute sound more evenly and require less sound volume from the main ones which might be part of the culprit where the neighbor's issue is concerned.

 

 

 


Hi John


1st priority was sorting as much leakage as possible, taming the room comes next.   
 

PA is QSC K12s left and right and a KS118 sub

 

Doing some Room acoustics engineering would be ideal, initial queries showed it to be too expensive - they’re working with a budget of a couple grand - this is a smallish but popular centre run by volunteers that mostly runs in the red.

 

Do you have access to acoustic design software or point me to where to access it  ? Ill go and measure It up if so 

 

regards

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12 hours ago, jozzafunk said:

...

Do you have access to acoustic design software or point me to where to access it  ? Ill go and measure It up if so 

 

 

Not able to help much there -- the main software I use is a calculator.  The internet has a wealth of info on room acoustics and design. A Google search will reveal all manner of resources.

 

Also visit:  https://auralex.com/acoustics-101/

 

 

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Now I'm being pedantic, There's no such thing as Owens Corning 704. (or at least not sold anymore)


There's a 703, 705, 706, and 707. The number is a formulation number and does not denote material size.

 

703 and 705 comes in thicknesses of 1, 2, 3 or 4 inches.

706 and 707 only in 1 or 2 inches.

Screen Shot 2020-06-21 at 3.35.18 PM.png

Screen Shot 2020-06-21 at 3.35.06 PM.png

 

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