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#2756897 - 02/18/16 05:24 PM Optimizing Basement Acoustics - Balancing Treatment Usage
Furious G Offline
Member

Registered: 02/17/16
Posts: 10
Loc: Ohio
Hello Ethan (and members),

First post here. Special thanks in advance to Ethan your forum and for choosing to share your wealth of experience as well as for all detailed / useful information shared in public forum. Extremely helpful in the planning and use of materials for my music basement workspace.

My main questions center around specifying and optimizing the choice of materials in the ceiling and floor for the usage goals within the given space, my basement.

Space usage / purpose:
I'm a full-time musician (performer / teacher). The uses of this basement space will be four fold:
1. Recording / Mixing - most of this will be direct or close-microphone recording (vocals, guitar / bass DI, sequenced drums, keys), so it's more important for this space to act like a control room than have the dynamics of a tracking room. Acoustic accuracy, neutrality and a strong, uncolored stereo is really important, especially in the mixing chair. (I may however evolve from this to additionally wanting to do live bands at some point.)
2. As an environment for teaching. I teach guitar, voice, bass and uke to students young and old. Soundwise for this, I want it to function similar to a control room (accuracy is important), so 1 and 2 are very similar, but this is where the aesthetics additionally come into play. I want it to be a warm welcoming environment that feels like another room of the house and not a 'basement' (what it is now). I also use recording as a teaching tool, so again emphasizing the tracking room mentality.
3. As a backdrop environment for a YouTube channel.This piece doesn't have as much to do with sound as aesthetics but there may be some live room recordings where the acoustics of the room come into play here, especially with dialogue . The channel will include blogs, teaching videos, acoustic / voice (maybe live) covers of songs and full-on arranged covers of songs (ex. heavy metal version of pop songs. Outside the box stuff).
4. Occasionally as a band rehearsal space (very infrequent) and even more infrequent (but possible) tracking space for drums.

The goals with the finishing materials are:
1. Serve the space acoustically for usage goals - mainly control room focused
2. Mold proof (inorganic so mold won't grow)
3. Aesthetically pleasing (for students, setting mood/vibe for recording)
4. Future proof (durable enough so I don't have to do it again)

Dimensions: 24 x 12 x 7. Stairs on back 12' wall opposite where mixing desk will be.

I'm using materials from the Total Basement Finishing system and a contractor to help with the job.

Existing construction of the room:

Ceiling - unfinished, wooden floor joists are 7 1/2 inches deep x 1 1/2 inches wide with 14 inches between.
Floors - bare concrete - taking the existing floor tiles off

For the walls I'm using Total Basement Finishings prefabbed materials - details follow:

Walls - A 1/2 inch cement board adhered directly to 2 1/2" of graphite-infused EPS rigid foam panels (they call them Basement to Beautiful panels), which in turn are fastened through the metal studs in the panels against the concrete foundation wall. The concrete board is covered with a washable off-white / beige 'slightly alligator-textured' vinyl finish. I'm hoping this texture might act as a diffusive surface as a bonus, however minimal. Anything can be mounted anywhere (hopefully great for playing with placement of acoustic treatment later) and screw holes patched with putty or toothpaste instead of having to worry about drywall repair.

Video link if you"d want a visual of this:
https://www.youtube.com/watch?v=B24pDEMQ-lw

Now finally onto the questions and what I need help with. I've watched the RealTraps videos several times, as well The Ultimate Home Studio that you and Doug did. Also read your Acoustics FAQ on your home page and your suggested Acoustic Basics link. Trying now to put all the info together for what is best for treating the space.

Question(s) 1:
Regarding the ceiling, I'm probably going to do the insulation / fabric idea. It seems like a home run win-win-win scenario. You keep ceiling height, 100% absorption, and bass trapping across the whole ceiling. Regarding the type of insulation - I've noticed you've mentioned rigid fiberglass (705) as the go-to in the acoustics treatment article and I've seen mention of the fluffy and Roxul as well. My joists aren't exceptionally deep (about 7 1/2 inches). What would you recommend between the three materials for my situation and how much (one/two batts, fiberglass / Roxul combo, etc)?

Question 2:
I have a 6 and 4 year old that have very heavy feet, and the mixing area is right below the living room (hardwood floor) so there is a ton of impact noise from the kids when they are active. Guessing mass is the answer here, but I don't want to do drywall ceiling. The company gave the option for installing a drop ceiling w tiles, but a read a response of yours to a post years back that said something along the lines of, "better yet, rip out the ceiling grid and…(fiberglass option)." This was the post that led me to all your information. Losing ceiling height, as I understand is always bad, and from what I've read about those tiles, they would do nothing to help my situation. Whatever isolation I can get from the noise coming from upstairs and vice versa would be a bonus. It seems like very complicated equation where I have to prioritize or trade one thing for another. Is there something simple materials-wise that could be added to maximize the existing equation of the insulation/fabric idea to give a bit of dampening tp the heavy footfalls?

Question 3:
Regarding flooring, I've seen the overall consensus of hard floor, soft ceiling. Makes perfect sense for all reasons listed in the sidebar (constant relative floor distance, aesthetics, getting the sense of ambience etc.) The company I'm using offers several floor finishing options and I've narrowed it down to one of two choices:

Carpet tiles:
http://www.mateflex.com/products/carpetflex/
MillCreek Flooring
https://www.youtube.com/watch?v=Di6Zn2VB4RU (long video - go to about 8:30 minutes into it. Also, they use the mahogany finish, I'd be using light oak.

Pros to carpet tiles for my sitch:
1. Absorption - the carpet on the tiles is not as thick as regular carpet so it won't suck up as much, but still give some absorption of mids and highs I believe?
2. Bass Trap? - curious to get a perspective on this. Because the whole floor also will have a small continuous air gap underneath and a fibrous membrane (carpet) on the front - will this also help with bass absorption theoretically?
3. Modular - if someone spills something, a tile can be taken up and replaced. If it wears, you can replace the worn section.
4. Comfort / thermal break - the tiles have spacers that raise it off the floor and provide a thermal break, making it warmer than the bare concrete or hard surface. Carpeting is easier on the feet, and can even be walked on barefoot which is huge for the kids and I.
5. Aesthetics - looking at the tan color - I like the hue in combination with the wall finish
6. Waterproof/moldproof - god forbid a plumbing leak, but safe here if that happens

Possible Cons:
I've read over and over 'don't put carpet in the control room - keep the floor hard. Carpet sucks the life out of the sound' Because these are a different animal, I guess I'm curious to get a perspective on how they react specific to acoustics. I've seen thin carpeting in control room pictures when using a simple Google search, so this has been a major point of confusion.

Pros to the MillCreek (PVC based wood flooring)
1. Hard surface, reflective - plays by the book for hard floor, soft ceiling
2. Aesthetics - looks good, more 'pro' or 'finished' than the square carpet tile look.
3. Also waterproof / mold proof

Cons:
1. Not modular - something gets damaged or cracked, scuffed (heavy speaker dents, etc), way harder to remove and isolate that specific piece without tearing up the floor
2. Slippery - floor traction is important in northern Ohio, esp with clumsy 10 year old students coming in on a snowy / rainy day with wet feet. Taking shoes off and walking around in socks also a challenge.

Given the two options, my gut keeps steering me towards the carpeting for all it's larger list of pros. Because it's thinner - I don't know how much it will differ acoustically from 'regular' carpeting, bit I'm hoping it will give just a bit of absorption and that the airspace under the tiles will work FOR the acoustic goal of the basement space by providing additional bass trapping. Given all of this information, what are your thoughts?

Once again, thanks Ethan, for all you've done for us home studio guys. Any helpful perspective you could give to this would be most appreciated.

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#2757705 - 02/21/16 10:55 AM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Furious G]
Ethan Winer Moderator Offline
MP Hall of Fame Member

Registered: 06/12/00
Posts: 8905
Loc: New Milford, CT, USA
1) For thicknesses of 6-8 inches or more, fluffy insulation is fine, and it costs less than rigid fiberglass.

2) I'm not optimistic you'll be able to do much about kids stomping around upstairs unless you do construction upstairs too.

I can't really tell you what floor type to get, though if it were me I'd go with carpet for its absorption and foot comfort. If you choose carpet, get something thick and push, and put a thick pad underneath. That extends its absorption down to at least the low midrange.

--Ethan

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#2757778 - 02/21/16 02:59 PM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Ethan Winer]
Rky Offline
Senior Member

Registered: 07/15/06
Posts: 162
Loc: Chicagoland,Illinois,USA
For the kids stomping, these ideas are from Rod Grevais' book Build Home Studio Like The Pros. Your post indicates you don't want to do this but if it's important to you... here it is:

First find out what amount of extra load your ceiling structure will carry. Then add mass to the underside of the subfloor with 2 (or 3?) drywall layers cut to fit and affixed directly the the subfloor then insulate the space with fluffy. Next the ceiling layers of drywall (2 or 3?) need to be decoupled with RC (resilient channel) attached to the joists and the drywall attached to the RC.

There are other things you can do too like add the mass to the floor above but if the floors are already finished that may not be what you want to do. You can also build a second ceiling below the existing but you'll loose even more headroom.

For efficient transmission isolation, use only 3 layers: the first mass, then air (or insulation) and finally another layer of mass (M-A-M). Each layer can be a composite of multiple pieces thick of drywall or whatever but don't have more than 2 composites layers of mass with one air space (insulation) between.

Here's a thread: https://www.gearslutz.com/board/studio-b...-like-pros.html


Cheers,
Rock

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#2757848 - 02/21/16 07:12 PM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Rky]
Furious G Offline
Member

Registered: 02/17/16
Posts: 10
Loc: Ohio
Thank you gentlemen, both, for the detailed responses and ideas.

Ethan, regarding the ceiling treatment, I think I understand the principal and result behind the idea but just want to clarify to make sure, so please correct me if there are inaccuracies in my line of thinking. Regarding the breathable fabric, it acts as a high (and some mid) frequency absorber, and the fluffy will also absorb some mids and low mids, If I go with the fluffy fiberglass, I want to stuff as much it (uncompressed?) into the joists as I can and fill the cavities all the way up to the floor above yes?

Regarding the wood joist cavities, (and the air mass pockets not taken up by the fluffy) these are acting as the bass traps. I noticed in the RealTraps videos that you try to space traps a bit from from the walls and corners when possible to get increased absorption in lower frequencies, and in the lower spectrum of the lower frequencies. On your webpage where you discuss this ceiling treatment option, your diagram shows the fabric, then rigid fiberglass, the air gap, then floor above in the joist cavities. Regarding bass absorption (cost aside) from a physics perspective, is it better to have the rigid fiberglass with air gap as pictured or the pink fluffy completely filling the cavities? I suppose I'm confused because it seems from a physics stand point I will get two different results. The cavities from bottom of ceiling joist to floor above measures about 7 inches - you said from 6-8 inches is fine, but is that the ideal win-win that will give me the best result overall?

Bridging from that line of thought, cost aside, regarding the fluffy stuff, 703, 705-FRK, or Rockwool (Roxul in my area) in respect to the ceiling treatment, what do you feel is the most well rounded material for my given situation? I know you said pink fluffy - I'm not sure I mentioned the other materials in the first post. I also keep seeing 'I would use rock wool, rockwool, rockwool…' recommended in forums in talks of bass traps, behind drywall etc. Haven't run across a thread that deals with this specific ceiling treatment that debates the pros and cons of the different materials. Would the difference in absorption behavior be negligible (and not justifiable from a money standpoint) if I went with rigid fiberglass or rock wool instead of the fluffy stuff?

Because the company I'm using offers a drop ceiling in their finishing options, I've strongly considered it - by it's nature a drop ceiling is decoupled and adds some mass for impact noise. I had seen another reply of yours to a post where you suggested to placing pink fluffy on top of all the ceiling tiles, (especially the perimeter / corners) where the individual already had a drop ceiling. From everything I've put together - it seems it's better not to have the drop ceiling in the first place yes? The biggest priority in room design is not creating a smaller 'shoebox' for large bass waves to get trapped in and misbehave - again, just making sure.

Rky, regarding the ceiling, part of the issue, as you read, is I don't want to lose any more ceiling height (a challenge shared by many and another reason why the drop ceiling didn't seem to be a good idea). If I added drywall to the cavities of the joists, would that help with impact noise a bit? I'm guessing the difference would be negligible because the vibrations are hitting the joist mass, and all of that is coupled.

From a different angle however, I CAN (and will) address the impact noise problem from above. The floors are hardwood and I plan to carpet the area that is above the mixing area (living room).

It seems I want to look towards a product that gives a large bump to the IIC rating based on preliminary research. I haven't done as much homework in this area, but I'm guessing the more effective the underlayment and the thicker the carpet, the softer the point of the 'blow' (or elephant stomps)? Is there an underlayment (Superfloor, GenieMat, Duracoustic S.T.O.P. etc) that anyone recommends in regards to giving the most bang for the buck before I lay the carpet down up there? Are there any other tricks (without damaging the integrity of the hardwood floor) that can help on the actual floor surface I can employ that will aid with impact noise?

Finally, (and back to Ethan), regarding the floor I think I'm going to go with the carpet tile option, for the comfort, flexibility (over regular carpet), the fact that they are mold-proof and moisture (again, it is a basement) will never cause a problem if something happens.

I've had no luck finding anyone's experiences with these in regards to how they react from an acoustics standpoint. Theoretically, I am for hoping for absorption of high (and some mid) frequencies and the airspace the tiles create with the concrete floor to provide some additional (probably nominal) bass trapping. If you turn the tile over, the polypropylene base that carpet tile is glued has a patterned square surface where you can see the bottom of the carpet which allows for some sound passage. The only thing I fear with using carpet is the 'sound sucking' or muddy effect that results from absorption of too many highs.

The link to the flooring material I'll be using again:
http://www.mateflex.com/products/carpetflex

Can anyone share some insight about the potential acoustic outcome of this product? Haven't had success finding usable testimony or experience relative to acoustics.

Thank you again everyone for your knowledge, helpful advice and insight!

Furious G

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#2758107 - 02/22/16 12:20 PM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Furious G]
Ethan Winer Moderator Offline
MP Hall of Fame Member

Registered: 06/12/00
Posts: 8905
Loc: New Milford, CT, USA
1st paragraph: Yes.

2nd & 3rd paragraphs: I never compared both ways - it's a lot of work to try two ceiling treatments in order to measure each, tearing one out before installing the other! But I'll guess that 12 inches of fluffy fiberglass filling the entire cavity is about as effective as 4-inch rigid fiberglass with 8 inches of air above. So do whichever costs less or seems easier to install.

4th: If it were my ceiling, and I didn't have upstairs isolation concerns, I'd skip the ceiling grid and just stuff the cavities then staple fabric under the joists. That costs less and gives more height.

Are those carpet squares really 11/16 inches thick? That's very thick, and so should be good acoustically. Don't worry about "sucking the sound out" of the room. Home-sized rooms where music is played should be mostly dead sounding. The notion that you want liveliness in a small room is a misguided audiophile concept. My Early Reflections article goes into great detail about that.

--Ethan

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#2759059 - 02/24/16 07:44 PM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Ethan Winer]
Furious G Offline
Member

Registered: 02/17/16
Posts: 10
Loc: Ohio
Ethan,

1st paragraph response - great! Thank you for clarifying.

2nd / 3rd paragraph - yes I agree that it would be quite a massive undertaking. The reason I raised the question - I've found about 6-7 definitive examples of people doing it the way you and Doug did his studio, but no one seems to report about the results after the work years later. Most will go into excruciating detail about the planning and progress, and then no word of if all that paid off. If adjustments had to be made after testing the room real world. Regarding the room that you guys did for the Ultimate Home Studio video, is Doug pleased with the results that he received now that he's had years of working it and the studio (specifically the control room) has been 'broken in?'

Regarding the floor tiles, here's a link: - (he talks about the carpet tiles specifically around two minutes in).
https://www.youtube.com/watch?v=WO-9XFxaLpw

These carpet tiles are very interesting. They are comprised of two parts: a polypropylene (semi-flexible but rigid plastic) base and the carpet tile insert. Each tile has 196 cone-shaped spacers underneath to raise the tile off the floor, and provide a thermal break (so the flooring is warmer and more comfortable than the basement concrete floor).

It doesn't create a floating floor in the traditional sense but there 1/4 inch air gap (height of spacers to the bottom of the tile) created when the pieces are all connected together. On top, there is a 1/8 inch recessed square where the polyolefin carpet tile adheres to the base. The actual thickness of the carpet itself is a little over a 1/4 inch. The total height of the the assembly (base + carpet) is 11/16 inch.

There is a photo on this site that shows the carpet and its base separately.
http://www.globalindustrial.com/p/buildi...18l-x-1218w-tan

I leaned towards this flooring originally because it seemed the design was optimal both for the basement environment (highly mold resistant carpeting material, modular, flood and future-proof), the comfort, and the acoustic treatment end of things. If you noticed there's a squared pattern on the top of the base where the carpet inserts. The carpet is not as breathable as a fabric you would use for a bass trap, but do you think, based on their design, that they will offer a small amount of bass trapping?

Appreciated your article on early reflections - refreshing to hear straightforward opinions based on common sense in respect to reflected sound in the home environment, not the ideal home environment imagined and then endlessly debated. Equally refreshing to finally hear a positive opinion / perspective on carpet with respect to its' use and absorption properties. My gut has told me from the beginning of planning materials for the space that carpet was the way to go and eliminating reflections is a good thing for my intended usage. I am trying to create as accurate and uncolored an environment as I can, as both a control room and recording area (mainly direct instruments, occasionally acoustic guitar, cajon) and a place learning for my students.

When it comes to carpeting, the words/phrases circling the forums: 'creepy,' 'unnatural,' 'TOO dead,' 'muddy,' 'lifeless' 'you want reflections off the floor.' 'NEVER carpet,' 'what major studios do you ever see that have carpet.' This has been a major source of confusion. I am working with a 24 x 12 x 7 basement, with given dimensions that I need to treat and make the best of - not a studio. When ever I've mixed in rooms with carpet, (and just a lot of absorption in general) when listening to direct sound from good monitors, it always seemed I had a wider stereo image, could distinguish highs / mids better (specifically differences in subtraction / addition of eq) because the room sound wasn't 'lively.' I guess I've always preferred the 'dead' sound but it always seemed strange to call that sound 'dead.' It's more exciting to my ears when I can hear 'just' the speaker rather than the delay, reflections and coloration of the room. Details to me come more alive and/ accurate.

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#2759119 - 02/25/16 06:45 AM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Furious G]
Rky Offline
Senior Member

Registered: 07/15/06
Posts: 162
Loc: Chicagoland,Illinois,USA
My 2 cents on the carpet tiles acting as bass traps is the 11/16" thickness is equal to, if my calculations are correct, the 1/4 wavelength of about 5 kHz. The basic idea of the porous absorber is that it will absorb it's best at a low frequency equal to it's 1/4 WL and above. Below that point, it's effectiveness rolls off as the frequency goes lower. Of course the specific materials come into play but in general, I don't think there will be much happening at bass frequencies but more significantly 5k and above.

Might be interesting if you can test your room before and after you install the carpet which BTW, I think is a good idea.

Cheers,
Rock

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#2759161 - 02/25/16 09:06 AM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Rky]
Furious G Offline
Member

Registered: 02/17/16
Posts: 10
Loc: Ohio
Rky,

After reading your post regarding Grevais' book, it got me thinking in more depth and I did some more research (forums, materials, etc). The goal, as you hit on the head, is best absorption AND isolation solution for the buck to a low ceiling equation in my case. The fluffy and fabric address the absorption, and if I can get some isolation on top of that, it would be a bonus. I want to be able to sing / belt some takes at 2:00 AM after a gig without worrying if it's going to wake the wife and kids up on the second floor. I know I cannot get TOTAL isolation given the limitations that I've presented myself, but want to do what I can. Aesthetics are also very important here too for what I need the space to do.

The killer in the mission statement is the 'for the buck' part. The basement finishing job itself is taking me to the cleaners. I'm a once and done guy though, and they guarantee for 50 years. The company is going to be doing the job about a week from now, and I'd like to be able to get the ceiling piece done in its' entirety shortly afterwards so I can really start working and be done with the construction part, just having to worry about bass trapping, diffusion and absorbing reflections with treatment on the walls as I go.

There were two solutions with the same goals in mind I've come across which seemed very similar to my situation

The first was one I ran across in Sayer's forum by a poster named knightfly seemed to follow Grevais' (M-A-M with additional A after the last M) that you spoke of intently:

10 inch deep floor joists, starting from subfloor above:

Layers within Joists:
1. 5/8 inch sheetrock glued to subfloor, acoustic sealant applied to joist/drywall contact
2. 2 inch of 3 1/2 inch soft fiberglass compressed
3. 2 inch of rigid 703 or rigid 3 pcf rock wool
4. Attached to joist 1.5 x 1.5 cleats on both inner sides of joist screwed and glued with another 2 inch of 3 1/2 inch soft fiberglass compressed in-between
5. Resilient channel attached to bottom of cleats
6. 2 more layers of 5/8 inch sheet rock (attached to resilient channel only), acoustic sealant attaching sheetrock to joist
7. 2 inch of 3 1/2 inch soft fiberglass compressed
8. 3. 2 inch of rigid 703 or rigid 3 pcf rock wool
9. Cloth covering / burlap
10. Bottom of joists cleated

The thread this is posted in has a picture that makes this easier to visualize (I hope it's ok to post links from other threads - if not, I'll take it down)
http://johnlsayers.com/phpBB2/viewtopic.php?f=2&t=475

This seems to be the be-all end all that I've found if you want to leave the joists exposed for absorption and isolation. Three concerns / adjustments I would have in my specific scenario:

1. Money and time factor it would take to do this on my end (I need to get working soon after the finishing is done and will have a bit more budget, but not a ton).
2. I only have 7 inch joists, so this would have to be modified
3. All this treatment seems like it would greatly help, but after all that treatment it still seems to me that the largest issue, the joists, will still be booming in my case. They are directly connected (coupled) to the subfloor and the transmission of the impact immediate.

The second solution I came across seemed to address the joists and use M-A-M from a poster named eirikur from the gearslutz forum:

1. Surround the joists and the subfloor with 12mm of huntonit (looked this material up - a bit confusing)
2. Then surround the layer of huntonit with a layer of 13mm drywall
3. In between the joists additionally Rockwool 45 sandwiched between 2 more layers of drywall

He also has a picture - which greatly helps me (I'm a visual guy)
https://www.gearslutz.com/board/studio-b...o-progress.html

The frustrating thing about all of these posts - there seems to be a ton of sound, solid planning and then no report on results and/or adjustments needed after the fact after work is done (recording, band rehearsal, to what degree it kept noise in the work environment and kept noise out from other areas etc).

Music is my living and this basement is going to be lesson studio by day, recording environment by night. Not a hobby. So the solution for the ceiling I come up with has to be a balanced four-sided square:

1. Sound isolation
2. Sound absorption
3. Aesthetically pleasing
4. Financially sound

With #4, it doesn't mean cheap, but if name brand product 'A' in the acoustic treatment area is two times more expensive as product 'B' that you can get in bulk at a discount store or more common, and has a negligible difference in the said acoustic goals - that's the kind of stuff I'm trying to find out ahead of time.

If possible, I want to use a substitute for drywall. As expressed, I don't want to cover the joists or lower the ceiling anymore, and want access to wiring and ductwork as well w/o having to cut through/replace/repair, so the traditional drywall ceiling is not the way for me. Trying to keep everything in the basement inorganic and moisture proof as well. (I know there's probably no way around this from the insulation angle). From the floor tiles to the walls, everything I'm using in the finishing (besides the laundry room doors - wood) have no organic materials for mold to feed on. Mass loaded vinyl, PVC etc…

Have you guys had any experience with or have any opinions about this stuff?:
https://www.youtube.com/watch?v=wv4IMnySxyc

Soo…all this being said, is do you guys have any thoughts and / or creative solutions on materials or specific approaches in addition to what's already been mentioned?

As an aside, the finishing contractor is updating the lighting fixtures and the wiring as well in the finished space. Regarding how the electrical, lights, outlets and fixtures should be run (separate circuits, placement of wiring in ceiling, types of recessed lighting fixtures) is there any thing you gentlemen could recommend to keep in mind for the '1 to 5 year down the road' philosophy that I have them do? I don't want to be looking at this job in any way at the end saying, 'I wish I would have thought of that.'

Link to lighting fixtures they typically use:
http://www.amazon.com/Cooper-Lighting-H27ICT-Shallow-Ceiling/dp/B000M5JU40

They also offer an option to Dryfall paint (black or white) the ceiling. Depending on how much $ I need to invest in treating the ceiling for the acoustic goals, I've considered this as well, because it seems like the treatment of the ceiling could turn into quite a project which could take longer than I expected. There will be this nice, finished area and then bare, exposed wood y'know? I like the industrial look and that might not be that bad for a bit in the interim. They said they would charge me $550 to paint the ceiling - not so sure that's a good value either.

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#2759173 - 02/25/16 09:30 AM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Furious G]
Ethan Winer Moderator Offline
MP Hall of Fame Member

Registered: 06/12/00
Posts: 8905
Loc: New Milford, CT, USA
Thick carpet over thick padding can absorb to below 1 KHz. It's not 100 percent absorbing! But it's still a useful amount:



After several years I can report that Doug's ceiling with 12-inch thick R38 insulation between the joists works very well.

--Ethan

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#2759190 - 02/25/16 10:13 AM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Ethan Winer]
Furious G Offline
Member

Registered: 02/17/16
Posts: 10
Loc: Ohio
Ethan,

Thanks again. As a visual guy, a picture (or a graph, or video) is worth a million words to me. After the basement is done my attention will turn (who am I kidding - it's already there) to the thickest, most effective underlayment for the carpeting in the living room upstairs. Any thoughts on specific products or materials?


Edited by Furious G (02/25/16 03:10 PM)
Edit Reason: Forgot to ask question

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#2759447 - 02/26/16 11:32 AM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Furious G]
Ethan Winer Moderator Offline
MP Hall of Fame Member

Registered: 06/12/00
Posts: 8905
Loc: New Milford, CT, USA
I'm not a carpet expert, but a competent carpet salesperson should be able to steer you to pads and carpet with more absorption.

--Ethan

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#2759773 - 02/28/16 11:15 AM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Ethan Winer]
Furious G Offline
Member

Registered: 02/17/16
Posts: 10
Loc: Ohio
Ethan, I'm leaning towards the Roxul Safe 'n' Sound product (less itch, fire resistance - God forbid). Do you think it's extra density will help slightly in the isolation side of things a bit?

I've seen a variety of opinions on the role of an 'airspace' in both isolation and absorption and its' effectiveness in the joists. In the video, you guys completely filled the joists with the fluffy.

I'm narrowing this down (I think) - looking at one of three approaches, and the one that will provide the best balance between absorption and and isolation. I think I understand the properties and sound consequences of the different treatments but correct me if I'm wrong.

1. One layer of Roxul (3 inches) on bottom of joist covered with breathable fabric (any suggestions?) leaving 3-4 inch air gap in the joist above the Roxul. For absorption, air gap will trap allow bass trapping at lower frequencies but will have the consequence of vibrating the subfloor upstairs resulting in lower isolation. High frequencies absorbed. Mids (most) absorbed.

2. Two layers of Roxul leaving a very minimal 1 inch gap between the sub-floor and top of the Roxul. Absorption, total high and mid, still don't have understanding of the difference of what this would do with bass as compared to one layer with the air gap. The increased density would help slightly with the isolation. Talked to the Roxul folks and they say the STC rating only takes a 3-5 point bump with two layers.

3. Fluffy fiberglass + Roxul + fabric. Roxul on the bottom of Joist. Guessing the sonic behaviors would be similar to treatment option 1?

4. Fluffy fiberglass all the way up. Easier on the pocket book, easier to get around ductwork and such. Guessing a slight noise isolation disadvantage because of decrease in density from fiberglass?

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#2759818 - 02/28/16 04:13 PM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Furious G]
Rky Offline
Senior Member

Registered: 07/15/06
Posts: 162
Loc: Chicagoland,Illinois,USA
G,

Are you still considering a layer or two of drywall installed between the joists? My guess is it would increase the STC the most using the least volume.

For #2 regarding LF absorption, if I'm correct, what I have learned from Ethan here is that more than 6" to 8" thick, higher density rigid FG/MW etc. is equal to fluffy. In other words, use fluffy for spaces >6" to 8". In your case, since you have 6"- 7" or so, it looks like it might be a toss up between rigid (Roxul in your case) and fluffy.

Cheers,
Rock


Edited by Rky (02/28/16 05:13 PM)

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#2759831 - 02/28/16 06:11 PM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Rky]
Furious G Offline
Member

Registered: 02/17/16
Posts: 10
Loc: Ohio
Rock,

The drywall piece between the joists is a large part of the equation I haven't figured out. Getting conflicting opinions. If it is worth it and will make an appreciable difference in bumping the STC. It's been 50/50 as far as opinions on this.

In my own head, the following is generally the physics of my impact problem right now. Sound waves are energy. Impact noises are very large concentrations of energy. If a foot, for example, hits the floor, sound radiates from that point of impact (and with my 'little ones' right now that impact sounds like they are double what they weigh). With respect to sound, the impact creates a thud, or combination of frequencies (heavily low spectrum weighted) which resonate into whatever surfaces are coupled / connected directly to them. My problem is the entire SURFACE area is coupled as far as the hardwood floor to the subfloor. The subfloor is connected to the joists.

The joists (and subfloor) become 'speakers' (esp for LF) which are the final resting points of this impact sound energy. So here's where the kicker comes in. Will adding drywall between the joists make an appreciable or a very nominal difference for the sound transmission going up, and specifically the impacts coming down?

I'm forgot to add a fifth goal to the original 4
1. Sound isolation
2. Sound absorption
3. Aesthetically pleasing
4. Financially sound

To add an implied 5th goal - 5. DIY novice (and novice is being generous) friendly. I'm a fast learner, but as stated before, I don't have a ton of free time to allocate to turning this into a lab experiment, so to speak. I've got to get this done pretty efficiently and turn my attention to other areas of the house (happy wife…happy…well, y'know the story).

I've tried to find an example of someone on the forums who has used drywall between shallow joists and fully filled them, but so far been unsuccessful in finding any result reports on if the acoustic outcome was satisfactory.

The logic makes sense of what you said for #2. Smaller space, go for higher density material. Also as a side, regarding the drywall between the joists, someone in another forum suggested against it because I'd be making the trapping cavities of the joists shallower, thus lessening it's ability to trap lower bass frequencies.

Thank you for addressing the drywall piece. I am literally 50/50 on that right now.

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#2759850 - 02/28/16 07:47 PM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Furious G]
Rky Offline
Senior Member

Registered: 07/15/06
Posts: 162
Loc: Chicagoland,Illinois,USA
G,

Without any actual results from specific tests, I think your 50/50 position is about the same as what I'd guess because I don't know either. The idea about adding mass to reduce footfalls might be going down the wrong road. The mass idea may apply more to airborne sound.

http://www.pac-intl.com/pdf/Condo.pdf

The above suggests soft floor coverings (carpet?) and underlayment. I believe you were going in that direction anyway.

Did you get on the geraslutz forum and ask Rod?

Cheers,
Rock

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#2759991 - 02/29/16 10:21 AM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Rky]
Furious G Offline
Member

Registered: 02/17/16
Posts: 10
Loc: Ohio
Thanks for the link Rock.

Threw a post up on Gearslutz similar to this Lumbergh and norton chimed in to give some helpful advice. Haven't seen Rod.

Lumbergh pointed me to this calculator:
http://www.acousticmodelling.com/multi.php
You plug in the materials, and it gives you an absorption graph. I haven't had much luck finding the flow resistivity factor of Roxul (which is one of the things they ask for for the materials.) I like this kind of thing though. Like to see it, hear it.

To Ethan, as an aside, thank you again for your (and Doug's) video 'Hearing is Believing.' Wonderfully done and one of the most effective demonstrations for why a room needs treatment. If my wife (who is not a musician) can hear sound improvement, it is not just a subtlety. I noticed a lot of folks like to go on and on in these forums about the theory, and principal of a thing, but yours is one of the few videos that allows the individual to HEAR the difference of treatment. As I expressed, I've had trouble within the multiple forums finding feedback on the results of said treatments in all of these rooms after they were done.

This journey into practical acoustic treatment, and learning your space's needs has been an extremely educational (sometimes admittedly frustrating) journey. I am surrounded by gear heads, esp when it comes to the guitar players and studio end of things out here. 'I got the (fill in the newest, most expensive, most technologically advanced mic, mixing board, guitar modeler, etc,' 'you're still mixing with that?' 'that modeler is 5 years old,' 'dude, if you're really serious, you should definitely step up to (fill in $1000 piece of gear) if you want your mix / guitar sound etc to be great.'

I can count on one hand the folks that don't look at me like a deer in the headlights when I say that I'm good with my gear - I have to make my new room sound good first. The analogy is when I see a guitar player come into a 200 person club with a half stack. Or the guy who buys a Lamborghini in Cleveland. Where are you going to drive that car? Unless it's just for show, is this pothole filled, seasonal road environment suitable to maximizing your purchase?

Sorry - rant done. Not a ton of guys making a living off doing music here either, much less feeding their family doing so. Maybe they're actually the smart ones…LOL.

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#2760104 - 02/29/16 05:49 PM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Furious G]
Furious G Offline
Member

Registered: 02/17/16
Posts: 10
Loc: Ohio
Just found a decent resource if it helps anyone else. The document is called "Controlling the Transmission of Impact of Sound through Floors." Gives a pretty comprehensive coverage of IIC ratings for different floor assemblies and materials. Looks like it was published by the Institute for Research in Construction - National Research Council of Canada.

Link:
https://www.nrc-cnrc.gc.ca/ctu-sc/files/doc/ctu-sc/ctu-n35_eng.pdf

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#2760403 - 03/01/16 07:51 PM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Furious G]
Furious G Offline
Member

Registered: 02/17/16
Posts: 10
Loc: Ohio
Ethan,

Do you think this stuff would perform well with the given ceiling treatment as an alternative to standard fabric or hurt my cause? Worried about fabric sagging over time as well as attracting dust.

Vinyl Coated Mesh Fabric


Edited by Furious G (03/01/16 07:56 PM)

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#2760459 - 03/02/16 05:06 AM Re: Optimizing Basement Acoustics - Balancing Treatment Usage [Re: Furious G]
Rky Offline
Senior Member

Registered: 07/15/06
Posts: 162
Loc: Chicagoland,Illinois,USA
Hi G,

Thanks for the link for floor impact.

About the mesh, it's my guess is will work fine acoustically but I question that it won't encapsulate the insulation fibers very well.

You're right to question the attraction of dust issue. Here's a somewhat related little story:

In the '80's when my bandmates and I smoked heavily, we built a home studio with mineral wool set in 2x4 framing on the walls covered with white burlap. The building had hot water heat and no central ventilation so when we all smoked, the room filled with a dense fog of smoke. Someone gave us a negative ion generator and when we turned it on the first time, wow, the smoke disappeared almost instantly! So we continued to use it. After a few weeks, I noticed the burlap fibers were extending out from the wall horizontally and were kind of brownish, yuck. I took a piece of tissue and dragged it over a section of the burlap and collected a nice sample of smoke and nicotine residue, double yuck.

So yeah, fabric can attract smoke and I guess dust too, especially if you charge the air with a negative (or positive?) ion generator: )

But seriously, as long as you don't smoke like a chimney, I don't think fabric would be a problem. I use those lint roller things to pick up dust off of fabric items all over my house where a vacuum cleaner is not practical or handy.

And finally, unless there is a charge involved, it's my impression that little dust will collect on the ceiling anyway. Pick a color like grey (the color of dust:) My 2 cents.

Cheers,
Rock

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