200mm Concrete slab db transmission loss

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200mm Concrete slab db transmission loss

Postby Bob » Wed Mar 10, 2004 11:23 pm

Does anyone have the multi-frequency transmission loss for a 200mm concrete slab ceiling (all by itself).

I want to compare it to Acoustik Mat, which when used in a system of: 200mm concrete slab + Acoustik Mat + floor ceramic tile gives

125hz 40db
160hz 43db
200hz 46db
250hz 49db
315hz 52db
400hz 55db
500hz 56db
630hz 57db
800hz 58db
1khz 59db
1.2khz 60db
1.6khz 60db
2khz 60db
2.5khz 60db
3khz 60db
4khz 60db

I tried using Insul.exe with a concrete density of 2242 kg/m^3, but I don't believe the results. Some webpages say that 200mm of dense concrete is STC 35, and others say it's STC 50.

Someone in another forum suggested that it's better to use this AcoustiK Mat than drywall on a floor over 2x10 wood joist system. ie.
a) carpet, underlayment, OSB, Acoustik Mat, OSB, 2x10 with insulation, 2 layers of gypsum, VS
b) carpet, underlayment, OSB, two layers of drywall, OSB, 2x10 with insulation, 2 layers of gypsum

1.59$/sqft cdn for 2' x 4' x 1/4" thick Acousik Mat (made from recyled tires)
Acousik Mat of 2' x 4' x 3/8" is 12lbs and the other acoustik 2' x 2' varies between 5lbs to 10lbs. The #304 1/2" is almost 12lbs.
Regards
Bob Golds
"The only thing we regret in life is the love we failed to give."
"Be a rapturist -- the backward of a terrorist. Commit random acts of senseless kindness, whenever possible" - Jake Stonebender
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Postby Eric.Desart » Thu Mar 11, 2004 7:18 am

Bob,

Do you have a link for this Acoustic Mat?

Eric
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Postby Bob » Thu Mar 11, 2004 8:09 am

Hi Eric:

They don't have a website.

I don't have a website large enough to put the pictures/brochure/laboritorytest they emailed to me earlier today, so I've emailed them to you.
Regards
Bob Golds
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Postby Eric.Desart » Thu Mar 11, 2004 9:55 am

Bob,

This is a standard type of floating floor, with a somewhat better property.

However when you look at the measurements you can notice that it doesn't do very much in the low frequencies, and even cause points where it becomes worse.
Note that the measurements only start at 100 Hz. The lower are worse.

Again this is the typical Mass-spring resonance behavior.

In fact the basic measurement of the original naked floor is included, but in a manner you aren't used to see it.

How is this measured?
There are 2 rooms on top of one another. The floor is designed as a standardized concrete measurement floor.

One puts a normalized hammering machine on top of the floor.
In the room below one measures the noise pressure.
One does this for the basic normalized floor, and for the same floor with the added floating floor.
That how impact noise is measured.

However there is a direct relationship with noise insulation.
This means, that where the curves remain about equal, you also won't have added sound insulation. Where it is negative you have amplification (higher sound pressure in recieving room). Where the difference is large (lower sound pressure in recieving room) you will have more sound insulation.

Basically you can compare both the original and the treated floor.

The difference is that the emission side is excited by a hammering machine rather than airborn sound. But the basic principles remain the same.
What you see on those graphs are the sound pressure levels in the receiving room for both untreated and treated floor.

Best regards
Eric

PS: I've no time, but if you look at google for measuring impact noise or look at B&K or others you certainly can find a picture of such a normalized hammering machine. (I don't know the English notion for it)
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Postby Bob » Thu Mar 11, 2004 10:53 am

Thanks for having a look Eric.

In fact the basic measurement of the original naked floor is included, but in a manner you aren't used to see it.
I see it now, the naked floor is on the top of the graph. It's the FIIC34 line.

However when you look at the measurements you can notice that it doesn't do very much in the low frequencies, and even cause points where it becomes worse.
I don't see that. I see a 28db TL drop at 100hz, and a perhaps an 8db transimission gain at 3125hz in one test (OCTAVE-ACOUS-5-.GIF). But given your traditional concern for the sub 250hz region I'm wondering if you see something 'worse' in the 100hz to 250hz on that graph that I'm not seeing.

Why does the one black line go down at high frequencies, and the other one go up? There must be something else to this test that I'm missing.

I don't have any published frequency data on concrete walls to compare this with. I've only got a bunch of wall diagrams with single STC values.

I'll do the google hunt you recommended and see what I turn up.
Regards
Bob Golds
"The only thing we regret in life is the love we failed to give."
"Be a rapturist -- the backward of a terrorist. Commit random acts of senseless kindness, whenever possible" - Jake Stonebender
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Postby Eric.Desart » Thu Mar 11, 2004 11:18 am

Bob,

I haven't studied the graphs in detail.
I explain the principle.

Every measurement will deviate a bit from one another.
Therefore it's even not interesting to find another 200 mm concrete floor measurement.
Such a graph clearly shows the principles and the behavior of the floor.

And the main principle here is:
This is a good floating floor for impact noise and sound insulation for low mid to high frequencies, and a bad floor for sound insulation for bass.

And there is NO magic material that can solve this since once more this is defined by the mass-spring resonance. Sometimes one doesn't see this mass-spring very clear due to damping of the floor combination, but that does not mean that it won't show more clear in other combinations.

Understand this and learn about it, and you will interpret such graphs based on acoustic principles rather than individual numbers, which will be different (more or less) anyhow in real life circumstances and between labs.

Only to find the reason for those slight dips and bumps, causes for an enormous amount of calculations and are probably to be assigned to the modal behavior in the floating floor or basic floor itself, which are specific for THAT measurement, with THOSE sizes and build-up.

Best regards
Eric
Last edited by Eric.Desart on Thu Mar 11, 2004 11:54 am, edited 1 time in total.
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Postby Eric.Desart » Thu Mar 11, 2004 11:34 am

Hello Bob,

I'm sorry, that I don't answer all your questions.
It's I don't have the time to go in-depth on all those things.

This isn't your fault at all so don't take this personally (I'm the guilty one).
I'm a bit overstressed lately having some health issues here. So I need to do more than I have the energy for.

I see you want to understand. I really respect and admire that.
But I can't give courses via a newsgroup, try to find a course from one or another Univ or something, to do this systematically. Or find a book about building physics or acoustics.

This top line on the graphs goes up in the high frequencies because such a hammering machine will excite high frequencies stronger than low frequencies in plain pure concrete.
This has to do with weight and the relation spectrum versus impact time etc. and no I'm not going to explain now.

Best regards
Eric

PS This message sounds less friendly than I meant. So read it and think I meant well.
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Postby Eric.Desart » Thu Mar 11, 2004 12:34 pm

Hello Bob,

A link to show some question marks
http://pcfarina.eng.unipr.it/Public/Pap ... oise93.PDF

Kind regards
Eric
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Postby Bob » Thu Mar 11, 2004 12:42 pm

Thank you again for your efforts, Eric.

Or find a book about building physics or acoustics.

Is there one you would recommend for me, available in english at amazon.com ?

(I'm currently reading Room Acoustics by Heinrich Kuttruff and finding it mostly dull.)
Regards
Bob Golds
"The only thing we regret in life is the love we failed to give."
"Be a rapturist -- the backward of a terrorist. Commit random acts of senseless kindness, whenever possible" - Jake Stonebender
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Postby Eric.Desart » Thu Mar 11, 2004 1:07 pm

Bob,

I entered a temporary topic in the links section for books

Classics are:
Beranek, Kinzler and Cremer

But I have my own stuff (course material in Dutch) and some German books.
So others can maybe point you better.

Eric
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Postby Eric.Desart » Thu Mar 11, 2004 5:26 pm

Hello Bob,

I re-entered a link here where the same two walls, build with very clear instructions, based on materials from the same production lots are compared in 24 European Labs.
This intercomparison was specially organised and funded by the European commission to check the compatibility between labs.

Check this and you will notice that interpreting measurements is not a matter of exact absolute values at specific frequencies.
Those walls were build in official accredited labs, with extreme care to guarantee maximimum compatibility between those measurements.

So, if one sees some strange numbers then:
1) They can be explained by experience as e.g. flanking, modal behavior, niche effects, measures etc., etc.,
2) A lot can't be easy explained.

So comparing measurements, can't be done by just strictly assuming that some differences really represent a difference in sound insulation.

Measurements & Testing Programme 1990-1994
Intercomparison of Laboratory Measurements of Airborne Sound Insulation
of Walls

http://web.unife.it/progetti/inter_lab/

(Had some trouble to find link back = changed versus the previous one we had, they renewed and reorganized their site)

Best regards
Eric
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Postby Bob » Thu Mar 11, 2004 7:49 pm

Hi Eric:

Thank's again, I'll look through the book list.

In thread I made two requests for concrete wall comparisons. I thought I'd explain my reasoning.

The first request was to compare the actual graph presented by AcousikMat when I didn't realize both floor systems were already on the same graph. Obviously comparing at the same time, with the same equipment, by the same tester, is somewhere between the best way and the only way. My bad.

The second request was because I tend to learn by examples. In this case it's a mass-spring issue, so I wanted to see some numbers on some other wall systems involving an 8" solid concrete wall. With that I could use those as both: intuition starting points (the spring isn't air here, the spring is also mass), and if I do the math it's good to have real results to compare against to see if I'm doing the math remotely correctly.

The well respected fellow in the other forum suggests that AcoustikMat is so much better than drywall on a floor that he would spit on anyone who put drywall on the floor. Rod Gervais seems to go the other way, at least for walls, and anything not involving gypsum he scoffs at because it costs more or works less. So the two experts disagre, which makes a mess of both rules of thumb (gypsum is good, and follow the experts). Which leaves me with your suggestion of analysing the discrete components and their acoustic interaction from an acoustic point of view, which is obviously still complex for me.

That brings me back to my own floor, which I'm still thinking of floating on kinetics RIM pucks. Like Paul, I'd not only like to know if it makes sense to have a floor of OSB/AcoustikMat/OSB on top of it, but why. And if such a OSB/AcoustikMat/OSB layer would be a triple leaf floor again.

Be well Eric.
Regards
Bob Golds
"The only thing we regret in life is the love we failed to give."
"Be a rapturist -- the backward of a terrorist. Commit random acts of senseless kindness, whenever possible" - Jake Stonebender
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Postby Eric.Desart » Thu Mar 11, 2004 10:08 pm

Hello Bob,

You do have too much energy :):):)

You're mixing messages from different groups together.
If you have a clear question point by point, I can try to answer them.
I'm no good in, or don't feel like puzzling. And I'm not checking every calculation you come up with. So it's easier to discuss clear defined principles and questions.

I have the feeling that you mix all kind of points trough one another.
What does have a floating floor to do with drywalls etc.?

Kind regards
Eric
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Postby Bob » Thu Mar 11, 2004 11:27 pm

Hi Eric:

Don't worry about little ol me.
When there is easy answer, that's great.
When there isn't (and so I get a few tidbits) that's fine too.

I think I've figured out what I'm going to do to isolate my room, but it'll probably take me a month to draw it all up and present it for comments and change recommendations. That at least will be very specific.
Regards
Bob Golds
"The only thing we regret in life is the love we failed to give."
"Be a rapturist -- the backward of a terrorist. Commit random acts of senseless kindness, whenever possible" - Jake Stonebender
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Postby Paul Woodlock » Fri Mar 12, 2004 1:25 am

Bob wrote:Hi Eric:

Don't worry about little ol me.
When there is easy answer, that's great.
When there isn't (and so I get a few tidbits) that's fine too.

I think I've figured out what I'm going to do to isolate my room, but it'll probably take me a month to draw it all up and present it for comments and change recommendations. That at least will be very specific.


Hey Bob!

Have you sorted out a plan for that dirty great I-Beam yet?


Paul
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Postby Bob » Fri Mar 12, 2004 2:31 am

Hi Paul:

The current plan is for a flat ceiling lower than the i-beam (no double i-beam, and no soffets).

This'll give me a space between leafs (flooring and gypsum) of about 16" or 400mm.
The lower double gypsum layer may be supported by Kinetics Springs with wires going down to a hat channel grid. This ceiling would be between RSIC walls, double gypsum both sides. The floor would be inside the walls as well (no floating walls, no double walls), on Kinetics RIM pads. The doors would be the double doors that I described at RO, although perhaps with sheet lead inbetween instead of gypsum.
Basically it's a very simple, very easy to construct room, that should take care of my various isolation problems.

Isolation problems include
a) I'm in an end townhouse, and although I've got 8" poured concrete walls, they only go up to the joists. I can hear my neighbours television through the walls on the next floor up.
b) the joists between units are not quite shared, but they are attached to each other.
c) my 50db furnace
So, the less sound I let get to the joists, the less noise makes it upstairs and to the neighbours.

Also the extra ceiling space gives me
a) enough room to run ductwork using multiple S-bend insulated flexible 6" ducts.
b) insulation under the between-the-joist-return-air under the gypsum layer I was planning on putting there.

Obviously this leaves me with less ceiling, and reduces my ability to put horizontal corner traps and ceiling absorbtion, since my new room becomes 78" tall. (6'6" or 198cm).

I had some cute ideas for wall absorbtion/difusion based on an idea by Russ Herschelmann. What you're looking at here is http://www.home-theater-guy.com/images/250_acoustic.jpg yellow is 4" of fiberglass, with Model C Art Diffusor http://www.acousticsfirst.com/artdif.htm and it's hard to see from the picture but the wood paneling on the bottom is spayed back (4" at top, 0" at bottom) to deflect the sound down into the floor.

The questions (for me, not Eric!) are:
a) Should I use Kinetics ICC, or do I have to extend my joists down to connect ICW springs. http://www.kineticsnoise.com/architectu ... ation.html The simple way of using ICC makes my room 192cm tall (too short), whereas ICW's could make the room 198cm, but it's hard extend the joists. On the other hand the rod/bolt in the middle of the ICW is probably a simple rod/bolt so if I could find one the length I want (longer) then I'd probably be ok to use ICW.
b) does the rest of the room still work with the shortened vertical space.
c) draw all this up so that people can see and understand, including framing and wiring diagrams.
Regards
Bob Golds
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"Be a rapturist -- the backward of a terrorist. Commit random acts of senseless kindness, whenever possible" - Jake Stonebender
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Postby Eric.Desart » Fri Mar 12, 2004 1:22 pm

Bob,

A minor comment.

I had a look to this STC calculator you referred in RO.

That's typical a show document.
They energetically average STC insulation based on a simple surface weighting.

This can give some idea but mathematically this is wrong. You can only calculate a weighted STC based on weighted frequency band values.

So the front page is more impressive than the content of this file.
I find this file more confusing than helpful.

Also the show with the gaps etc. is only calculated as a surface with STC = 0.

Eric
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Postby Bob » Fri Mar 12, 2004 8:38 pm

Eric:

I'm not sure why this post is in this thread, rather than in 'door seal calcs'.

I had a look to this STC calculator you referred in RO.

I presume you're referring to http://www.componentacoustics.com/Sound ... lator.html
You can only calculate a weighted STC based on weighted frequency band values.
For a change I disagree a bit. Although if I can paraphrase from Star Trek, I still trust your instincts better than my facts.

I have the math for the sort of calcs that they are doing in that sheet, and I even checked the calcs using my math independantly of the technique that they are using and it's ok.

Although the words 'STC' are being banded about on the spreadsheet, if you ignore that and use the calculation ability by entering db TL for each frequency one at a time, and write the results down for the usual 125/250/500/1k/2k/4k, then you do get the frequency band values.

When using the spreadsheet I ignore the top parts about Walls/Floors/Doors/Windows and just use the 'custom' part at the bottom. Relative to doing the log math, I find this spreadsheet to be quite a timesaver.

The first time I saw these calcs being done for gaps around doors was in http://www.mom.gov.sg/MOM/OHD/Others/N&VIBPart4.pdf on page 5, where they did the same calcs as the spreadsheet showing one frequency, but recommending that the calcs be done over and over for each frequency band.

The only problem is
It's hardly possible to calculate this correct.
A gap is as well a filter as a resonant channel.

Obviously 100% correct is impossible here. I was hoping for a +- 4db accuracy.
I'm not sure if your comment makes the whole exercise of using the spreadsheet pointless for this door-gap-seal calcs, although it should still be useful for door vs wall estimates. But apparently we can't calculate the door.
Regards
Bob Golds
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Postby Eric.Desart » Sat Mar 13, 2004 9:29 am

Bob wrote:Eric:

I'm not sure why this post is in this thread, rather than in 'door seal calcs'.
I had a look to this STC calculator you referred in RO.

I presume you're referring to http://www.componentacoustics.com/Sound ... lator.html
You can only calculate a weighted STC based on weighted frequency band values.
For a change I disagree a bit. Although if I can paraphrase from Star Trek, I still trust your instincts better than my facts.
.


Sorry, I hadn't seen this "door seal calcs" thread yet when I entered my message. If I did, I should have put it there. So you're right it's better placed there.

Yes I referred to that calculator.
And this are not my insticts but just acoustic math.
STC is not an energetic weighting. Only this fact alone makes it uncorrect to use a related single number rating as basis for a subsequent energetic calculation.
If I'm not sure about something, or I tell an opinion or assumption, I clearly will state that.

It will be about correct, but how correct ........?
STC (told about it before) tries to represent an energetic weighting, but dates from a period that logarithmic calculation, due to the lack of calculation means (therefor only accessible or usable for few) is arithmetically and graphically build-up, with additional boundary conditions to limit possible errors.
This means that STC can and will range between + and - errors. Using those numbers for further calculation can cause those errors to be reenforced or neutralized. You just don't know.
So the only manner to calculate this correctly is calculating the individual bands and THEN applying the STC calculation procedure.

They calculate gaps plainly as a surface with a 0 dB TL. I can assure you that small gaps with a relative large depth versus width do not just behave as a simple surface ratio, but have a modal behavior and act also as a filter.

Furthermore they just average everything as if one can do one single thing with the averaged TL of a total room as if one wants to calculate the total soundpower radiated by a room when somewhere free-hanging in space.

As such this calculator is 1 single formula, questionably applied, without any reference to, or explanation of the question marks, and the rest is show.
They better should have shown the formula and explained how it can be used.
Or explain something on this calculator page.

Kind regards
Eric
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Postby Bob » Sat Mar 13, 2004 4:40 pm

They calculate gaps plainly as a surface with a 0 dB TL.

I thought they did that because they had doors without seals, you could blow through the gap around the door, hence 0db.
So in RO I tried to use 30db TL for seals, because I remember reading that for some compression seal advertisement somewhere. There could be better seals, or worse seals, and of course different TL for different frequences for seals.

Your note that the gap behaves differently than a flat surface makes sense.
Since it's a door, who's primary duty is to reduce noise through it, a Filter, which reduces transmission at various frequencies, is a good thing so I'll ignore it and just smile that it's there.
For Model behaviour I'm wondering if it's a bit like mutliple tubes (depth of gap, width of gap, perhaps an angle?). Resonance in a tube, amplifying a few frequencies, and if so would it help to have the spacing between seals set to some multiple of that. Basically try to build a filter at the resonance, or perhaps a little helmholtz in the door itself.

Does anyone know if it is it easier to open a door with rubber compression seals around the thin side of a door, or with felt around the thin side of the door?

Changing the subject a bit (i.e. back to the thread topic) I've found that I do have multi-frequency TL numbers for concrete wall systems in Noise Control In Buildings by Cyril M. Harris. I may inter-compare within the wall systems in the book (e.g. those with magnetic seals and those without - to give me approximate TL numbers for magnetic seals for multiple frequencies)
Regards
Bob Golds
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"Be a rapturist -- the backward of a terrorist. Commit random acts of senseless kindness, whenever possible" - Jake Stonebender
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