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Author Topic: Mass/Isolation/Frequency transfer data  (Read 4558 times)

Sigert

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Mass/Isolation/Frequency transfer data
« on: March 17, 2009, 12:02:13 pm »

Is there data available describing correlation between mass, isolation and frequency? Or is this the sort of data people pay for?
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Ethan Winer

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Re: Mass/Isolation/Frequency transfer data
« Reply #1 on: March 17, 2009, 03:15:27 pm »

There's a ton of info here, and elsewhere on the same site:

 http://www.greengluecompany.com/understandingSoundproofing.p hp

--Ethan

Sigert

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Re: Mass/Isolation/Frequency transfer data
« Reply #2 on: March 17, 2009, 04:45:06 pm »

That's very nice info Ethan, thanks. It confirmed what I'd already gathered so far: STC is not an appropriate qualification when dealing with (live) music.

I'm still without an answer to my question though.
Given a space devided in two by a single leaf wall with infinite length and width. If I put a rockband on one side producing 115dB of rock 'n roll noise (with equal energy in all octaves), and a grown person (with no abnormal hearing loss) on the other side, how many Kg/m
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Thomas Jouanjean

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Re: Mass/Isolation/Frequency transfer data
« Reply #3 on: March 17, 2009, 05:36:28 pm »

Maybe time to enrole in a proper engineering course Sigert...  Rolling Eyes

To put you in the right direction:

- What happens when I double the mass?
- What about rigidity?
- Snell-Descartes law... since we are in a random incidence in your case.

3 more related tips:

index.php/fa/11700/0/
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Thomas Jouanjean
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Sigert

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Re: Mass/Isolation/Frequency transfer data
« Reply #4 on: March 17, 2009, 06:39:06 pm »

Thanks Tomas. That should keep me busy (read: quiet) for a bit. Time to crunch some numbers. Munch munch Smile
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Sigert

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Re: Mass/Isolation/Frequency transfer data
« Reply #5 on: March 17, 2009, 08:59:37 pm »

Z = impedance
m = mass
theta = angle of incidence (relative to normal incidence)
c = speed of sound in air

D = Angular momentum?? (whatever it may be)
EDIT: Is this the target frequency, but converted to radians?
w = Angular frequency?? (also at this point, still a mystery to me)
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andrebrito

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Re: Mass/Isolation/Frequency transfer data
« Reply #6 on: March 22, 2009, 09:06:24 am »

There are several models to calculate these, some are a really pain in the ass taking into account flanking transmissions.

But I would say you would have to be crazy or immensely rich to want to have a rock band rehearsal space near a space someone living particularly at night.

Noise disturbance laws are VERY strict.

BTW

w = 2 * pi * f


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Sigert

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Re: Mass/Isolation/Frequency transfer data
« Reply #7 on: March 27, 2009, 09:59:24 pm »

Quote:

What happens when I double the mass?

If I understand things correctly, adding more mass to a boundary will lower its resonance frequency AND increase its resistance to excitation.
Quote:

What about rigidity?

Rigidity seems to be the resistance of an object to being deformed under stress. Rigidity is not a direct property of a material. It relies both on the geometry of the body and on the elasticy of the material.
Quote:

Snell-Descartes law...

In physics, the laws that describe the deflection of a wave as it makes its transition from one material into another. The measure of change in angle is a constant, a property of the material itself.

Tieing things together proves to be a toughy. Th
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Thomas Jouanjean

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Re: Mass/Isolation/Frequency transfer data
« Reply #8 on: March 28, 2009, 06:54:12 am »

Z is impedance. 'm' is mass of the partition in dAN (or ~kg) per m
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Thomas Jouanjean
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J.F.Oros

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Re: Mass/Isolation/Frequency transfer data
« Reply #9 on: March 28, 2009, 08:32:16 am »

That graph would have been even more interesting if we could zoom on the 0-500Hz range (where the fun usually is  Very Happy ).
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Thomas Jouanjean

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Re: Mass/Isolation/Frequency transfer data
« Reply #10 on: March 28, 2009, 12:28:45 pm »

J.F.Oros wrote on Sat, 28 March 2009 07:32

That graph would have been even more interesting if we could zoom on the 0-500Hz range (where the fun usually is  Very Happy ).


I know.

We live in a crual world.

(If you look carefully you can see "it" though. The beast.  Twisted Evil )

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Thomas Jouanjean
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Sigert

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Re: Mass/Isolation/Frequency transfer data
« Reply #11 on: March 30, 2009, 11:41:20 am »

I can't find any info on those formula you posted earlier, Tomas. And nobody I talk to seems to know anything usefull about them either. Maybe I just hang out with the wrong people. Laughing

Re-reading the first formula, it occured to me that (assuming a broadband source) the only variable is mass. So that must be what people refer to as the 'mass law', right? Doubling the mass means doubling the isolation of a boundary. That seems reasonable for a single leaf wall, from what I read, up to its primary resonance frequency.

Second question: in those formulas, what does 'D' stand for?
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Thomas Jouanjean

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Re: Mass/Isolation/Frequency transfer data
« Reply #12 on: March 30, 2009, 01:56:52 pm »

'D' is rigidity of the partition. It's calculated like that:

D= (Eh
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Thomas Jouanjean
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Sigert

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Re: Mass/Isolation/Frequency transfer data
« Reply #13 on: March 31, 2009, 09:07:47 am »

I took both the "mass law" and "Rigidity" formula given earlier in this thread and whipped up an Excell graph. Pretty huge numbers there, but not at all sure what they mean. I can't believe these are in themselves isolation values. That'd be crazy. Surprised

Data used in calculations is what info I gathered about a 2layer sheetrock wall.
h=0.025 m
E=2,3*10^9 N/m
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andrebrito

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Re: Mass/Isolation/Frequency transfer data
« Reply #14 on: April 01, 2009, 04:32:31 pm »

Place the x axis in log please ! Much better way to check that chart
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