the worlds cheapest sound isolation tips

[Brian Dayton]

Not that it makes a difference from a practical point of view (since one shouldn't build concrete ceilings without rebar),
but do you think the flanking sound travels mostly through the concrete, or mostly through the rebar ?

if i tap my foot on the floor of my office

[humor]If you get that foot calibrated, think of the money you could save on IIC tests.

i know, those tests are even worse than wall tsets.  I cry alot when i think it (running alot of IIC tests).

I think its through the concrete, or the concrete + rebar system (if the concrete is actually bonded to the rebar)


if you bond something stiff inside something else stiff they behave mostly like a simple single system as long as the wavelength of sound is alot bigger thant he thickness of the system.

[Eric Desart]

An interesting recent document which is made and related to new Belgian standards 2006 related to flanking, impact and airborn sound in linked houses or appartment buildings.

Disadvantage: It's Dutch, but 90 % (or at least lots) are self explaining pictures. I assume there must also be a French version, but haven't looked deep enough yet.
 And English we normally don't bother too much about that ( these few other guys not speaking Dutch ....).

Be carefull please with copyright when using the pictures.  This doc is from an official institute.

http://www.destadswinkel.be/test/downlo ... olatie.pdf

You'll see that floating floors are really a standard concept for us when comfort insulations are desired.

Eric

Bert, if you want to more correct use flanking numbers then use EN 12354 and not that old graph.

[Savant]

Brian,

On the origins of the STC curve, I did a little hunting in the JASA archives.  One of the better papers I found was:

Sound Insulation and the Apartment Dweller by T.D. Northwood in JASA Vol 36, No. 4, April 1964.

It gives a little background, plenty of opinion, and even delves into NC curves, which - like STC curves - were relatively new back then, too.

It would appear that other references point back to the committee that developed ISO 717.  It seems the intent, at the time, was that the ASTM committee was basically following the ISO committee's lead on sound isolation rating.  It wouldn't appear that it fully happened that way.  When/why STC diverged from Rw might be something we never know.  (Or do we know?  Maybe it's just me?  :? )

[Brian Dayton]

Brian,

On the origins of the STC curve, I did a little hunting in the JASA archives.  One of the better papers I found was:

Sound Insulation and the Apartment Dweller by T.D. Northwood in JASA Vol 36, No. 4, April 1964.

It gives a little background, plenty of opinion, and even delves into NC curves, which - like STC curves - were relatively new back then, too.

It would appear that other references point back to the committee that developed ISO 717.  It seems the intent, at the time, was that the ASTM committee was basically following the ISO committee's lead on sound isolation rating.  It wouldn't appear that it fully happened that way.  When/why STC diverged from Rw might be something we never know.  (Or do we know?  Maybe it's just me?  :? )

if you read the standard that teaches how to calculate STC - ASTM E413 -  you find some itneresting things.  It states the intended utility of the single number rating

"These single-number ratings correlate in a general way with subjective impressions of sound transmission for speech, radio, television, and similar sources of noise in offices and buildings. This classification method is not appropriate for sound sources with spectra significantly different from those sources listed above"

I guess that basic commentary and the very-tempting nature of the strong correlation between these:

-STC
-Aweighted noise reduction, in dB, for the frequency spectra from 125-4000hz for a noise source that is flat in all bands

lead to my quasi-conclusion.


In no way am i a history buff, and i hope my statement above was properly disclaimed as my own hunch.

I would be curious to know exactly how that atrocity came into being.


Alot of the reason why STC has such a high frequency of cutoff (125hz) may relate to the general assumption in ancient times that low-frequency data would deviate much more greatly from lab to lab than would high frequency data.

I would strongly suspect that isn't so, based on personal experiences and an analysis of NRC, Orfield, Riverbank, USG and other labs datas over the years.

There are IMMENSE mid/high freq variations amongst the labs, even when flanking limits cannot necessarily be given as the cause, and the low-freq variatiosn aren't necessarily larger.

Now, for the reference panel, a non-resonant simple mass-law panel, i would guess that mid/high frequency variatiosn from lab to lab would be minimal, while low-freq deviatiosn might be large.

but....

....

.... a typically tested double leaf wall is no mass law panel, and atl ow frequencies the radiation behavior is completely different - typically pistonic resonance/decoupling behavior - and i believet hat it is the difference in radiation behavior at low-freqs that would cause typical double leaf walls to be MUCH CLOSER to each other among different labs than would simple panels.  At least until below the MSM region, where wild deviatiosn would again occur.

thist opic - testing for TL - gets me a little hot and bothered, so i better shush up now.

[Brian Dayton]

scatter plots of STC minus A-weighted reduction, from 125-4000hz for flat source signal, for all data poistn from IR811 and IR761


I did 25 at-random data poitns from our tests at Orfield, and one varied from this A-weighted reduction by more than 1.

pretty darn consistent, hence my hunch

[bert stoltenborg]

Bert, if you want to more correct use flanking numbers then use EN 12354 and not that old graph.

Yeah, until they gonna shoot that one off because some genius thought out something new  :mrgreen:  :mrgreen:  :mrgreen:

Where do I find that, or do I have to buy it?

By the way, I'm not using a graph, it's a calculation.

Ri;j = 0.5Ri + 0.5Rj + Dv;i;j +10log(S/(sqrt(Si/Sj)))

Only graph in it is to determine the Dv;i;j, de verbindingsdemping van wand of vloer (i) in het zendvertrek naar wand of vloer (j) in het ontvangvertrek (dB).
This is the formula you asked me to inform angelo campanella about.

This is not right anymore?

[Terry Montlick]

Brian,

On the origins of the STC curve, I did a little hunting in the JASA archives.  One of the better papers I found was:

Sound Insulation and the Apartment Dweller by T.D. Northwood in JASA Vol 36, No. 4, April 1964.

It gives a little background, plenty of opinion, and even delves into NC curves, which - like STC curves - were relatively new back then, too.

It would appear that other references point back to the committee that developed ISO 717.  It seems the intent, at the time, was that the ASTM committee was basically following the ISO committee's lead on sound isolation rating.  It wouldn't appear that it fully happened that way.  When/why STC diverged from Rw might be something we never know.  (Or do we know?  Maybe it's just me?  :? )

The "ancient" roots of this curve are from Beranek back in the 40's. The Bolt, Beranek, and Newman company worked on noise control for airplane speech intelligibility during WWII, and this is apparently where this work started in the US. The first full-blown NC curves in my files (called SC curves originally) are from a 1953 paper, which simply references them as "curves used by one consulting firm," i.e. BBN!

Regards,
Terry

[Savant]

Looks like Eric had similar thoughts to you back in '03.  Check out the post at the bottom of this page:

http://johnlsayers.com/phpBB2/viewtopic.php?t=775

I was going to bring up USG's MTC rating here until I reread the document Eric had written up (attached to the above JLS post and also here).  Eric, it's uncanny how thorough you are.  Like you answer my questions before I even think of them...  8O  :mrgreen:

In terms of acoustical history, I will say this: I much prefer the STC-type ratings we have these days compared to what was the norm in the old days.  Flipping through an old Paul Sabine book, I came across "Average reduction" numbers in decibels.     {Acoustics and Architecture - BIG file (> 16 MB) - SLOW download.  See, f.e., Table XVII on page 271 of the PDF.}  I have to believe we've made some progress...  :?

[Savant]

The "ancient" roots of this curve are from Beranek back in the 40's. The Bolt, Beranek, and Newman company worked on noise control for airplane speech intelligibility during WWII, and this is apparently where this work started in the US. The first full-blown NC curves in my files (called SC curves originally) are from a 1953 paper, which simply references them as "curves used by one consulting firm," i.e. BBN!

Cool.  NC curves were "originally" published by Beranek: "Revised Criteria for Noise Control in Buidlings", Noise Control, Jan. 1957, pp 19-27.  (This may only be for ASA members, but issues of Noise Control are online:  List of 1957 issues is here (maybe) - no promises the PDF will download for you if you're not an ASA member...)

Best regards,

Savant

[Brian Dayton]

Looks like Eric had similar thoughts to you back in '03.  Check out the post at the bottom of this page:

http://johnlsayers.com/phpBB2/viewtopic.php?t=775

I was going to bring up USG's MTC rating here until I reread the document Eric had written up (attached to the above JLS post and also here).  Eric, it's uncanny how thorough you are.  Like you answer my questions before I even think of them...  8O  :mrgreen:

In terms of acoustical history, I will say this: I much prefer the STC-type ratings we have these days compared to what was the norm in the old days.  Flipping through an old Paul Sabine book, I came across "Average reduction" numbers in decibels.     {Acoustics and Architecture - BIG file (> 16 MB) - SLOW download.  See, f.e., Table XVII on page 271 of the PDF.}  I have to believe we've made some progress...  :?

well you know what they say - "sometimes norwegian boys think like great minds"    :mrgreen:   (i'm norwegian)


MTC offers practically no benefit relative to STC, and in many cases the opposite is true and it is more misleading.  As an example, alot of the USG RC tests from back in the day were done at labs that seem to show substantially higher TL at 125 and 160 than the NRCs lab or Orfields lab, so the RC wall would recieve fairly minimal #'s of penalties at 125 and 160, while a non-RC wall would recieve many due to its resonance behavior falling in those bands.  Thus the margin of RC to no-RC was increased by MTC, when the low-freq reality is that they are closer than STC implied.

Same for 24 -vs- 16" stud spacings.