I'll check this when I have MS Excel back active
I indeed start thinking I made a reasoning error which I shouldn't have.
This relates to the speed of sound in the panels.
Spyrow wrote:
....... in the link I gave you, -which you ridiculed because of its architectural base-
Eric wrote:
It's nicer that you write: School of Architecture and Fine Arts (somehow a dep. of or related to that Univ. you refer)
I know that site, and it's rather simplified stuff.
Often an architectural education does not go very deep in physics and acoustics. They all have seen it. Their education is very broad but not in-depth in all areas. And they think in standard building practices.
Note that Architects use acousticians for critical projects.
Maybe "to ridicule" is harder than what I wanted to say. I'm sorry, sometimes I'm not able to find the exact words in english.
By the way, did you check the files? I don't understand what you say with "reasoning error".
Spyrow,
I come back to this, when I find the time and have the Excel going.
If I made a reasoning error I gladly will confirm that.
Without checking things mathematically I feel unsure...
In the time between, from a practical point of view, nothing changes for you.
The things which are important and which aren't, I told.
My uncertainty doesn't change that. The only thing for me that documented worthwhile improves the MSM which is the dominant factor is Green Glue.
And that's not only theoretically but based on practical experience as well.
And if there are other materials out there capable of doing the same then they should document it, not tell stories.
And I'm not selling GG here, you can build walls without as well.
You got the references, the files, you can check NRC/IRC and the tests from the Green Glue site.
For 95% of what I respond on the net, I use what I know, without checking other's formulas/docs. For me formulas live, and here I feel that I made a made a likely reasoning error which means that I have to go more in-depth back for myself.
If I link to documents it's because they much better explain as I can.
If this 3rd thickness dimension plays a roll in that formula than it is related to the speed of sound in that panel. To check this relationship versus the constants in that formula I have to go back to the basics.
I indeed didn't like this cool sounding sentence about ridiculing that site (and that's NOT language, I'm also not English, but still know what ridiculing means, and you being Spanish as well).
Hey Eric, I know what ridicule means in english and spanish but I said that it was harder than what I wanted to say because sometimes I don't find the exact words to translate, and I've already said sorry for that.
Let's get that out, I really apreciate your time explaning things here.
If we do our design correctly, each wall will have a different resonant frequency so there is theoretically half of the energy at each WALL resonance to be transmitted through the space to the next wall. If then we also take it a step further and have different spacing between walls, those cavities will also have different resonances.
Even if we don't do different cavities and assume that it will all average out to a single resonance for the cavity itself, the mass on one side of the equation will have things spread more evenly. No one frequency will dominate.
Bryan,
I have (for years now) tried again and again to point out that this is just not worth the effort.........
Coincidence is a high enough frequency that the TL value of the wall ( at that frequency) even though it's taking a dip from the frequencies above and below it - is still so high a TL value that the dip is just abouit meaningless............
But the added mass of maintaining the multiple thicker layers (versus thining drywall out to compensate for coincidence) is VERY meaningful for low frequency TL values - which is where we have the problems.
Take some time and study any of the double wall assembllies and you'll see exactly what I mean. Read through IR 761 as thoroughly as I have and you will have it inscribed in your brain in permanate marker (color of your choice).
It just isn't worth the effort...........
Put as much mass on the wall as you can afford- and forget the rest - becuase it isn't of much more value than any salesman's snake oil............ and a LOT cheaper in the end if you have to deal with subs labor.
Sincerely,
Rod
I have (for years now) tried again and again to point out that this is just not worth the effort.........
Rod,
In this case it's not really a matter of being worth or not. (I don't think Brian referred to coincidence which in itself rarely matters as you state yourself)
Once you combine part of walls with different isolation properties, the weighted TL average will be mainly defined by the weakest parts of both spectral TL curves per frequency band.
The confusion in Bryan's arguments here is that he approaches this, and reasons, arithmetically, rather than logarithmic.
Rod,
In this case it's not really a matter of being worth or not. (I don't think Brian referred to coincidence which in itself rarely matters as you state yourself)
Once you combine part of walls with different isolation properties, the weighted TL average will be mainly defined by the weakest parts of both spectral TL curves per frequency band.
The confusion in Bryan's arguments here is that he approaches this, and reasons, arithmetically, rather than logarithmic.
Eric,
I understand - and stand corrected...........
Thanks.
Rod