Originally Posted by Bigus
No, you are repeating mistruths spoken in your own words. I have and will continue to report them. It of course isn't my job to decide what that means.
We will get there. First step is to make sure you are not taking a position against some of the top experts in the industry and simple mathematics of how signal energy is computed.
In the way Toole stated it, not so much.
Not much? You mean not at all. Right? Because I just quoted your expert in this area, Dragon, saying you better know and accept that dead cold. Or else there is no hope for you.
A dispute over semantics perhaps, but he gives enough context to make his point clear. There is still perceptually relevant information in a "simple" broadband ETC when non-broadband surfaces are ubiquitous, but the danger of misinterpretation rises, and the results could be "untrustworthy." What makes the results "untrustworthy" of course is misapplication, misunderstanding, and/or misinterpretation of the tool, all of which are more likely in such cases. But the actual data isn't wrong, it just is what it is.
He made it very clear on what creates misapplication: "All of this is especially relevant in room acoustics because acoustical materials, absorbers, and diffusers routinely modify the spectra of reflected sounds. Whenever the direct and reflected sounds have different spectra, simple broadband ETCs or impulse responses are not trustworthy indicators of audible effects.”
And again, Dragon agreed. And you said "not so much" disagreement above. I have yet to see any of you point to a single thread where you asked the user to run anything but broadband ETC. Indeed I have seen people like Local fight tooth and nail saying against Nyal that this is the only way to run ETC. So the way the tool is run is exactly as quoted in Dr. Toole's statement: broadband ETC. What is left then is proving that what he says about acoustic products changing the "spectra of reflected sounds" is incorrect. I have shown you how that is actually the case. You seem to be saying that is not right with the protests of misinformation. So to prove your point that there is misinformation here you need to demonstrate how both Dr. Toole and I are wrong in this regard.
While you ponder that impossible challenge, let me remind you of the rest of Dragon's post:
Originally Posted by dragonfyr
Thus, for those, unlike the intended crowd above, who have a few functioning brain cells, you have several CORRECT choices in properly using the tool!
As the tool can be used for a near limitless array of applications, (including a plethora of well designed variations) with regards to boundary investigations a simple rule of thumb implies that one:
1.) Ascertain the spectral nature of the boundaries followed by the behavior of any existing treatments. This will most probably require that one remove any treatments and first establish a baseline of performance for the boundaries.
2.) Once this is established and any lack of uniform broadband behavior rectified, insure that any treatments employed (assuming they are necessary and perform the desired function) are also broadband.
Starting at the top, I am assuming you are not accusing Dragon of spreading misinformation. Indeed, you said he is the higher authority than you in ETC. Yet we see his rule #1 routinely violated by him and others. Folks are being asked to run ETC or if ETC is already run in a room results trusted. I have quoted many instances of this and we have the freshest one in the parallel thread post this quote from Dragon. See http://www.avsforum.com/t/1421599/etc-isd-gap-question
. Indeed Dragon notes this to OP in the other thread that there is such a problem in his second reply. Yet he continues relying on the data anyway.
Please confirm that you are in agreement with Dragon’s rule #1.
So we are down to #2. That premise relies on all acoustic products being broadband. Note that Dr. Toole did not give this out. He made a categorical statement that all of these products modify the spectrum. But before we go there, you do accept that if a poster comes here that has random treatment on the walls that say include 6 to 8 inch diffusers which you called “hardly broadband” then this rule is violated. Correct?
Second challenge. An assumption he makes and you have repeated that because a products is “broadband” it is not filtering the spectrum differently than another broadband acoustic product. I gave two examples of this in my earlier post to you that clearly contradicted this statement. The absorption coefficient of a diffuser is a complex animal that is different than the scattering/diffusion that it performs to the signal. You rarely if ever have that information about a diffuser and even if you did, per example that I provided, it looks nothing like a broadband absorber. Here they are again:
If these were two electronic EQs, there is no way you would hear the same sound at the other end. Saying otherwise is spreading misinformation. You are violating the basics of energy computation math. Again, I am not the only one telling you this. So did Dr. Toole.
Then there is the issue of of-axis signal. The sound that bounces off the walls is not the direct signal from the speaker. Presumably the speaker is either pointed at your ear or close to it and never at the side wall or the ceiling. The spectrum of the sound hitting the side wall then is different than the spectrum hitting the floor, or the back wall. You say you have dipole speakers. You think that has constant directivity and what comes out the sides is the same as what comes out of front and back? I hope not.
You can misuse a tool and "generate" (Toole's words) "faulty data" (Toole's words), but he also stipulates "simple broadband" and describes the application, which if one is familiar with the tool knows is perhaps an incorrect use of the tool for the application.
Perhaps an incorrect use? Now are you not so certain he was right? In just a few lines you back-peddle this far? But good to see you say it is incorrect use of the tool. Your challenge is to show what other way people were told to use it. Just show me three links where people were told to use it any differently than this “incorrect” method.
Thus, pointing out that the erroneous actions of the user in misusing a tool could generate faulty data (relative to what is expected of a correct use and application) is fairly benign and at least he provides enough context to be clear about what he means, even if perhaps not worded optimally.
Really? It is not the fault of the poster telling them to run ETC that way? Here are multiple instances of Local instructing people to run it that violate Dragon’s rules: http://www.avsforum.com/t/1413173/does-sound-sounds-better-in-a-room-full-of-furniture-and-stuff-or-without/510#post_22223617
Please explain to me why it was the fault of the poor person being told to use the tool in that incorrect manner and not that of Local. You can’t of course. the misinformation arrow therefore points right back at you. The only way to deflect it is to show that you have advocated any different. Where would we read a post of yours where you warned people about such issues Bigus? Where have you personally discussed any of the ways ETC could show wrong information or "whacky" as Dragon put it? Is there any trace of you being aware of these issues until this thread? And what you have done about it?
So here is the summary. A world class expert in this field tells you in black and white that you cannot trust data you get from broadband ETC when you have acoustic products (and by implication furnishings) in a room. After a lot of kicking and screaming Dragon finally agrees. He says the solution is to start with an empty room. Problem is that none of you are on record insisting on only that type of data to be analyzed. Instead, any ETC results are encouraged and trusted. Some go as far as create huge arguments against any other type of ETC than broadband. Then the second argument is made that if the user deploys broadband material then all is well. On that front, none of you have been about to counter the simple mathematics or solve the riddle for the simple test cases I showed above. This is all of course puts aside the high order bit that we can make all the decisions we need as far as reflections without the data from this tool. Dr. Toole does it his book as do all the acoustic experts who design a room before it is built and hence anyone running ETC. But somehow you think you need ETC to tell you were the reflections are and can't think of any other means to accomplish what others do day in and day out.
Then there is the totally illogical position of never ever sharing with us how you have used ETC to solve these problems yourselves! Yet you walk around chanting its benefits. You don't think as the leader of the band you should be full of personal data as such? You expect people to go do things that you can't show you have done yourself? Give us a link to where you have used the tool correctly . If none exists, then you have no argument. You really don't.
I asked you if Dr. Toole would use ETC to analyze a room. What comes out is the sound of crickets. If you had read his work and seen him recommend it then you would quote him. You don’t so the conclusion is that you have not read his work or if you have read it, he did not recommend such. Members have to decide at the end of the day if they want to follow the recognized authorities who not only state their case with ETC but follow it with mathematics and listening tests which are published in highly praised manner, or some anonymous posters who think a technical case is made up of chanting “misinformation.” And go from being accused by their mentor on this very topic to have zero understanding of it and that of acoustics.