Does sound sounds better in a room full of furniture and stuff or without ? - Page 19 - AVS Forum
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post #541 of 871 Old 07-17-2012, 04:42 PM
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I recognize the practical problems with properly implementing Diffusers in residential settings. The size issue has been brought up many times. And 6-8" well depth is hardly adequate to make a broadband device. These things need to be big - just the way it is. High frequency diffusion and scattering may offer some benefit, but if you really want the achieve a signifant fraction of the potential benefits you have to pony up the space. Aesthetics is certainly another consideration. I personally probably won't implement extensive diffusion if in the end I can't "afford" the additional absorption added to the room from a cloth covering. Some ways to minimize the effect are to use as permeable a cloth as possible, spaced well away from the diffuser (more space), avoid covering otherwise bare walls with cloth (especially spaced from the wall), use semireflective facing when possible on broadband absorbers...

I guess it does make Amir's showroom picture look a bit silly. I suppose it serves its intended purpose quoted well though: show products.




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post #542 of 871 Old 07-17-2012, 04:45 PM
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Originally Posted by Bigus View Post

lol, no. More demands from Amir. Show me this, answer that, can you even tell if there is a difference or not!!!*%(*( No. You have made it abundantly clear you have no interest in learning, therefore I'm becoming less interested in teaching you.
When I wrote that question I was confident that you couldn’t answer. It was like a kid showing up to school claiming to have created cold fusion on the kitchen table. Asking him to show it is a way of saying, no it is not possible. An answer was not expected at all and confirmed by your reply.
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Get off your high authoratative horse. You aren't a top researcher in the field. I dispute your interpretation, not their data.
I was talking about Dr. Toole which Dragon has already called an idiot. As to disagreeing with my conclusions, I have put forward his:

”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."

You have and continue to dispute his recommendations and conclusions. To wit, earlier you did the same with the RT60 measurement helping with overall absorption. So please don’t pretend that your disagreement is with me. You are taking on top experts in the field.
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I'm not a cut-n-paste kind of guy.
Please don't use that tired and worn out debating tactic. That's a tag line that Dragon has coined and repeatedly uses for everyone who argues with him when he runs out of answers. Check out this quote from him:
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Originally Posted by dragonfyr View Post

It died [the thread] as there are not enough familiar with what the response represents as well as not enough folks who could use Google fast enough to find sufficient out of context statements in order to sustain the nonsense.

He said that in a thread where I was not participating but the rest of you were! The man cries wolf this way 1000 times more than any wolf cries in his lifetime! smile.gif Don't try to live in his insecure camp by using the same line he used on you. It adds noise to the conversation and nothing more.
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I speak to what I know. If proven wrong, I note that and learn something. I can read the articles referenced (when available), but see no need to quote them extensively.
Extensively? You have not quoted any! Three posts on this topic and you have provided no specifics, no data, and no references. No nothing. Just more of your opinion.
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I have no need to prove myself to you or anyone else. I have no need to express my thoughts using someone else's words.Yet again, one standard for the great Amir, another for us? Keep casting your stones...
I asked you to do as I did:
I provided simulations of the problem. You did not.
I provided research data from companies in this field. You did not.
I shared personal knowledge of real customer scenarios. You did not.
I quoted experts in this field. You did not.

What you have done is express an opinion and expect it be taken at face value when it goes against all of the above. If you are happy with that stance, that’s great. You need not do more.

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post #543 of 871 Old 07-17-2012, 05:16 PM
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Originally Posted by Bigus View Post

I recognize the practical problems with properly implementing Diffusers in residential settings. The size issue has been brought up many times. And 6-8" well depth is hardly adequate to make a broadband device.
Everyone here quotes Dr. Toole on why acoustic products should be "broadband." Now watch them distance themselves from him in an instant:

Dr. Toole:
"To reduce the level of the reflection, use diffusers. Like absorbers, to be effective at lower frequencies, they need to be thick. Even properly engineered surfaces may need to be about 8 inches (0.2 m) thick."

That is a far cry from "hardly adequate." In addition, such products are also used to get rid of flutter echo (due to parallel walls reflecting sound to each other). There, thinner products are fine since flutter echo is a problem of higher frequencies. And hence my comment about 6 inches also being sufficient in other uses.
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These things need to be big - just the way it is. High frequency diffusion and scattering may offer some benefit, but if you really want the achieve a signifant fraction of the potential benefits you have to pony up the space.
High frequency? Is 500 Hz high frequency in your book? http://www.rpginc.com/ProductDocs/MODF_Modffusor/Modffusor%20875_Acoustical%20Data.pdf. That's an 8 inch product. It has near flat diffusion down to 500 Hz. And then slopes off into the transition area. That is perfectly fine for a broadband diffuser and a far cry from "high frequency" product.
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Aesthetics is certainly another consideration. I personally probably won't implement extensive diffusion if in the end I can't "afford" the additional absorption added to the room from a cloth covering. Some ways to minimize the effect are to use as permeable a cloth as possible, spaced well away from the diffuser (more space), avoid covering otherwise bare walls with cloth (especially spaced from the wall), use semireflective facing when possible on broadband absorbers... Which when you think about it, does make Amir's showroom picture look a bit silly. I suppose it serves its intended purpose quoted well though: show products.
Show products? We don't show any products in that theater. The purpose of the cloth is to demonstrate that we can hide all the technology and let the person be lost in the movie. And it does that perfectly with superb fidelity. You have confused yourself with idealistic junk you read on forums from people like Locahost who are sitting in their condo imagining a theater with 48 inch diffusers. And sadly throw yet another insult toward a major industry expert: Keith Yates. Next you are going to tell me if you don't have a 12 cylinder car with 600 horsepower, you don't have a car....

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post #544 of 871 Old 07-17-2012, 05:46 PM
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Originally Posted by amirm 
When I wrote that question I was confident that you couldn’t answer.
lol, and I could say that about, what, a couple of dozen questions I have asked? You're really grasping now. biggrin.gif

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It was like a kid showing up to school...
Ha! Just what I first thought when I read your "retort" above. Reminds me of an ages old schoolyard saying... I know you are but... biggrin.gif Not to mention that your question had little semblance to the statement I made. cool.gif

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An answer was not expected at all and confirmed by your reply.
And we are to make the same assumption regarding all the unanswered questions posed to you? Wait, let me get in a few more really irrelevant ridiculous ones before the bell rings... tongue.gif

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As to disagreeing with my conclusions, I have put forward his:

”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."

You have and continue to dispute his recommendations and conclusions.
I think it's dangerous to read more into a statement than is contained in its words. "Simple broadband ETC's" as were used in the Clark test/paper? Sure, I agree. Fortunately the tool can be used much more comprehensively and properly. Perhaps Toole meant that there is danger in blindly using the tool, thinking all "big spikes" require absorption, and treating away without engaging the brain, utilizing our knowledge of psychoacoustic principles, correlating with other measurements... then again, sure, I agree. If he actually meant, in a very generic and broad sense, "ETC lies, provides false data, and is not a useful tool in optimizing a listening space" as you have claimed, then I disagree. I simply don't see that conclusion contained in his statement above nor get that impression from what I have read of his papers and other writings. You have met the man, I have not. If he does indeed hold this very opinion, as do you, then I disagree with him too. I will likely never meet him, so it really doesn't matter. Bottom line, I don't agree with your spin on things, and I don't take your word for it that you speak for him.

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To wit, earlier you did the same with the RT60 measurement helping with overall absorption.
I actually said it isn't entirely useless, so long as you keep in mind what it is and what it means. Not that actual posts have ever gotten in the way of you speaking for others.

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Please don't use that tired and worn out debating tactic.
Tired and worn out like asking a blitzkrieg of often irrelevant questions and answering precious few in return? Like slinging piles of quotes at the wall and hoping some of it sticks? Like complaining about professional behavior any time the questions get a bit uncomfortable, only to follow a few posts later with unmitigated character assassinations? Like taking old posts out of context in an attempt to spin them how you wish? Like making up things and attributing them to other posters when you can't find old posts you can spin in a useful way? Like appealing to authority when I dare to question an absurd conclusion you have reached? Debating tactics. rolleyes.gif

Truth is, I really don't feel the need to "prove" that what I say is true. I recognize that for the benefit of other members, it might help to have confirmation from literature or simulations or measurements or whatever, but honestly, who else reads a thread like this? My goal isn't to educate anyone else at this point, but to educate you and hopefully prevent you from doing damage with your recommendations in the future. Most of them are great. Some are not, and you become extremely dogmatic when questioned on them.

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I speak to what I know. If proven wrong, I note that and learn something. I can read the articles referenced (when available), but see no need to quote them extensively.
Extensively? You have not quoted any!
So... you understand what I said or not? I said I see no need to quote articles extensively (i.e., in contrast to how you do). You point out that I in fact do not quote articles extensive like you do. ?? You're the google master. I know that any time I say something you go straight to searching to (a)understand it, (b)see if it is true, and (c)see if you can find something that contradicts it. Why go through the trouble when in the majority of cases it isn't the data that is question, but your interpretation of it. It is logical mistakes, misplaced assumptions, and erroneous conclusions. Referencing the very data you misunderstand isn't going to help remove your confusion. If I can't do that by pointing out the basic fallacies in how you think, it's not going to happen.

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I asked you to do as I did: so have I...
I provided simulations of the problem. You did not. simulations aren't the problem...
I provided research data from companies in this field. You did not. data isn't the problem...
I shared personal knowledge of real customer scenarios. You did not. got me!...
I quoted experts in this field. You did not. I'm not disagreeing with the experts...
On the other hand, I have answered tons of your questions. You have not.

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What you have done is express an opinion and expect it be taken at face value when it goes against all of the above.
Actually, I typically make statements of fact, true or false. But we all know you have a genetic irregularity that prohibits you from understanding the distinction.

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If you are happy with that stance, that’s great. You need not do more.
Exactly! Thanks for understanding. BTW, I can still hear your noodle baking... biggrin.gif

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post #545 of 871 Old 07-17-2012, 05:53 PM
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Originally Posted by amirm 
High frequency? Is 500 Hz high frequency in your book?
Yup. Sorry, Toole's words taken into consideration, 500Hz is still limited in bandwidth. And where is the rest of my quote? wink.gif I didn't say it isn't without some use, but I don't consider it broadband, nor reaching nearly the full potential diffusion can offer.
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Show products? We don't show any products in that theater.
You showed quite a potpourri of scatterers and diffusers in that pic of your theater. wink.gif

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And sadly throw yet another insult toward a major industry expert: Keith Yates.
I actually think he probably designed a superb sounding space within the required restraints in a showroom, namely "here are the products you can choose from that we carry to treat your room." If you in fact offer custom designed treatments for any space, why not have that done for your showroom?

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post #546 of 871 Old 07-17-2012, 08:05 PM
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Originally Posted by Bigus View Post

Yup. Sorry, Toole's words taken into consideration, 500Hz is still limited in bandwidth.
Limited in bandwidth? Let me quote Dr. Toole for you on the product spec I showed you:

'Figure 21.12 [graph from Dr. D'Antonio] shows a comparison of a standard version of a Schroeder diffuser with an RPG Modffusor in two configurations. These designs get better as they get larger. At 7.9 in. (0.3 m) deep and exhibiting useful diffusion down to about 300 Hz, they appear to meet the requirements for wideband diffusers and, interestingly, are very close to Gilford’s 1/7-wavelength estimate for depth requirements (Gilford, 1959)."

And in how to provide general absorption in the room:

"If RPG Modffusors (exposed absorption coeffi cient = 0.2, fabric covered it is 0.6) were used along the side and rear walls, and they would contribute about 128 × 0.2 = 26 sabins, but if they were covered with fabric for appearance, that would increase to 77 sabins."

Seems like you are finding yourself on the other side of Dr. Toole's recommendations again...
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And where is the rest of my quote? wink.gif I didn't say it isn't without some use, but I don't consider it broadband, nor reaching nearly the full potential diffusion can offer.
No, you said this and I quote: 'And 6-8" well depth is hardly adequate to make a broadband device. These things need to be big - just the way it is. High frequency diffusion and scattering may offer some benefit, but if you really want the achieve a signifant fraction of the potential benefits you have to pony up the space. "

"Hardly adequate" and "significant fraction" describe the performance of an 8 inch diffuser that goes down to 500 Hz flat and still retains a third of its alpha by 300 Hz?
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You showed quite a potpourri of scatterers and diffusers in that pic of your theater. wink.gif
So you have no idea what those products are but knew they would not perform?
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I actually think he probably designed a superb sounding space within the required restraints in a showroom, namely "here are the products you can choose from that we carry to treat your room."
eek.gif Where do you get assumptions like this? We can source and do sell any acoustic product. We are not a grocery store with these things sitting on shelves and people buying and taking them home. Everything is custom ordered and it makes no difference to us if the customer buys one of those devices as opposed to any other. Everything there was chosen by Keith per his design requirements with no such constraint in mind. The same is true of any other design or showroom in this business. How can you be this unfamiliar with how this business works? You think Dennis Erskine has lined up his shop with acoustic products and gives customers a shopping cart to pick the units that look less "silly" to them?
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If you in fact offer custom designed treatments for any space, why not have that done for your showroom?
Custom as in we fabricate them? If so, no, we don't fabricate diffusers. We do fabricate absorbers and have done so for our theater. In that picture you see the simpler ones on the wall. There is a custom one that uses the whole front wall as an absorber. It is designed using a proprietary algorithm by Keith so there was no choice but for us to fabricate it. Diffuser manufacturing is quite bit of work and precision is required. We make far more money designing systems than being in woodworking business smile.gif.

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post #547 of 871 Old 07-17-2012, 08:15 PM
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for a reflection phase grating (based on QRS or PRS) with a design frequency of 250hz, assuming normal incidence, it will require ~24" depth.
and you still need to take into account minimum seating distance for a reflection phase grating which for the above criteria would require ~13.5ft to be in the far-field.
and you still need to take into account the object itself needs to be physically large with respect to wavelength - depth is not the only criteria. also, random-incidence coefficients aren't relevant as the ingress angle of incidence can be determined as we do not have a reverberant sound-field in our spaces (which changes the performance).

but it's funny to hear you keep ranting about that of which you are not experienced.

but please, do continue!
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post #548 of 871 Old 07-17-2012, 08:23 PM
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Originally Posted by Bigus View Post

On the other hand, I have answered tons of your questions. You have not.
Last time I answered your questions, you kept arguing and arguing and then started to tell me I was answering my own questions! So at the risk of being insane by giving you another chance to ask your questions, go ahead and list them. Please keep them brief so that if you deny you asked something, I can point to them. The floor is all yours.
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Actually, I typically make statements of fact, true or false.
If you don't mind, let's make sure from here on if you state a fact, it is a true one. And not one where we have to wonder which is which wink.gif.
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But we all know you have a genetic irregularity that prohibits you from understanding the distinction.
Me and a few other billion people on this planet! biggrin.gif Per above, I appreciate just seeing the truthful facts this time around.
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Exactly! Thanks for understanding. BTW, I can still hear your noodle baking... biggrin.gif
Hear noodle baking? You think that compares remotely to you washing Dragon's dirty hands? Or him calling me Mr. Bob. Or less sharp than his scanner? Learn to be funny or leave the insults to true masters in this thread. smile.gif

And what the heck is the sound of noodle baking? Who bakes noodles? You boil noodles. If you bake them, they become hard and make no sound. Oh I get it. This was another one of those false facts!!! biggrin.gifbiggrin.gif

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post #549 of 871 Old 07-17-2012, 08:41 PM
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Originally Posted by amirm 
So at the risk of being insane by giving you another chance to ask your questions, go ahead and list them. Please keep them brief so that if you deny you asked something, I can point to them. The floor is all yours.
As far as I'm concerned this is just another stall tactic, or another attempt to see how much busy work you can goad someone into doing, or both. You can search the thread as easily as I.

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If you don't mind, let's make sure from here on if you state a fact, it is a true one.
If I make a statement of fact that isn't true, it is called a mistake. Or an error. Or whatever. I make some of those. I admitted to one just a few posts back. I find it hard to believe a billion people have that hard of a time with the concept. It is easily found with a quick Google search, which you no doubt did long ago. Why not share what you found? wink.gif

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Hear noodle baking? You think that compares remotely to you washing Dragon's dirty hands? Or him calling me Mr. Bob. Or less sharp than his scanner? Learn to be funny or leave the insults to true masters in this thread. smile.gif

And what the heck is the sound of noodle baking?
In case you missed it, it is a reference to The Matrix. And to my post a few back. And I have no idea what they sound like... somehow that sounded more appropriate than saying I could still see your noodle baking. smile.gif

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post #550 of 871 Old 07-17-2012, 08:50 PM
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Originally Posted by amirm 
Limited in bandwidth?
Matter of definition I suppose. Published company product sheets aside, I find 8" for diffusion down to 300hz hard to believe. In any case I was speaking generically about Diffusers for which the math is well documented. And even then, yes, I consider 500hz not to be broadband.
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eek.gif Where do you get assumptions like this?
I think you're being a bit naieve. He was tasked to design a showroom, not a home theater. Part of that is certainly visual. Not only were you aiming to show how products could be hidden, but how visually impressive those products look when lit up. Its all in the psychology of the consumer mindset. Nothing wrong with that at all. But I still think it is naieve to pretend or believe that each of those products was chosen and placed solely according to optimizing sound.


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post #551 of 871 Old 07-18-2012, 06:33 AM
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Originally Posted by Bigus View Post

As far as I'm concerned this is just another stall tactic, or another attempt to see how much busy work you can goad someone into doing, or both. You can search the thread as easily as I.
I already searched for your questions and answered them: http://www.avsforum.com/t/1413173/does-sound-sounds-better-in-a-room-full-of-furniture-and-stuff-or-without/390#post_22197924
http://www.avsforum.com/t/1413173/does-sound-sounds-better-in-a-room-full-of-furniture-and-stuff-or-without/420#post_22200919
http://www.avsforum.com/t/1413173/does-sound-sounds-better-in-a-room-full-of-furniture-and-stuff-or-without/420#post_22201025

As I noted, what ensued was you saying I was answering my own questions. So I am not going to do that again smile.gif. If you value asking your questions less than typing what you just did, then I am not going to argue with that.
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If I make a statement of fact that isn't true, it is called a mistake. Or an error. Or whatever. I make some of those.
If you read Dr. Toole's book you would make far fewer of those wink.gif.
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I find it hard to believe a billion people have that hard of a time with the concept. It is easily found with a quick Google search, which you no doubt did long ago. Why not share what you found? wink.gif
I am at your service. This is what popped up (a link to my previous post with the same)
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Originally Posted by Google 
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Originally Posted by dragonfyr View Post

Yeah, and it is available where? Look bigus toolus, the qualification regarding both minimum phase systems was mentioned how many times? I'm tired of ms. congeniality constantly following me around like one other lost puppy dog some may know and trying to make points that simply do not exist had someone actually bothered to read the entire post for meaning. I am tired of this. blah blah blah. More social commentary from one who has yet to offer any contribution to the subject of acoustics. But just as with acoustics, don't let facts confuse you! ...But just keep repeating the Big Lie as you posture as Mr. Congeniality. What would be a radical change would be if you spent just one fraction of the time you spend sanctimoniously criticizing others delivery and actually attempted to pursue some of the information that has been presented that you claim to want so badly. JUST ONCE.
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Originally Posted by Bigus View Post

ETC can certainly identify where specular reflections of sufficient gain are occurring. That is without doubt valuable information to have. But despite many suggestions to the contrary, ETC doesn't tell you what to do with those locations. It can confirm that your treatment did what you wanted it to in that location, but the bigger problem remains that knowing what you want to do isn't well defined. Test, yes, my comment goes beyond the usefullness of ETC as a tool. I don't question that (and there are many valuable tools one can use). I've raised this concern/question before and it never receives much attention. Likely, as I'm becoming more convinced, because there just isn't a really good answer.
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Originally Posted by Bigus View Post

So maybe you just want to find an example of someone using ETC to locate problem spots in a way optimized for multichannel surround, an emulate the approach taken. Well, I'm still looking.
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But Everything I have found is people in studio environments working with two channels, or people in ht environments using rew in the frequency domain and/or treating their room as if it only had two channels.
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Originally Posted by Bigus View Post

An add on question, one that has been posed by myself and others in the past months, is if we identify ETC as the correct tool what is the correct goal?
I think this thread has helped a lot in answering "*if* ETC is the correct tool." If it has not, read my answers above smile.gif.

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post #552 of 871 Old 07-18-2012, 07:14 AM
 
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Originally Posted by amirm View Post

I think this thread has helped a lot in answering "*if* ETC is the correct tool."



All that has been demonstrated is that only a fool uses a time domain tool in order to ascertain frequency domain behavior - especially considering that one first generates a frequency response prior to convolving the impulse response and then the ETC and is apparently both too ignorant to know that as well as to use that data provided.:rolleyes

And then compound that by demonstrated flawed processes and improper treatment techniques to conclusively prove that both the treatment and the proposed analysis process is wacked. But congratulations on showing folks how NOT to do it! You have succeeded admirably in demonstrating how NOT to do something! :

Still have no idea regarding the use of the Domain Map, huh?

And then he hallucinates that ANYONE with half a clue has suggested walking into a previously treated room and simply pulling out their trusty "ETC meter" (Where does he get this stuff..oh wait, I think I know, but I would seriously suggest washing your hands first...) and thinking that that is all there is to analysis – conclusively proving once and for all that ANYONE proposing this is a complete fool.

But then these same folks who have posited the improper use of non-broadband treatments and then lament that the treatments are not broadband Yup, that "ETC meter" must be flawed!

It is amazing that what he complaining about is precisely what his mentors posit as a prudent procedure as they demonstrate how to misuse the tool and that such erroneous process results in misleading data! Duh!

What he has conclusively provided is a tutorial in some of the procedures that should NOT be followed!

And after I filled my engine with a mixture of sand and oil, I took my oil filter back and demanded a replacement as obviously it is defective!rolleyes.gif

Next he will demonstrate how sticking a thermometer in a glass of ice water will provide an improper measure of your body temperature!!! You see, thermometers are an improper tool with which to tell time!

But please tell us again how someone following improper procedures invalidates the proper use of a tool…

And then he STILL laments that data does not "tell you" what to do, further demonstrating that he is simply a useless tool instead of a knowledgeable operator who is able to intelligently INTERPRET data.

And after all is said and done, this guy, who has spent his entire time fighting his own hallucinated straw man argument, is trying to sell you something.

Whose buying? ...Especially when his entire response model has been reduced to the need to simply scatter some pieces of furniture about a room.

LOL!

As much fun as it is to watch the nonsense that results when someone reads a book and then declares themselves an expert, its time to ignore this drivel.
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post #553 of 871 Old 07-18-2012, 07:53 AM
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Originally Posted by dragonfyr View Post

As much fun as it is to watch the nonsense that results when someone reads a book and then declares themselves an expert, its time to ignore this drivel.

how many auralex t'fusors on the wall does it take to look like an expert?

it's a shame dedicated (custom) listening rooms and showrooms presented here were simply unable to utilize custom (broadband) diffusers for treatment - designed and incorporated with respect to the room's total response at conception. hmm, it's strange that the condo dwellers don't seem to have any particular issue constructing reflection phase gratings...maybe i should have just purchased a 12pk of t'fusors instead. rolleyes.gif
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post #554 of 871 Old 07-18-2012, 09:05 AM
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Yep, diversion as usual. You spent more time trying (and failing) to cherry pick examples than you would have just answering questions...
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Originally Posted by amirm View Post

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Originally Posted by Bigus View Post

As far as I'm concerned this is just another stall tactic, or another attempt to see how much busy work you can goad someone into doing, or both. You can search the thread as easily as I.
I already searched for your questions and answered them: http://www.avsforum.com/t/1413173/does-sound-sounds-better-in-a-room-full-of-furniture-and-stuff-or-without/390#post_22197924
http://www.avsforum.com/t/1413173/does-sound-sounds-better-in-a-room-full-of-furniture-and-stuff-or-without/420#post_22200919
http://www.avsforum.com/t/1413173/does-sound-sounds-better-in-a-room-full-of-furniture-and-stuff-or-without/420#post_22201025
Where's my "rolling on the floor laughing" icon when I need it? lol!

You found three "questions", only one of which was actually a question. Another you argue with a statement insisting that small rooms have a reverberant field, and post an ETC measurement attempting to convince us that the noise floor of the room is a "late" reverberant soundfield! This is just too funny. And the third you make an overly generalized statement about dipoles when you really only meant the limited case of their use as surrounds. What I said was entirely true, but you couldn't just say "oh, I just meant surrounds." Yeah, way to answer all my "questions." Keep up the good work.

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I find it hard to believe a billion people have that hard of a time with the concept. It is easily found with a quick Google search, which you no doubt did long ago. Why not share what you found? wink.gif
I am at your service. This is what popped up (a link to my previous post with the same)...
Dude, what on earth does that have to do with your failure to distinguish an opinion from a statement of fact?!? Need we review your "debating tactics" again? rolleyes.gif Here, I'll do you a favor...
Quote:
from: here

factual statements: statements that haven't been verified or falsified beyond a reasonable doubt, but conceivably could be. ("There is intelligent life in outer space.")

opinion: statements that cannot be objectively verified or falsified. ("Human cloning should be banned." "Tom Cruise is sexier than Brad Pitt." "Beach vacations are better than mountain vacations.")

and if that is still confusing, here is one of a thousand gradeschool worksheets to help you work though this.


Now, what exactly are you implying by underlining the following statement and posting it over and over: But despite many suggestions to the contrary, ETC doesn't tell you what to do with those locations. ?

It's seems like you're trying to say "aha! see what you said!" and I'm thinking, "yeah... exactly". I've been trying to say the same thing throughout this thread. My position hasn't changed. But you keep reposting this as if you think it says something else, as if it somehow makes a point that apparently only you are aware of in your head. Why don't you share that with us?

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post #555 of 871 Old 07-18-2012, 10:39 AM
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Originally Posted by dragonfyr View Post

All that has been demonstrated is that only a fool uses a time domain tool in order to ascertain frequency domain behavior -
No one was attempting to do that at all. What was demonstrated was that the advice you two give in day in and day out, leading to folks like Bigus walking around half (or maybe totally) confused was wrong. You had no business telling people to run them in anything but an empty shell, devoid of carpeting furniture, any manner of acoustic products, etc. Why that is wrong is because all of these absorb sound frequencies in a non-uniform manner and therefore, none of the spikes can be compared to each other.

As I said, this is a usage scenario made up by you two not realizing the limitations of the measurement. Since you have now conceded that in very clear terms and stating that all such treatment needs to be removed first, we are in much better shape as there is agreement on both sides -- your buyer's remorse notwithstanding. What is not dealt with from your vantage point is the psychoacoustics factor that tells us these reflections can be either good or bad. The knowledge of how reflections are perceived can answer that. But if you know, you have no need for the measurement!" What good is it to know the front wall reflection was at -3 db or -5 dB when the same course of action is applied to it as far as absorption? Further, your ETC tool is worthless to measure the "after effect" due to filtering of the frequencies by that device per earlier point. Unless you live in the fantasy land of 48 inch diffusers in Blackbird studio.

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especially considering that one first generates a frequency response prior to convolving the impulse response and then the ETC and is apparently both too ignorant to know that as well as to use that data provided.:rolleyes
I have repeatedly asked you and Bigus to walk us through an example of how you would apply frequency response measurements to correct your ETC errors. You have collectively refused. And smartly so because that problem is not solvable in any reasonable way. You can prove me wrong by answering the quiz I gave to Bigus. If a reflection from an RPG diffuser is at -2 dB and from floor is -4 dB, please compensate for the error in both and give us apples vs. apples values to compare. Don't leave something an exercise for the reader where you yourself can' solve the problem!
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And then compound that by demonstrated flawed processes and improper treatment techniques to conclusively prove that both the treatment and the proposed analysis process is wacked.
I showed examples of products from Dr. D'Antonio's company that is blessed by Dr. Toole to be "broadband." Here is the product brochure: http://www.rpginc.com/product_Modffusor.cfm

"Offers broad bandwidth sound diffusion in a decorative, wood cabinet."

So any continued concern you have is yours, not that of the experts you cite on this very topic. There is a difference in real world, vs sitting at a computer keyboard and dispensing impractical advice which you yourself would not follow.
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But congratulations on showing folks how NOT to do it! You have succeeded admirably in demonstrating how NOT to do something! :
That's right. Don't ever run it in the manner suggested by you two as I documented earlier. Folks were told to run it when the room had DIY treatments, fabric covered walls, furniture, carpeting, professionally designed room with acoustic products, etc. All have been declared by you as "improper treatment" and therefore, creating wrong ETC results per your repeated statements including this post. So for vast majority of member applications, you concede that the use was inappropriate. Before and after. Unless of course they are ready to deploy multi-feet diffusers, with no fabric on the so that they can poke their eyes out when they feel like doing that! biggrin.gif
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And then he hallucinates that ANYONE with half a clue has suggested walking into a previously treated room and simply pulling out their trusty "ETC meter"
I quoted three test case by Localhost that I personally knew about: http://www.avsforum.com/t/1413173/does-sound-sounds-better-in-a-room-full-of-furniture-and-stuff-or-without/510#post_22223617

Heaven knows how many times he has spread this misuse on this forum and others. I have not tried to search for your posts but maybe you have a perfect record of always warning people that ETC generates wrong results for anything other than a carpet-less empty room and that the reflection values cannot be trusted in either case since how we perceive them can be positive or negative.
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(Where does he get this stuff..oh wait, I think I know, but I would seriously suggest washing your hands first...) and thinking that that is all there is to analysis – conclusively proving once and for all that ANYONE proposing this is a complete fool. But then these same folks who have posited the improper use of non-broadband treatments and then lament that the treatments are not broadband Yup, that "ETC meter" must be flawed!
As I said, if 8 inch acoustic products is not deep enough, you are dealing with a nearly non-existent segment of the membership and real life professionally designed home listening rooms and theaters. But by all means, Bigus is looking for your tutorship to build deeper ones. There is a dirty hand to be washed there and you owe him that! biggrin.gif
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And after I filled my engine with a mixture of sand and oil, I took my oil filter back and demanded a replacement as obviously it is defective!rolleyes.gif Next he will demonstrate how sticking a thermometer in a glass of ice water will provide an improper measure of your body temperature!!! You see, thermometers are an improper tool with which to tell time!But please tell us again how someone following improper procedures invalidates the proper use of a tool…And then he STILL laments that data does not "tell you" what to do, further demonstrating that he is simply a useless tool instead of a knowledgeable operator who is able to intelligently INTERPRET data.And after all is said and done, this guy, who has spent his entire time fighting his own hallucinated straw man argument, is trying to sell you something.Whose buying? ...Especially when his entire response model has been reduced to the need to simply scatter some pieces of furniture about a room.LOL!As much fun as it is to watch the nonsense that results when someone reads a book and then declares themselves an expert, its time to ignore this drivel.
Well, the only nonsense, other than stream of consciousness like above paragraph is this post trying to distance yourself from what you have agreed to, i.e. what I have been saying and what Dr. Toole has been saying. See my link above. You are now on record saying ETC generates wrong results in just about any home listening situation presented in this forum. Good luck calling yourself an idiot from here on smile.gif.

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post #556 of 871 Old 07-18-2012, 12:28 PM
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How about you provide the alternative. You have a "typically furnished" room... there's an angled fireplace in the corner behind you, a mini-L in the other corner as the door opens into a hallway, typical speakers flanking a center console on which sits a 65" flatscreen with a center channel beneath, several windows down the right hand side of the room covered with lined drapes, a sofa, a couple of chairs, one stuffed and the other wooden with a leather covered thin cushioned seat and back, a bookshelf on the right wall, a couple of tables with lamps on them, one in the corner there, the other over by that chair, typical carpet and underlay, 9" ceiling with a ceiling fan/light in the middle. Anything sound really out of the ordinary? You've decided you want to make the room sound better. Much better... as good as you can without stripping it to a bare shell. The wife gives the go ahead.

What does Amir do? You take an RT60 measurement (heavens knows where you found an appropriate spot past critical distance, but whatever, maybe you average many such readings or something). It reports 0.3s.

Now what? Speech doesn't sound that great. Balance seems skewed. Soundstage collapses to one side. Bass rings on several notes and is generally muddy. There is a harshness to some sounds that you think might be an echo, but don't know from what.

You've studied psychoacoustics extensively. That was your career, right? You own a company that designs custom theaters. You've read a book. You've even met Dr. Toole. And his/your path to a great sounding room is a compelling, beautiful story. What is it? Do I need treatments? Do I move furniture? What furniture? Where? How much? When do I stop? Can I trust my ears? Amir does not allow me to use ETC, so what do I do? And in the corollary case, if I was willing to strip the room bare first, what would be the difference? Follow a packaged plan that tells me to place this here, that there, and figure that's as good as it gets, or can you be more specific for how to treat my room? Would I have to invite you over personally to use your singularly unique talent of just looking at a room to identify problems, derive optimized solutions from first principles from your extensive knowledge of psychoacoustics, and trust your uniquely unbiased ears to confirm that the changes and amounts of were correct?

And I think I'll let your noodle keep baking a while yet on the other question. The funny thing is that I'm pretty sure earlier in the thread you explicitly said this was possible and could be used for just this purpose, but that it wasn't useful because you needed "psychoacoustics." I think you were arguing at dragon at that point who mentioned this ability and use of the tool. Now you say the math and physics make it impossible, period, the facts don't lie. lol smile.gif You also said ETC was useful in the hands of an expert, now it gives wrong data that can't possibly useful because physics and math make the comparisons faulty. Do you even know what your name is at this point? biggrin.gif But go ahead and focus on the easier question first... tell us how to design and/or modify a room to achieve optimum sound with eyes, ears, a book, and an RT60 measurement.

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post #557 of 871 Old 07-18-2012, 01:21 PM
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First thing you do is rob a bank as Keith Yates and Amir don't come cheap:)
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post #558 of 871 Old 07-18-2012, 01:31 PM
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First thing you do is rob a bank as Keith Yates and Amir don't come cheap:)
lol, true that! I don't want Amir to describe a plan of treatment, I want him to describe the process of determining such a plan. He says he knows, he can give us salvation. We're still waiting. wink.gif

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post #559 of 871 Old 07-18-2012, 02:29 PM
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Bigus,

If you don't mind, before we move on to your more complex scenario, perhaps as a warm-up exercise, amirm could answer the simple question I asked him several days ago.
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Originally Posted by amirm 

And what if you have a preference otherwise? Well, then put an absorber there. You still do not need ETC. As I have repeatedly noted, acousticians routinely design rooms and spec the acoustic products before they are built. You are saying that is an impossibility because only ETC is able to determine where a reflection occurs? You don't know how to put a 2x3 foot panel on the side wall such that it absorbs the first reflections otherwise?
Quote:
Originally Posted by audiophilesavant 

I have 96 square feet of side wall between the front of my speaker and my listening position. Can you tell me exactly where I should place the 6 square foot panel you are referring to within that area to optimally minimize side wall reflections? Would a smaller or larger one work better, and if so, what size should it be and exactly where should I optimally place it? Do I need more than one panel? If so, how many do I need and where exactly should I optimally place them?

Days later and still no response…
Quote:
Originally Posted by audiophilesavant 

Would you just eyeball it, or would you use a tool like a mirror, a measuring tape, a protractor, a laser, a dart, a ouija board, or something else?

This is the type of practical question AVS members seek answers to, not some esoteric theoretical debate about whoseamadoodle's theorem.

If you don't know or simply don't want to answer the question, just say so, and I'll seek advice from someone who does.
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post #560 of 871 Old 07-19-2012, 06:56 AM
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Originally Posted by Bigus View Post

What does Amir do? You take an RT60 measurement (heavens knows where you found an appropriate spot past critical distance, but whatever, maybe you average many such readings or something). It reports 0.3s.
I am pretty sure I was not in that room making said measurement smile.gif. The number is a curious one. Can you please post the measurement graph you took so that I can see what is there?

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post #561 of 871 Old 07-19-2012, 07:22 AM
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Originally Posted by amirm 
I am pretty sure I was not in that room making said measurement smile.gif. The number is a curious one. Can you please post the measurement graph you took so that I can see what is there?
0.3s is curious? It's within the target accepted range, and as you quoted Toole as saying, it isn't completely unexpected for a well furnished room like this. And what "graph" are you talking about? This is a single RT60 value at 500Hz, precisely what you said was sufficient.

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post #562 of 871 Old 07-19-2012, 08:09 AM
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Originally Posted by Bigus View Post

0.3s is curious? It's within the target accepted range, and as you quoted Toole as saying, it isn't atypical for a well furnished room like this. And what "graph" are you talking about? This is a single RT60 value at 500Hz, precisely what you said was sufficient.
I asked for the graph because it would show whether you have performed the measurement or not. That is what the tools produce. There is no RT60@500 Hz meter reading in any tool. You look up that value in the range of frequencies. Let’s put your unfamiliarity with this tool aside. It is not the main point. The main point is the way you went about the exercise.

Let me outline what I think you are doing. You are giving me a set of diagnostics and then challenging me to tell you what disease the patient has. Presumably you have a disease in mind as otherwise you wouldn't know if I gave the right answer! smile.gif And therein lays the problem. You have to describe the symptoms correctly for the type of disease you have in mind. You can't just make them up on the basis of "accepted range." Accepted range for what? For them to be acceptable they would need to be consistent with the other data presented and with the disease in mind.

Let's look at this if this were a medical test since that is your profession. If I told you that I have had occasional chest pains but that I am a healthy 30 year old that has exercised all his life, where in reality I am 56, heavily overweight, smoke, and the last time I lifted anything was the TV remote, wouldn't the odds of you coming up with the right diagnostic of heart disease go down? Of course it would. There is a reason the doctor would not give you that diagnostic over the phone and would insist on seeing you and making the measurements himself so that he knows it is correct diagnostic data.

In the medical field, the person creating the hypothesis for your exam knows that field and hence creates correct combination of scenarios for the med student to investigate. That way there is an appropriate answer that is consistent with the data given. In this case you profess to not know the method Dr. Toole advises yet proceed to create a scenario anyway? That doesn’t make sense. You can't throw random stuff at the wall, some of which is critical to be right conclusion and still expect the right diagnostic. Unless of course you are expecting some random answers which are not instructive and useful.

Likewise here, you said speech does not sound great. Well, one of the causes for that is late arriving reflections which show up in RT60 measurements. If that is the reason and your RT60 is at 1.0 seconds and instead, you tell me it is 0.3, that obviously going to lead to the wrong diagnostic because the person would incorrectly rule out an overly live room. What may then be left over is a poor performing speaker and not the room. I suspect that is not the answer you were searching for.

If you want this exercise to work, you need to ask the questions and not proceed to answer them yourself randomly unless you expect random answers back which by definition cannot be examined to be right or wrong.

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post #563 of 871 Old 07-19-2012, 09:16 AM
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Originally Posted by amirm 
I asked for the graph because it would show whether you have performed the measurement or not.
This is a hypothetical scenario. Sorry if that wasn't clear.
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That is what the tools produce. There is no RT60@500 Hz meter reading in any tool.
But you have said that is the only frequency value necessary. Indeed, lower frequencies are probably entirely useless, and even 500Hz is questionable, but for "general liveliness" I'll grant you that, and that is all you said was necessary.
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The main point is the way you went about the exercise.
I think you have misunderstood the purpose of the questions I asked. I thought that was abundantly clear, especially after my response to Randy. I'm not asking you to derive or prescribe specific treatments for any specific problem. I'm curious as to the process you believe will get me from point A (any point A) to point B which is an optimized listening environment given whatever limitations are imposed (cost, geometry, ability to strip bare, etc.). If it confused you that I provided a hypothetical RT60 value, I'm sorry. If you really think the conditions as I described them are out in left field, however, I'd like to know why you think that, as I put thought into what I was saying to make sure the pieces fit together and were potentially representative of a real space.
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Let me outline what I think you are doing. You are giving me a set of diagnostics and then challenging me to tell you what disease the patient has.
No, I did that earlier with the response to your challenge, and you certainly couldn't tell what the disease was there. Now all I'm asking, since you say you know and since you say the way we have described the process is so flawed, is for you to describe the correct process. Not the diagnosis. If a patient walked in with abdominal pain, I could describe the process without worrying about the resultant diagnosis or any specific treatment. I'd want history, do a physical exam, check some basic labs. Dependent on those, I might get a RUQ ultrasound, or maybe just send them home with or without some meds. Or I might want a CT, or MRI, or ERCP, or any number of additional labs drawn, or I might send them straight to surgery. There may be many possible outcomes based on the specifics, but the process is rational and describable.

I provided you with a general overview of just the sort of typical "well furnished" room you say can be great, with a reasonable RT60 value you say is both in the expected range (and correlates to the description of the room), and am asking you to describe a similar process that, for whatever the problems are, will identify them and derive appropriate solutions. The "symptoms" could be anything. I said poor speech intelligibility, ringing bass (those often go hand in hand), soundstage collapsing to one side, etc. It could be HF harshness, amorphous image, lack of soundstage depth, or whatever subjective descriptors you wish to apply. Doesn't matter. You have a room and an RT60 value. How do I proceed?

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post #564 of 871 Old 07-19-2012, 01:21 PM
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Originally Posted by Bigus View Post

But you have said that is the only frequency value necessary.
I had. I was just commenting on you asking "what graph." Ethan post such a graph on the first page;

dlr_rt60.gif

As you see it is not a single number. Per your wish for outlining the procedure it is useful to have the right process described for getting that piece of data.
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Indeed, lower frequencies are probably entirely useless, and even 500Hz is questionable, but for "general liveliness" I'll grant you that, and that is all you said was necessary.
It is what Dr. Toole, Olive, Bradley, Yang, etc. have said is sufficient wink.gif. This is a quote from latter two's research on speech:

"It was desired to create test conditions with T60 values of 0.3, 0.6, 0.9, and 1.2 s, which were thought to correspond to the full range of likely conditions in typical elementary school classrooms. A T60 of 0.6 s is often thought to be near optimum [7] and is referred to in the ANSI S12.60 classroom acoustics standard [12]. A T60 of 0.3 s is representative of the lowest T60 values likely to be found in a normal classroom. T60 values of 0.9 and 1.2 s could occur in real classrooms but were expected to lead to increasingly less suitable conditions with lower speech intelligibility scores."

As long as experiments confirm and correlate listening preferences in this regard, the measure is a reliable one to use especially in the coarse grain application of it.
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I'm curious as to the process you believe will get me from point A (any point A) to point B which is an optimized listening environment given whatever limitations are imposed (cost, geometry, ability to strip bare, etc.). If it confused you that I provided a hypothetical RT60 value, I'm sorry. If you really think the conditions as I described them are out in left field, however, I'd like to know why you think that, as I put thought into what I was saying to make sure the pieces fit together and were potentially representative of a real space.
Yes, it is an odd piece of data you put forward. Dr. Bradley performed a research project measuring noise level, transmission loss and in our case, reverberation time as a function of frequency in 600 Canadian homes (he works for NRC there). The median was 0.4 seconds. The standard deviation was 0.1 seconds. Assuming standard distribution, 70% of the bell curve is in the range of 0.3 to 0.5 seconds. This means your hypothetical scenario with 0.3 seconds falls in the 15% of the homes surveyed. That is one reason I said the value you picked was "curious." The second reason is that lacking late reflections, then it is odd to suspect the room is at fault if you continue to have speech quality issues. What could cause a bit of that is if you had tried to absorb early reflections but your scenario did not indicate that. So as you see, you did paint a rather odd scenario with that one number!
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I provided you with a general overview of just the sort of typical "well furnished" room you say can be great, with a reasonable RT60 value you say is both in the expected range (and correlates to the description of the room), and am asking you to describe a similar process that, for whatever the problems are, will identify them and derive appropriate solutions.
Well, at 0.3 seconds, you are definitely "well furnished." smile.gif So yes if you are at 0.3 I would be very careful and not deploy any more absorption in the room. Take a look at Ethan's graph above. You see that the before numbers are in 0.8 second range. The "after" numbers are in 0.2 to 0.25. I expect that room to be rather dead which for his music mixing applications may be fine but is not recommended for home use. Certainly not a good number for a living room where you want people to feel comfortable talking.
Quote:
The "symptoms" could be anything. I said poor speech intelligibility, ringing bass (those often go hand in hand), soundstage collapsing to one side, etc. It could be HF harshness, amorphous image, lack of soundstage depth, or whatever subjective descriptors you wish to apply. Doesn't matter. You have a room and an RT60 value. How do I proceed?
So you didn't mean for me to address those specific issues? I am confused about what you are asking me to do. Is there something wrong with the sound in your room or not? If there is something wrong, what is it if it is not those? If there is nothing wrong, then what are you chasing?

I will address some of those comments for the sake of discussion but they would be random tidbits:

Speech Intelligibility. If you have killed a lot of early reflections, that could cause that per Bradley/Yang NRC research. Another cause would be poorly designed speaker. The center channel level could be too low and out of calibration. If it is movie soundtrack, the dialog could have just been mixed poorly that way. You could also be thinking that but in reality there is no problem there.

Soundstage collapsing. This is really odd. You mean it is fine then all of a sudden it flattens? What are the conditions when it has not collapsed? If it is always shifted, then be sure to check levels and timing. It is surprising how much this helps to get things right and of course how easy it is to do it. This is one of the reason auto room correction features work as well as they do since they set these parameters accurately.

High Frequency Harshness. This is very likely a speaker problem. You would need to rule this out by getting both on-axis and off-axis data including directivity. Sadly this is rarely provided. Other sources could be amps clipping. Don't think of fixing either by messing with the room. Bad speakers need to be fixed by replacing them with good speakers. Above transition frequencies, the speaker dominates the overall sound you hear, not the room. Compare two speakers and them compare a speaker with or without absorber. I am confident you will find the former to be far larger difference.

Lack of soundstage depth. I would look to recording as the first issue. Maybe speakers.


Ringing. I assume you are not really hearing ringing but rather measured the low frequency impulse response and arrived at that observation. Run your analysis tool and capture a frequency response graph. Set the smoothing to 1/12 or 1/24th and pay attention to frequencies below 100 Hz. No doubt you have some massive peaks in there. They can be pulled down with simple parametric EQs. If you are using REW, it has ability to automatically generate filter coefficients for a number of low cost DSPs. You can either use that or visually do it based on what the graph says. Measure after to see if you have pulled that down. Listen to the effect. Boominess will likely go way down.

And oh, this reminds me, you didn't say if you had a sub. I assume if you have a center channel that this is 5.1 so you have one. If so, the DSP goes in the path of that. If you don't have one and have folded the bass into mains, you have to tell me if you can loop them in there or not.

The other thing to do is optimize your seating position. Since your room is not a rectangular box, we can't tell you what that location is. But you can measure it with REW or your favorite tool. Overlay the graphs and see which one is smoothest. Similarly, speaker positioning can be very helpful. Again, nothing can be given to you remotely as your room does not fit a standard box. If you are open to more subs, then I recommend getting at least another one. Then if the funds allow it, get the JBL BassQ. This box is unique in that it optimizes multiple subs using a special algorithm that varies level, timing *and* filter settings for each sub. It iteratively searches for an optimal solution to smoothest base response. The permutation it tries is huge so no human can easily accomplish the same. It works very well in this scenario since as I said, none of the standard speaker/sub placement recommendations apply. A much higher end version of that is in JBL Synthesis SDEC-4500. This is what we have in our theater and I have purchased for mine. Harman has patented this algorithm so for this bit, you either go with them or do without. You can read more about it in Dr. Toole's book (I think it is covered there) or the AES paper: In-Room Low Frequency Optimization, Todd S. Welti and Allan Devantier.

Slightly different take on this topic is covered in my WSR article. Shorter version here: http://www.madronadigital.com/Library/BassOptimization.html

Note that SFM optimizes for multiple seating so your wife will be happier too smile.gif.

As you can tell, once you have general absorption right the room, the main focus should be on low frequency optimization. There is really nice low hanging fruit there. You can trust your meter there and rely on good bit of science to improve your experience. As I explained in a previous post, reducing the ringing time will subjectively make higher frequencies sound better because the overhang from bass does not cover the nature rhythm of a lot of music which is around 0.4 seconds.

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post #565 of 871 Old 07-19-2012, 02:16 PM
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http://www.nrc-cnrc.gc.ca/obj/irc/doc/pubs/nrcc50831.pdf

lol - that's what happens when copy-paste parroting is taken out of context and the actual article isn't even read nor understood.

yes, unamplified speech studies again. you guys sure love to present these, dont you?
Quote:
Originally Posted by ncr 
"The subjects were located approximately one critical
distance from the loudspeakers
and hence would have experienced approximately equal
amounts of direct and reflected sound for an omni-directional source."

i'd love for anyone here to show me past Dc in their home listening room. anyone? anyone?

Quote:
Originally Posted by nrc 
"It has been shown for adult listeners, that added early
reflections arriving within about 50 ms after the direct sound have the same effect as
increasing the level of the direct sound and hence the added early-arriving reflections can
usefully increase the S/N by 7 dB or more [8]."
Quote:
Originally Posted by nrc 
...then added early reflections would usefully increase
S/N values
and hence would be expected to improve speech intelligibility.
Quote:
Originally Posted by nrc 
Although they were largely successful, they did not give the
actual signal-to-noise ratios of their conditions and they made no attempt to confirm that
their conditions would represent the balance between early- and late-arriving sounds that
would commonly occur in real rooms
.
Quote:
Originally Posted by nrc 
As the predominant source of interfering sound in classrooms is usually the children, it
seems that the most common situation in elementary school classrooms is the case where
the noise source is closer than the talker to the listener.
For this case we would expect
increased levels of early-arriving reflections to increase intelligibility scores because they
would be relatively more important for the more distant speech source.

damn - so you still have such poor SNR in your home listening space that the direct signal is hindered beyond intelligibility such that early reflections are REQUIRED to increase the perceived gain of the speech signal (fused within haas interval) in order to be considered intelligible? probably not the best idea to build your home listening room next to a train yard.

and if early reflections are required in order for the direct signal to be intelligible due to SNR issues, then you may need to focus more on sound isolation issues than internal room acoustics - that, or learn how to use the 'volume knob' on your AMPLIFIED sound system.

how many screaming children do you have in your home reproduction space?
Quote:
Originally Posted by nrc 
Of course there
are also many particular situations where early-arriving reflections are critical to
understanding speech, such as when the talker is not facing the listener, or is at a more
distant position in the classroom from the talker where the level of early-arriving speech
energy can be as much as 7 dB or more greater than the direct sound

you may wish to point your source(s) towards then listening position. installing the speakers backwards is generally considered 'user error' - that is, unless you subjectively prefer that type of 'sound'.

or, can you show me a measurement of the indirect energy being higher in gain than the direct signal? show me past Dc in your home listening space. anyone? anyone?

did toole/olive perform their listening tests on 13yr old school children too?

the constant push of these speech room studies for unamplified speech in poor SNR environments is laughable - it's like you guys are just pruning the papers for keywords and not understanding the environment.

please, keep going!!. keep thinking gain is the only factor re: intelligibility.
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post #566 of 871 Old 07-19-2012, 03:05 PM
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Quote:
Originally Posted by amirm 
I was just commenting on you asking "what graph."
I asked "what graph" because I wanted to know why you would possibly want a graph, having said you only needed the single data point. And one SD is now "curious"? Interesting take on statistics. Glad our pediatricians don't share the same view!!! eek.gif
Quote:
I am confused about what you are asking me to do.
Yes, that is painfully apparent at this point. I think we have our answer.

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"Ringing. I assume you are not really hearing ringing but rather measured the low frequency impulse response and arrived at that observation. Run your analysis tool and capture a frequency response graph. Set the smoothing to 1/12 or 1/24th and pay attention to frequencies below 100 Hz. No doubt you have some massive peaks in there."


hey Bigus - are you-yourself able to hear persistent modal resonances within a bounded acoustical space? maybe it is all just your (collectively, our) imagination regarding the audibility of LF modal ringing...
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post #568 of 871 Old 07-19-2012, 04:09 PM
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Quote:
Originally Posted by localhost127 View Post

yes, unamplified speech studies again. you guys sure love to present these, dont you?
i'd love for anyone here to show me past Dc in their home listening room. anyone? anyone?
While the concept of critical distance (the point at which the direct sound equals the level of the reverberation) does not exist in smaller spaces, similar transition region exists. From Dr. Toole:

'This transitional sound field appears to extend over the entire range of listening distances we commonly employ in small rooms. It is therefore necessary to conclude that the large-room concept of critical distance is also irrelevant in small rooms. This said, there is still a perceptible transition that occurs as a function of distance, beyond which the front soundstage—real and phantom images—appear to change. Because critical distance is not the appropriate measure, a new one is needed. A reasonable hypothesis is that it is related to the ratio of direct to early-reflected sound and the extent to which laterally reflected sounds, especially, contribute to a perception of ASW, image broadening, frontal spaciousness, and so on.

Your issue here as with RT60 is unfamiliarity with new ways these metrics have been demonstrated to be useful in smaller spaces. The rules are completely different as they should be given the differences that that do exist. But the metrics have uses as described.
Quote:
damn - so you still have such poor SNR in your home listening space that the direct signal is hindered beyond intelligibility such that early reflections are REQUIRED to increase the perceived gain of the speech signal (fused within haas interval) in order to be considered intelligible? probably not the best idea to build your home listening room next to a train yard.
Your read of research and our listening environments is incorrect. Before i get into that, the purpose of providing this quote was that top researchers besides Dr. Toole use reverberation times as a metric in assessing the quality of sound in smaller spaces contrary to what you say and Bigus repeating. In this case, it was in relation to classrooms which we can all agree are small spaces relative to auditoriums and such. Since you have read the report and seen the numerous mentions of reverberation time, I trust we are done saying this is just something Dr. Toole has made up.

I thought I had responded to your general point here regarding that research but now can't find it. So here it is anyway. A movie soundtrack will have other sounds playing in other speakers while the dialog is going on. It can and does also reflection situations in real life where a person talking is indeed in a train, car, restaurant, etc. And of course when we listen to music, there is plenty of other things going on beside the singer's voice. In one's room, you could have the hum of the projector and in a living room the activities of everyday life. We have an open kitchen and our two boys love to come and cook together and talk. So no, it is not the case that we are listening to pure voices with nothing else going on. Speech in our content is surrounded by other 'noises" above which we wish to understand what is being said.
Quote:
and if early reflections are required in order for the direct signal to be intelligible due to SNR issues, then you may need to focus more on sound isolation issues than internal room acoustics - that, or learn how to use the 'volume knob' on your AMPLIFIED sound system.
First, it is not "if." It is documented in that research. Second, you can't turn up the level of speech because no one has given you a separate track for it. The center channel in movies can have anything in it. You can't just turn it up thinking it is always speech. If you do, when it is used for other things like special effects, it will be very center heavy. And in 2-channel music, there is no center channel at all so you can’t compensate that way even if you could. Last but not least, the research showed up to 9 dB gain due to reflections. This represents 7 times more power! If you had 50 watts before you removed reflections now you may need 350 watts to get to the same place. Don’t think these smaller numbers are really small. Your speaker sends sound in all direction and killing most of them will sharply reduce your efficiency.
Quote:
you may wish to point your source(s) towards then listening position.
Why would I get rid of useful reflections and then mess with the speakers to compensate? Even if I did, it is unclear if there is a benefit there. From Dr. Toole's summary of Bradley/Yang research:

"Remarkably, even attenuating the direct sound had little effect on intelligibility in a sound field with sufficient early reflections."
Quote:
did toole/olive perform their listening tests on 13yr old school children too?
While Bradley/Yang do discuss age differences, the overall nature of our human system is not different enough to matter in this context.
Quote:
the constant push of these speech room studies for unamplified speech in poor SNR environments is laughable - it's like you guys are just pruning the papers for keywords and not understanding the environment.
please, keep going!!. keep thinking gain is the only factor re: intelligibility.
Question was asked by Bigus directly about speech. He actually did not say it was the speaker that was problematic. Keep in mind that the directivity of human voice is pretty similar to speakers. That means it nicely mimics how reflections occur as we talk. I noted a few pages back to Bigus that an alternative to using RT60 is to have someone talk at the location of the speaker. If you can understand that person well, your room is probably in good shape.

People frequently complain about dialog intelligibility in their 5.1 systems on these forums. There has been many times I have turned to my wife and asked, "what did they say?" No, I am not going deaf. smile.gif She does the same thing to me. smile.gifsmile.gif So speech intelligibility is important to consider.

It is natural to use one's gut to think reflections must be bad for speech. We picture rooms with a ton of echo and think that is what is happening. But early reflections are not perceived as echoes at all. Instead they help amplify the sound for us as more of the source energy is used. And the brain likely uses the differing signal in each ear to better determine what is being said. I realized you had up to now made this layman case against preserving reflections due to speech and now have serious angst regarding data being put forward disproving it. But disproving it we must. We don’t want to build our rooms based on folklore.

BTW, Dr. Toole presents an array of such tests ranging from artificial sounds to speech and music. So there is data across the board.

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post #569 of 871 Old 07-19-2012, 04:26 PM
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Quote:
Originally Posted by Bigus View Post

I asked "what graph" because I wanted to know why you would possibly want a graph, having said you only needed the single data point. And one SD is now "curious"?
It is based on my personal experience of measuring living rooms. And I have done a number of them. I have yet to see one at 0.3. Why don't you measure your real room and report back?
Quote:
Interesting take on statistics. Glad our pediatricians don't share the same view!!! eek.gif
What is that supposed to mean? Here is how the math works:

350px-Standard_deviation_diagram.svg.png

According to Bradley's research, your 0.3 second number is at the -one standard deviation vertical line (border between light and dark blue). There is 85% of the graph to the right of your measured value. So statistically you fall in the remain 15% of the test cases. As I noted earlier to you, you can't randomly make up these factors. Please read the research next time and you will see why someone who already has sees these issues in what you proposed.
Quote:
Yes, that is painfully apparent at this point. I think we have our answer.
It took fair bit work to answer your questions Bigus. You asked that I do that. Answer your questions. You asked many questions. I answered them and did not get personal. And this is how you respond?

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post #570 of 871 Old 07-19-2012, 04:33 PM
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I remain open to the possibility that increasing lateral reflections improves intelligibility. But the classroom research certainly doesn't prove that as it fails to isolate the variable you claim it does. That's a huge confounder. Does at least some of this research control for measured spl at the listening position?

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