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post #61 of 267
Now calm down, boys.
post #62 of 267
Quote:
Originally Posted by jim19611961 View Post

Quote:
Originally Posted by arnyk View Post

Not only can you throw absorbers at your walls at random, there's a fair chance that if you do that enough you will probably obtain an audible benefit.


Quote:
Originally Posted by kbarnes701 View Post

 I agree that nobody should just take some acoustic 'gubbins' and plaster it anywhere at random - but I don't think anyone was suggesting that.

Arny's quote here seemed to being saying exactly that as I read it. And this statement was my point of contention.

Guilty as charged. And I gave technical reasons why, some of which you simply dismissed like the web eggspurts do.

And then you ran off and said that if you don't install 8" thick absorbers after a thorough analysis of the room with test equipment, your room would end up far worse than doing nothing. Right?
post #63 of 267
Quote:
Originally Posted by arnyk View Post

Guilty as charged. And I gave technical reasons why, some of which you simply dismissed like the web eggspurts do.

And then you ran off and said that if you don't install 8" thick absorbers after a thorough analysis of the room with test equipment, your room would end up far worse than doing nothing. Right?

You just cant agree to disagree can you?

And you resort to the very thing you accuse me of by putting words in my mouth.

So, someone is an eggspurt (whatever that is) if they don't agree with your reasoning? Yes I disagree with your reasoning and ive made it clear why. Your welcome to disagree with me Arny, but name calling is a bit childish, don't you think?
post #64 of 267
Quote:
Originally Posted by jim19611961 View Post

Quote:
Originally Posted by arnyk View Post

Guilty as charged. And I gave technical reasons why, some of which you simply dismissed like the web eggspurts do.

And then you ran off and said that if you don't install 8" thick absorbers after a thorough analysis of the room with test equipment, your room would end up far worse than doing nothing. Right?

You just cant agree to disagree can you?

That's what I'm doing.

Quote:
And you resort to the very thing you accuse me of by putting words in my mouth.

Example?
Quote:
So, someone is an eggspurt (whatever that is) if they don't agree with your reasoning? Yes I disagree with your reasoning and ive made it clear why. Your welcome to disagree with me Arny, but name calling is a bit childish, don't you think?

Reasoning, schemasing. Where are the reliable facts to back your wild assertions up?

For example you seem to have made the claim that thin (say 2"=4") absorbers can't be used to create a room that has reasonably flat frequency response and that what one needs is 8" absorbers or die. Not true and if I could get you off the ceiling there's a reason why.
post #65 of 267
Quote:
Originally Posted by arnyk View Post

That's what I'm doing.
Example?
Reasoning, schemasing. Where are the reliable facts to back your wild assertions up?

For example you seem to have made the claim that thin (say 2"=4") absorbers can't be used to create a room that has reasonably flat frequency response and that what one needs is 8" absorbers or die. Not true and if I could get you off the ceiling there's a reason why.

Ive shared my views and you can make what you want of them. If you want proof, go find it yourself. Your onging miss representations of my ideas and assertions to claims I haven't made is tiring and ive had enough.

Have a nice day.
post #66 of 267
Thread Starter 
Just chiming in to my own thread here…smile.gif

I moved into a new place not too long ago and when I first set-up my room, it had quite a noticeable echo in it. This was due to the hard walls (drywall) and hard floor (laminate). I have since put down an area rug in the middle of the room and added a number of acoustic panels in my room. A got a bunch of 48” x 24” and some 12” x 12”. They are all 2 inches thick. I’m an amateur with this stuff, so I used the mirror method to find many of the first reflection points and put many of my panels at those places.

The echos have been significantly reduced and the sound from my system is noticeably better. My receiver also has Audyssey, which I find improves the sound further. While I’m sure an expert could diagnose the room acoustics down to a science and improve things even more, I think even a little treatment by an amateur like myself can make a noticeable improvement.
post #67 of 267
Quote:
Originally Posted by jim19611961 View Post

Quote:
Originally Posted by arnyk View Post

That's what I'm doing.
Example?
Reasoning, schemasing. Where are the reliable facts to back your wild assertions up?

For example you seem to have made the claim that thin (say 2"=4") absorbers can't be used to create a room that has reasonably flat frequency response and that what one needs is 8" absorbers or die. Not true and if I could get you off the ceiling there's a reason why.

Ive shared my views and you can make what you want of them.

Are they not flawed stories designed to scare little boys? If so, shame, shame.
Quote:
If you want proof, go find it yourself.

All the internet eggspurts say that. What is the reason for that? I suspect its because they don't work on the basis of proof and facts, so when pressed for them, they have none.
Quote:
Your onging miss representations of my ideas and assertions to claims I haven't made is tiring and ive had enough.

You talk about misrepresentations, but you when pressed for particulars, you run away.
Quote:
Have a nice day.

It is always a good day when an internet eggspurt is put on the spot. ;-)
post #68 of 267
Quote:
Originally Posted by mcnarus View Post

Now calm down, boys.

 

It's absorbers at dawn now.... :)

post #69 of 267
The playground squabbling in this section is what is tiring to me!
post #70 of 267
Quote:
Originally Posted by buckchester View Post

Just chiming in to my own thread here…smile.gif

I moved into a new place not too long ago and when I first set-up my room, it had quite a noticeable echo in it. This was due to the hard walls (drywall) and hard floor (laminate). I have since put down an area rug in the middle of the room and added a number of acoustic panels in my room. A got a bunch of 48” x 24” and some 12” x 12”. They are all 2 inches thick. I’m an amateur with this stuff, so I used the mirror method to find many of the first reflection points and put many of my panels at those places.

The echos have been significantly reduced and the sound from my system is noticeably better. My receiver also has Audyssey, which I find improves the sound further. While I’m sure an expert could diagnose the room acoustics down to a science and improve things even more, I think even a little treatment by an amateur like myself can make a noticeable improvement.

Simply MAHHHHvelous!!!!!

That's what's supposed to happen!

Good Job Buckchester....Enjoy!!

CV
post #71 of 267
Quote:
Originally Posted by buckchester View Post

Just chiming in to my own thread here…smile.gif

I moved into a new place not too long ago and when I first set-up my room, it had quite a noticeable echo in it. This was due to the hard walls (drywall) and hard floor (laminate). I have since put down an area rug in the middle of the room and added a number of acoustic panels in my room. A got a bunch of 48” x 24” and some 12” x 12”. They are all 2 inches thick. I’m an amateur with this stuff, so I used the mirror method to find many of the first reflection points and put many of my panels at those places.

The echos have been significantly reduced and the sound from my system is noticeably better. My receiver also has Audyssey, which I find improves the sound further. While I’m sure an expert could diagnose the room acoustics down to a science and improve things even more, I think even a little treatment by an amateur like myself can make a noticeable improvement.

Thanks for starting this thread buckchester and everyone for sharing their opinion!

I was spending a lot of time researching and determining how to incorporate a new high end DAC into my system. The feedback here just saved me a lot of time, money, and avoided what likely would have ended up in a big disappointment.

For anyone interested, I found this interview of Anthony Grimani very useful in understanding room acoustics:

http://www.avsforum.com/t/1494052/acoustics-101-with-anthony-grimani

I was going to engage his company to provide advise on my room treatment requirements.

But after reading this thread, I decided to have a go at doing it myself first based on his information, and see what sort of results I can get.

Thanks again everyone!
post #72 of 267
Quote:
Originally Posted by superaaaaa View Post
 
Quote:
Originally Posted by buckchester View Post

Just chiming in to my own thread here…smile.gif

I moved into a new place not too long ago and when I first set-up my room, it had quite a noticeable echo in it. This was due to the hard walls (drywall) and hard floor (laminate). I have since put down an area rug in the middle of the room and added a number of acoustic panels in my room. A got a bunch of 48” x 24” and some 12” x 12”. They are all 2 inches thick. I’m an amateur with this stuff, so I used the mirror method to find many of the first reflection points and put many of my panels at those places.

The echos have been significantly reduced and the sound from my system is noticeably better. My receiver also has Audyssey, which I find improves the sound further. While I’m sure an expert could diagnose the room acoustics down to a science and improve things even more, I think even a little treatment by an amateur like myself can make a noticeable improvement.

Thanks for starting this thread buckchester and everyone for sharing their opinion!

I was spending a lot of time researching and determining how to incorporate a new high end DAC into my system. The feedback here just saved me a lot of time, money, and avoided what likely would have ended up in a big disappointment.

For anyone interested, I found this interview of Anthony Grimani very useful in understanding room acoustics:

http://www.avsforum.com/t/1494052/acoustics-101-with-anthony-grimani

I was going to engage his company to provide advise on my room treatment requirements.

But after reading this thread, I decided to have a go at doing it myself first based on his information, and see what sort of results I can get.

Thanks again everyone!

 

If you need any help with REW, drop by the REW HDMI/USB mic thread where you'll find a bunch of guys more than willing to help a REW noob.  You really don't need to hire an expensive consultant to make a huge difference to your room with REW and some knowledge of acoustic treatments.

post #73 of 267
Quote:
Originally Posted by kbarnes701 View Post

If you need any help with REW, drop by the REW HDMI/USB mic thread where you'll find a bunch of guys more than willing to help a REW noob.  You really don't need to hire an expensive consultant to make a huge difference to your room with REW and some knowledge of acoustic treatments.

Thanks kbarnes.

I purchased the Dayton Omnimic around a year ago, and have used that to measure my room. At the time, my room was a shared open lounge, so my ability to treat the room was limited. As such, I only briefly played around with the mic and didnt bother to look into room treatment.

I also used REW previously with a Behringer Feedback destroyer, to change the response of my sub - next door neighbours made a comment about their floors shaking, so I calibrated my sub to prevent any frequences being played below 50Hz. frown.gif

I've just moved into a new house, and am in the process of completing a dedicated and highly sound proofed home theatre room.

Once I'm done, I'll pull out this kit again and get some tips from the REW HDMI/USB mic thread thread.
post #74 of 267
Quote:
Originally Posted by superaaaaa View Post
 
Quote:
Originally Posted by kbarnes701 View Post

If you need any help with REW, drop by the REW HDMI/USB mic thread where you'll find a bunch of guys more than willing to help a REW noob.  You really don't need to hire an expensive consultant to make a huge difference to your room with REW and some knowledge of acoustic treatments.

Thanks kbarnes.

I purchased the Dayton Omnimic around a year ago, and have used that to measure my room. At the time, my room was a shared open lounge, so my ability to treat the room was limited. As such, I only briefly played around with the mic and didnt bother to look into room treatment.

I also used REW previously with a Behringer Feedback destroyer, to change the response of my sub - next door neighbours made a comment about their floors shaking, so I calibrated my sub to prevent any frequences being played below 50Hz. frown.gif

I've just moved into a new house, and am in the process of completing a dedicated and highly sound proofed home theatre room.

Once I'm done, I'll pull out this kit again and get some tips from the REW HDMI/USB mic thread thread.

 

You will be more than welcome in that thread. It has a great mix of very experienced acoustics guys and REW users and a lot of novices too. And it is a friendly thread where help is freely given and experiences freely shared. Hope to see you there.

post #75 of 267
Quote:
Originally Posted by superaaaaa View Post

Thanks for starting this thread buckchester and everyone for sharing their opinion!

I was spending a lot of time researching and determining how to incorporate a new high end DAC into my system. The feedback here just saved me a lot of time, money, and avoided what likely would have ended up in a big disappointment.

For anyone interested, I found this interview of Anthony Grimani very useful in understanding room acoustics:

http://www.avsforum.com/t/1494052/acoustics-101-with-anthony-grimani

I was going to engage his company to provide advise on my room treatment requirements.

But after reading this thread, I decided to have a go at doing it myself first based on his information, and see what sort of results I can get.

Thanks again everyone!
Oh no. You have the opportunity to use Tony's services and instead are going by what random folks post on an Internet forum??? Tony is in top 5 or so high-end theater designers club. He doesn't subscribe to the 1970s school of audio acoustics that is routinely prescribed here. He has done hundreds of theaters. Folks here have just treated their own rooms and called themselves the expert. Much of the advice given here runs foul of the research in the last two or three decades. The notion that some "ETC" meter tells us what is or is not good sound in a room is absurd. It was used in the old days because folks were desperate for a some easy way to solve the complex problem of room acoustics. Through tons of controlled listening tests and simple analysis of how we hear, we know that almost all of what is prescribed in this thread by likes of Jim, Keith, etc. is just wrong. Let me show you some examples:
Quote:
Originally Posted by jim19611961 View Post

There are lots of online sites that simplify the matter and lay out a simple plan that will take you part of the way. The crucial advantage here is that a plan exists. Basically:

1) At least 4" thick absorber (24"x48" minimum) at 1st reflection points (i.e. sidewalls and ceiling), plus thick rugs at the floor 1st reflection point. Finding 1st reflection points is easy using a mirror.
2) Floor to ceiling 2' across filled corner absorbers in all four corners of the room as bass traps.

Ask him for one, just one, published objective test that demonstrates #1. I guarantee you he has none to offer. That practice is for people mixing and creating music. Hence the reason is it discussed and used in Gearslutz forum. You are not in that business and your hearing works differently. We have research to show us that. From my response to Jim in the REW thread that you are told is the place you need to go: http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs/3330#post_23405455
Quote:
Originally Posted by amirm View Post

...Fortunately such tests have been done and results readily available such as this from Dr. Toole's book:

'It was in this room [reference listening room being built at NRC research institute] that experience was gained in understanding the role of first reflections from the side walls. The drapes were on tracks, permitting them to easily be brought forward toward the listening area so listeners could compare impressions with natural and attenuated lateral reflections (see Figures 4.10a and 8.8). In stereo listening, the effect would be considered by most as being subtle, but to the extent that there was a preference in terms of sound and imaging quality, the votes favored having the side walls left in a reflective state. In mono listening, the voting definitely favored having the side walls reflective. See the discussions in Chapter 8, and Figures 8.1 and 8.2, which show that attenuating first reflections seriously compromises the diffusivity of the sound field and the sense of ASW/image broadening."

Please forgive me for being direct but what you say Jim simply is not supported in research. Testers overwhelming vote like above and it is nothing like random selection of colors. Here is related back up from Dr. Toole's private presentation:

"In double-blind listening tests where listeners compare music with and without the side-wall reflections, the results consistently indicate a preference for the reflections.

Listeners given the opportunity to adjust the sound level of the reflection to maximize “preference,” chose levels that were above the levels of natural room reflections. "


I can cite more references but it honestly feels like I am trying to tout the benefits of meat to vegetarians smile.gif. There seems to be no openness to accepting proper research here. Simply put, people interested in the performance of audio in their room need to start with the position that they fit the groups tested above and will have a preference for having side reflections than not. And therefore these room models are wrong as a result. That is what the science tells us. Let's not put that aside and side with our own notions and pass them as the statement of what it is.

Now if you have listening tests that state otherwise, that show completely random choice such as picking colors, let's see them. I have debated this topic numerous times and that data is never put forward but maybe this is my lucky moment smile.gif. In absence of that, let's at least acknowledge that our views are seriously undermined by people with impeccable credentials that have tested such things.

As I mentioned to Jim, I can cite peer review papers after papers that demonstrates what I said. Yet you can follow the links in Kbarnes' signature and see the exact opposite prescribed.

More examples. Jim said this earlier:
Quote:
Originally Posted by jim19611961 View Post

As far as average rooms starting out too reflective, this is true but...... A carpeted room especially is too reflective in the mids and bass usually. Carpet absorbs highs but little else, so putting up foam that basically only absorbs highs is lessening reflections in the very frequency range that you don't need the help in.

He is right that the carpet in the room is too thin to be effective at bass frequencies. But it turns out it doesn't need to be! Listening tests show that our sensitivity there is for frequencies > 500 Hz and a thick carpet with padding gets us that absorption. Is it me just saying that? Nope, top researchers in the field say so from one of my posts last year:

----

Let's look at a great example of this from AES paper on the design of the reference listening room at Fraunhofer Institute (FHG). Just in case you don't know who FHG is, they are the German government funded research group that brought us MP3 compression and contributed to AAC audio codec. They wrote a nice paper on the design of the room where they were trying to do everything by the book. Let's see a key section on the floor effect/treatment:

Vision and Technique behind the New Studios and Listening Rooms of the Fraunhofer IIS Audio Laboratory
Andreas Silzle, Stefan Geyersberger, Gerd Brohasga1, Dieter Weninger and Michael Leistner
Fraunhofer Institute for Integrated Circuits IIS, Am Wolfsmantel 33, D-91058 Erlangen, Germany
Innovationszentrum für Telekommunikationstechnik GmbH IZT, Am Weichselgarten 5, D-91058 Erlangen, Germany
Fraunhofer Institute for Building Physics IBP, Nobelstraße 12, D-70569 Stuttgart, Germany

Figure 11 shows sections of the first 30 ms of two impulse response measurements, band pass filtered from 1 kHz to 8 kHz, both from the center loudspeaker to the reference listening position. The graphs are almost identical with each other, except around 13 ms. The first 10 ms with zero signals represent the direct sound travel time, the strong peaks at 10 ms originate from the direct sound. In the measurement of the untreated room with the regular carpet covered floor (black graph), a second peak at 13 ms with 0.6 amplitude relative to the direct sound, which is equivalent to 4.5 dB attenuation, represents the reflection caused by the floor. The time delay of 3 ms corresponds exactly to the 1.7 m path length difference between direct and reflected sound. This strong reflection violates the requirements of the standard. It can however be attenuated to a negligible level with little effort by placing a piece of moderately absorbing material (e.g. 50 mm thick porous material, about 1.5 m x 1 m) on the floor at the mirror point, i.e. the point, where the sound is reflected on the floor. The measurement result for this case is presented with the red graph in Figure 11. None of the reflections exceeds 0.3 amplitude relative to the direct sound, which is equivalent to more than 10 dB attenuation."


This is Fig. 11:

i-hZqQTpM.png

By now folks following the school of running these time domain tools such as ETC and doing away with these reflections would be giving each other high fives smile.gif. Sadly for them but fortunately for goodness of audio science, FHG folks did one other important test: audibility. Coming from background of audio compression and science of audio in general, folks at FHG know that what a meter shows is not the same as what the ears capture and the brain interprets. It is that science that allows us to compress an audio file to 128 kbps at 9% of its original file size yet have it sound so close to the CD. And how if you set it to 384 Kpbs you get "near lossless" fidelity yet 75% of the bits are still thrown out! But we digress smile.gif. Back to our FHG researchers, we read this further in the report:

"3.1.4. Subjective room assessment"

[....]

Regarding the floor reflection, the audible influence by removing this with absorbers around the listener is negative – unnatural sounding. No normal room has an absorbent floor. The human brain seems to be used to this.
"

----

I will stop here smile.gif. It is OK if you don't understand much of what I posted. Contact Tony and he will. Ask him what he thinks of Jim's approach. Then compare his and Jim's credentials. By the way, I have no association with Tony.
post #76 of 267
Quote:
Originally Posted by kbarnes701 View Post

You will be more than welcome in that thread. It has a great mix of very experienced acoustics guys and REW users and a lot of novices too. And it is a friendly thread where help is freely given and experiences freely shared. Hope to see you there.

Definitely kbarnes. Looking forward to it.

Hi Amir,

Thanks for chiming in. I learnt a lot from Tony's presentations. It was very informative, yet easy to understand.

In one of the presentations, he discussed human hearing perception, and how the brain is use to translating a level of echo based on the real world environment. If the room is too dead, it would sound unnatural.

I have no doubt Tony is very knowledgable, based on years of experience and research in this field. If I go down the path of engaging a professional, he's on top of my list. I've already made contact with him over xmas/new years.

But as a first step, I want to get a better understanding of the elements of measuring a room's acoustic response, and how it translates to what I'm hearing. I also wouldn't mind having a go at treating the room myself, and see how I go. If I'm not satisfied with the results, I can always engage Tony for advice. After all, part of the joy of this hobby is the journey and what can be learnt a long the way.
post #77 of 267
Quote:
Originally Posted by amirm View Post

Quote:
Originally Posted by superaaaaa View Post

Thanks for starting this thread buckchester and everyone for sharing their opinion!

I was spending a lot of time researching and determining how to incorporate a new high end DAC into my system. The feedback here just saved me a lot of time, money, and avoided what likely would have ended up in a big disappointment.

For anyone interested, I found this interview of Anthony Grimani very useful in understanding room acoustics:

http://www.avsforum.com/t/1494052/acoustics-101-with-anthony-grimani

I was going to engage his company to provide advise on my room treatment requirements.

But after reading this thread, I decided to have a go at doing it myself first based on his information, and see what sort of results I can get.

Thanks again everyone!
Oh no. You have the opportunity to use Tony's services and instead are going by what random folks post on an Internet forum??? Tony is in top 5 or so high-end theater designers club. He doesn't subscribe to the 1970s school of audio acoustics that is routinely prescribed here..

I watched Anthony Grimani's video and found absolutely nothing there that I haven't read here. Common sense, all. It was like listening to Ethan without the East Coast accent! ;-)

Please compare and contrast Anthony Grimani's views on acoustics with "...the 1970s school of audio acoustics that is routinely prescribed here".
post #78 of 267
Quote:
Originally Posted by arnyk View Post

I watched Anthony Grimani's video and found absolutely nothing there that I haven't read here. Common sense, all. It was like listening to Ethan without the East Coast accent! ;-)
A little story. FBI arrested one of the earliest computer hackers years ago. I was reading the report of that and they talked about how he would sit in his bedroom, working on the computer for a while, fall sleep, then wake up do some more and then fall sleep again and so on. I was surprised how FBI knew his sleeping patterns. Fortunately the article answered that. They were tracing his line and could see him type. When he would fall sleep, his head would fall on the keyboard and they would see a set of keys repeating for a couple of hours! And naturally when he woke up, it would be proper keys used to hack into the system.

If you thought that Tony's video is "nothing you have read here" and is "common sense and all" I suspect as with the hacker, you started the hour long video, quickly got bored and fell sleep only to wake up at the end! biggrin.gif I can't blame you. Watching long videos can get boring but I suggest you watch it again after noting the points below.
Quote:
Please compare and contrast Anthony Grimani's views on acoustics with "...the 1970s school of audio acoustics that is routinely prescribed here".
It might be a great thing to actually annotate the video and expand on them in words and answer questions on them. If there is interest, I will do so. I think it will be highly educational but also tremendous amount of work. So for now, I will just hit on some highlights:

1. In the full hour video not once, let me repeat, not once he talked about using ETC measurement. So right away it disagrees with this proclamation in this thread and many others elsewhere:
Quote:
Originally Posted by jim19611961 View Post

If you do not have definite FR, ETC and Decay goals in your room design, then you don't have a plan at all. And if you have no plan, you cant expect or assume to bring the room to any kind of focused goal which is necessary for optimized performance.

No, he does have a plan. It simply is above the pay grade of people who have not followed the science and continue to follow this 1970s measurement.

Take out ETC from REW thread and I bet 70% of posts in that thread disappear. Good thing too given the huge number of posts in that thread! smile.gif Notice that I made the same point about not using ETC. If you read Dr. Tool’s book, you will get the same message. Isn’t remarkable then that folks here continue to cling to it despite having no credential, experimental listening test, or psychoacoustics knowledge?

2. Note how he is able to design the entire room without measurements! eek.gif Let me repeat: he is able to design exactly where every acoustic product goes, and number of them with no measurements at all. Indeed that is necessary condition to create a new theater or listening space for a client. You have to design the room and spec all the products that go in it prior to it being built. You cannot build it, measure it with ETC or other nonsense, and then go screw around with panels and such. That is not how professional work is done.

Again, this is the same advice Dr. Toole would give and as would I. This is shocking to many. But you see him clearly articulating it. As would any other top acoustician. So this notion that you need a thousand page Room EQ Wizard (REW) thread that Kbarnes and crew has no place in modern acoustics design. Yes, there are useful measurements. But not of the type emphasized in these threads.

3. In every bit of advice, he follows it with how we hear. Again, you see I, Dr. Toole, etc. do that. Not so with the typical poster here. As he and the rest of us say, no microphone exists that can hear what we hear with two ears and a brain. You must use your ears and knowledge of how they work in anything you do to your room. If the person does not mention them and with proper attribution to AES or ASA papers, run, run away from them.

Take out acoustic comments that violate this rule and you can dismiss with another 10 or 20% of chatter in this forum and REW thread.

4. If you know a bit about acoustics, i.e. having read a lot of posts here, you will be in *worse* shape trying to learn from such videos. Why? Because you will hear things that you have read, and not notice important detail that also goes with it. This causes you to reinforce your wrong beliefs. Example: early in the video Tony talks about reflections in the room. He draws all these lines and quickly one concludes that “reflections are bad.” This is the most common advice given in these forums and indeed is the foundation of self-appointed experts in forums. But listen carefully and in one sentence he tells you that reflections are around us in our everyday spaces and as such, the brain knows how to tune them out by a fair amount!

Once more, same thing I, Dr. Toole, etc. tell you. This is what I call modern acoustics. We know these things because in the last two decades or so, we have performed controlled listening tests and isolated each and every one of these effects in the room.

Note that you can *not* do the same in your room. If you put a panel at the first reflection point as dictated constantly in this forum, it does NOT mean that absorbing the first reflection is a good thing!!! No you read that right. When you add any panel to your room you also absorb hundreds of later reflections as the sound continues to bounce around the room. You cannot isolate that effect from that of absorbing the very first reflections. Research in this area uses anechoic chamber as to only turn on or off a single reflection.

5. You say there is nothing that addresses the 1970s school of acoustics. He actually does but doesn’t say 1970. He refers to the so called LEDE concept that was the bible then, and continues to be the bible for many creating recording spaces. LEDE is Live End, Dead End or the practice of absorbing all the reflections in the front of the room and leaving the rear reflective. Look at the REW and many other threads where people talk about so called “room models” with LEDE or variation thereof their favorite. Yet as Tony and the rest of us say until we are blue in the face, such rooms do not produce good sound. They simply do not.

6. If a person is giving you advice and does not mention Dr. Toole’s work at least once, they don’t know what they are talking about. Run and run away fast. Dr. Toole is the father of modern acoustics. His and his team’s contributions to our world are without rival. Tony uses his name to talk for example on why golden ratio of room dimensions is a myth as is slanting walls and such.

7. Note how he (and again the rest of us) say that Equalization is *mandatory* for good sound in a room. If someone tells you that you can get there with just acoustic products, they are plain wrong. You cannot achieve the best response without it. And that manual parametric EQ outperforms any automatic system such as the beloved Audessey. He doesn’t say this in the video but I guarantee you that none of his 500 rooms he has designed have Audessey room EQ in it.

8. Note that Tony is not an acoustic researcher. So don’t look to his videos to dig into the concepts such as psychoacoustics. He of course emphasizes its role strongly --- something else absent from forceful advice given by folks here – but he won’t dig into the theory. I, Dr. Toole, etc. do. Unfortunately that topic is quite complex and requires considerable amount of knowledge of audio, mathematics, access and ability to understand ASA and AES research papers, etc. You see me showing some of that in my post in this thread and countless others. So if that is what you are looking for Arny, you need to see other people’s work.

But, if you hire Tony, you will get the benefit of that work as Tony for the most part practices the research. And to emphasize, I did not say go and watch the video and then go do your own room. I said to hire Tony. Watching the video is not enough to learn the science.

9. Note that he does not give the typical wrong advice that you can stick some fiberglass in the corners and think you have a “bass trap.” The sound velocity is zero at the wall and such absorbers only work at maximum velocity which is away from the wall. He instead talks about his own product that is a pressure based absorber. And the pressure is at maximum at the wall. Filter out the number of threads in this forum of violation of this basic concept that we would get rid of half the posts smile.gif.

OK this is getting long smile.gif. I will stop here. But I hope people let the message sink in that if you follow stuff you read online, you wind up in the wrong place as far as optimizing your room. There is just too much wrong, and old information there.
post #79 of 267

Not all that long ago, someone here on AVS didn’t even know what the letters 'ETC' stood for. Now he's a world-class expert. Go figure.

post #80 of 267
Quote:
Originally Posted by kbarnes701 View Post

Not all that long ago, someone here on AVS didn’t even know what the letters 'ETC' stood for. Now he's a world-class expert. Go figure.
Thanks for the reminder Keith wink.gif. I wanted to mention that by far, the biggest reason misinformation persists is due to people not wanting to lose face. Once the say something here, they are loathe to correct it. Keith is a well mannered guy and indeed the REW thread is quite friendly. But try to tell Keith he is wrong and daggers come out. Worse yet, even when you show him that he is wrong, he will put cotton in his ears and refuse to listen. This is a perfect example of it. He made the same claim in the REW thread about me not knowing what the E in ETC stands for. And this is the answer I provided there: http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs/780#post_22900623

Quote:
Originally Posted by kbarnes701 View Post

Remember, Jerry, you are talking to someone who argued about ETCs for page after page in another thread. And then it was discovered he didn't even know what the E stood for wink.gif I guess the cut and paste let him down.
You rely too much on random claims on the Internet Keith. Here is the post in question: http://www.avsforum.com/t/1413173/does-sound-sounds-better-in-a-room-full-of-furniture-and-stuff-or-without/720#post_22260722
Quote:
Originally Posted by amirm View Post

Quote:
Originally Posted by dragonfyr View Post

First of all, "E" does NOT stand for "energy", but I find it humorous that you are still tilting at that 30 year old windmill.
AES paper:
The Analytic Impulse and the Energy-Time Curve: The Debate Continues
D. B. (Don) KEELE, JR.

AES Paper:
Uses and Abuses of the Energy-Time Curve*
JOHN VANDERKOOY AND STANLEY P. LIPSHITZ**

AES Paper:
USING BASIC ENERGY TIME CURVE (ETC) MEASUREMENTS
Don Davis, Joe Martinson

AES Paper:
Determining the Acoustic Position for Proper Phase Response of Transducers*
RICHARD C. HEYSER
"The amount and phase of this arrival pattern of energy is more accurate displayed in the energy-time curve[3]”

Reference "3" is the original paper where Heyser discussed the concept of ETC:
[3] R. C. Heyser, “Determination of Loudspeaker Signal Arrival Times, Parts I-III,” J. Audio Eng. Society

AES Paper:
Controlling Early Reflections Using Diffusion
JAMES A S ANGUS
"An idealised energy time curve for a room is shown in figure 1"

You were saying?
Quote:
Obviously you are not aware of the other earth shaking discovery that the proper term for the ETC is the ENVELOP Time Curve. A modification made, not by Toole, but by Dr. Patronis and Don Davis MANY years ago, much in the same way that they corrected we early participants in the seminars that the term "time alignment" is improper slang, seeing as how one cannot align time but that we can only align signals with respect to time, hence the proper terminology being "signal alignment".
You are taking tea to China. Look at the term and explanation I used in post 176 of this thread:
Quote:
Originally Posted by amirm View Post

ETC is designed to make the impulse response easier for humans to interpret by filling in the valleys with the "envelop."

Now let's look at how you have been referring to it:
Quote:
Originally Posted by dragonfyr View Post

For energy above the Schroeder critical frequency, fc, where energy behavior changes from modal standing waves to focused specular waves, we use the impulse response convolved into the Energy time curve or ETC response
Quote:
Originally Posted by dragonfyr View Post

You mean aside from the fact that what you have posted is instead a frequency domain spectrogram and not a time domain ETC response that has absolutely nothing to do with that to which we were referring and is even more unusable for identifying and analyzing specular energy characteristics???

Localhost claiming the same:
Quote:
Originally Posted by localhost127 View Post

. the ETC is the time-domain measurement for the specular region - to identify how specular energy is impeding the listening position. from the direct signal, to sparse high-gain reflections incident from room boundaries, to later-arriving reflections, to the eventual decay of the energy until it is fully damped. gain with respect to time.

Let me add another reference since we are talking about REW. Here is the introduction to REW in the help file: http://www.hometheatershack.com/roomeq/REWV5_help.pdf

"Welcome to REW

REW (Room EQ Wizard) is a Java application for measuring room responses and countering room modal resonances. It includes tools for generating test signals; measuring SPL; measuring frequency and impulse responses; generating phase, group delay and spectral decay plots, waterfalls and energy-time curves;..."


Clearly you did not read the thread you are talking about Keith or per above, the help file for REW. Even if you had, it is outside of the spirit of this thread to agitate members instead of focusing on the technical matter at hand. If you think ETC is useful, explain how and we can discuss it. Show me that I am wrong that way. You can start with addressing why the energy from the speaker is the same in all directions. Stand behind your speaker for example. Does it tonally sound the same or does it sound like there are less highs? How about to the side? If what you hear is different, then what the microphone "hears" is also different. And that impacts the levels displayed in the impulse response. It has to: the math says so, the listening tests say so, and the experts that do this for a living say so. I open to you disputing it but not with response like above.


So clearly Keith was wrong to take the version of the events from ETC proponents in that thread. A mistake doesn't get more clear than this, right? His friend was the one that didn't know what ETC stood for and they say I did. This is Keith's reaction to my post above:
Quote:
Originally Posted by kbarnes701 View Post

In the spirit of keeping this terrific thread on track, this age-old advice is worth remembering...


G44

And he is here repeating the same thing as if I did not correct him. The same thing unfortunately happens with correcting his acoustic view and that of the very vocal members. They cannot and will not accept the science because it would require them to make an about face on advice they have given to many. So ego wins and misinformation persists.

If you want to really learn this topic, get Dr. Toole's book: Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms
http://www.amazon.com/Sound-Reproduction-Acoustics-Psychoacoustics-Loudspeakers-ebook/dp/B008VSMXNK/ref=sr_1_1?ie=UTF8&qid=1390248149&sr=8-1&keywords=floyd+toole

41FGPJdL6TL._BO2,204,203,200_PIsitb-sticker-arrow-click,TopRight,35,-76_AA278_PIkin4,BottomRight,-43,22_AA300_SH20_OU01_.jpg

I suggest getting the Kindle version so that you can search through as you will be going back to it time and time again. By the way, I have offered to pay the cost of the book for the first ten people who are arguing they know better. None, and I repeat, none have taken me on the offer! Instead, they spend hours and hours here feeding each other acoustic folklore. Now you see why I said to use the advice of a professional instead of relying on posts here.

By the way, as good as Dr. Toole's book is, it still can be hard to understand without reading the underlying research. So to help with that, with his kind permission I have expanded on some of the key topics such as audibility of first reflections. You can see the articles here in my library: http://www.madronadigital.com/Library/Library.html and the specific one for reflections here: http://www.madronadigital.com/Library/RoomReflections.html. There are also other important articles there on optimizing the bass frequencies which is the most critical aspect of optimizing your space.
post #81 of 267

LOL!

post #82 of 267
Anyone here ever watch 'Annie Hall'? The scene where Woody Allen's character brings in Marshall McLuhan to settle an argument with a guy who keeps referencing Marshall McLuhan?

Can someone please arrange for Floyd Toole to come here? tongue.gif
Edited by krabapple - 1/20/14 at 4:48pm
post #83 of 267
Quote:
Originally Posted by krabapple View Post

Anyone here ever watch 'Annie Hall'? The scene where Woody Allen's character brings in Marshall McLuhan to settle and argument with a guy who keeps referencing Marshall McLuhan?

Can someone please arrange for Floyd Toole to come here? tongue.gif

I say bring in Woody Allen considering the humor in some recent posts.
post #84 of 267
Quote:
Originally Posted by kbarnes701 View Post

LOL!
Quote:
Originally Posted by jim19611961 View Post

I say bring in Woody Allen considering the humor in some recent posts.

You guys are laughing at the expense of collective knowledge of the forum. I have repeatedly invited top industry experts to come and participate and answer questions directly. I am confident that they would confirm the same exchange of information I have had with them so I have no fear. What happens next? They search for their name and find so many unprofessional remarks such as what I am responding to that I get an angry response back that they would not ever set foot in such a place.

Even the people who come here get treated like dog meat. Here is Nyal who does a lot of acoustics work. He joins the REW thread and posts the summary from his white paper. What happens next is that the thread creator dumps on him big time that he doesn't know enough, this and that. What would you do if you were an industry person and some random dude posting on an Internet forum wrote this reply to you? http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs/630#post_22881476

Still, Nyal keeps his cool as he always does and responds to him. Here are some parts of his reply; you can read the whole thing here: http://www.avsforum.com/t/1449924/simplified-rew-setup-and-use-usb-mic-hdmi-connection-including-measurement-techniques-and-how-to-interpret-graphs/690#post_22891499
Quote:
Originally Posted by Nyal Mellor View Post

Hi, I do not want to derail this thread, but I would like to answer some of your specific questions and also provide some more on where we are coming from.

The main thing to bear in mind is that our perspective is that acoustical model are just imperfect representations of reality. Each model is a by product of a particular time in history. As acousticians learn more and have better tools available to them the models change. I do not think you have to design a room based on any one acoustical model.

The white paper represents a 'stake in the ground' by Jeff and I and is a statement of our current knowledge, understanding and real world experience in designing and implementing room acoustic solutions for two channel systems. The targets describe a room that has good spectral balance in the direct and reflected sounds in the midrange/treble and reasonably flat response with low modal ringing in the bass frequencies. Many of the room models do not cover all the aspects of room acoustics that Jeff and I think are important. For example LEDE focuses nearly exclusively on the use of ETC, to the detriment of a lot of other things, and without covering the potential issues in general use of the ETC.

[...]

- I do not believe all 'strong early reflections' are destructive. I am in the 'Toole' camp when it comes to that.
- I do not believe in designing LEDE rooms for reproduction so any discussion of ISD is not relevant to me. LEDE was to me a product of a particular age of studio building and the use of particular speakers with poor off axis performance in that era.

Notice how polite he is despite being insulted on his way in. And what does he say? The LEDE model is antiquated and he doesn't use it. And indeed all "room models" are antiquated and obsolete. Tony never mentioned any room models. In the 500 pages of Dr. Toole's book you don't hear anything about following room models other than to say what the rest of us say in their poor performance and reasons we should not follow them. Yet the poster that is challenging Nyal says otherwise: "In the second post of this thread, I recommended, and for those reading this, am recommending again, that you all read this fine document that details each of the most popular room models from which to choose then pick one to model your own room after." Heaven forbid someone making him look bad by disagreeing with that old school suggestion.

Nyal does have (very) limited use for ETC in matching performance of speakers and such. In his hands, using filtered ETC which no one here has any idea what it is or what to do with it, you could extract this bit of data. Outside of that, what you hear from Nyal, is what you hear from me, Dr. Toole, Tony, etc.

So did Nyal hang around the thread? Nope. Like me he has better thing to do that to deal with obnoxious posters with signatures that are longer than their posts.

Can you imagine being in a professional conference and having someone do a "LOL" in response who has no degree, qualifications, industry experience, etc. when a luminary like Dr. Toole presents the material? Would Keith do that in real life? I would think not. But somehow on a forum, all maturity goes out the window and with it, we sacrifice any option we could have to hear such data first hand. See how the poster talks about Dr. Toole: "They may have heard of Floyd Toole (whom I also admire and respect, but...) " But what? What is your qualifications to disagree? What listening tests and controlled studies you can put forward? Exactly how do you "admire someone" but then give advice that in every angle goes against what your idol says in no uncertain terms?

So this is another reason we have so much misinformation in this forum. By making sure no expert sets foot here, the only thing people read is the wrong info these lay people post over and over again. They cover each other's back, providing an air of consensus. So folks believe. It is logical but truly sad for this forum which otherwise has a ton of useful information.

Thank heavens that Dr. Toole and Tony both teach classes at CEDIA conference once a year in September. Dr. Toole's class is comprehensive covering speakers and room acoustics and goes on for day and half across three sections. Tony's course is much shorter, I recall it being half a day. For a few hundred dollars, you would learn more there than spending an eternity here.
post #85 of 267
Quote:
You guys are laughing at the expense of collective knowledge of the forum.
No, Amir, that's not what we're laughing at. smile.gif
post #86 of 267
Quote:
Originally Posted by mcnarus View Post


No, Amir, that's not what we're laughing at. smile.gif
You must have been the one that they put this sign up for:

Sign2Tree.jpg

smile.gif
post #87 of 267
Quote:
Originally Posted by mcnarus View Post


No, Amir, that's not what we're laughing at. smile.gif

I've read Dr. Toole's book, I've been reading his white papers and presentations (and Sean Olive's) for years, and I get the whole 'first reflections aren't necessarily evil' thing. I recommend his book to everyone who shows an interest in better home audio sound.

What I'm saying is, I'd feel more confident if it was Floyd Toole explaining to us what Floyd Toole believes, than this guy.
post #88 of 267
Quote:
Originally Posted by krabapple View Post

Quote:
Originally Posted by mcnarus View Post


No, Amir, that's not what we're laughing at. smile.gif

I've read Dr. Toole's book, I've been reading his white papers and presentations (and Sean Olive's) for years, and I get the whole 'first reflections aren't necessarily evil' thing. I recommend his book to everyone who shows an interest in better home audio sound.

What I'm saying is, I'd feel more confident if it was Floyd Toole explaining to us what Floyd Toole believes, than this guy.

One practical tool for studying room acoustics is to get ahold of a good reverb package for an audio editor. I'm sure there are dozen or more of them as freeware for Audacity in the form of VST plug ins. They have parameters for all this stuff and you can listen to your favorite recordings as you twiddle the knobs. If you can start out with really dry recordings, so much the better.
post #89 of 267
Quote:
Originally Posted by arnyk View Post

One practical tool for studying room acoustics is to get ahold of a good reverb package for an audio editor. I'm sure there are dozen or more of them as freeware for Audacity in the form of VST plug ins. They have parameters for all this stuff and you can listen to your favorite recordings as you twiddle the knobs. If you can start out with really dry recordings, so much the better.
Nope, won't be the same thing. Creating reflections using electronic means does not at all simulate what happens with the identical thing occurring with speakers in the room! From my article on room reflections which provides details of the original paper from Clark that tests this: http://www.madronadigital.com/Library/RoomReflections.html

"As further evidence here, Clark in 1983 set out to test to create four different scenarios that involved comb filters:

1. Using two speakers playing a mono signal. The second speaker’s sound combines with the first creating comb filtering.
2. A reflector held vertically to the right of the listener and in between him and the speaker. While the distance there was shorter than typical wall reflection, the reflection nevertheless creates comb filtering just the same.
3. Same as #2 but the reflector held horizontally.
4. Creating the comb filter electronically by delaying the signal and combining it with itself. This is the same thing I did in my earlier simulation.

The important factor is that Clark made sure that the amplitude of the reflection (simulated or otherwise) was kept constant in all four scenarios. On the surface one would expect the effect to be similar because the reflection levels were the same. Yet the results were anything but!

In scenario #1, the addition of a second speaker was considered to have “moderate and pleasing effect.“ This, despite the fact that comb filtering was generated as a result of the second speaker. Clearly the listeners liked the effect more than they were concerned with any frequency response variations.
Scenario #2 was stated as having “very small effect.” What looked awful on a frequency response measurement was barely noticed. Turning the reflector horizontal did make it a bit more noticeable (for this reason you should absorb floor reflections with thick carpeting/pad). But still, in the grand scheme of things, it did not have the same magnitude effect as scenario #1.

The most surprising was scenario #4 where the outcome was “greatly degrading effect.” Let me repeat: the same distortion created electronically and sent out of the speaker was a very negative thing. The reason is that when comb filtering is created that way, we don’t get the nice benefit of the image widening, or the psychoacoustic factors that reduced its severity. This is how Clark concludes the paper:

“Two speaker mono was considered superior to the one speaker, one path mono. A reflection from a vertical surface was barely audible but a horizontal reflector was more audible. An electronic delay comb filter was highly audible and annoying.
"

Quite fascinating, no? That we can simulate exactly the same thing that happens with a reflection in the room, i.e. a delayed signal added to itself electronically and it sounds "annoying." But have the same thing happen in the room and it has a pleasing effect! The why is explained in my article and in Dr. Toole's book. Totally non-intuitive but of course absolutely true.

In another very contentious thread I ran a blind test version of this. I put forward the the measurements in both cases and asked if they sound the same. No one could answer it. Their beloved "ETC" [sic] failed to tell them the audibility difference. After letting them suffer for a while smile.gif, I gave this extensive answer. Arny was present in the thread but apparently sleeping at the keyboard once again. biggrin.gif. Again a more end to end story in my article and across multiple sections in Dr. Toole's book.
Quote:
Originally Posted by amirm View Post

Alright, let’s get into the details of this research. The work was done by David Clark. He is an AES Fellow, and board of governor’s award winner. Some of you probably know him more for his blind tests of amplifiers. The research paper here was presented at AES conference in 1983. As I noted, it set out to see whether there is good correlation between time measurements and later in the report, frequency domain and how we hear.

The experiment was pretty simple. A rectangular room was used with two speakers in typical stereo fashion, aimed at the user. They were pointed at the listener in the center line. Three scenarios were tested (plus some minor variations):

1. Both speakers playing mono sound
2. Single speaker playing but with a reflector used to represent both a “wall” reflector and a “desk” type reflector (vertical and horizontal correspondingly) in separate tests.
3. Single speaker playing but with no reflector. Input signal was instead modified with delay to represent the same effect as #2. I.e. replacing the acoustic mixing of the reflection with electronic.

Due to reflections and or interference from two speakers, in all three cases comb filtering occurred. So all represent “distorted” signals relative to what is played. Here are the three outcomes from listeners:

• Two speaker time delay - moderate and pleasing effect.
• Reflector time delay - very small effect.
• Electronic time delay - greatly degrading effect.

I earlier showed the time domain response for all three in the same order. Here they are again with frequency response added to them demonstrating the comb filter notches:

i-vrLJBM9.png

As noted, despite the extreme similarity between the time domain measurements, results vary from pleasing to greatly bad. The one that is greatly bad is the last one: electronically created comb filter. Let’s dig into this one.

We had a distortion which was created in the room with the sound arriving at the ear and reflected one coming some time later mixing with it, creating comb filtering. The same distortion as then generated using electronic means and the time domain display confirmed to have similar results. Put another way, we have equivalence in distortion as measured by a tool. Yet the human reaction was wildly different. In the case of the real reflector the user could barely tell it was there. So certainly not a bother. But as soon as we pulled the distortion upstream of the speaker, they user clearly expressed distaste for the comb filtering effect.

How can the same distortion be perceived so differently? I remember hearing this from Dr. Toole in his presentation the first time. I was like, did I hear that right? It can’t be. Distortion is distortion. So I put it aside. Sometime later, I read the explanation of the same test in his book and this time with a reference to Clark. I wanted to make sure there was no context lost. So I go and get the paper and read for myself only to realize Clark’s version of this even more compelling!

To understand the difference, let’s look at the frequency response measurements. Start with the right two. The last one is the electronic comb filter and the one before is with the reflector. We see immediately that unlike time domain, there is a distinct difference. The dips are deeper in the electronic version. Why is that? Because in a real room there are other reflections that fill in those gaps whereas that did not occur with the electronic version.

The leftmost frequency response is a special one that is measured for the two ears of the listener by the head shifted to the right of the room’s center line by 12 inches. Look at drastically different sound that the ear is hearing. The brain must interpret the two different signals. That it does by combining both and hence, not nearly hearing the difference as shown. So no way can a single mic measurement ever express this fact.

Not demonstrated here is the fact that the ear lacks sufficient resolution to hear the notches as the frequencies go up. I will cover this later when I talk about how psychoacoustics works here in a more detailed manner.

For now, let’s read some of the comments by Clark in his paper:

“In this study a cascaded ell-pass circuit and three full-band dual path systems were evaluated in a realistic listening environment. Two speaker mono was considered superior to the one speaker, one path mono. A reflection from a vertical surface was barely audible but a horizontal reflector wee more audible. An electronic delay comb filter was highly audible and annoying. “

Notice that the same level of reflection from horizontal angle had a different effect than a vertical angle. These are things that meters just can’t recognize. More comments:

”A comb filter response can be preferred over flat [frequency response].
More lateral sound than a single speaker provides can be preferred.
Response notches are almost inaudible if the notches are filled in by reflections within 10 ms.
Response notches are annoying if not filled in by reflections.
Vertical (well) reflection notches were subtly audible.
Horizontal (desk) reflection notches are more audible.
Time responses can look the same and sound different.
Frequency responses can look the same and sound different [here he means at high level looking the overall shape/i.e. the appearance of comb filter].
A single test mic hinders getting directional information relevant to audibility.


All of this is covered by Dr. Toole. He uses the waterfall displays from Clark’s paper. Those also look very much the same unless you really squint and try to see if the depth of the troughs.

From Dr. Toole’s book:

” 9.1.1 Very Audible Differences from Similar-Looking Combs
To add realism, just imagine that there is more than one reflection, some earlier and many later than the one we have been considering, each with a distinctive interference pattern when it arrives at the ears and, of course, slightly different at each ear. Clark (1983) conducted some listening evaluations and measurements that illustrate these effects very well.”


Bottom line is that this tool can show erroneous information. It is a fact that it does that because it is not spectrum aware, cannot capture even what one ear hears let alone two. And no human can make up for its failings by staring at its results. So the notion that it provides he data to act up is just wrong. It can’t and won’t do that reliably.

As I noted earlier, in the hands of someone skilled ETC and Impulse Response tools are useful. But you better know the full psychoacoustic effects before trusting what you see there. This is not an expectation one can have of ordinary users as evidenced by the fact that even our resident experts could not make sense out of these measurements.

As with a lot of psychoacoustics data, the results can be highly non-intuitive. Fortunately, in this case the results are very fortuitous. That we actually like these kinds of “distortion.” And that our brain has figured out a way to put reflections for the most part to good use.

And oh, while somewhat unrelated to this core research, Clark performed one more test of difference in perception of time vs frequency:

” A circuit consisting of cascaded first-order all-pass sections was constructed Fig. 11. Two channels each use 15 cascaded opamp sections to achieve e delay of nearly 8700 degrees over the audio bend with taps at intermediate delays. Approximately 7 ms of delay at low frequencies is also produced. The circuit centers about 630 Hz, the geometric center of the audio range. Although this circuit does not represent all possible time delay and phase shift characteristic, it is felt that the amounts end rates of change off these characteristics are worse than what is encountered in high quality equipment.

No one to date has been able to detect the presence of this circuit in hundreds of sensitive double-blind tests on speech or music program material with peripheral equipment including time coherent speakers and headphones. A change in sound can be detected using a narrow pulse as a test signal by a slight TEE-OOM sound. Even this clue disappears however below a meat 1000 or so degrees. The inescapable conclusion is that frequency response is what we hear when phase shift, time dispersion and frequency response are all occurring simultaneously.”


So we see that the body of research is quite broad here. It is not by any means focused on Dr. Toole. What you are reading is the sum total of research data by many experts in the industry. It all points to the direction that I have been explained and as Dr. Toole meticulously covers. Please spend a minute and let this data sink in. I know for me it advanced my understanding of acoustics. I am confident it will do the same for you smile.gif.
post #90 of 267
Quote:
Originally Posted by amirm View Post

Quote:
Originally Posted by arnyk View Post

One practical tool for studying room acoustics is to get ahold of a good reverb package for an audio editor. I'm sure there are dozen or more of them as freeware for Audacity in the form of VST plug ins. They have parameters for all this stuff and you can listen to your favorite recordings as you twiddle the knobs. If you can start out with really dry recordings, so much the better.
Nope, won't be the same thing.

Never said it was.

I guess there is a need to review some basics about learning.

Answer me this Amir: Is it necessary to risk crashing a 747 in order to teach pilots how to recover from accidental mid-air mishaps like a stall? Or, is time spent in a flight simulator which as good as they are but is not at all exactly the same thing as flying a real airplane (been there, done that), a good idea for teaching such things?

QED.
Edited by arnyk - 1/21/14 at 11:01am
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