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Cathedral vs flat ceiling
Old 4th February 2009 | Show parent
  #181
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Glenn Kuras's Avatar
 
🎧 15 years
Quote:
Frank, by restricting the context Ethan is right in his calculations.
Brian got a similar result, but then stretched things by considering a whole room made of the same material. We can play with these numbers forever, and they will not describe reality. There are other factors involved-
The surface finish.
The mounting method and other real world contextual factors.
Coincidence effect.
Multiple bounces.
And probably many more. Real scientests don't use the word 'proof' so lightly
Just to add to this, when a lab shows a number of say .01 or .06 (numbers that low) it becomes very unacceptable to use on any kind of equation. So all and all these numbers are pretty useless in the real world.

Ethan you may want to fix your page to take it off. You and I know that it does not "prove" anything in a real world setting, for a HOST of reasons, which both of us have found by testing in the lab.

Further more the only way to REALLY test something like this is to test your own room with the structure with your kind of wood (with finish) to determine if it was/is a good thing to do.

So with that said, back to the poster.

You can change the flooring from concrete, but you might want to test it with and without the wood to determine how well it worked out for you.

Glenn
Old 4th February 2009 | Show parent
  #182
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🎧 15 years
Quote:
Originally Posted by Ethan Winer ➑️
Dan, why are you doing this? Seriously.

Why do you keep referring to an imaginary rigid slab, when that is exactly what the poster said he had, and which is exactly what I answered.
This is something Bryan could answer, he being more of a expert in construction then both of us x 1000 put together, but maybe the way the wood is laid down would be the best way to go about this. Take it off the floor 1 or so inches and I am sure it is going to change things A LOT.
Old 4th February 2009 | Show parent
  #183
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🎧 10 years
Quote:
Originally Posted by Ethan Winer ➑️
Dan, why are you doing this? Seriously.

Why do you keep referring to an imaginary rigid slab, when that is exactly what the poster said he had, and which is exactly what I answered.
But while the slab is not imaginary, the idea of lying wood directly to the slab without an underlament is. There will be a reaction between the three components.

I guess I don't understand what all of the discussion is getting us without an agreement on an appropriate test is?

Spencer's suggestion of testing his room pre/post wood floor seems relivent to me, as it will take into account all of the real world factors that for some reason can't be agreed upon. While it's results can't be construed as a definative "does wood sound different than concrete" test, it can tell us what effects an actual wood floor of a certain finish and species does to change the sound of a room with a concrete foundation of a certain finish. Which is what we are all talking about yes?
Old 4th February 2009 | Show parent
  #184
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1 Review written
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Seriously?

Ethan, I call it three times you call it 0. whatever.
I believe my three times will scale perfectly. At a gazillion square metres, the absorption at 4kHz will still be three times that of 125Hz.
Show me the math to prove how your dB's will scale to a real world dimension.?
The 'imaginary rigid slab' refers to the fact that it is not rigid. Wood is mounted resiliently.
Now come in off that ledge and come for a pint with us :-)

Best, DD

Last edited by DanDan; 4th February 2009 at 06:57 PM.. Reason: Typo
Old 4th February 2009 | Show parent
  #185
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Glenn Kuras's Avatar
 
🎧 15 years
Quote:
Now come in off that ledge and come for a pint with us :-)
If we are going out for pints I sure the hell don't want to talk about this. Gees it is bad enough we are all geeks online, but in REAL LIFE??? tutt

Ethan and I went out for a drink in NY a year ago and I am happy to say that not once did the subject of room acoustics come up.
Old 4th February 2009 | Show parent
  #186
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🎧 10 years
Quote:
Originally Posted by Ethan Winer ➑️


You already agreed with me above and said they sound close enough to not matter! Spencer said the same thing too a few posts back. So why do you continue to push this? That is what weakens the discussion - all the posturing and chest thumping.

--Ethan
Speaking of miss quoting... I said that if the studio had a very small budget THEN there wouldn't be much of a point of placing wood over the concrete because the money would probably have a greater impact on sound quality if you spent it on higher quality microphones or studio monitors. If you have some money on the other hand, then by all means, put the wood floor in!
Old 4th February 2009 | Show parent
  #187
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🎧 10 years
Quote:
Originally Posted by [email protected]
there was a "slight" difference in reflectivity between concrete and wood at certain frequencies. Now put it in a room and lets watch slight morph into noticable
Quote:
Originally Posted by Ethan Winer ➑️
Yes, I agree that the total sound in a room will experience multiple bounces, and that will be audible. But each bounce is softer than the one before, so then we have to decide how bounces are practical to allow. If we have a room that's totally empty with 10 audible bounces, that has no relation to a studio anyone would actually use!

This is why I continue to emphasize that my intent has always been a single surface only, especially a floor on solid ground. But not an entire room made of cement versus entire room made of wood, which is what this thread has morphed into.

--Ethan
I have continued to watch this thread. The above exchange was the point above where it occurred to me that Ethan appears to be talking about a non-real world one dimensional test that he would then extrapolate from to conclude that a room will sound no different. Pretty much everyone else is saying that its not possible to extrapolate in that way using only that data and you have to take more into account (some of the things being unknowns to us but including the interaction between reflections etc).

FWIW I too am in the process of refurbing my place ( https://gearspace.com/board/photo-di...ld-refurb.html ) The live room floor will be polished concrete after the first phase. A 4inch thick wooden floor will be laid over the concrete in the 2nd phase. If anyone can come up with a real world useful test I'd be willing to give it a go.
Old 4th February 2009 | Show parent
  #188
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🎧 10 years
Quote:
Originally Posted by Ethan Winer ➑️
Hell, I've been doing this stuff for 40 years, so I have arguably much more experience than all of you young kids put together. heh But that doesn't automatically make me right either.

--Ethan
Andre B. is doing (or has done...I'm can't remember which) a masters degree in Acoustics from a very prestigious acoustics university as I recall Andre Vare saying. If you were a wise man you would listen to him....and not insult him by calling him a kid.
Old 4th February 2009 | Show parent
  #189
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🎧 15 years
I guess the whole point IMO is that whatever is not reflected is absorbed by definition. So, if we can't scale reflectivity, we can't scale absorption which we all know isn't true.

If we truly can't scale it, then having wood over a 1'x1' square and the rest being concrete will sound no different than having all of the surfaces covered completely with wood. I disagree with that.

Any discussion of theoretical does the OP no good. He's asking questions about real world situations and if it would make a difference between wood and concrete on the floor. I say it should be measurable, if not audible.

Bryan
Old 4th February 2009 | Show parent
  #190
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🎧 15 years
As to the slab - well, that depends on a ton of different things.

Yes - you can get some additional feel and some absorption by building a small floor system under it. It'll cost money, time, and headroom that may or may not be available. What it will certainly also do is provide additional isolation by forming a resonant cavity.

If the cavity can be damped and tuned to be out of sync with the rigid slab below, isolation will be improved, feel will be improved, and you'll get a little more bottom end absorption out of the deal. Where would depend on the specifics of the underlayment, depth of the cavity created, etc.

Bryan
Old 4th February 2009 | Show parent
  #191
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1 Review written
🎧 15 years
Acceptable Test

I think there is something about Scalability which we are all missing.
Someone with the Maths chops should be able to show why either my
'over three times' or Ethan's 0.23 dB don't hang together very well. There must be a reason why coefficients are used, as opposed to dB.

Trev, You have the answer. I would accept a test done there. The fact you intend polishing the concrete is the so far missing ingredient.
I am near enough for phone calls. I might even come over if welcome!
I volunteer to devise and oversee such a test.
I would use ISO guidlines. Measure Freq Response and RT down to 48th Octave. 20-20K. I would include Hi Fidelity music recordings of playback.
The test would need the majority of your acoustic treatment, and your speakers, to be in place before the floor goes in. Is that doable.?

Incidentally you can polish a turd. Just pop it in the freezer for a while :-)
DD

Last edited by DanDan; 4th February 2009 at 07:35 PM.. Reason: Humour
Old 4th February 2009 | Show parent
  #192
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Storyville's Avatar
 
🎧 10 years
Ok, I'm not an expert on this so here's my logic, and anyone can feel free to validate or debunk my thoughts:

The degree and quality of reflection are going to be based on two basic things: The natural resonance of the material, and the porousness of the surface.

So, if you have a dense, hard material like concrete, you are going to get more reflection and more ringing. If you have wood, which has opening between the planks and is less dense, you will get softer/warmer reflections. Of course this is highly dependent on what is behind the wood, and whether or not the wood is varnished and how the space between planks is filled. This speaks nothing as to natural resonances, because I'm sure different concretes and different woods have different properties.

I also tend to see wood used more frequently in concert halls and studios. That might be for visual aesthetics.
Old 4th February 2009 | Show parent
  #193
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🎧 10 years
There's differences in the resonant properties from one species of wood to the next. Made evident in guitar building. A solid body telecater made from swamp ash sounds different than the same guitar made from say poplar or mahogany. Given these diffences within the family of wood, how can it be that concrete will behave nearly the same as wood, since not even all wood is the same?

It's intersting to me that there are so many different opinions here, it's what makes the world go 'round no? Some say the difference is unmeasurable, with all of us having varying beliefs all the way up to significant. Even more interesting though, is that even between the difference believers, some say concrete will be more favorable than wood.

I'm really looking forward to Spencer and Rimski conducting some tests!
Old 4th February 2009 | Show parent
  #194
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Ethan Winer's Avatar
 
🎧 15 years
Lightbulb

Quote:
Originally Posted by DanDan ➑️
Someone with the Maths chops should be able to show why either my 'over three times' or Ethan's 0.23 dB don't hang together very well.
The math is simple enough that even I can do it. heh

What you are comparing is two skyscrapers, one 100.00 meters high and another 100.18 meters high. This is the difference between how much cement absorbs and how much wood absorbs, as expressed in the data. What I'm doing is comparing the 0.18 difference to the overall height.

--Ethan
Old 4th February 2009 | Show parent
  #195
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1 Review written
🎧 15 years
Good try

Ethan, creative interesting analogy. I will have to take out the text books to see if dB can be used to compare heights. dB's were historically power ratio measurements?

Using my even simpler Linear Math and adapting the same analogy:-

Lets position ourselves 500m in the air and 500m from both skyscrapers.

In a 100kph wind.
A 100m skyscraper deflects 0.2 m
The other 100m skyscraper deflects 0.7 m
The difference in deflection is 0.5m, not so visible perhaps
Extrapolate to 1000m, the difference is now 5m, quite noticeable no?

OR

10 log (0.7/0.2) =5.44dB Difference.

DD
Old 4th February 2009 | Show parent
  #196
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Weasel9992's Avatar
 
🎧 15 years
Quote:
Originally Posted by DanDan ➑️
Ethan, creative interesting analogy. I will have to take out the text books to see if dB can be used to compare heights. dB's were historically power ratio measurements?

Using my even simpler Linear Math and adapting the same analogy:-

Lets position ourselves 500m in the air and 500m from both skyscrapers.

In a 100kph wind.
A 100m skyscraper deflects 0.2 m
The other 100m skyscraper deflects 0.7 m
The difference in deflection is 0.5m, not so visible perhaps
Extrapolate to 1000m, the difference is now 5m, quite noticeable no?

OR

10 log (0.7/0.2) =5.44dB Difference.

DD
EXACTLY.

Frank
Old 4th February 2009 | Show parent
  #197
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Glenn Kuras's Avatar
 
🎧 15 years
Quote:
Originally Posted by bpape ➑️
I guess the whole point IMO is that whatever is not reflected is absorbed by definition. So, if we can't scale reflectivity, we can't scale absorption which we all know isn't true.

If we truly can't scale it, then having wood over a 1'x1' square and the rest being concrete will sound no different than having all of the surfaces covered completely with wood. I disagree with that.

Any discussion of theoretical does the OP no good. He's asking questions about real world situations and if it would make a difference between wood and concrete on the floor. I say it should be measurable, if not audible.

Bryan
Bryan,
Now that is something I think everyone could understand. Well said
Old 4th February 2009 | Show parent
  #198
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lank81's Avatar
 
🎧 10 years
Cathedral

So I see we have a lot brains in this room and I wanted to get some input on a room in my house that I'm fixing up to be the studio instead of my spare bedroom. The room is basically 20 x 22 with 12' cathedral ceilings. Not smiley faced ceilings but more of a triangular type of ceiling - take a look at the first pic on this page
Cathedral Ceiling Framing - Imagine this on all four sides meeting at 12' with a little 1 x 1 area of flat ceiling. The side walls before it goes up in to the angled ceiling is 3.5 feet. Anyways, for sound dampening so it doesn't run through the floor I was going to put down 1/2" homasote followed by laminate hard wood floor. This will be sitting on top of 3/4" wood plank floor already. As for the walls I was going to put up 5/8" drywall and then make DIY Bass Traps / Wall mount absorbers out of OC 703 & 705 and some GOBOs for make shift vocal booth, etc. Now how do I go about configuring where the traps and wall mounts should go? Any other info that can help out acoustics would be great as well.

Thanks,
Lank
Old 4th February 2009 | Show parent
  #199
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johndykstra's Avatar
 
🎧 10 years
Quote:
Originally Posted by lank81 ➑️
So I see we have a lot brains in this room and I wanted to get some input on a room in my house that I'm fixing up to be the studio instead of my spare bedroom. The room is basically 20 x 22 with 12' cathedral ceilings. Not smiley faced ceilings but more of a triangular type of ceiling - take a look at the first pic on this page
Cathedral Ceiling Framing - Imagine this on all four sides meeting at 12' with a little 1 x 1 area of flat ceiling. The side walls before it goes up in to the angled ceiling is 3.5 feet. Anyways, for sound dampening so it doesn't run through the floor I was going to put down 1/2" homasote followed by laminate hard wood floor. This will be sitting on top of 3/4" wood plank floor already. As for the walls I was going to put up 5/8" drywall and then make DIY Bass Traps / Wall mount absorbers out of OC 703 & 705 and some GOBOs for make shift vocal booth, etc. Now how do I go about configuring where the traps and wall mounts should go? Any other info that can help out acoustics would be great as well.

Thanks,
Lank
I'd suggest starting a thread and posting a link. It's too hot in here for apllied physics.
Old 5th February 2009 | Show parent
  #200
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🎧 10 years
Quote:
Originally Posted by DanDan ➑️
Ethan, creative interesting analogy. I will have to take out the text books to see if dB can be used to compare heights. dB's were historically power ratio measurements?

Using my even simpler Linear Math and adapting the same analogy:-

Lets position ourselves 500m in the air and 500m from both skyscrapers.

In a 100kph wind.
A 100m skyscraper deflects 0.2 m
The other 100m skyscraper deflects 0.7 m
The difference in deflection is 0.5m, not so visible perhaps
Extrapolate to 1000m, the difference is now 5m, quite noticeable no?

OR

10 log (0.7/0.2) =5.44dB Difference.

DD
Since you haven't responded yet...does this mean you agree Ethan?
Old 5th February 2009 | Show parent
  #201
Gear Head
 
🎧 10 years
Maybe as said before too hot in here, but I'll just throw in my 2 cents.

What I believe Ethan is referring to is the theoretical similarities between the SURFACE of wood and cement. This would mean that we're talking about the difference of a concrete slap vs the same concrete slap with a infinite small layer of wood. This might sound the same.

However all test data is recorded with actual layers of wood on top on concrete with some added material beneath which start to do their thing in the equation as well.

The whole question is then When are we talking about wood?

Since wood in the real world is not infinitly thin, but it will have a thickness whereby other factors than just the surface will come in as well (like mass, the material between wood and concrete) the whole discussion seems a bit odd, since wood will automatically apply that it comes whith it's real life properties besides just the surface.

However I don't think we can prove the theoratical point of Ethan wrong since it is impossible to measure an infinite thin layer of wood.
Old 5th February 2009 | Show parent
  #202
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1 Review written
🎧 15 years
Epitaph for this Thread

There is a great appetite out there for single number descriptors of sound.
We would like to be able to say a 12 inch thick wall made of concrete stops sound passing through by 90% or 90 Homers or whatever. A great deal of work has been done on this and the result is enormously convoluted terms. e.g.

DnT,w(C:Ctr)

and that nT,w is supposed to be subscript.....WTF!
Such ratings even take account of the type of noise we are expecting to pass through and have different fake spectra to simulate traffic noise, housing estate noise, aircraft noise and so on. I believe most of it is a kludge. We are working with historic measurement methods and instruments, in a very restricted range. They have gone to the ends of the earth adding on all sorts of terms, spectra, and stats, in order to persuade these old measurements to describe reality as experienced by us humans. I would particularly like to note the inclusion of curves, agreed standardised curves, which may point to the way forward. However I think it likely that we will never find a single number to describe a sound or tonality in as much details as say, a Waterfall plot.
One could say this thread has struggled with a similar endeavour. There was an attempt to use a single term to describe the 'sound' of wood and concrete. This migrated to philosophy, then a quick trip around Uranus, so to speak ;-), then back to a fancy number juggling side- show :-)
It won't work. Greater minds than ours wouldn't dream of tackling that one.
So at times we don't have the crutch of science to help us, so we have to continue our work using Craft and Art and Experience. Well, how bad, there are plenty of nice Violins out there, designed and made by eye, feel, smell, experience etc.

Terminally, DD
Sound Sound - Homepage

Last edited by DanDan; 5th February 2009 at 06:34 PM.. Reason: Clarity
Old 5th February 2009 | Show parent
  #203
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Ethan Winer's Avatar
 
🎧 15 years
Lightbulb

Excellent summary of the technical issues Dan! Hopefully that will end the bickering for good.
Old 5th February 2009 | Show parent
  #204
Here for the gear
 
🎧 10 years
CAn hear a difference

Imagine , I started reading this thread because I am 'treating" a room with a cathedral sp ceiling. Wow I got alot more than I bargained for ..but as someone with very little knowledge of acoustics (compared to the all of the posters) I have to say something ...I CAN hear the difference between the two types of rooms , concrete vs wood. How subtle that is is "subjective" ...science was mentioned , (another disclaimer) I am no scientist either , but science is based on observations yes tests but also those observations are provided by our senses ...hearing.

Thanks all for the interesting thread. As a guitar player (Ok I'm not really a good guitar player) I don't have to tell you all how subjective "tone" is but that is why we need some scientific way to measure things Ok not really sure where I meant to go with the thread other than to say I can hear a difference .....
Old 7th February 2009 | Show parent
  #205
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seven's Avatar
 
🎧 10 years
Quote:
Originally Posted by spencerc ➑️
Hey Everyone...I haven't had time to catch up on the many new posts today (but I will later tonight).

I only have a minute and so I wanted to say, I think I have a way of solving this for good (hopefully). I'm going to be constructing my studio this spring/summer, and I will do tests before/after I lay down the hardwood.

Thanks,

-Spencer
This weekend I am starting the build on my small live room which will be on an existing 15x10 slab. I'm planning on making the inside ceiling around 9-10 feet. Not huge but workable for me.

I intend on covering the cement with wood mostly for the insulation/warmth* factor.

I am more than willing to test before and after as well - if we can create an appropriate test to conduct (which software to measure with, mike placement, source/speaker placement, etc)

It might be a couple months out before I've built enough to test, but the offer stands along side of spencerc.

Something came to me while reading this thread. Most of it has to do with large amounts of concrete vs sheets of plywood or strips of wood. It doesn't seem to be equal tests as you can't really "pour" an 8 inch thick wood floor.

It makes me wonder how a plywood sheet on a 2x4 wall would sound vs a sheet of cement board of the same thickness on 2x4s. Cement board should reflect the same as poured cement and it seems logical it would feature the same variables as the wood regarding the structure.

How about something very solid made of wood, like a log cabin, with 1 foot thick wood as a wall vs an old army bunker with 1 foot think concrete walls. Granted the log cabin would need to have a flat surface on the inside instead of the common rounded raw timber.

Hmm.. I should reassess posting anything outside of offering to test the room. I don't really like cans filled with worms. Ah hell..

CLICK - Submit Reply



*warmth as in heat - aka: anti-cold. Not warmth as in how it sounds.
Old 7th February 2009 | Show parent
  #206
Deleted 56021e5
Guest
For musical purposes DnT,w(C:Ctr) is not good to use.
Old 7th February 2009 | Show parent
  #207
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Ethan Winer's Avatar
 
🎧 15 years
Lightbulb

Quote:
Originally Posted by seven ➑️
I am more than willing to test before and after as well - if we can create an appropriate test to conduct (which software to measure with, mike placement, source/speaker placement, etc)
Excellent! If everyone agrees, I'll start a new thread "How to test the sound of a floor" or some such and propose a method. Then we can all chime in and try to agree ahead of time how you (and Spencer) should do this. But let's do it in a new thread, okay? IMO this thread has worn out it's welcome. It doesn't even have the correct thread title! heh

--Ethan
Old 7th February 2009 | Show parent
  #208
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🎧 15 years
Quote:
Originally Posted by Ethan Winer ➑️
Excellent! If everyone agrees, I'll start a new thread "How to test the sound of a floor" or some such and propose a method. Then we can all chime in and try to agree ahead of time how you (and Spencer) should do this. But let's do it in a new thread, okay? IMO this thread has worn out it's welcome. It doesn't even have the correct thread title! heh

--Ethan
Sure, why not? The problem as I see it is this: there is no way to extrapolate from the data how the room "sounds", at least as I understand your assertion. So what's the point? You'll show what you expect to show I'm sure, then we'll ask, "but how does it sound?", and we'll be right back where we started from. We have lab test data already, and we got nowhere in the debate. If you want this to be a worthwhile test, you'll have to agree to some kind of subjective element and accept the results as authoritative. Otherwise it's pointless.

I'm not trying to be difficult; I'm trying to avoid another 10 pages of back and forth that goes nowhere.

Frank
Old 7th February 2009 | Show parent
  #209
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Trev@Circle's Avatar
 
🎧 10 years
I agree. Just measuring a single reflection wouldn't do it. I guess you'd have to develop what would amount to a double blind a/b test (before/after wood) whereby the same pre-recorded material was fed into the room and re-recorded (this time with the room sound added) both before and after.

Quote:
Originally Posted by Weasel9992 ➑️
Sure, why not? The problem as I see it is this: there is no way to extrapolate from the data how the room "sounds", at least as I understand your assertion. So what's the point? You'll show what you expect to show I'm sure, then we'll ask, "but how does it sound?", and we'll be right back where we started from. We have lab test data already, and we got nowhere in the debate. If you want this to be a worthwhile test, you'll have to agree to some kind of subjective element and accept the results as authoritative. Otherwise it's pointless.

I'm not trying to be difficult; I'm trying to avoid another 10 pages of back and forth that goes nowhere.

Frank
Old 7th February 2009 | Show parent
  #210
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johndykstra's Avatar
 
🎧 10 years
dan's criteria seems fair enough. Along with the reflection test, you also can do a waterfall plot of the whole room, and re-record program music for an a/b listen. obviously, since it'd be your room, the tester can feel free to post their personal comments. I personally think the personal comments will be the most valuable.heh

+2 for a new thread
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