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Author Topic: Does Wood Really Sound Warm?  (Read 7826 times)

Thomas Jouanjean

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Re: Does Wood Really Sound Warm?
« Reply #30 on: February 20, 2009, 03:13:44 am »

Ethan Winer wrote on Wed, 18 February 2009 11:22

I don't know for sure either, but it seems that absorption would be maximum on axis and minimum when "grazing" edgewise.


In many cases, absorption is better with an incidence other than perpendicular.

Ethan Winer wrote on Wed, 18 February 2009 11:22

The bottom line for me is that it makes no sense that a slab of wood bonded to solid cement can absorb 1 KHz by 80 to 90 percent at any angle!

The huge drop in absorption around 3 KHz is also very telling, no?

--Ethan


Sure, you can believe what you want. I understand you can be puzzled by this - but please listen to what 3 professional acousticians told you here. This is a complex issue, and likely no one can give you a definitive answer. What I'm telling you is: don't draw fast conclusions based on partial data. You are way too definitive in your approach of things. Be cautious. I would take that article off-line.

Again, I agree it's healthy to question things - and it's okay to wonder about the absorption of wood as measured in the graph. I would not rule it out though because it is likely a serious measurement. If we take the example of your bass traps, how much sense does it makes that such a thin "limp" membrane makes them according to your data so much better in the LF range? When there is considerably more energy involved at 100Hz than 1kHz?

I think it's about time this discussion ends, understanding that the partial data we have is not enough to rest anybody's case. We have various opinions stated, and some hints at what may be happening - let's leave it at that Smile
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Thomas Jouanjean
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Ethan Winer

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Re: Does Wood Really Sound Warm?
« Reply #31 on: February 20, 2009, 02:20:25 pm »

Thomas Jouanjean wrote on Fri, 20 February 2009 03:13

 don't draw fast conclusions based on partial data.

As far as I can tell, the data I based my reflectivity amounts on is not partial. And assuming the data was measured in a lab, the test conditions are well known - measured flat on a floor - and so correspond directly with the premise of how different floor materials sound. If I'm missing something important I'd love to hear it! Or if you think the way I converted absorption to reflectivity is flawed, I'd like to hear that too. I'm not trying to be combative, but so far I'm not convinced there's anything wrong with my approach.

This has nothing to do with who is or is not a professional acoustician. I don't understand way so many people, not just here but at Gearslutz too, want to cease the discussion of something that is so critically important to studio design. Confused

Quote:

I would not rule it out though because it is likely a serious measurement.

I'm sure it's a serious measurement. But without knowing the thickness of the material being tested, or whether it was against a solid backing or in free air, or even knowing for sure how 0 and 90 degrees are intended, that to me falls under what you call "partial data," no?

BTW, I just found that book on Google Books and here's what little it says about the wood specimens:

"Measurements were performed on disks of 31 - 101 mm in diameter [1.2 - 4 inches] and 2 - 11 mm thickness [0.08 - 0.43 inches]."

So this implies to me that they were investigating properties of wood as used in musical instrument construction, with the wood free to vibrate. Versus bonded to a rigid backing like a floor.

--Ethan

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Re: Does Wood Really Sound Warm?
« Reply #32 on: February 20, 2009, 02:24:50 pm »

I don't see how you can imply that... what I imply is that the samples are circular because of the Kundt tube geometry maybe ?

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Ethan Winer

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Re: Does Wood Really Sound Warm?
« Reply #33 on: February 20, 2009, 03:06:49 pm »

andrebrito wrote on Fri, 20 February 2009 14:24

I don't see how you can imply that.

Imply what? I made a number of statements. Very Happy

--Ethan

Thomas Jouanjean

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Re: Does Wood Really Sound Warm?
« Reply #34 on: February 20, 2009, 03:15:52 pm »

Ethan Winer wrote on Fri, 20 February 2009 13:20


but so far I'm not convinced there's anything wrong with my approach.


Your approach is that you seem to take a very particular case, from which you generalize and draw conclusions, which are IMO sloppy at best. You also fail to digest or really consider information that goes against your conclusions. This is not the way to do it.

Ethan Winer wrote on Fri, 20 February 2009 13:20

I don't understand way so many people, not just here but at Gearslutz too, want to cease the discussion of something that is so critically important to studio design. Confused


I agree it is important to studio design, this is why so many of us here are very cautious with the issue. Designing is about finesse of judgement and balance. Acoustics is as much a science as it is an art.

We all see what your position is, and see where this is going.

What I would like to see to take this discussion further and keep it interesting is data about how various implementations of wood in a room affects the overall response. Then we can see where (and if) it makes a difference.

If anybody has more hard data or interesting, precise information to share with us about this subject, please PM me. It will be very welcomed!

Until then, I'm locking this thread.


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Thomas Jouanjean
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Thomas Jouanjean

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Re: Does Wood Really Sound Warm?
« Reply #35 on: February 20, 2009, 06:27:14 pm »

Okay - more extracts from the book out of which Andre took the Graph, and to which Ethan provided a link in Google Books.

It indicates that:

1- behaviour is very dependent on conditions of installation and species of wood.

2- It also indicates that wood has a real absorptive capacity, and that although the impedance tube measurement can be influenced by external factors, it is pretty reliable and the behaviour of the wood as shown in the graph can be explained by the "motion of the air contained in the cavities of wood cells".

3- It also states that in some other and particular set of conditions, wood can also present a lower and more even absorptive behaviour:

"Watanabe et at (1967) noted that for all species analyzed, when thin specimens (10 mm maximum thickness) are exposed to the incident sonic energy in the anisotropic planes of wood LR or longitudinal tangential (LT), the absorption coefficient is small and quite constant for all frequencies."

IMHO, what this shows in fine is that wood has indeed a tendency towards audible "coloring", but the complexity of it's behaviour and multiple ways of implementing it prohibits any precise pronostic as to the extent of the "coloration".

So, all in all, it likely has a sound, and how much you get of it will vary quite a bit from case to case. It is also likely to behave differently from say, Linoleum or Concrete, the authors mentioning the effect of air in the wood cell structure as a reason for it's absorptive behavior, properties (air) that cannot be found in similar fashion in both linoleum and concrete.

This part of the article does not assess the re-emission factors in wood, which could possibly lead to more coloring.

Of course, YMMV.

Thread unlocked Smile

I hope other contributors can come up with more infos!
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Thomas Jouanjean
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Thomas Jouanjean

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Re: Does Wood Really Sound Warm?
« Reply #36 on: February 20, 2009, 06:44:51 pm »

Ethan Winer wrote on Wed, 18 February 2009 11:22


The bottom line for me is that it makes no sense that a slab of wood bonded to solid cement can absorb 1 KHz by 80 to 90 percent at any angle!
--Ethan


Well, sounds like it does make sense! The authors state that only wood of less than 10mm thickness in a very particular set of conditions shows low and even absorption like showed in your article.

Otherwise, wood seems pretty absorptive around 1kHz. The data you used in your article was for a very specific case, as a parquet of "over 10mm thickness" would be, according to the authors, expected to show more than enough absorptive behaviour to effectively have an impact on perceived sound.
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Thomas Jouanjean
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Ethan Winer

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Re: Does Wood Really Sound Warm?
« Reply #37 on: February 21, 2009, 01:42:54 pm »

Thomas Jouanjean wrote on Fri, 20 February 2009 18:27

Thread unlocked Smile


Great, thanks. I didn't understand locking a thread where acousticians are discussing such an important acoustics issue.

Quote:

The data you used in your article was for a very specific case, as a parquet of "over 10mm thickness"


All I did was find "Internet" data Very Happy for various materials. I'm not so sure that > 10 mm is a standard thickness for parquet wood flooring. 10 mm is 0.4 inches, and the first link Google came up with is for tiles 0.31 inches thick (7 mm):

http://www.fastfloors.com/catalog/productline.asp?productlin eid=19247&productid=134727&REF=CZT1334564

Quote:

I hope other contributors can come up with more infos!


I too would love to see more data for different types of standard wood-over-concrete floors. We may settle this yet. Laughing

--Ethan

Thomas Jouanjean

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Re: Does Wood Really Sound Warm?
« Reply #38 on: February 21, 2009, 02:31:03 pm »

Ethan Winer wrote on Sat, 21 February 2009 12:42


Great, thanks. I didn't understand locking a thread where acousticians are discussing such an important acoustics issue.


I had a feeling this would go the GS way (running in circles leading to bickering etc).
I will never allow this on this forum.

Ethan Winer wrote on Sat, 21 February 2009 12:42

All I did was find "Internet" data Very Happy for various materials. I'm not so sure that > 10 mm is a standard thickness for parquet wood flooring. 10 mm is 0.4 inches, and the first link Google came up with is for tiles 0.31 inches thick (7 mm):


We just installed a 1.8cm thick beautiful oiled parquet in a studio, CR & LR. Darius @ Amsterdam Mastering did just the same too.

Your original question: "The conventional wisdom is that wood surfaces impart a "warm" sound to a room, compared to cement, linoleum, or drywall. But is this really true?"

With the information we have, the answer leans toward a "Yes, but...", not the opposite. Especially since you are talking about "surfaces" in your question which is indefinite (so it could be just any surface, not just the floor!).

It has a sound of it's own, which by looking at the graph can explain the adjective "warm" that is used in describing it.

Your article's conclusion: "Although some people believe that wood and cement and linoleum all sound different, any difference they heard is most likely due to other factors such as the size and shape of the rooms, and other surfaces present."

Can you agree that this is not the right conclusion to give? It's rather misleading.

IMHO, I think you should rework it all and show at least that thickness matters a lot in how much of the "sound" you get. You should as well at least mention and talk a bit about the re-emission factors, which are IMHO pbly the most important ones. Adressing only reflectivity, and furthermore only partially feels to me like looking at the whole subject through a peephole at night.

What do you think?
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Thomas Jouanjean
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Ethan Winer

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Re: Does Wood Really Sound Warm?
« Reply #39 on: February 21, 2009, 04:09:21 pm »

Thomas Jouanjean wrote on Sat, 21 February 2009 14:31

I had a feeling this would go the GS way (running in circles leading to bickering etc). I will never allow this on this forum.

Excellent. It's a shame the GS moderators don't have the same attitude. Sensible people are perfectly capable of discussing things without getting angry or tossing insults. Only a few get frustrated and become nasty.

Quote:

We just installed a 1.8cm thick beautiful oiled parquet in a studio, CR & LR. Darius @ Amsterdam Mastering did just the same too.

I would have loved to see some room measurements before and after putting in the floor! Was the wood on top of solid concrete?

Quote:

With the information we have, the answer leans toward a "Yes, but...", not the opposite.


"The information we have" is the crux of it. I give much more credibility to the data shown in my report than to the data in the book Andre posted. First, the data I used to calculate reflectivity agrees with most other data I've seen. It also agrees with what I consider common sense. I know what material sounds like when it absorbs 70 percent or more at mid and high frequencies, and wood does not sound like that at all. Below are a few online AbsCo charts, with the one I used first. In all cases, the values for wood on cement are well below 0.10. However, it's entirely possible some or all of these online resources are derived from the same source!

http://www.saecollege.de/reference_material/pages/Coefficien t%20Chart.htm
http://www.acousticalsurfaces.com/acoustic_IOI/101_13.htm
http://online.physics.uiuc.edu/courses/phys199pom/Student_Re ports/Fall02/Alan_Truesdale/Alan_Truesdale_Absorbtion_Coeffi cients.pdf
http://www.sengpielaudio.com/calculator-RT60Coeff.htm
http://www.wsdg.com/dynamic.asp?id=resources/technology/abso rbtion

The reason I discount the data in the book Andre linked is because we have no clue about the specific samples or how they were measured. All we know is a broad range of sizes and thicknesses, but no idea what type of sample is shown in that particular graph. Indeed, what we do know is the samples were most likely not attached firmly to a backing since they were measured at various angles in an impedance tube. I suppose it's possible the wood samples were glued to a thick rigid backing, but I doubt it because doing that makes no sense if the goal is to measure the wood. We also know the samples were thin and small, and the data in that graph disagrees with all the other data I can find.

Quote:

Your article's conclusion: "Although some people believe that wood and cement and linoleum all sound different, any difference they heard is most likely due to other factors such as the size and shape of the rooms, and other surfaces present."

Can you agree that this is not the right conclusion to give? It's rather misleading.

I cannot agree yet. Sorry!

Quote:

show at least that thickness matters a lot in how much of the "sound" you get.

That's a great idea. Do we have data for wood on cement at various thicknesses?

Quote:

You should as well at least mention and talk a bit about the re-emission factors

Does re-emission happen with wood on cement, or only with wood on joists? Do we have any re-emission data? I agree that the more data we can see, the more complete the conclusion will be.

--Ethan

Thomas Jouanjean

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Re: Does Wood Really Sound Warm?
« Reply #40 on: February 21, 2009, 05:48:47 pm »

Ethan Winer wrote on Sat, 21 February 2009 15:09


Was the wood on top of solid concrete?


Yes.

Ethan Winer wrote on Sat, 21 February 2009 15:09


"The information we have" is the crux of it. I give much more credibility to the data shown in my report than to the data in the book Andre posted. First, the data I used to calculate reflectivity agrees with most other data I've seen. It also agrees with what I consider common sense.


You do realise that there is considerably more info on the subject in the article submitted by andre than in any of your supplied data? It's also not a question of common sense but a question of understanding the data. What your data shows is what is also shown and explained as an exception in the Watanabe & Hayashi study: that, all other things being equal, under a certain thickness absorption becomes uniform and lowers.  You can't derive a conclusion like yours, that "wood is no different than linoleum", based on the exception.

That would be common sense.


Ethan Winer wrote on Sat, 21 February 2009 15:09

the data in that graph disagrees with all the other data I can find.



Because it's not the same data at all! Only parts of it bears similarities. Your data only shows (probable) reverb chamber measurements with thin layers - and again it was shown how that affects the results. The book shows much more in-depth measurements, with various samples in various conditions. Therefore it is normal it bears different results with "all the other data you can find".

Ethan Winer wrote on Sat, 21 February 2009 15:09

I cannot agree yet. Sorry!


You don't have to.

But I can't help thinking you fail to see the forest for the tree here. What I expect from this discussion are not final, undeniable facts but to determine the most plausible explanation and to show that this is a complex issue that in itself prevents any straight definitive answer.

We can outline certain behaviours. Concluding like you do in your article is not okay by any remotely scientific standards.

Ethan Winer wrote on Sat, 21 February 2009 15:09

That's a great idea. Do we have data for wood on cement at various thicknesses


I'll check in my database, but we do know now about the 10mm benchmark. That is a lot already! And this phenomenon is not linked to whether or not the wood is on cement or joists. Just thickness.

Ethan Winer wrote on Sat, 21 February 2009 15:09

Does re-emission happen with wood on cement, or only with wood on joists? Do we have any re-emission data? I agree that the more data we can see, the more complete the conclusion will be.


Re-emission is a very, very tricky subject. Way more complex than the one at hand. What you need to know is that it's everywhere in any solidian that vibrates.





Ethan, your question has been answered I believe, by others and myself. We'll have to agree to disagree. My personal view is that your approach is lacking in many ways.

I am going to close that thread now. I don't think we can really go any further and I believe there is enough information for each and everyone interested to make up his own mind about it all - which is what matters.

To everyone, feel free to PM me if you have something relevant to add to the thread. I will then re-open it.
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Thomas Jouanjean
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franman

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Re: Does Wood Really Sound Warm?
« Reply #41 on: February 22, 2009, 12:04:51 pm »

Ladies... let's all play nice here please?? I've been on the road all last week and missed this really fun exchange. Let's all agree to 'disagree' and let's ALL act professional and we ALL are professionals.

PS: Glenn, you got any spare popcorn??? Cool
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Thomas Jouanjean

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Re: Does Wood Really Sound Warm?
« Reply #42 on: February 22, 2009, 01:53:55 pm »

Hey Francis,

There is no problem... I just want to avoid endless discussions on the subject when I think we have covered it all and the rest would've been just beating a dead horse and re-debating points on and on with a risk of seeing this thread turn like the similar GS thread.

There is no room for that here.

Some users have asked me to reopen, so I will do so. But I would really like something constructive.

If a user has had a problem with the fact that I have closed the thread (seeing me heavy handed when it's not how it should be seen), feel free to PM me about it.  Smile

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Thomas Jouanjean
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Ethan Winer

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Re: Does Wood Really Sound Warm?
« Reply #43 on: February 22, 2009, 02:11:40 pm »

franman wrote on Sun, 22 February 2009 12:04

Glenn, you got any spare popcorn??? Cool

Here ya go:

http://www.freesmileys.org/smileys/smiley-fc/popcorn.gif



Laughing

Ethan Winer

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Re: Does Wood Really Sound Warm?
« Reply #44 on: February 22, 2009, 02:23:13 pm »

Again, I'm trying very hard not to appear combative, but I feel the important points are being overlooked.

Thomas Jouanjean wrote on Sat, 21 February 2009 17:48

You do realise that there is considerably more info on the subject in the article submitted by andre than in any of your supplied data?

But how does that book address the core question of my article, which is the sound of wood floors over concrete? And how is the data in that book useful if we don't even know the size or thickness of the material sample used for the graph? Why should that incomplete data take precedence over the well-known properties of floor material as shown in every one of the absorption links I posted?

Whatever, we've all made our points. I still feel the burden of proof that a wood floor on cement sounds substantially different than a floor of plain cement has not been met. Thomas, it would be great if you're able to measure this the next time you're about to install a wood floor over a concrete slab.

BTW, this morning I added a second paragraph to the Conclusion part of my article to explain that the data is somewhat limited because it doesn't go higher than 4 KHz. To me this is a minor issue, but I want to be accurate and fair.

--Ethan
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