Rather than divert the DIY treatment thread with yet another theoretical discussion, I've started this and moved the relevant bits from that thread over here.

This thread picks up from a bit of a digression on the DIY Acoustic Treatment thread. I've moved to here the bits in that thread which were taking it off topic, as follows:

Quote:

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Ethan Winer:

Paul,

> I hesitate to use the word 'bass trapping' as standing waves can affect lo-mid performance as well. <

In fact, you can and will get standing waves at higher frequences too. Play a 1 KHz or 2 KHz sine wave through your loudspeakers then walk from the front of your room toward the back. You'll hear an obvious tremolo warble as your ears quickly pass through all the peaks and nulls. You don't have to use sine waves either. The exact same effect occurs with sustained flute and clarinet notes.

--Ethan

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Quote:

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Paul Woodlock:

Ethan...


Well as standing waves occour at each harmonic above the fundermental, I wouldn't disagree that standing waves occour at much higher freqeuncies. They are definitely there according to theory.

However I would contend that the peaks and dips you are hearing at those freqeuncies are FAR MORE LIKELY to stem from the path length differences of reflections v. direct sound, path length differences of reflections v. other reflections, etc, etc rather than standing waves.

IMO and experience, standing waves from the lowest fundermental freq determined by the dimensions up to around 500Hz are the one's where treatment is necessary in general. Individual rooms of course will have varying requirements.

This is why I think it's good to choose an absorption device for trapping that has good specs not only in the 'bass', but in the lo-mid as well.


Paul

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Quote:

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Ethan Winer:
Paul,

> They are definitely there according to theory. <

They are definitely there in practice too! If you take the time to play some 1 and 2 KHz (or even higher) tones as I described you'll immediately see I am correct.

> I would contend that the peaks and dips you are hearing at those freqeuncies are FAR MORE LIKELY to stem from the path length differences of reflections v. direct sound, path length differences of reflections v. other reflections, etc, etc rather than standing waves. <

Absolutely not. They are entirely due to and caused by comb filtering off the various room surfaces. You remember those pesky 1/4 wavelength peaks and nulls, right? In fact, this is further proof that standing waves have nothing at all to do with room modes. Go ahead and try it and I'm sure you'll notice the tremolo effect I described earlier. (Unless you happen to have absorption on the rear wall that the speakers are facing.)

--Ethan

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Quote:

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OVU:
Quote:
>this is further proof that standing waves have nothing at all to do with room modes.<


Sorry, you really have lost me now.

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Quote:

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Ethan Winer:
0,

> Sorry, you really have lost me now. <

Okay, let's try it this way: If you define standing wave while avoiding the word mode - just describe what it is using plain English - then I'll know better how to explain my point in a way you can understand.

--Ethan

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Quote:

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0VU:
E,

Quote:
Okay, let's try it this way: If you define standing wave while avoiding the word mode - just describe what it is using plain English - then I'll know better how to explain my point in a way you can understand.



How about we just try whatever explanation you feel covers it. And don't worry too much about plain English or me understanding it - I'll try to cope.

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Quote:

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Ethan Winer:
0,

> How about we just try whatever explanation you feel covers it. <

No, that won't work. I need to know what you think a standing wave is first. Sorry, and I swear I'm not trying to be patronizing or condescending.

--Ethan

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Quote:

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Paul Woodlock:

Quote Ethan Winer:
Paul,

> They are definitely there according to theory. <

They are definitely there in practice too! If you take the time to play some 1 and 2 KHz (or even higher) tones as I described you'll immediately see I am correct.

> I would contend that the peaks and dips you are hearing at those freqeuncies are FAR MORE LIKELY to stem from the path length differences of reflections v. direct sound, path length differences of reflections v. other reflections, etc, etc rather than standing waves. <

Absolutely not. They are entirely due to and caused by comb filtering off the various room surfaces. You remember those pesky 1/4 wavelength peaks and nulls, right? In fact, this is further proof that standing waves have nothing at all to do with room modes. Go ahead and try it and I'm sure you'll notice the tremolo effect I described earlier. (Unless you happen to have absorption on the rear wall that the speakers are facing.)

--Ethan



To highlight a speciic part of your post....

Quote:
> Paul says: I would contend that the peaks and dips you are hearing at those freqeuncies are FAR MORE LIKELY to stem from the path length differences of reflections v. direct sound, path length differences of reflections v. other reflections, etc, etc rather than standing waves. <

Ethan Replies: Absolutely not. They are entirely due to and caused by comb filtering off the various room surfaces. You remember those pesky 1/4 wavelength peaks and nulls, right?



The 'comb filtered' frequency response you describe at the higher frequencies talked about in this thread, is MAINLY caused by reflections at these frequencies. So of course placing absorption on the reflective surfaces will diminish the 'tremolo effect' you describe.

I'm well aware of this tremelo effect btw. you've only got to move your head slightly while listening to music to hear HF fluctuate in volume at various freqs.

You say this is 'further proof' that 'standing waves' are nothing to with room modes. Firstly I have never seen ANY proof of this. So could you kindly explain the initial proof and clarify the 'further proof' above?


The problem is Ethan, is that 0VU, myself and the rest of the world don't agree with your postulation. It's not impossible that you have come up with something entirely new in the science of acoustics.

I would suggest, bearing that in mind, you would make your theories a LOT EASIER to understand if YOU explained to US in DETAIL, jutst exactly what you think a Standing Wave is, and EXACTLY WHY room modes have nothing to do with standing waves.

Myself and 0VU's definition of a standing wave can be found on probably every Website that deals with tutoring basic physics, so there's no point in repeating it here. Google is quicker for everyone.

I have an open mind, and I'm willing to listen to anyone's theory. But in order to listen, you must say something.


Paul

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Quote:

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0VU:

E,

Sorry, momentarily distracted there.

Quote:
> No, that won't work. I need to know what you think a standing wave is first. Sorry, and I swear I'm not trying to be patronizing or condescending.<



Rather than risk this getting lost in a discussion of the detail of various definitions of standing waves, I'd prefer you just explained how "standing waves have nothing at all to do with room modes". Perhaps the quickest way to go is if you simply state the definition you prefer and then explain your theory from there.


Incidentally, I have a feeling that we may be in danger of dragging this thread away from it's present real-world, practical basis into another theoretical discussion. I don't want that to happen so if that's likely, it'd be better if this were taken to another thread so as to keep the present one on topic.

0VU

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OK - that was where we got in the other thread. Discuss.

Thanks OVU....

I still don't understand how a "standing wave" can be heard.



Maybe someone can explain how the eardrum is vibrated if the areas of low and high pressure do not actually move in the room. Sound is, after all, a pressure wave of alternating bands of low and high pressure that we perceive from the vibration of the eardrum.

Or is a standing wave a situation where the energy combines to cancel out itself?

I did a search on google and this looks like a good explanation.

Greetings


think of it this way....


Pluck a guitar string..... Although the string is vibrating, the wave in the string itself doesn't move ( where can it go? ) and is therefore a Standing Wave.

While it still vibrates, lightly touch the string just over the 12th fret. You'll damp the fundermental freq. , leaving the 2nd harmonic and even harmonics above. The 12th fret position, is now a point of no displacement ( node ) for the wave of the 2nd harmonic ( and above ) of the gtr string. That's a Standing Wave.


Now get a Whip and crack it ( don't forget the thigh boots ). You'll see the wave travel along the whip to the end. Ouch! That's a Travelling Wave.

In both cases particles in the string and whip do not move location, but are displaced about a fixed point.

Right! I need a coffee. Back later

....

Back..

Further to get back to ethan's argument.....


I think Ethan is getting standing waves confused with the fixed areas of cancellation and addition that occour when 2 or more travelling sound waves collide as a result of different path distances due to surfaces in the room.

Play a sine wave a certain distance from a reflective surface and sure you'll get a cancellation at a 1/4wavelength from the wall. But the sound waves causing this are not standing waves, they're 'travelling' to the wall and back.

When you excite the air in a room ( i.e by a speaker ), sound at freqencies which correspond to the resonant freqeuncy of the airspring between two or more surfaces in the room act as standing waves rather than travelling waves.

Now for reasons I don't actually know, the maximum vibration ( anti-node )of these standing waves happens at the boundary of each surface. While the point of minimum or no vibration ( node ) occours halfway between the surfaces ( for the fundermental frequnecy at least ). this is opposite to the stnading wave in the guiter string, as the boundaries ( nut and bridge ) are always the point of no vibration. ( anyone care to exaplin this difference? .... pretty please )

This explains why you can hear a lot of bass if you get real close to the wall, and why the very centre of the room usually has the least amount of bass becuase you're at the anti-node of all 3 fundermental axial(*) nodes

Corners are the junction of two or more surfaces, and two or more standing wave's anti-nodes, so the vibrational energy is greatest in a corner. Tri-corners where 3 surfaces meet are even better per se.

Ethan claims standing waves are nothing to do with standing waves. Which he could be forgiven for, if he's also confused between travelling waves causing cancellations v. and standing waves caused by MSM ( wall-air-wall ) resonances.

Room modes, As I see it, is the term for the collection of various resonant wall-air-wall frequencies in the room itself. I know of 3 different types of room modes.

(*)1. Axial modes are the standing wave freqeuncies caused by air being excited between two surfaces

i.e front to back, left to right and up and down

2. Tangential Modes are the standing wave freqeuncies caused by air being excited between 4 surfaces.

i.e 4 walls, 2 walls and floor and ceiling, etc

3. Oblique Modes are the same but for 6 surfaces.

Tangential Modes, I have repeatedly heard, can have more than a little bearing on the acosutic performance of the room, and it's been advised to use a room mode calculator that shows ALL mode types.


Anyway, that is how I see things. I beg any corrections as I'm here to learn more about this stuff



Paul

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Pauls Studio Build Diary at http://forum.studiotips.com/viewforum.php?f=1

Here's the way I look at it: all the problems you get are caused by refections - you hear one sound straight from the speakers and the same sound delayed bounced off a wall (or 2 or 3 or more) and you get the potential for cancellations.

The 'standing wave' is just a special case of this where the dimensions of the room mean that the 2nd and subsequent refelections reinforce the 1st refection giving the potential for a greater null or peak.

Simple eh?

(too simple )

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Midipicks - the all new MIDI Guitar forum...

This site provides an explanation that makes sense to me.

"In conclusion, standing wave patterns are produced as the result of the repeated interference of two waves of identical frequency while moving in opposite directions along the same medium. All standing wave patterns consist of nodes and anti-nodes. The nodes are points of no displacement caused by the destructive interference of the two waves. The anti-nodes result from the constructive interference of the two waves and thus undergo maximum dispacement from the rest position."

Not quite as amusing as Paul's Madam Whiplash example...

Yeah, that's exactly right fruity - a standing wave is caused by two travelling waves going in opposite directions.

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Midipicks - the all new MIDI Guitar forum...

Quote Paul Woodlock:

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Now for reasons I don't actually know, the maximum vibration ( anti-node )of these standing waves happens at the boundary of each surface. While the point of minimum or no vibration ( node ) occours halfway between the surfaces ( for the fundermental frequnecy at least ). this is opposite to the stnading wave in the guiter string, as the boundaries ( nut and bridge ) are always the point of no vibration. ( anyone care to exaplin this difference? .... pretty please )

---

There isn't really a difference, but you've got a bit confused!

Starting with the guitar string - the classic way to think about this is a load of balls (!) attached by springs. If you pluck the string the balls in the middle move up and down the most. The balls at the end move the least - obviously because they are fixed! But there's something else going on too : the springs. If you look at how the tension in the springs varies you'll see that in the middle it varies the least because two balls in the middle are at the top of the 'sine shape' where it's almost flat, so they move very little relative to each other, and hardly stretch the spring at all.

On the other hand if you look at the springs right at the end you'll see that the tension varies the most because one ball is fixed and the next moves up and down in the steep part of the 'sine shape'.

So, going back to air - the movement of the air right next to the wall is zero just like the guitar string. But the pressure variation right next to the wall is maximum which is why you can hear the bass there (your ears are measuring the pressure variation, not the air movement).

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Midipicks - the all new MIDI Guitar forum...

Ah, the joys of comparing transverse and longitudinal waves!

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http://www.magicbeansrecords.com

Quote cc.:

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Quote Paul Woodlock:

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Now for reasons I don't actually know, the maximum vibration ( anti-node )of these standing waves happens at the boundary of each surface. While the point of minimum or no vibration ( node ) occours halfway between the surfaces ( for the fundermental frequnecy at least ). this is opposite to the stnading wave in the guiter string, as the boundaries ( nut and bridge ) are always the point of no vibration. ( anyone care to exaplin this difference? .... pretty please )

---

There isn't really a difference, but you've got a bit confused!

Starting with the guitar string - the classic way to think about this is a load of balls (!) attached by springs. If you pluck the string the balls in the middle move up and down the most. The balls at the end move the least - obviously because they are fixed! But there's something else going on too : the springs. If you look at how the tension in the springs varies you'll see that in the middle it varies the least because two balls in the middle are at the top of the 'sine shape' where it's almost flat, so they move very little relative to each other, and hardly stretch the spring at all.

On the other hand if you look at the springs right at the end you'll see that the tension varies the most because one ball is fixed and the next moves up and down in the steep part of the 'sine shape'.

So, going back to air - the movement of the air right next to the wall is zero just like the guitar string. But the pressure variation right next to the wall is maximum which is why you can hear the bass there (your ears are measuring the pressure variation, not the air movement).

---

Cheers for that CC.

Gotcha. Well explained.


Paul

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Pauls Studio Build Diary at http://forum.studiotips.com/viewforum.php?f=1

0VU,

> Perhaps the quickest way to go is if you simply state the definition you prefer and then explain your theory from there. <

It's very simple: Standing waves are waves that are standing still. Where does that happen? Only at node points! Nodes are caused by equal-level waves traveling in opposite directions. You can have node points outdoors caused by reflections off a wall, where there obviously are no room modes.

I realize the term "standing wave" has been misappropriated by some acousticians, but that doesn't make it correct. Even if you can find it in a book. The only book that can claim to define a word or term is the dictionary. My dictionary says "...where the amplitude varies from place to place [and] is constantly zero at fixed points and has a maxima at other points."

You can have zero and maximum wave pressure at fixed points outdoors, and you can have them at non-modal frequencies inside a room. Standing waves also occur in electrical wires when an impedance mismatch causes energy to be reflected back down the wire toward the source. They can even occur at a junction of two water pipes if the pipes do not fit properly and some water is reflected back into the oncoming stream. Indeed, I first learned about standing waves 40+ years ago in an electrical context. To my way of thinking standing waves have nothing to do with room modes, and they have everything to do with reflected waves.

--Ethan

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The acoustic treatment experts

Quote cc.:

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Yeah, that's exactly right fruity - a standing wave is caused by two travelling waves going in opposite directions.

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Quote Ethan Winer.:

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Standing waves are waves that are standing still. Where does that happen? Only at node points! Nodes are caused by equal-level waves traveling in opposite directions.

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Just to clarify and avoid future confusion. Standing waves are caused by equal frequency waves traveling in different directions, including opposite. The waves can be different levels travelling perpendicular and still cause standing waves as long as the frequency at the node center is equal in both waves.

A standing wave has no direction, it is a point in space.

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John D. Geisen
Owner DPS

This is potentially off topic but I think it's important for those new to acoustics or those looking for greater understanding of acoustics to understand that a graphical representation of a wave is, in most cases, not a picture of the wave. It is a graph of two and sometimes three descriptive properties of a wave drawn relative to each other. Since these properties are often not legended in the graph* it is important to know which properties are being graphed.

In particular, a standing wave is most often shown in a two dimensional line graph plotting Amplitude vs. Time. The waveform created in this graph is not a physical picture of the pressure wave. It is a graph of pressure measurements made at a single point in space over time.

* - forumees often cut and paste a picture from a website or do a screen shot and crop out the desired graph with the assumption that everyone reading the graph knows what the axis titles are. This isn't as bad here as on some other forums but worth mentioning nonetheless.

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John D. Geisen
Owner DPS

John,

> Standing waves are caused by equal frequency waves traveling in different directions, including opposite <

Yes, and I have a litte more to offer here too. The more I think about it, the more I realize that "misappropriate" is the correct word to use when discussing standing waves as described by acousticians. In a true standing wave situation the waves literally are standing still for their entire length. Using the water example I gave earlier because it's simple to understand, water does not compress very much under pressure. So the entire length of the back flow can be said to be standing still, starting at the point of the reflection created by the mismatched junction.

Waves in the air are very different because air is extremely springy. When a standing wave is created in the air the waves are in fact travelling toward each other from opposite directions. It's only at the precise null center that anything is standing still. So there really is no such thing as an acoustic standing wave except for at the exact null point where the deepest cancellation occurs.

--Ethan

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The acoustic treatment experts

Quote:

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"misappropriate"

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Ethan:

I think you are right, that word does seem to fit the circumstances... though I suggest you might want to look it up in a dictionary... the word may be more "appropriate" than you intended.



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http://readyacoustics.com
http://forum.studiotips.com

Quote Ethan Winer:

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John,

> Standing waves are caused by equal frequency waves traveling in different directions, including opposite <
 
... the more I realize that "misappropriate" is the correct word to use when discussing standing waves as described by acousticians. ...
 
In a true standing wave situation the waves literally are standing still for their entire length.....It's only at the precise null center that anything is standing still. So there really is no such thing as an acoustic standing wave except for at the exact null point where the deepest cancellation occurs.
 
--Ethan

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I do agree: A creative concept.

At that exact null point is the highest particle velocity (so anything is certainly not standing still).
The deepest cancellation (as you call it) is the crossover point between relative over and under pressure versus the ambient pressure. This is the point of maximum kinetic energy and kinetic means movement which is the opposite of standing still.

But I accept, acousticians are burdened by knowing acoustics which is a very limiting factor.

In your concept does the sound stop somehow?

Eric

Can you suggest any good text books?

Maybe something comprehensive but not too esoteric.

Thanx.

Eric,

> At that exact null point is the highest particle velocity (so anything is certainly not standing still) <

Yes, you are correct, thanks. I knew that waves stand still where the opposing pressure is maximum, but that occurs at a peak location, not the center of a null.

However, the underlying concept of a standing wave remains, as does my original point: At a predictable distance from a reflecting boundary there are a series of points where the wave is completely motionless. If a wave approaches a boundary at a right angle, the first point is 1/2 wavelength from the boundary. Other points occur at 4/4 and 6/4 and 8/4 wavelengths, etc. (comb filtering). At other angles the distance will vary but still be predictable. Again, the main point is this has nothing to do with room modes, and everything to do with reflections. Standing waves can occur at any frequency outdoors against a wall where clearly there are no modes.

It's also worth mentioning the relationship between acoustic velocity and pressure versus electrical voltage and current. Voltage is like velocity in that you can have a huge amount of it, but if there's no current flowing (pressure) then no work is being done. An AC power outlet has a dangerous amount of voltage available, but until you plug in a lamp or TV, no current will flow and your electric bill will not increase. Likewise, the velocity is very high at an acoustic null point, but you don't hear anything there because there's no pressure.

--Ethan

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The acoustic treatment experts

Fruitfarmer

Have a look here.
http://forum.studiotips.com/viewtopic.php?t=46

One book will go more in-depth to certain topics than the other, and the degree of mathematics can differ a lot.

I have my own courses. I'm Dutch. So I have books in several languages.

Beranek is a classic in education, but Kinzler, Cremer etc. too.
For studios there are other classics.

I find it difficult to advice.

Ethan.
You know I don't agree with your standing wave approach, but I do applologize.
We covered that topic that often and that lengthy that I'm scared to restart that.

You call standing waves what anywhere is referred too and teached as interference patterns.

I never seem to find the time to make a related page with animations.
I think the page Jeff referred to in an other thread as his favorite, and the traditional educational tutorials on the net clearly explain what standing waves and room modes are.

There is no need to invent new physics

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The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

Eric,

> You call standing waves what anywhere is referred too and teached as interference patterns. <

What I don't understand is why you think an interference pattern is not a standing wave. Consider the basic words:

Standing Wave means a wave that's standing still. At the root it is a wave and that requires energy. At some places along the wave's path there is no wave motion, even though there is energy, so therefore at those places it is a standing wave.

A Room Mode is a propensity (ability) to vibrate at a specific frequency. A mode can exist even when there's no energy to excite it. A tuning fork has a propensity to vibrate at A-440, but there's no wave until you actually strike it. A room mode is exactly the same. It's not a wave at all. It's a potential condition - an ability to vibrate at a particular frequency. But it's not a wave.

--Ethan

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The acoustic treatment experts

Ethan:

Single Hz pink noise... 1/4 wave nulls from all walls... the 100 Hz band has a peak because it was measured... standing waves are misunderstood, new terminology and a new theory are required

Don't you get tired of having to make up a new pretend science for every phenomena you take under consideration... another chapter in your "new school" acoustics everytime you run into something you don't understand?

Its a slow motion intellectual train wreck and folks starting to learn the topic do not deserve this treatment, its abusive. You really need to stop.

But not just for the sake of other folks... do it for your own sake as well. Wouldn't it be easier in the long run for you to just pick up a frickin' text book and learn the subject?

Think of all the time and effort it would save.

Or, in the alternative, at least go to some other source for you raw material. If you are gonna do the moonbat pretend science thing, is there really any need to "misappropriate" terms and concepts from real science... it only gets you bitch slapped by "real" acoustic experts.

Instead, maybe you could tie it all back to aromatherapy or the Illuminatae.. at least your diatribes would have a punchline.



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http://readyacoustics.com
http://forum.studiotips.com

Quote Foz:

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.....But not just for the sake of other folks... do it for your own sake as well. Wouldn't it be easier in the long run for you to just pick up a frickin' text book and learn the subject?

Think of all the time and effort it would save.
.....

---

I know

Paul

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Pauls Studio Build Diary at http://forum.studiotips.com/viewforum.php?f=1

Are you guys argueing about whether the combination of an incident wave and a reflected wave can be called a standing wave?!?!

You've made me go and look in my University text book now (which is more than I ever did while I was there)

It seems to think that it can ("The Physics of Vibrations and Waves" by H.J.Pain 3rd ed.) - he uses just this case as an example to calculate the standing wave ratio.

I've lost the will to live now.

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Midipicks - the all new MIDI Guitar forum...

Scott,

> Don't you get tired of having to make up a new pretend science <

Don't you get tried of insulting me while handily evading every point made?

Pick up a college-level text on basic electronics and look up standing wave, then tell me if it says anything about room modes.

--Ethan

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The acoustic treatment experts

Quote Ethan Winer:

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Scott,

> Don't you get tired of having to make up a new pretend science <

Don't you get tried of insulting me while handily evading every point made?

---

Now that is truly rich I'd be Bill Gates if I had £1 for every point you've evaded.

Scott isn't insulting you. On the contrary, he's giving you some well meant advice for your own sake.

CC Quote:

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Pick up a college-level text on basic electronics and look up standing wave, then tell me if it says anything about room modes.

--Ethan

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And you expect people to take you seriously?

Quote CC:

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Are you guys argueing about whether the combination of an incident wave and a reflected wave can be called a standing wave?!?!

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I don't think so CC. Ethan is boldy claiming Room modes have NOTHING to do with standing waves.

However the world of science and education thinks otherwise.

Here's what the University of Southampton, UK, has to say about standing waves and modes ( including room modes ) in various situations. http://www.isvr.soton.ac.uk/SPCG/Tutorial/Tutorial/Tutorial_files/Web-stan ding-waves.htm

Cue more evasion and 'semantics pedantics'.


Paul

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Pauls Studio Build Diary at http://forum.studiotips.com/viewforum.php?f=1

Quote Paul Woodlock:

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Quote CC:

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Are you guys argueing about whether the combination of an incident wave and a reflected wave can be called a standing wave?!?!

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I don't think so CC. Ethan is boldy claiming Room modes have NOTHING to do with standing waves.

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Where did Ethan say this? I found him saying "standing waves have nothing at all to do with room modes" - that is not the same thing!

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Midipicks - the all new MIDI Guitar forum...

cc,

You like to play word games not?
The topic is about Room acoustics.
The way you say it in defense of Ethan is as well PLAIN wrong.

As God and 10 people are my witness:
In order to prevent those incredible exhausting over and over repeating discussions, where confusion is more used as a handy tool to look clever, I wrote others in private BEFORE Ethan's replies.

And this is a literally quote:

Quote Eric wrote privately:

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It is this linguistic finesse that Ethan uses to trick you by provoking that Room modes and standing waves are not related.
So he really hopes that you should say that they are the same. SO DON'T unless putting it in a clear context.
...snip...
Ethan doesn't need to understand standing waves. It's enough for him to prove that you are wrong to cause confusion to come out as the expert himself.

---

I can't be more honest than showing myself.

And if you now like to play with the words as I formulated them: please do. I won't play along. I'm Dutch have little feeling for English and for me it's about the content.


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The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

Eric, I don't want to play word games, but flipping that sentence round changes its meaning - that's why I pointed it out.

All Ethan seems to be saying is that to get a standing wave you just need a reflection, not a room mode. What is wrong with this?

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Midipicks - the all new MIDI Guitar forum...

Quote cc.:

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....

All Ethan seems to be saying is that to get a standing wave you just need a reflection, not a room mode. What is wrong with this?

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That, is NOT the same as this.....

Quote:

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standing waves have nothing at all to do with room modes

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This discussion is now getting absolutely ridiculous.


PAul

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Pauls Studio Build Diary at http://forum.studiotips.com/viewforum.php?f=1

OK, if you take that one sentence out of context it doesn't - but if you look back everytime he says it's not to do with room modes, he also says that it is to do with reflections. For example:

Quote:

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However, the underlying concept of a standing wave remains, as does my original point: At a predictable distance from a reflecting boundary there are a series of points where the wave is completely motionless. If a wave approaches a boundary at a right angle, the first point is 1/2 wavelength from the boundary. Other points occur at 4/4 and 6/4 and 8/4 wavelengths, etc. (comb filtering). At other angles the distance will vary but still be predictable. Again, the main point is this has nothing to do with room modes, and everything to do with reflections. Standing waves can occur at any frequency outdoors against a wall where clearly there are no modes.

---

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Midipicks - the all new MIDI Guitar forum...

Quote cc.:

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OK, if you take that one sentence out of context it doesn't - but if you look back everytime he says it's not to do with room modes, he also says that it is to do with reflections. For example:

Quote:

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However, the underlying concept of a standing wave remains, as does my original point: At a predictable distance from a reflecting boundary there are a series of points where the wave is completely motionless. If a wave approaches a boundary at a right angle, the first point is 1/2 wavelength from the boundary. Other points occur at 4/4 and 6/4 and 8/4 wavelengths, etc. (comb filtering). At other angles the distance will vary but still be predictable. Again, the main point is this has nothing to do with room modes, and everything to do with reflections. Standing waves can occur at any frequency outdoors against a wall where clearly there are no modes.

---

---

CC, with respect....


Ethan's argument that standing waves exist outside of room modes and then using that argument to say the following "In fact, this is further proof that standing waves have nothing at all to do with room modes. " is IMO nonsense.


Just becuase a standing wave can occour in situations OTHER than room modes, DOES not mean that mode frequencies are 'nothing' to do with standing waves.

And hether you say "modes have nothing to do with standing waves", OR "standing waves have nothing to do with modes", is exactly the same.

'nothing' is a symetrical argument, and means the same both ways around.

Just becuase a steering wheel is used on a bus, doesn't mean steering wheels have nothing to do with cars.

That's why this discussion has gotten ridiculous IMO.

All I wanna do is learn a bit more about the subject. And I would suspect, do others reading this.

This stupid trail of wordplay and logical nonsense designed to cover up some people's lack of acosutical knowledge is doing nothing for anyone's education here.

let's look at at what's really happening here....

Do you really think that if Ethan explained the science of acoustics, including standing waves, correctly then people like Eric or Jeff would still take issue with him. Of course they wouldn't. Science is science, reagrdless of whether someone is liked or not.

Yet Ethan's psuedo scientific writings have been challenged by experts on many threads on may forums.

That says something to me.


Paul

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Pauls Studio Build Diary at http://forum.studiotips.com/viewforum.php?f=1

Paul,

> is IMO nonsense <

Rather than call it nonsense, why don't you explain to us why it's nonsense. Please be specific.

> Just becuase a standing wave can occour in situations OTHER than room modes <

Okay, now we're finally getting somewhere. If you recall, I disputed the original contention by Eric and Jeff and maybe others that room modes are standing waves. Now you agree with me that standing waves can occur in situations other than room modes. This is huge because you are confirming what I have been saying for two years now:

Standing waves are the result of basic acoustic interference and so can exist outdoors where there are no modes. Therefore, room modes are a subset of basic acoustic interference. And since standing waves can occur outside of a room they can by extension occur inside a room at non-modal frequencies.

--Ethan

--------------------
The acoustic treatment experts

Quote Ethan Winer:

---

..... Now you agree with me that standing waves can occur in situations other than room modes. This is huge because you are confirming what I have been saying for two years now:
......--Ethan

---

Neither I, nor anyone else to my knowledge, has ever claimed otherwise.

Sorry to disappoint, but you'll have to find other ways to be proved right. It's not 'huge' at all.

First you say, standing waves have nothing to do with room modes, and now you're saying standing waves do have something to do with room modes, but exist outside them also.

Why the change?


Paul

--------------------
Pauls Studio Build Diary at http://forum.studiotips.com/viewforum.php?f=1

Paaaauuuuuul, please!!!!!!!

cc ,

I will answer you later partly.
This goes too far, becomes too time consuming.
I intent to write an article about it, but that takes time.
That's why I said I will make a web page about it when having the time. Then I'm sure all my words are weighed.

I give you a summary though.
I do not agree with Ethan, his FAQ is wrong and misleading, so are lots of his articles.
Even when I try to imagine how Ethan sees those stopping waves, I have no idea how to picture this.

And while knowing and agreeing that it is utterly unfair and unpolite from me to end a message like this, while still not having the energy to go in-depth on all those topics individually, I will prepare something at least showing some of my aversion.

And sorry I really have no idea how to control others's emotions, from which I do know the background, and know they are honest.

--------------------
The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

Quote Ethan Winer:

---

Paul,

Okay, now we're finally getting somewhere. If you recall, I disputed the original contention by Eric and Jeff and maybe others that room modes are standing waves. Now you agree with me that standing waves can occur in situations other than room modes. This is huge because you are confirming what I have been saying for two years now:

Standing waves are the result of basic acoustic interference and so can exist outdoors where there are no modes. Therefore, room modes are a subset of basic acoustic interference. And since standing waves can occur outside of a room they can by extension occur inside a room at non-modal frequencies.

--Ethan

---

I saw those replies only after I entered my previous message.
Reading this message:
Ethan I HAVE AN EXTREMELY DIFFICULT TIME NOT TO USE WORDS NOW WHICH BY DEFINITION MUST BE MODERATED.

YOU FANTASIZE WHAT I AND JEFF SAID. IN FACT YOUR WHOLE REASONING IS JUST COLLECTING WORDS AS THEY SUIT YOU.
There's only one thing I'm really jealous about: you really do believe yourself don't you? As said before, threads with you don't need acousticians.

I deleted the rest of this message. It could only be moderated, while still representing my real thoughts.
I stop this thread for me. I only answer further via articles and a web page.

One can wonder why Ethan's:
Look at the FAQ second in the list on my article page,
is banned from RO for MANY months (with a try in-between of 2 weeks).

But Ethan I really must complement you. You are an EXPERT, pity it isn't acoustics.

--------------------
The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

Eric,

> I HAVE AN EXTREMELY DIFFICULT TIME NOT TO USE WORDS NOW WHICH BY DEFINITION MUST BE MODERATED. <

Does anyone aside from cc have any on-topic points that contribute to the understanding of standing waves? When someone says "his FAQ is wrong" with no further explanation, or "you expect people to take you seriously?" what they're really saying is "I have nothing of substance to offer."

> Ethan's FAQ ... banned from RO for MANY months <

I'm glad you brought that up because it highlights a logic error I see here repeatedly. That error is called "argument from authority" and the following is from the excellent Logical Fallacies article you can find on THIS web site:

Quote:

---

Dr. X believes A, Dr. X speaks from authority, therefore A is true. This is really just a special case of Non-Sequitur, since it does not necessarily follow that those who speak from authority are always correct. Often this argument is implied by emphasizing the many years of experience, or the formal degrees held by the individual making a specific claim.

---

This logic error applies here because in this entire thread the only arguments against me have been along the lines of "Ethan's psuedo scientific writings have been challenged by experts" and "the world of science and education thinks otherwise" and "it only gets you bitch slapped by 'real' acoustic experts."

Guys, if you have anything substantive to offer, this would be a good time to let us know.

--Ethan

--------------------
The acoustic treatment experts

E,

Rather than simply edit your last post and leave it covered with ***xxx*** type comments I thought I'd try to respond to a few of the points raised.

I'm not sure why you felt the need to quote Eric's comment - other than to divert attention from your own behaviour - but he had the decency and good manners to moderate his own post - and I thank him for that. What remained was still for some people rather strong and on the wrong side of the line of moderation but in the light of your response I decided to leave it.

A few comments on your post:

Quote:

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Does anyone aside from cc have any on-topic points that contribute to the understanding of standing waves?

---

Several people, including cc, Paul, thefruitfarmer, DigiPenguin and Eric have made good, on topic remarks in this thread.

Quote:

---

When someone says "his FAQ is wrong" with no further explanation, or "you expect people to take you seriously?" what they're really saying is "I have nothing of substance to offer."

---

No - I think that what they're saying is that your FAQ is wrong. As a moderator I take no view on this, despite it being a personal sleight, as you have been happy enough to make similar unproven comments on a number of occasions. (On a personal level I agree that there are things in your FAQ that I would disagree with and I know that I'm not alone in that.) (Eric had already said that he didn't have time for the detail and made that remark in a brief summary.) I agree that it's rather unfair to leave the point floating without expansion but I expect that as Eric said, his explanation will be forthcoming in the fullness of time.

On the "you expect people to take you seriously" comment, I thought about "moderating" that when I saw it earlier as I felt it was a little OTT but decided to let it stand, partly in the light of your response and partly because saying, as you did "Pick up a college-level text on basic electronics and look up standing wave, then tell me if it says anything about room modes." is one of the more ...er.. unusual remarks I've seen in this, or any other, thread. You could just as well say [Pick up a college-level text on basic hydrodynamics and look up standing wave, then tell me if it says anything about room modes] or [Pick up a college-level text on basic acoustics, look up standing wave, then tell me if it says anything about electrical reflections at impedance mismatches.] I think you'll find that most college-level texts on a given subject tend to stick within their own areas of discussion. They might mention in passing, similar phenomena in other disciplines but ime it would be as unusual for a text on electronics to go into detail about an acoustic phenomenon as for a text on acoustics to mention in detail electrical phenomena.

If you want to read a text that mentions room modes and standing waves then I'd suggest trying one on acoustics - you'll notice that the vast majority find them to be related subjects (though not the same thing). Suggesting, as you seem to be that non-inclusion of a mention of room modes in a discussion of standing waves in an electronics text is somehow proof of your statement that the two are unrelated is rather spurious.

Quote:

---

Ethan winer:
When someone says "his FAQ is wrong" with no further explanation, or "you expect people to take you seriously?" what they're really saying is "I have nothing of substance to offer."

---

By the same assessment,

Quote:

---

Ethan Winer:
Eric,

> I HAVE AN EXTREMELY DIFFICULT TIME NOT TO USE WORDS NOW WHICH BY DEFINITION MUST BE MODERATED. <

Does anyone aside from cc have any on-topic points that contribute to the understanding of standing waves? When someone says "his FAQ is wrong" with no further explanation, or "you expect people to take you seriously?" what they're really saying is "I have nothing of substance to offer."

> Ethan's FAQ ... banned from RO for MANY months <

I'm glad you brought that up because it highlights a logic error I see here repeatedly. That error is called "argument from authority" and the following is from the excellent Logical Fallacies article you can find on THIS web site:

Quote:
Dr. X believes A, Dr. X speaks from authority, therefore A is true. This is really just a special case of Non-Sequitur, since it does not necessarily follow that those who speak from authority are always correct. Often this argument is implied by emphasizing the many years of experience, or the formal degrees held by the individual making a specific claim.



This logic error applies here because in this entire thread the only arguments against me have been along the lines of "Ethan's psuedo scientific writings have been challenged by experts" and "the world of science and education thinks otherwise" and "it only gets you bitch slapped by 'real' acoustic experts."

Guys, if you have anything substantive to offer, this would be a good time to let us know.

--Ethan

---

doesn't say to me that the poster has very much to offer apart from an escalation in the off topic argument!

Quote:

---

> Ethan's FAQ ... banned from RO for MANY months <

I'm glad you brought that up because it highlights a logic error I see here repeatedly. That error is called "argument from authority" and the following is from the excellent Logical Fallacies article you can find on THIS web site:

Quote:
Dr. X believes A, Dr. X speaks from authority, therefore A is true. This is really just a special case of Non-Sequitur, since it does not necessarily follow that those who speak from authority are always correct. Often this argument is implied by emphasizing the many years of experience, or the formal degrees held by the individual making a specific claim.

This logic error applies here because in this entire thread the only arguments against me have been along the lines of "Ethan's psuedo scientific writings have been challenged by experts" and "the world of science and education thinks otherwise" and "it only gets you bitch slapped by 'real' acoustic experts."

---

So just to get this clear, as you don't seem to be saying anything here; is the content of the comment:

Quote:

---

Eric Desart:
One can wonder why Ethan's:
Look at the FAQ second in the list on my article page,
is banned from RO for MANY months (with a try in-between of 2 weeks).

---

true or untrue? Is "Look at the FAQ second in the list on my article page" banned on RO (assuming that refers to recording.org)? A straight, one word answer will suffice. If you want to explain the one word answer then fine but please answer first then keep to the point in any explanation. If it is true I'd be very interested to know why. If not then I sincerely hope that Eric will apologise and retract the comment.

Quote:

---

in this entire thread the only arguments against me have been along the lines of "Ethan's psuedo scientific writings have been challenged by experts" and "the world of science and education thinks otherwise" and "it only gets you bitch slapped by 'real' acoustic experts."

---

All of which comments, though harsh, often crude and confrontational, are imo not without validity. AFAIK, your writings have been challenged by people who have reasonable claim to be regarded as experts in their field, your theories on standing waves and room modes certainly seem to fly in the face of accepted science - that's not to say you're wrong, just that the comment is correct - and you are certainly taking a lot of flack from the more experienced acousticians responding to your posts. Whether they are more "real" than you is another matter and I would edit that out but it's rather pointless at this stage (I will though, if you want me to).

Quote:

---

Ethan Winer:
Guys, if you have anything substantive to offer, this would be a good time to let us know.

---

A lot of good substantive points have been offered. Just because you disagree with many/most if not all of them, and chose to ignore some, it doesn't mean that they aren't substantive. Implying that other people's viewpoints are invalid merely because you don't share them is rather rude and does you few favours.

Folks,
Yet again, we have a thread which is wandering off topic through a combination of personal attacks and deliberate misdirection. If we could stick with the science we might get somewhere.

Though I'm beginning to wonder! Is there any point in continuing with this thread and trying to get it back on track or is it a complete waste of our time and should we just put it (and ourselves) out of it's misery and lock/delete it now?

Oh well I guess this makes me as guilty as everyone else of posting off topic. Sorry.

Greetings OVU

Thanks for that post.

I'm used to debating in a more exuberent and emotional manner, and I guess that's why it's been a little difficult adjusting to the expectations of this forum. However, I am trying

I am pleased that you can see why it's been difficult not to cross the line, when faced with such provocation.

I personally ask you not to close the thread. For one Eric needs to link up to his forthcoming articles, and besides I think even Ethan's theories will ultimately help the learning process for people, because it's very contentious nature will draw some excellent info from the experts showing how it really is.



Paul

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Pauls Studio Build Diary at http://forum.studiotips.com/viewforum.php?f=1

0VU,

> Rather than simply edit your last post <

I can't imagine why you would consider editing my post. I have made no insults, only pointed out the insults of others against me. This is a huge distinction! If you believe I have made inciteful or insulting comments in this post or others, I request that you leave them so others can judge. In fact, your extensive editing and toning down of the many insults against me served only to hide evidence of the ulterior motives of my detractors.

I will answer every one of your points using the same detail as you did, even though not one of your points is remotely related to the subject of standing waves.

> I'm not sure why you felt the need to quote Eric's comment <

To show that so far he has offered little of substance, only more insults.

> other than to divert attention from your own behaviour <

What behavior? This is not the first time you accused me of "bad behavior." In another thread you stated, "Ethan hasn't been above some name calling and frankly childish behaviour." At that time I replied:

Quote:

---

That's a serious charge that's neither true nor fair. I have always been cordial to Eric, even when he's insulted me personally and professionally ... If you can show examples of me calling names or being childish I'd love to see them.

---

You never replied. If you have an example of me behaving badly, either show it now or stop accusing me of that, okay? I'm sorry to say your own bias is becoming quite apparent.

> he [Eric] had the decency and good manners to moderate his own post <

There is no decency in wasting forum bandwidth with posts that say only "I'm very frustrated trying to think of something to say here, other than insults that I know will be moderated."

> Several people, including cc, Paul, thefruitfarmer, DigiPenguin and Eric have made good, on topic remarks in this thread. <

That's why I was careful to say, "the only arguments against me have been..." John Geisen's point that "Standing waves are caused by equal frequency waves traveling in different directions, including opposite" was excellent and on-topic.

> I think that what they're saying is that your FAQ is wrong <

You would think so, but they never have anything specific to criticize. They just say it's wrong. This is a common theme with Eric and his followers, to claim that I'm wrong but without ever explaining how or why I'm wrong.

> there are things in your FAQ that I would disagree with <

Again, either state your specific technical objections or stop accusing me.

> "Pick up a college-level text on basic electronics and look up standing wave, then tell me if it says anything about room modes." is one of the more ...er.. unusual remarks I've seen <

It is an absolutely valid remark! And it was stated a lot nicer than Scott Foster's earlier comment to me, "pick up a frickin' text book and learn the subject." Rather than criticize me by saying my statement is "unusual" you should explain why it's not correct. Standing waves do occur in radio cables, and there are no room modes in those cables. Standing waves also occur at non-modal frequencies inside a room and at all audio frequencies against a boundary outdoors. If you dispute either of the two previous sentences, please explain how they are wrong.

> a mention of room modes in a discussion of standing waves in an electronics text is somehow proof of your statement that the two are unrelated is rather spurious <

It's not spurious at all. I never said room modes and standing waves are unrelated. What I said - and proved beyond any doubt - is that a standing wave is not the same thing as a room mode. This too is a huge distinction.

> true or untrue? Is "Look at the FAQ second in the list on my article page" banned on RO (assuming that refers to recording.org)? A straight, one word answer will suffice. If you want to explain the one word answer then fine <

The one-word answer is No. At least, not currently. This is so far off-topic I'm astonished you brought it up, but I'm glad to explain. In fact, I started to do that in my previous reply, but then decided that Kurt Foster of Recording.org is hardly an authority on acoustics so whether he approves of my FAQ or not is irrelevant.

As many SOS regulars know, I wrote THIS FAQ to explain the basics of acoustic treatment. When I founded the Acoustics forum at Recording.org (RO) several years ago I put a "sticky" post in that forum requesting that newcomers read the FAQ first and then ask follow-up questions. My FAQ served the forum very well for about a year. Then Eric Desart showed up and petitioned RO principals Chris Bialuski and Kurt Foster to remove me as a moderator because I'm not qualified to explain acoustics. He also told them my FAQ is full of errors, and I use it to drive traffic to the RealTraps web site even though it never resided on the RealTraps site. Of course, the entire purpose of my FAQ is to show people how to build their own treatment so they don't have to buy it from me or anyone else. Think about that.

Kurt Foster, who knows little about acoustics and so can only choose which "expert" to believe, removed me as moderator and asked me to stop posting a link to my FAQ. I asked him what specifically he disagreed with and he admitted he was not qualified to comment. But since Eric is an expert and Eric says my FAQ is wrong, then it must be wrong. Talk about "argument from authority!" After a month or so I was finally able to get Kurt to at least look at my FAQ, so he could see it was not an advertisement for RealTraps. At that time he posted publicly at RO that it's okay for me to link to my FAQ again. I have since stopped posting there because every time I did five guys from StudioTips would show up and hurl insults. Sound familiar?

> your writings have been challenged by people who have reasonable claim to be regarded as experts in their field <

I have already shown they are not the experts they claim to be, by proving beyond all doubt that a standing wave is not the same thing as a room mode. I have also shown that standing waves occur at non-modal frequencies, which is another thing Eric had disagreed with before but can no longer dispute. I have a long list of other technical gaffs and errors made by Eric Desart. I see no point in listing them all here, but I will if you really want me to. Bear in mind that for two years now these "experts" have denied that basic quarter-wavelength comb filtering occurs at a single boundary.

Their entire case that I am not an expert, and only pretend to be, is based on this disagreement over the definition of room modes and standing waves, and quarter-wavelength comb filtering. I have clearly shown that I am right and they are wrong on both of these issues, so who really is the expert?

So, is this what we're reduced to - each side trying to show that the other is a moron? More to the point, just because someone has a degree doesn't mean they're always right. And just because someone doesn't have a degree doesn't mean they're wrong. To be perfectly clear, I have no idea what formal credentials Eric and his followers may or may not have because they never listed them publicly. But whether Eric has a Ph.D. or is totally self-taught is unrelated to the facts about standing waves.

If Eric continues to insist that a standing wave is the same thing as a room mode, I ask him directly to explain this: Radio stations employ a Standing Wave Ratio (SWR) meter between the transmitter and antenna to measure the ratio of direct and reflected energy. This lets the engineers make adjustments to ensure that maximum transmitter power gets to the antenna, rather than be reflected back into the transmitter's output and wasted. Since clearly there are no room modes in a radio transmission line, how can one be the same as the other?

--Ethan

--------------------
The acoustic treatment experts

Ethan's last post:
>I never said room modes and standing waves are unrelated.

A prior post from Ethan:
>In fact, this is further proof that standing waves have nothing at all to do with room modes.

Tim ;o)

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Studio: www.kymatasound.com