IM Distortion, Speakers and the Death of Science


One topic that often comes up is perception vs. measurements.

"If you can't measure it with common, existing measurements it isn't real."

This idea is and always will be flawed. Mind you, maybe what you perceive is not worth $1, but this is not how science works. I'm reminded of how many doctors and scientists fought against modernizing polio interventions, and how only recently did the treatment for stomach ulcers change radically due to the curiosity of a pair of forensic scientists.

Perception precedes measurement.  In between perception and measurement is (always) transference to visual data.  Lets take an example.

You are working on phone technology shortly after Bell invents the telephone. You hear one type of transducer sounds better than another.  Why is that?  Well, you have to figure out some way to see it (literally), via a scope, a charting pen, something that tells you in an objective way why they are different, that allows you to set a standard or goal and move towards it.

This person probably did not set out to measure all possible things. Maybe the first thing they decide to measure is distortion, or perhaps frequency response. After visualizing the raw data the scientist then has to decide what the units are, and how to express differences. Lets say it is distortion. In theory, there could have been a lot of different ways to measure distortion.  Such as Vrms - Vrms (expected) /Hz. Depending on the engineer's need at the time, that might have been a perfectly valid way to measure the output.

But here's the issue. This may work for this engineer solving this time, and we may even add it to the cannon of common measurements, but we are by no means done.

So, when exactly are we done?? At 1? 2? 5?  30?  The answer is we are not.  There are several common measurements for speakers for instance which I believe should be done more by reviewers:

- Compression
- Intermodulation ( IM ) Distortion
- Distortion

and yet, we do not. IM distortion is kind of interesting because I had heard about it before from M&K's literature, but it reappeared for me in the blog of Roger Russel ( http://www.roger-russell.com ) formerly from McIntosh. I can't find the blog post, but apparently they used IM distortion measurements to compare the audibility of woofer changes quite successfully.

Here's a great example of a new measurement being used and attributed to a sonic characteristic. Imagine the before and after.  Before using IM, maybe only distortion would have been used. They were of course measuring impedance and frequency response, and simple harmonic distortion, but Roger and his partner could hear something different not expressed in these measurements, so, they invent the use of it here. That invention is, in my mind, actual audio science.

The opposite of science would have been to say "frequency, impedance, and distortion" are the 3 characteristics which are audible, forever. Nelson pass working with the distortion profile, comparing the audible results and saying "this is an important feature" is also science. He's throwing out the normal distortion ratings and creating a whole new set of target behavior based on his experiments.  Given the market acceptance of his very expensive products I'd say he's been damn good at this.

What is my point to all of this?  Measurements in the consumer literature have become complacent. We've become far too willing to accept the limits of measurements from the 1980's and fail to develop new standard ways of testing. As a result of this we have devolved into camps who say that 1980's measures are all we need, those who eschew measurements and very little being done to show us new ways of looking at complex behaviors. Some areas where I believe measurements should be improved:

  • The effects of vibration on ss equipment
  • Capacitor technology
  • Interaction of linear amps with cables and speaker impedance.

We have become far too happy with this stale condition, and, for the consumers, science is dead.
erik_squires
andy2

A computer can perform addition much faster than any person on earth but that does not mean the computer is smarter or even better.


You are right and even in actual A.I. the clever new algorithm( that beat any human in any finite game) can only reconstruct a totality with external parts.... This is an external connection to the whole....Even a quantum computer linked to a modern classical computer would not be able to be connected to the Life evolution source like we are and all humans through the Billions of cellular life in us....The soul is this connection with life that makes any life the whole....Without any calculus... The link is internal without distance …. With the calculus of the Turing Machine linked to a quantum computer the link will be whatsoever external....Out also of the universal memory field of life...

Like say Roger Penrose : " consciousness is not computable"

The engineering transhumanism is a myth of a less evolved nature than the myths of the past, because myths of the past were first step to evolution of the spirit and always are.... Transhumanism myth is the abolition of the spiritual freedom, by childish fear and faustian refusal of death, reducing the internal living link of all life to an external dead one... A technocratic totalitarian inferno...
The brain can detect angle to about 1-2 degrees. A computer can do it 100 times better. A computer can detect tones that are 1/1000 of an octave apart with ease, even 10 times that. The ear/brain, not even close.
That is missing the point.  Sure objectively the computer can do quite many things better and faster than a human mind, but no computer that I know of can interpret musical reproduction the way the ear-brain can.

What you said is the equivalent of saying a computer is "smarter" than a human because it can perform mathematical operations such as addition, subtraction ... millions of times faster than a human brain.  

A computer can perform addition much faster than any person on earth but that does not mean the computer is smarter or even better.

A computer can do it 100 times better. A computer can detect tones that are 1/1000 of an octave apart with ease, even 10 times that. The ear/brain, not even close.
We dont need to improve our speakers beyond what humans can hear. 
I dont understand your point.... the ears-brain create the sound in some particular room...This is truism evident for all...

«A computer can detect tones that are 1/1000 of an octave apart with ease, even 10 times that. The ear/brain, not even close.»

This is a fallacy....

Using a measured number precision in one dimension parameter against the many parameters complexities of the ears-brain, and saying that the ears is less able to resolve information linked to sound...
But that simple signal in the audio chain before it becomes sound .... it is simple, and to assign the complexity of "sound" and "human hearing", and "human interpretation" to a simple electrical signal .... well that is the "audio complexity fallacy", and it is a fallacious argument that has 0 merit.
The simple signal in the audio chain does not become magically a sound, it is the ears-brain that create the sound in a particular room...And i never attributed myself the complexities of the ears-brain to a simple electrical signal...

It is precisely my point, that it is not possible to attribute the complexities of the ears-brain to the electrical signal....A musical sound is create by the ears-brain, in a particular acoustical field, from a particular electrical grid, in a controlled mechanical resonant-vibrating audio system....


Measures systematically implemented are necessary to improve engineered Electrical component....This is good.... But if the engineer is not an audiophile also, who want to buy his design?
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You are applying the "audio complexity fallacy". You are taking the very high complexity of a 3d, time variant sound field coupled with the high complexity of human hearing and human preference and applying that to simple things in the audio chain.
You judge too swiftly, I only said that the ultimate judge is the ears.... The eye must read the results of measurements and the ears must decide and work to correlate his experience with numbers and curves to improve measures in a increased ongoing experiments....
I want some audiophile engineers measure more and more and always better.... Who is the fool who dont want that?

Perhaps you suffer of the "Engineer fallacy" saying that numbers and curves are all that exist ? This reduce simply to the maps and territory fallacy or confusion...


« Behind the cloud of numbers are ideas» Husserl


I am sure that you dont like philosopher then I will make a citation by a great statistician:


« The numbers are where the scientific discussion should start, not end » Steven Goodman

Steven N. Goodman is an American Professor of Medicine and of Health Research and Policy (Epidemiology) at Stanford School of Medicine.[1] He has extensively contributed to statistics and probability analysis within the biosciences, and in 1999 he coined the term "p-value fallacy".[2]

I can assure you that the " p-fallacy" in statistics is more interesting to read about than your homemade " audio complexity fallacy" that is only a game for audiophile thread forums ...

Concocted "fallacy" and real one are not the same....You have now a real one to ponder about....
The best way to tune a speaker is by ear. If it cannot be heard theres no point in measuring it. Instruments made hundreds of years ago without measuring equipment are still used today by musicians. If it could be done by ear then, it can be done by ear now.
First you need a very low noise signal generator with jitter in the femto second range.

Here are some basic measurements one can take:

1. Sinewave sweep from 10Hz to 50KHz measure jitter in time domain at each freq. increment with an oscilloscope.
2. Square wave sweep from 10KHz to 50KHz then measure jitter in time domain at each freq. increment with an oscilloscope.  
3. Measure phase noise jitter from 1KHz to 20KHz at 1KHz increment.   This measurement is done in frequency domain so you can look for any peak or dip in the frequency so you can compare before and after break-in.
4. With a network analyzer, measure the freq. and phase response. The network analzyer will do a sweep so you don’t have to do that manually as in step 1, 2,3.
andy2
The point is not to measure those that are viewed as too subjective. The point is to measure quantifiable objective parameters.

>>>>>No shirt Sherlock. But which parameters? Duh?
Gentle readers, I implore you, how would you measure depth or height of soundstage, transparency, separation of instruments, perceived resolution, bass articulation, naturalness of high frequencies, air, presence, and warmth? Hel-loo! Is there a soundstage meter? Is there a glare meter?
The point is not to measure those that are viewed as too subjective.  The point is to measure quantifiable objective parameters.

Cut me some slack, Jack.
Everybody does when you post :-)
You are applying the "audio complexity fallacy"
Who define this as "fallacy" and why?


For sure no measuring apparatus can rival ears....This is not a fallacy to say that...
The point is to measure some quantifiable objective - before and after. As for equipment, I would need:
1. A really good analog oscilloscope that can measure jitter in time domain.

2. A really good phase noise analyzer to measure in frequency domain

3. A really good vector network analyzer to measure the freq. and phase response. The excitation signal can be varied in amplitude if you want to see how the cable response with different input amplitude.

These would measure the before and after and then comparing the result. Here is a link from Troels, in which he modified a small woofer freq. response and listen for the affect on soundstage and detail.
http://www.troelsgravesen.dk/W12CY003.htm

I suspect the pre-break-in measurement will be relatively "peaky" vs. the after break-in.  

But at the end, as I said above, one still has to listen.
I don’t get it. Why would you assume phase or compression changes?

When you don’t know what you will find you cast a large net. I’m not assuming, I’m saying this is a starting direction based on my observations.  We were asked to show examples of how we would investigate issues currently not measured. This was one example.

When you don’t know what you will find, you don’t know ahead of time how to measure it. You pick a possible explanation, then go prove/disprove it.

Otherwise we are logically stuck back where we started from, arguing metrics and measurements that are old enough to have grandchildren.

Best,

E
I don’t get it. Why would you assume phase or compression changes? 
OK, someone was really determined to measure break in, you know instead of just talking about it, how would one actually go about it?

Truthfully, we would need to invent a metric, just like I was discussing at the beginning of the thread.

How would I do it?  Based on what I've heard from capacitor break-in, I would go down at least the following routes:

1.  Look for phase shift and fine comb filtering effects at small and large signal levels

2. You would measure music play back before and after then look for anomalies in phase and amplitude.

3. Look for signal compression at small and large amplitudes.

Both of these approaches would measure before and after break-in has allegedly occurred.  Then work backwards from what we find into some easy to use tests.

Best,

E


Gentle readers, I implore you, how would you measure depth or height of soundstage, transparency, separation of instruments, perceived resolution, bass articulation, naturalness of high frequencies, air, presence, and warmth?

You dont measure these things because they arent real. Its all an illusion. What you measure is the frequency response. The more even it gets the better the illusion. 
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Heaudio123, I hate to be the one to burst your bubble but the soundstage physical dimensions of depth, width and height are provided on the recording generally speaking, some recordings better than others and some systems better than others. The reason all three physical dimensions are embedded in the recording is due to the reverberant decay, first and second reflections, echos, etc., you know, just like almost any physical space. It’s a misunderstanding of the facts to say the sound is a result of two sources since even one microphone is capable of capturing all three physical dimensions. Didn’t you know that?
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OK, someone was really determined to measure break in, you know instead of just talking about it, how would one actually go about it? Gentle readers, I implore you, how would you measure depth or height of soundstage, transparency, separation of instruments, perceived resolution, bass articulation, naturalness of high frequencies, air, presence, and warmth? Hel-loo! Is there a soundstage meter? Is there a glare meter? Cut me some slack, Jack.
andy2
... the problem is the equipment required to measure the "breakin-in" phenomenon can be quite expensive that very few cable companies can afford. 
What equipment is that?
doesn’t occur in any meaningful way and hence cannot be measured.
Actually, when it comes to speaker drivers (such as woofer, tweeter ....), it has been shown that break-in does change Thiele-Small parameters.

As for breaking in cables, it may require more sophisticated and expensive equipment to measure. Not only that, it’s probably not trivial to measure so it does take some knowledge. These two reasons are probably why you don’t see any publish data.


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Measuring process, and listening experience in a controlled environment, are not opposites things... They are complementary...
I agree. 

There are still things that are difficult to grasp such as cable breaking-in, an in which case, people are demanding "measurement".  The problem is the equipment required to measure the "breakin-in" phenomenon can be quite expensive that very few cable companies can afford.  

I’m saying what we measure is not enough, but we take it to mean all that is knowable.
I agree with that. I should have been clearer in my post.
The fact that the data we are offered is insufficient to correlate to the listening experience, fuels the belief "if it sounds good it’s good". As a broad, blanket statement it is incorrect IMO; If however, we say "if I like the way it sounds, it is good for me", i.e. a subjective value statement, it is totally acceptable.

However, if by "good" we mean accurate reproduction of source material, then "what sounds good (to me)" may or may not be good technically speaking!

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Measuring process, and listening experience in a controlled environment, are not opposites things... They are complementary...

Except for some who are allergic to good engineering design research, or for those who want to reduce anything to what they call " science" which is only bad "scientism"... I am with the people who want to correlate, and improve ears and design....This correlation between the ears and the measure process is and will be without end to an unlimited improvement...


«History of science IS science»  Goethe
This whole thing really ought to have been settled long ago. The whole measurement thing is the province of Julian Hirsch and Stereo Review. If they measure the same they are the same. The whole listening thing goes back to J. Gordon Holt and Stereophile. The listener is the final arbiter of performance.

In the marketplace of ideas, as in the literal marketplace, Hirsch and Stereo Review are dead. Gone. And good riddance.

Their spirit lives on, like some malevolent poltergeist, wasting the time of audiophiles the world around.

Science isn’t dead. Merely inadequate. Understand the difference.
the high number of available options for each system component and the variability of how well specific system component parts perform with other specific system component parts.
This is very important for sure....


But after you have linked compatible components, the most important factors are their embeddings in 4 dimensions: mechanical resonance-vibrations grid, electrical grid of the house not only of the system or of the room, the passive treatment of the acoustical space, and after that an active treatment of the acoustical space....


Measuring is an active temporal evolutive process, be it at his best for speakers for example, it cannot replace the 4 embeddings to guarantee a good S.Q. ….My opinion is we need feed-back measuring process not only in a designer shop but also in our room with our particular embeddings methods and particular electronic components...With the progress of science this is already there, if not this will be possible tomorrow...
     Very interesting and thought provoking thread thus far.  I believe I’m highly capable of stopping this intellectual, educational and inspirational audio forum brainstorming session juggernaut dead in its tracks with my highly suspect thread contributions. If you all refrain from doubting my capacity to do this, I guess I can refrain from intentionally deploying my vast capacities to train wreck this excellence.
     I agree with the premise that past and current objective speaker standard measurements poorly correlate with the subjective individual perceptions of the sound qualities of specific speakers.  At best these standard measurements, such as impedance and efficiency rating, are most useful in determining the viable amps to drive them with.  Perhaps speaker type is the best current indicator of subjective sound qualities perceived.
     From my perspective, the biggest hindrance to creating a high quality and enjoyable home audio system is the complexity involved due to the high number of components, the high number of available options for each system component and the variability of how well specific system component parts perform with other specific system component parts.       This results in an extremely high number of possible unique system combinations or permutations that requires knowledge and experience to simplify.  Personally, it took me decades of knowledge building, experimenting and accumulated experience to assemble a high quality audio system that I deeply enjoyed.  Slow learner you say?  Perhaps, but I think it may seem like an especially daunting venture, or more appropriately an adventure, to assemble an enjoyable audio system to the newcomers to our hobby.       I believe improved objective measurements of audio gear, that incorporate the knowledge gained from the field of psycho-acoustics, and are somehow more closely correlated with subjective listening would likely be difficult but also very useful.

Tim

It seems that your brain work well indeed.... It will be difficult to improve your words argument.... I like the question you ask in this thread even if i cannot answer it myself....Measurement is a time improving historical process for sure.... Thanks and happy Easter....
What does "death of science" mean here?

Here I take science to mean science in the public realm, as opposed to academic or manufacturer’s research. Because science involves progress and invention, so long as the educated public is stuck with a handful of metrics set in stone by the 1980’s that we discuss, I say that this science is dead. It has not progressed much at all. It had a fruitful life from the invention of the telephone up until the 1980’s and then died quietly.

I think the general consensus here is (& @erik_squires certainly makes the case): we measure irrelevant things.


Oh, no, not saying that. I’m saying what we measure is not enough, but we take it to mean all that is knowable. Imagine measuring the earth by it’s diameter and mass and saying that’s all we must know about it, and that tells us everything we need to know about the earth. Well, if your sole interest is gravitational, momentum and orbit, then yes, I supposed that’s true, but these two metrics ignore:

  • Geology
  • Geography
  • The composition of the ecosphere including liquids, gasses and plant and animals.
  • Tectonic activity
  • Weather
  • Biology and evolution

I’m not saying the earth’s diameter and mass are irrelevant, far from it, but I do think we are stuck somewhere far from knowing everything about say, capacitors or amplifier/speaker interaction. We just accept that publishers publish mass and diameter and that science is done and then must leave the rest to popular opinion, social media and taste makers.


I disagree.

If it was easy everybody could do it. - Old audiophile axiom

An ordinary man has no means of deliverance. - Another old audiophile axiom
You are applying the "audio complexity fallacy". You are taking the very high complexity of a 3d, time variant sound field coupled with the high complexity of human hearing and human preference and applying that to simple things in the audio chain.
Thanks for your interesting point...

I am not sure if I understand it clearly...


My point is I am interested in all design improvement with measurement for sure...

But the main point in Audiophile experience (not in engineering " per se" ) is to controls embeddings, with whatever electronic component...But I wish for the best electronic component there is to begins with, and for that measurement are important to define norm...


Using "audio complexities" to make void any measurement theory is not my point at all...Only fool are against improved engineering. But the main point for all users after making some buying choice, reading design goals and measurements, is to embed finally in the optimal way this electronic component....This fourthly complex embeddings is not reducible to measurement... Is this the " audio complex fallacy" ?

Happy Easter to you....
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I have Uncertainties, but- I believe Fast FURrier Transform works great, for skinning Schrodinger’s Cat. 
@kenjit  
MLSSA & FFT are very useful tools
For what?
For measuring loudspeaker response.




How can the audio industry (HIFI) benefit from new measurements that would shine a light on whats really going on? Audiophiles are paying for what subjectively steals headlines. Look at how the Wilson Sasha daw measures in room and tell me consumers want more measurements? sorry, I agree with you but telling folk that spend as much on wire as we do on the family car they need more measurements is going to bounce. just sayin'.
@alymere
The science is not dead; it’s getting more and more interesting.
I agree. 
I think the general consensus here is (& @erik_squires certainly makes the case): we measure irrelevant things.
So, it's not science but how it is applied to audio that is (mostly) dead (of meaning).
Mostly... 

(BTW, speaker response measurements, can be very useful; MLSSA & FFT are very useful tools. )






It is the human ears that judge the superiority of any electronic component, not in the abstract, disembodied standardized field of measurement necessary for implementation of the engineering protocols, but in the embodied particular multiple embeddings of your room and house and in a particular individualized audio system....

Then the most important underestimated facts in audio are the controls of the 4 basic embeddings : mechanical, electrical, and the passive and active controls of the acoustical field of the room ... There are others dimensions but these 4 one are fundamentals...


Buying first a high quality design electronic component is very important, but the evolution of the design of electronic component in the last 50 years, as big as it is, is not on par, nor on the same scale, than the difference in S.Q. gained by a rightful implementation of controls protocols for the 4 embeddings...

This is my audiophile journey lesson...Nobody explain me that clearly, I discover it myself by listening experiments, slowly first in the first 5 years, and swiftly in the last 2 years...


Improving electronic design is very important, but learning to listen and resolving in a simple and affordable manner the 4 embeddings problems are the crux of audio and the more fundamental problem...


Most of us we owns already a good audio system, the real question is not about the way to upgrade the design of an electronic component by buying a new improved one; the real question is : Do I know from having heard it already, how my audio system, as it is now, behaves in an optimal controlled environment ?


The answer for most people will be no....Frustrated by the limitations of their actual system, without knowing that the limitations comes from the lack of control of the embeddings, more than from the already good design of their actual system " per se", they turn themselves prey to marketing ploy and upgrade, without even having heard their system in his optimal possibilities to begins with...


This is what I learned ...

Note:
I am not a closed mind, and I am conscious of the importance of improved engineering methods and products...

I looked about that suggested here and it seems interesting : the GedLee Metric..

I am interested for sure also in new design, for example ZOTL technology...
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ivan_nosnibor

"Erik, I don’t think it is so much the death of science that has stopped the adoption of better measurement methods so much as it has been the rise of marketing. Not just the sheer amounts of advertising, but journalism and also the advent of the internet of plenty have conspired to distract us (the consumers) from the notion or concept of what a relevant set of measurements might look like or the significance of its role."


Nailed it!

The entire industry currently runs on implicit advertising and marketing. It discovered decades ago that honesty and openness have little or no relationship to commercial success.

There are no longer any actual claims of sonic superiority in any audio product now being marketed. 

None whatsoever. Think about that.

And more to the point, why should they bother when we golden-eared consumers can't even agree whether we want more data, or even which data we particularly want?

Children in the world of adults.








So what do room measurements and treatments (or old fashioned equalizers) bring to the table? Does it not take flawed sound, badly measured sound if you will, and adjust it to measure better for the individual consumer in a specific locale. This would seem a better solution as it incorporates unique parameters; room, my equipment, and my ears. I understand the desire to eliminate sow's ears but you assume objective, standardized, and constantly improving measurement techniques  by audio press or manufacturers. Not sure about that.  Joe

"Once we get into the non-linear things, it can get complicated real fast." - Richard Feynman

Very true!!

Fortunately as long as loudspeakers are not pushed past their linear excursion limits, non-linear distortion is highly unlikely.

What is NOT unlikely is this: Linear distortions to which the EAR has a NON-LINEAR perception response. So it can sound like a system distorts as the SPL goes up, when what is really happening is, the ear is having a non-linear perception of what is actually a linear distortion.

This is one of the reasons why listening tests should include some high-SPL listening, because there are linear distortions which are inaudible at low SPLs but which can set your teeth on edge at high SPLs.

Duke
"Linear Time Invariant systems are important because we could solve them" Richard Feynman.

Once we get into the non-linear things, it can get complicated real fast.  


Erik says “The idea of modeling multiple non-linear systems at once to derive a master model of behavior could probably be its’ own thing.” It certainly is. I recently finished a little project where I applied a machine-learning neural network model to classify 1000 clips of music according to a ‘harmonic signature’ (mostly “live content” case #1, or mostly “synthesized”, case #2). Interestingly, although FFT, spectral centroids, RMS energy etc. were important in defining the signature, the most compelling predictors were the Mel-Frequency Cepstral Coefficients. Why is this important?

Because the purpose of these coefficients is try to capture exactly what audiokineses refers to as “the transfer function of a device (how that device alters the input signal) through a psychoacoustic (i.e. perception-based) lens.” Two examples will explain: ‘the sound of a baby crying.’ Why is the baby crying? Hungry? Lonely? Needs diaper changed? We could do technical analysis forever and not know – but the mother knows instantly. Someone singing, “I don’t know what to do.” Why? Boredom? Lost love? We know from the voice; not just the context.

I think that psychoacoustic perception is exactly where we need to look to understand that last 10% or 20% beyond the point where purely technical/engineering analysis stops reliably explaining what we know to be true in our ears.

The science is not dead; it’s getting more and more interesting.