Misleading Measurements

[fas42]

All that really matters in this whole conversation is whether there is some mysterious, "third force", that adds content to what one hears when listening to a musical instrument - or not. I say, the instrument, and possibly objects which are not air around it are the sole contributors - which means that a decent microphone will pick up purely what matters, which is the sound generated by the playing of the instrument, in the particular environment. Replay of the capture, to an adequate accuracy, will not be additive - because it can't be ...

 

I see @bluesman as having an agenda, to ascribe the veiling of conventional playback to something which can't be dealt with - IME this is completely incorrect; suitably '"debugged" reproduction doesn't have veiling issues - the problem simply evaporates, just like a morning mist 😉.

[bluesman]

2 hours ago, Jud said:

So I'm completely new to this, and what I'm reading on pp 40-41 of the following source sounds like what @bluesman is describing in instrumental tuning (and performance?), but not like the sum and difference frequencies of intermodulation distortion. So can folks who know tell me how clueless I am? 🙂

 

http://kellerphysics.com/acoustics/Lapp.pdf

You’re not clueless at all. That “beat” frequency is the “difference” intermodulation product of the combination of the two fundamentals.  It’s created by the interaction of the two compression-rarefaction trains of molecules moving through the air, and it’s a distinct and separate wave of compressions & rarefactions generated by the intersecting pulsatile waves.  The summation of sine waves is a graphic representation of the summation of the pressure waves created by transduction of electrical energy into kinetic energy.  You can see it and you can hear it.

 

There’s also a summed product of the two guitar strings.  But all IM products are much lower in SPL than the fundamentals, so that sum frequency is down in the mix of harmonics of the main tones.  The reason you can ”hear” a 5 Hz difference tone is that it’s modulating the amplitude of the fundamentals even though it’s well below the audible spectrum of human audition.  Once the intermodulation products are high enough in frequency to be directly audible, they’re heard as separate tones from the fundamentals.  

In the words of one of several similar scientific discussions, “As the two tones get further apart, their beat frequency starts to approach the range of human pitch perception, the beating starts to sound like a note, and a combination tone is produced”.

 

[Summit]

7 hours ago, fas42 said:

All that really matters in this whole conversation is whether there is some mysterious, "third force", that adds content to what one hears when listening to a musical instrument - or not. I say, the instrument, and possibly objects which are not air around it are the sole contributors - which means that a decent microphone will pick up purely what matters, which is the sound generated by the playing of the instrument, in the particular environment. Replay of the capture, to an adequate accuracy, will not be additive - because it can't be ...

 

I see @bluesman as having an agenda, to ascribe the veiling of conventional playback to something which can't be dealt with - IME this is completely incorrect; suitably '"debugged" reproduction doesn't have veiling issues - the problem simply evaporates, just like a morning mist 😉.

 

It’s like UFOs 😄. Many observations, many investigations, many theories but in the end the vast majority of UFOs can be identified as ordinary objects or phenomena.

[Audiophile Neuroscience]

18 hours ago, pkane2001 said:

Maybe yours is an opinion, mine is the result of actual testing and validation. As I said, I tested this on multiple devices.

 

This is just getting silly now. Paul if you cannot see this , take a step back. You are beginning to sound like Frank.

[Audiophile Neuroscience]

17 hours ago, bluesman said:

I think this added layer of intermodulation is at least part of that famous veil that we all want removed from our music on playback.  But "IMO", believing that all IM is the product of nonlinearities and is distortion is counterproductive. And if I'm correct, inducing distortion as you advocate for evaluation, testing and development would be the wrong way to approach the problem.

 

Perhaps best not to define it as "intermodulation".

[Audiophile Neuroscience]

18 hours ago, pkane2001 said:

Heck, I have spent many months building many different types of distortion simulations into DISTORT (non-linearity & compression, multiple different kinds of jitter, different dither types, noise shaping, amplifier cross-over distortion, oversampling and filters, negative and positive feedback, various types of noise, etc.) I have plans to add a number of others. It's not because I think these are all completely unimportant, or else I wouldn't waste the time. 

 

I hate to be the bearer of bad news but just because someone creates an App doesn't make the App valid.

 

18 hours ago, pkane2001 said:

 

But, let's ignore that for now. This discussion is not really about DISTORT, or at least it shouldn't be.

 

then don't bring it up

[Audiophile Neuroscience]

16 hours ago, pkane2001 said:

Distortion: any frequency content that was not present in the original signal

Intermodulation Distortion: amplitude modulation of one signal by another caused by a non-linearity in the signal chain

 

From Wikipedia: 

 

I am not convinced Wikipedia is really our guide of all things scientific but from the same Wikipedia reference

"Distortion is the alteration of the original shape (or other characteristic) of something"

 

IMO we are talking about interference patterns of sound waves in air, specifically beat frequencies. I just don't get why that should be so controversial as a concept

[Audiophile Neuroscience]

16 hours ago, pkane2001 said:

Just check out my other software, DeltaWave (I hate to bring this up, as this will likely start another tangential argument). It does exactly what you want:

 

says who?

[bluesman]

1 hour ago, Audiophile Neuroscience said:

Perhaps best not to define it as "intermodulation".

Good thinking - how about “tone sex” or “sine wave intercourse”?  The mechanics are almost the same.  Energetic pulses intertwine, and many deny the existence of the resulting offspring. 😝

[Audiophile Neuroscience]

14 minutes ago, bluesman said:

Good thinking - how about “tone sex” or “sine wave intercourse”?  The mechanics are almost the same.  Energetic pulses intertwine, and many deny the existence of the resulting offspring. 😝

Ahem....maybe "inter-tonal relations " suggests a marriage of greater harmony 👨‍👧‍👧☺

[fas42]

2 hours ago, Audiophile Neuroscience said:

 

 

IMO we are talking about interference patterns of sound waves in air, specifically beat frequencies. I just don't get why that should be so controversial as a concept

 

It's controversial if you try and connect perceived beat frequencies with lines on a spectrum, from a microphone capture.

[bluesman]

2 hours ago, Audiophile Neuroscience said:

Ahem....maybe "inter-tonal relations " suggests a marriage of greater harmony 👨‍👧‍👧☺

So does THD measure the activity of single tones that have no mates and must generate their own harmonics?  
 

Perhaps we’ve also been misled by other measurements we took for granted.  I’ll never listen to music again without appreciating its inner struggles and our former insensitivity to them.

 

Sine waves have feelings too. We just need a way to measure them.

[pkane2001]

22 hours ago, bluesman said:

You're probably going to respond that I don't understand what you're saying - but I don't have a clue what you mean by distortion "present in the source material".  What kind of distortion do you think there is in a live performance by a symphony orchestra, an acoustic jazz trio, a string quartet or a piano concerto?  And what do you think is causing it?  Do you hear it at a live performance?

 

If the intermodulation products among instruments and voices are distortion, there can be no such thing as an undistorted musical performance.  If that's true, why are we wasting our time trying to reproduce one?

 

I think we are talking about two different things. You're talking about musical instruments, and I'm talking about the playback system to reproduce recorded sound. There's a whole lot that's going in a musical instrument to produce a recognizable sound that we like and recognize. The discussion of music production and sound synthesis is an interesting one, but can I suggest that an audiophile forum and a thread dedicated to audio playback measurements isn't the best place for it? My opinion only, of course, but the context here is important. Everything I've said and quoted and measured and shared applies to the playback system. Seems to me that most of your argument has been about the acoustic instruments, including what you called "natural IM". These are two very distinct topics and deserve separate treatment, so I'm just going to stop here.

[pkane2001]

 

 

7 hours ago, Audiophile Neuroscience said:

 

says who?

 

Those who understand what it does, of course.

[pkane2001]

7 hours ago, Audiophile Neuroscience said:

 

I am not convinced Wikipedia is really our guide of all things scientific but from the same Wikipedia reference

"Distortion is the alteration of the original shape (or other characteristic) of something"

 

IMO we are talking about interference patterns of sound waves in air, specifically beat frequencies. I just don't get why that should be so controversial as a concept

 

Wikipedia was just the simplest, most accessible text. Any number of textbooks and papers say the same thing. But it's not a controversy, except to those who want to continue to argue. This topic has run its course, IMO, but you can continue if you'd like.

[bluesman]

2 hours ago, pkane2001 said:

You're talking about musical instruments, and I'm talking about the playback system to reproduce recorded sound.

And this thread is a discussion about misleading measurements.  If (as I believe and, to my mind, have supported well) the “interaction” among the notes generated by the instruments in a performance is captured in recording and reproduced in playback, then IMD measurement in the playback equipment may be misleading.  There’s so much more acoustic intermodulation (which is not distortion) being heard in playback that the minuscule added IM products from the equipment may well be immaterial to SQ.
 

This is firmly on topic. It just seems to be a difficult concept for many to grasp. That does not make it wrong.

[pkane2001]

13 minutes ago, bluesman said:

And this thread is a discussion about misleading measurements.  If (as I believe and, to my mind, have supported well) the “interaction” among the notes generated by the instruments in a performance is captured in recording and reproduced in playback, then IMD measurement in the playback equipment may be misleading.  There’s so much more acoustic intermodulation (which is not distortion) being heard in playback that the minuscule added IM products from the equipment may well be immaterial to SQ.
 

This is firmly on topic. It just seems to be a difficult concept for many to grasp. That does not make it wrong.

 

Good, so you made a claim. I've not disagreed with it, in fact, I stated that I make no claims about the audibility of HD or IMD or their importance in the audio chain.

 

Now, can you substantiate your claim with something other than your personal opinion? This is an objective forum, after all.

 

[Audiophile Neuroscience]

8 hours ago, bluesman said:

Sine waves have feelings too. We just need a way to measure them.

 

Surely someone has an App. Have you checked Google Play Store?🤷‍♂️🙂

[Audiophile Neuroscience]

5 hours ago, pkane2001 said:

12 hours ago, Audiophile Neuroscience said:

 

says who?

 

Those who understand what it does, of course.

 

Understanding does not confirm validity or the truth or value of a tool. Neither does subjective or anecdotal appraisals nor the assertions of the App or tool creator. It's fine if you wish to make amusing toys but not fine for useful tools,  leading to unacceptable errors and misleading measurements/conclusions.

[pkane2001]

5 minutes ago, Audiophile Neuroscience said:

 

Understanding does not confirm validity or the truth or value of a tool. Neither does subjective or anecdotal appraisals nor the assertions of the App or tool creator. It's fine if you wish to make amusing toys but not fine for useful tools,  leading to unacceptable errors and misleading measurements/conclusions.

No, of course not, but understanding what something does and how, is a good first step to having a rational discussion. Any discussion prior to it is just a waste of time.

[Audiophile Neuroscience]

6 hours ago, pkane2001 said:

 

You're talking about musical instruments, and I'm talking about the playback system to reproduce recorded sound. There's a whole lot that's going in a musical instrument to produce a recognizable sound that we like and recognize. The discussion of music production and sound synthesis is an interesting one, but can I suggest that an audiophile forum and a thread dedicated to audio playback measurements isn't the best place for it?

 

Totally disagree.

 

3 hours ago, bluesman said:

And this thread is a discussion about misleading measurements.  If (as I believe and, to my mind, have supported well) the “interaction” among the notes generated by the instruments in a performance is captured in recording and reproduced in playback, then IMD measurement in the playback equipment may be misleading.  There’s so much more acoustic intermodulation (which is not distortion) being heard in playback that the minuscule added IM products from the equipment may well be immaterial to SQ.
This is firmly on topic. It just seems to be a difficult concept for many to grasp. That does not make it wrong.

 

Yes, and how better to understand what should be looked for in the audio signal and on playback of that signal but to refer to the gold standard reference, the music that is supposed to be captured in the first place. We want measurement tools that know what to look for and find what we can hear.

[pkane2001]

2 minutes ago, Audiophile Neuroscience said:

Totally disagree.

Shocking! I’m so surprised 😮 

[Audiophile Neuroscience]

Just now, pkane2001 said:

No, of course not, but understanding what something does and how, is a good first step to having a rational discussion. Any discussion prior to it is just a waste of time.

 

I agree Paul that understanding of how a tool is supposed to work or what and how it does it, is a good first step. That does not equate with validity, which is the point here. Any rational discussion based on the use of a tool must be preceded by how valid the tool is. This has been a recurrent theme in audio fora in the quest against misleading measurements and faulty conclusions.

[pkane2001]

2 minutes ago, Audiophile Neuroscience said:

 

I agree Paul that understanding of how a tool is supposed to work or what and how it does it, is a good first step. That does not equate with validity, which is the point here. Any rational discussion based on the use of a tool must be preceded by how valid the tool is. This has been a recurrent theme in audio fora in the quest against misleading measurements and faulty conclusions.

And constantly raising questions about the validity of something you don’t understand, have not studied or even tried to use, is what you’re  doing here. If you want to have a rational conversation about validity, then let’s have it, but not before you take that first step.

[sandyk]

8 minutes ago, pkane2001 said:

And constantly raising questions about the validity of something you don’t understand, have not studied or even tried to use, is what you’re  doing here. If you want to have a rational conversation about validity, then let’s have it, but not before you take that first step.

 

 Can we please get off the subject of the tools that you have designed, and back to the original topic ? 

 You could always start a thread in the General Forum area and invite discussion of their uses and validity