Audio Science: Does it explain everything about how something sounds?

[Tony Lauck]

John, the limits of human hearing have been tested and re-tested thousands of time over many, many years. I don't know what methodologies have been used other than the standard hearing tests I get when we go to an audiologist, but after all these years, i suspect the conditions and test methodologies are too many to mention. I understand that some people will question anything that disagrees with what want to believe, but what we're talking about here is not some relatively recent test, like the 30 years of Harman listening studies, that we can poke at with a blunt stick looking for flaws to help us rationalize our way to different conclusions. 20 - 20khz is the scientific community's long-held and rather broad, conservative, definition of the range of human hearing (most humans don't meet that standard). To say that acceptance of those limits is myopic is like saying belief in evolution is myopic. I mean we could have been left here by aliens; it could happen. That evolution stuff is just a theory, after all.

Worry over whatever you like. Go in search of imperceivable problems to wrestle with if it makes you happy. When it comes to audio reproduction, I don't intend to concern myself with the sounds of things humans can't hear. And that's not myopic, it's rational.

Tim

Here we see, in classic form, the difference between "objectivists" and "subjectivists". It comes down to what you mean by "conservative". Confining ourselves to test signals, you call the 20 kHz upper limit "conservative". By that you mean a number that includes the vast majority of humans. This is an conservative number based on the average human. However, it is not what I would call a "worse-case" number. A worst-case number would have to include "all" humans. Speaking from personal memory, 50 years ago I had no trouble hearing 21 kHz. I am sorry to say that today I am a normal human, in that I can barely hear test tones at 12 - 13 kHz.

The music I listen to does not consist of test tones. Somehow, I am able to distinguish the difference between the presence and absence of frequencies above 20 kHz in music. I can also tell how adjusting equalization in the range 15 kHz to 20 kHz affects the "air" in recordings, even though I am unable to hear single tones in this frequency range. This does not contradict any known laws, only theories based on linear approximations. Linear approximations are used because they simplify the mathematics, but the ear (and even the air itself) are not linear systems.

I'm sorry, but I have more than a little disdain for people who (a) do not understand this mathematics and (b) persist in repeating the same nonsense after having this explained to them. If they can't do the math, they should abstain from using mathematical arguments that they do not understand, because they will not understand the limitations of the arguments, specifically where they are inapplicable. A little knowledge is a dangerous thing. Not to know, but not to know that you don't know, can lead to difficulties.

 

[Fitzcaraldo215]

Thanks but I wrote to Chris many times, many years ago after being told to have a break. This was because I reacted badly to a suggestion of Chris's that I share some of my technical background when I suggested that a $12 RF attenuator was worth trying on the output of a Hiface USB to SPDIF converter (I would still react badly to such a form of censorship). He never answered any of my emails to be reinstated after my break became a break of indefinite duration.

Tricky situation. But, I now understand your ingognito monicker at CA Forum.

 

[Groucho]

If by "nice problem" you mean "difficult problem" then I agree with you.

The hifi world seems to regard everything as extremely difficult and burdensome! Or makes it so, even if it isn't.

The thing that makes it a nice problem, for me, is that it involves playing around with 'nature' in a computer. If I had to bet on it, the person who works on this problem will never hear the result of their work (above the Brownian motion of air molecules in their own ears) but they will be able to point at the simulated and/or measured result and say "It couldn't be any better". It's a low stakes, self-contained problem that involves processing audio with mathematics and/or 'heuristics'. Maybe it's just me, but I like that sort of problem

 

[jkeny]

Tricky situation. But, I now understand your ingognito monicker at CA Forum.

Cool, thanks for the understanding.

 

[jkeny]

The hifi world seems to regard everything as extremely difficult and burdensome! Or makes it so, even if it isn't.

The thing that makes it a nice problem, for me, is that it involves playing around with 'nature' in a computer. If I had to bet on it, the person who works on this problem will never hear the result of their work (above the Brownian motion of air molecules in their own ears) but they will be able to point at the simulated and/or measured result and say "It couldn't be any better". It's a low stakes, self-contained problem that involves processing audio with mathematics and/or 'heuristics'. Maybe it's just me, but I like that sort of problem

Maybe you would be interested in Rob Watts claim that he simulated -200dB digital noise in development of his latest Chord DAC, DAVE - he claims that he can hear when it is there Vs when it isn't. So I'm guessing somewhat on the details of this experiment although I only know what he said in interview & posted here.

Good question. Noise floor modulation is very difficult to measure, as ADC's (even the very best) have very significant noise floor modulation. Firstly, what is noise floor modulation? When a sine wave signal is used in a DAC, you get different types of distortion - harmonic distortion (distortion of integer multiples from the sine wave fundamental) enharmonic distortion (distortion products that are non integer) and changes to the noise level. So for example you may have a DAC that produces noise at -120dB with -60dB sine wave (traditional dynamic range test) but the noise with a 0dB sine wave maybe -115dB - thus the noise has increased by reproducing a higher level sine wave - in this case the noise floor (seen by doing an FFT measurement) would increase by 5dB.

Now noise floor modulation is highly audible - it interferes with the brain's processing of data from the ear - and immeasurably small levels of noise floor modulation is audible. I know this as I have listened to noise floor modulation at around -200dB - these numbers are derived from simulation - and heard the effect when the noise floor modulation mechanism was switched on and off.

The problem with noise floor modulation is measuring it, as ADC performance is far worse than Hugo's, and certainly worse than Dave's. With my old Audio Precision (AP) I used to use a fixed frequency passive notch filter to remove the fundamental, then fed the residual into the AP. From this one could determine noise floor modulation, but the AP was not good at resolving small noise floors. But around October 2014 AP launched the APX555, and this had a clever system to enable more accurate measurements of distortion and noise floor. What this instrument does is the employ two ADC's per channel, and an automatic notch filter, so one ADC uses notched out fundamental, and another ADC for the fundamental. The instrument then stitches the two plots together in the digital domain.

It also had a very high purity analogue oscillator - the system has residual THD at 2.5v of -150dB. Since I need a high purity analogue source to test the pro ADC project, and since Dave at that time exceeded the old AP measurement capacity, once AP launched the APX555 I went out and purchased one.

 

[Phelonious Ponk]

Right, And you think this is an easily solvable issue? There are many sources that give rise to noise floor modulation - it's case of firstly identifying the conditions & sources of them, the perceptible effect of each one & then finding a way of dealing with each one. This ain't no easy task but do you not think others aren't working on this too? Look at Uptone Audio's Regen device, for instance - the underlying operation theory for it's audible improvement is because it improves the signal integrity of the USB signal which reduces the self-generated (fluctuating) noise at the USB receiver which is in the USB audio device. This very low level of fluctuating noise is hypothesised to affect the DAC/clock/analogue output circuitry. There is certainly an audible effect whether this is the correct explanation for it is not fully confirmed, yet

Didn't say it was easy, but if most manufacturers are ignoring this issue and, to use your phrase, indulging in "spec based marketing" it should be an opportunity to excel above them. Go for it.

Tim

 

[Phelonious Ponk]

The hifi world seems to regard everything as extremely difficult and burdensome! Or makes it so, even if it isn't.

You think? I guess that's one way to justify the absurd prices. The irony being that the most absurd prices often come from companies without the resources to take on the extremely difficult or burdensome.

Tim

 

[853guy]

The ear is the microphone.

No, it’s not.

A microhone does not have an outer structure (the auricle) focussing sound to the diagphram (tympanum), effectively boosting the sound pressure over 30x for frequencies above 3kHz.

A microhone does not have a canal, designed to more readily conduct vibrations directly to the tympanum (the canal itself is made up of two parts, the last two-thirds of which are bony and transmit vibrations), the purpose of which is to amplify frequencies between 3-12kHz.

Microphones do not have real-time gain control like the middle ear, which has three bones (the ossicles) that transmit sounds from the ear canal to the cochlea and are connected to two muscles that react when confronted with very loud sounds, mechanically peak-limiting the signal, separate from the muscles operating the ear drum.

Neither do they posess a sophisticated real-time frequency analyzer (the basal and apical ends of the cochlea) and non-linear acoustic amplifier (the outer and inner hair cells) of the inner ear.

All of the above are part of the mechansensationary apparatus of the ear’s physiology, mechanically amplfiying/limiting/equalizing sound before the mechanotransduction conversion process of mechanical signal into neural ones and the transmission of information to the primary auditory cortex, the first place sound is believed to be consciously processed by the brain.

None of this takes into account infrasound the body registers but the brain does not consciously perceive, though studies of sub-20Hz sound are revealing the nervous system has the ability to.

 

[Groucho]

You think? I guess that's one way to justify the absurd prices. The irony being that the most absurd prices often come from companies without the resources to take on the extremely difficult or burdensome.

Tim

I wonder if it is unavoidable that the natural state of audiophiles - even the objectivists - is misery. The objectivists think that they are unaffected by the imaginary, psychological stuff, but they aren't. Just like the subjectivists they are prone to hearing imaginary differences but believe that their objectivist credentials remain intact if they attribute them to real, measurable idiosyncrasies of their systems. All systems are going to have these idiosyncrasies, but there is no proof that these are what the audiophiles are hearing. BUT there is no proof that they aren't, and that is all that matters. They can never fix all the problems - if 32 bit floating point isn't good enough they'll have to use 64 bit. But, undeniably, 64 bit calculations are going to introduce some errors. Are they audible? Well, you'd think not, but if they're correlated with the signal then that makes them a special case that defies normal analysis, so maybe so. There can be no end to it. Subjectivists go down a rabbit hole of cable lifters and magic stones; objectivists go down a rabbit hole of ever-diminishing scales.

 

[FrantzM]

Maybe you would be interested in Rob Watts claim that he simulated -200dB digital noise in development of his latest Chord DAC, DAVE - he claims that he can hear when it is there Vs when it isn't. So I'm guessing somewhat on the details of this experiment although I only know what he said in interview & posted here.

Peer reviewed?

Interesting claim . Would also be interested to know how (and with what ) he measured such an absurdly low level ... Could use that for the search for th Tachyon or other elusive particle ...

 

[jkeny]

Peer reviewed?

Interesting claim . Would also be interested to know how (and with what ) he measured such an absurdly low level ... Could use that for the search for th Tachyon or other elusive particle ...

You must have missed where he said "these numbers are derived from simulation"
You must have missed the part where the new APX555 can measure down to -115dB (still in the land of the "inaudible", right?)

You must not have read the link I posted as I didn't copy over all the post.
If you had read it you would have seen this


And his comments attached to the image

Here we have a 1kHz signal at 2.5v RMS and distortion is below -150dB (blue trace). The no signal is the red trace, and you can see that the noise floor is identical in both cases, close to -180dB. 0dB is at 6v RMS, the maximum output of Dave. Clearly, there is no measurable noise floor modulation at all, even with the noise floor close to -180dB.

 

[FrantzM]

You must have missed where he said "these numbers are derived from simulation"
You must have missed the part where the new APX555 can measure down to -115dB (still in the land of the "inaudible", right?)

You must not have read the link I posted as I didn't copy over all the post.
If you had read it you would have seen this
View attachment 21681

And his comments attached to the image

Still doesn't explain how he arrived at these abysmally low numbers.. from -115dB to -200 dB is a galaxy away ...
The question remains was that peer reviewed? i am nto sure i would take a marketing claim not reviewed formally as a proof ...

The point remains that our Audio system does not do anything out of the realm of physics. We may impart all kinds of emotions to them.. Organic, nattural , etc it boils down to translating electricity into sound waves. Physical phenomenon thus explainable by Science...
Again the per absurdo argument could be that: " since there are things we cannot explain therefore Science cannot ever explain. A logical fallacy and that seems to be the premise of many posts here . This is physics after all.. isn't it? ... sound waves ? Electricity? What else is there? That can't be explained by Science?

 

[853guy]

The point remains that our Audio system does not do anything out of the realm of physics. We may impart all kinds of emotions to them.. Organic, nattural , etc it boils down to translating electricity into sound waves. Physical phenomenon thus explainable by Science...
Again the per absurdo argument could be that: " since there are things we cannot explain therefore Science cannot ever explain. A logical fallacy and that seems to be the premise of many posts here . This is physics after all.. isn't it? ... sound waves ? Electricity? What else is there? That can't be explained by Science?

Yes, of course, physics is the container of all life.

But an audio system isn't just translating electricity into sound waves. Someone first went and captured emotion and art, and turned that into electricity and stored it in some sort of medium to then be played back via a system of components that act non-linearly, especially when connected together, and especially when playing back the complex, always-changing musical signals of time/amplitude/pitch, inherent in which is the intent of an artist to communicate something about the human condition.

Science can explain the human hearing mechanism, the occurrence of perception (and misperception), and the effect of hearing sounds and silence over time (music) on our physiological, emotional and psychological state. Furthermore, it can explain - and is completely fundamental to - the development and existence of the century and a bit of our recording/playback gear. Yay science, you rock!

And if all our playback and recording gear did was record and playback the same signals we use to test and measure them, then I think there would be little to debate - we would buy gear solely based on those specs, and be happy.

But art defies physics, because it says something physics can't, and won't submit itself to the same criteria. And when the human being makes art, she uses paint and canvas, both of which can be easily explained as physical matter. But the effect of what she does with that matter on another human being... well, that's something capricious in nature, debated for centuries, caused outrage, offence and theft, and been the impetus for madness in many of its practitioners.

Art is what gets played back by our humble audio systems. Science can't explain it, and I doubt it ever will.

 

[FrantzM]

Yes, of course, physics is the container of all life.

But an audio system isn't just translating electricity into sound waves. Someone first went and captured emotion and art, and turned that into electricity and stored it in some sort of medium to then be played back via a system of components that act non-linearly, especially when connected together, and especially when playing back the complex, always-changing musical signals of time/amplitude/pitch, inherent in which is the intent of an artist to communicate something about the human condition.

Science can explain the human hearing mechanism, the occurrence of perception (and misperception), and the effect of hearing sounds and silence over time (music) on our physiological, emotional and psychological state. Furthermore, it can explain - and is completely fundamental to - the development and existence of the century and a bit of our recording/playback gear. Yay science, you rock!

And if all our playback and recording gear did was record and playback the same signals we use to test and measure them, then I think there would be little to debate - we would buy gear solely based on those specs, and be happy.

But art defies physics, because it says something physics can't, and won't submit itself to the same criteria. And when the human being makes art, she uses paint and canvas, both of which can be easily explained as physical matter. But the effect of what she does with that matter on another human being... well, that's something capricious in nature, debated for centuries, caused outrage, offence and theft, and been the impetus for madness in many of its practitioners.

Art is what gets played back by our humble audio systems. Science can't explain it, and I doubt it ever will.

Art is a different level of interpretation. One can ,ake "Art" of things that are utterly simple to fabricate .. A book for example or a manuscript of a great piece.. Just a vulgar piece of paper with some ink blots. it elicits emotions that can be powerful .. That is not the subject of the debate here ...

Science may not even care about explaining what we see or get from those writings.. The delivery of the book to us is eminently and entirely explainable by Science as it is the delivery of the music that is the matter of the discussion and it can be explained by Science as well. I would grant anyone that certain matter of the delivery are not well or completely understood ... Same with anything: Our knowledge is never complete ... shall never be . We do know a great deal however about how our music is delivered to us .. we do not know it all ut enough to have us quite satisfied with the ersatz.

 

[853guy]

Art is a different level of interpretation. One can ,ake "Art" of things that are utterly simple to fabricate .. A book for example or a manuscript of a great piece.. Just a vulgar piece of paper with some ink blots. it elicits emotions that can be powerful .. That is not the subject of the debate here ...

For me, it has to be, Frantz.

I seriously, seriously do not give a flying fig about gear, and even less about format. What is a cigarette? A "nicotine delivery device". What is an audio system? An "art delivery device". If art, and its effect on our emotions are absent from the pedological method of enquiry into this dialectic, then honestly, I can't see the point for the end-user. For the inventor, manufacturer, marketer, distributor and retailer, certainly. But for me, I just listen to music, and precisely for the "powerful emotions" it (can) elicit.

If those powerful emotions are absent, then the gear can measure however it wants, I won't be using it as a delivery device. (That's just me).

But that's not to say I'm not fascinated by what science can tell us about this process. I am so grateful we have those committed to pursing excellence in manufacturing components for musical playback. And I consider many of them to be bona fide geniuses. But I can't agree with the narrow-minded, rigidly-held mind set of some who insist that steady-state signals and their reproduction in one component isolated from the playback chain can give us all we need for evaluation. I need more than that. Art is at stake.

 

[Tony Lauck]

The hifi world seems to regard everything as extremely difficult and burdensome! Or makes it so, even if it isn't.

The thing that makes it a nice problem, for me, is that it involves playing around with 'nature' in a computer. If I had to bet on it, the person who works on this problem will never hear the result of their work (above the Brownian motion of air molecules in their own ears) but they will be able to point at the simulated and/or measured result and say "It couldn't be any better". It's a low stakes, self-contained problem that involves processing audio with mathematics and/or 'heuristics'. Maybe it's just me, but I like that sort of problem

I spent a few days looking into this a while back. I realized that it would take me at least several months of study before I would be competent to proceed with serious investigation, and this just dealing with the mathematics and algorithms, not any circuit design or psychoacoustics. (Not to say that someone smarter than me couldn't do this in an afternoon...)

 

[Fitzcaraldo215]

I think that the title of this thread "Audio Science: does it explain everything about how something sounds?" is naive and a set up. Of course it does not explain EVERYTHING, and I do not think you will find a true audio scientist or engineer who insists that it does or that the ultimate proof for you and your system is not in the listening.

To many, Darwin's Theory of Evolution was and is distorted by detractors into meaning simply that man descended from the apes, as they go on from there to demonize the entire theory. Of course, it means no such thing, although that might have been one of many possible initial oversimplified interpretations of Darwin. But, that particular interpretation is not one considered useful or relevant by evolving science since then.

I see many similar superficial anti-audio science arguments here and elsewhere that perform a similar oversimplification and distortion of the very definition of what audio science is in order to bash the offending, now mere straw man concept. Of course, there are objectivist wanna be's who do a similar thing to subjectivists in order to bash them personally and their beliefs. But, that is not necessarily based on rigorous or good science either, or good ethics for that matter. As with all things, there is good and bad - good audio science and bad, good practitioners and bad.

Science does not preclude observation. In fact, it is fundamentally based on observation. Audio science does not preclude listening for yourself and deciding what you like best. What audio science can do, at its best, is to provide more useful information and more insight into what is happening and why. It is interested in general, universally applicable information rather than the anecdotal observations of one individual under one set of listening circumstances - "one guy listening to one system in one room with his choice of recorded music". Proper science also understands full well that individuals differ in their acuity and sensitivity to musical sound - it has observed and measured that phenomenon.

Contrary to some assertions here, much audio science is about gathering and analyzing the perceptions of many individuals in listening to music under controlled, unbiased conditions. Those perceptions or preferences embody each individual's own personal value system as to what is important - emotion, feeing good, getting goosebumps, foot tapping and/or any other more purely sonic virtues. Audio science is not, as some have said, purely about making electrical or acoustic measurements with steady state test tones.

Some seem to have a great aversion to electrical or acoustic measurements. I have no idea why this is true. I find them useful, though their correlation with our perceptions and preferences is still evolving science and it gets into psychoacoustics. I do believe that measurements over the years of audio equipment have helped make that equipment better on average. No equipment maker wants his creation to be called out by measurements as not fulfilling his own specifications or performing erratically relative to the competition in published tests. But, if you go back far enough in the history of hi fi, not all equipment "measured the same" as it might superficially appear today in many common, simple performance measures with certain classes of equipment.

But, there is also a big gap between common published audiophile-grade measurements and much more sophisticated professional measurements because of the gap in knowledge necessary to comprehend them, as well as the difficulty in performing them.

In any case, there are no science police forcing anyone to accept scientific test results or measurements or upon which to base their own equipment purchase decisions. That there is nonetheless such hostility in some camps about audio science is not a complete surprise. It is largely a result of incomplete, superficial understanding of what audio science really is and emotional reactions to the fear and uncertainty that entails.

 

[jkeny]

Still doesn't explain how he arrived at these abysmally low numbers.. from -115dB to -200 dB is a galaxy away ...

Are you just being obstinate & awkward - the -200dB was simulated in the digital domain; the -115dB was the measuring limit of the new APX555. Does this matter - they are both outside the limit of audibility, right - so why does it matter which measurement you take - the point is still the same - the thresholds of audibility may need to be revisited.

Let's just imagine, for a moment, that I am right - it would probably answer one aspect of the great dilemma - "why measurements don't correlate with listening" - I see a lot of measurements either being ignored because they are below -80dB or the measurements aren't done to uncover these low values.

The question remains was that peer reviewed? i am nto sure i would take a marketing claim not reviewed formally as a proof ...

Ah yes, marketing claims from leading engineers like Rob Watts (whose credentials in the field are pretty damn good) & I guess that applies to Martin Mallinson too (also with highly respectable credentials) - these must be dismissed. I'm just showing you different sources that point to the same thing - the standard thresholds of audibility may need some revising Dismiss al of it as is your wont.

The point remains that our Audio system does not do anything out of the realm of physics. We may impart all kinds of emotions to them.. Organic, nattural , etc it boils down to translating electricity into sound waves. Physical phenomenon thus explainable by Science...
Again the per absurdo argument could be that: " since there are things we cannot explain therefore Science cannot ever explain. A logical fallacy and that seems to be the premise of many posts here . This is physics after all.. isn't it? ... sound waves ? Electricity? What else is there? That can't be explained by Science?

What point are you trying to make - it's just electricity & therefore everything needed is already known? There's no answer to that really as it so far off the mark that it's impossible to even begin answering.

 

[jkeny]

Sorry, Fitzcaraldo, to pull you up on this but you are a supporter of Archimago's measurements & have stated that you see nothing wrong with them.
In your above post you say "But, there is also a big gap between common published audiophile-grade measurements and much more sophisticated professional measurements because of the gap in knowledge necessary to comprehend them, as well as the difficulty in performing them."
So are you saying that Archi's measurements fall well short of much more professional measurements & what is the distinction between these two categories of measurements?

 

[FrantzM]

Are you just being obstinate & awkward - the -200dB was simulated in the digital domain; the -115dB was the measuring limit of the new APX555.

Ah yes, marketing claims from leading engineers like Rob Watts (whose credential sin the field are pretyy damn good) & I guess that applies to Martin Mallinson too (also with highly respectable credentials) - these must be dismissed. I'm just showing you different sources that point to the same thing - the standard thresholds of audibility may need some revising Dismiss al of it as is your wont.


What point are you trying to make - it's just electricity & therefore everything needed is already known? There's no answer to that really as it so far off the mark that it's impossible to even begin answering.[/QUOTE]

REad the post above by Fitzcaraldo and try to keep without ad hominem when you are out of arguments