[Phronesis]

From an eminent physicist, Carlo Rovelli:

https://newrepublic.com/article/118...cist-explains-why-science-not-about-certainty

"Science is not about certainty. Science is about finding the most reliable way of thinking at the present level of knowledge. Science is extremely reliable; it’s not certain. In fact, not only is it not certain, but it’s the lack of certainty that grounds it. Scientific ideas are credible not because they are sure but because they’re the ones that have survived all the possible past critiques, and they’re the most credible because they were put on the table for everybody’s criticism.

The very expression “scientifically proven” is a contradiction in terms. There’s nothing that is scientifically proven. The core of science is the deep awareness that we have wrong ideas, we have prejudices. We have ingrained prejudices. In our conceptual structure for grasping reality, there might be something not appropriate, something we may have to revise to understand better. So at any moment we have a vision of reality that is effective, it’s good, it’s the best we have found so far. It’s the most credible we have found so far; it’s mostly correct."​

 

[KeithEmo]

I'm kind of looking at all this from the opposite direction.

Most people I know agree that, even if you're standing on the sidewalk, listening through an open window, you can usually tell the difference between a live band playing and a recording. And I find the distinction to be especially vivid when someone inside the room whacks the cymbals really hard. Therefore, clearly, we are FAR from able to make a recording that accurately replicates the live performance.

I don't know exactly what's missing; maybe it's those ultrasonic components; maybe it's just that the first hit actually registers 165 dB, and neither the microphones or the speakers can handle it accurately, or maybe, when it comes to commercial recordings, it's just that the cymbals always get hit by a limiter.... but there's something that falls short of "it really sounds exactly the same". (To be candid, I've heard recordings of vocalists where I probably couldn't tell the difference, and perhaps a few horns, although many horns seem to lose that "sharp tearing sound" in recordings, but the cymbals never sound exactly right to me.)

Therefore, my assertion is simply "something isn't perfect yet" - so let's find out what it is. (And, since ultrasonic components are a known characteristic of cymbals, and cymbals seem to be a prime example of "something we haven't got perfectly right yet", until all the nit-picking disputes started, that seemed like an easy thing to actually rule out - or fail to rule out.)

And, yes, I'm perfectly willing to concede that the difference may turn out to be something that's bad for your hearing... but that's not really relevant to the question at hand. (Standing five feet from the cymbals at a live performance probably is bad for your hearing.)

Frequencies double with each octave, so 20,000Hz to 40,000Hz is the same amount as 20Hz to 40Hz- about one octave. An extra 6Khz above 20 is about a third of an octave. So when you sing do re mi, you don't even get to mi. It doesn't amount to a hill of beans if you know what the numbers represent. Also, I believe that study was talking about 26kHz being audible at something like 100dB. If they played a core frequency at that volume, you would flinch and rip the headphones off. I doubt if anyone here in this group can hear much past 16kHz. Most of us probably fall somewhere at or under 15kHz. And it doesn't matter anyway because frequencies above that are pretty much useless in music.

You're right about the danger of testing hearing of very high frequencies. A guy here put up test tones and people were reporting that they could hear 20kHz, but it turned out they were doing it by cranking the volume to ungodly volumes. Not a smart idea! People get this idea in their head that the extremes matter more than the core. The opposite is true.

 

[Phronesis]

I'm kind of looking at all this from the opposite direction.

Most people I know agree that, even if you're standing on the sidewalk, listening through an open window, you can usually tell the difference between a live band playing and a recording. And I find the distinction to be especially vivid when someone inside the room whacks the cymbals really hard. Therefore, clearly, we are FAR from able to make a recording that accurately replicates the live performance.

I don't know exactly what's missing; maybe it's those ultrasonic components; maybe it's just that the first hit actually registers 165 dB, and neither the microphones or the speakers can handle it accurately, or maybe, when it comes to commercial recordings, it's just that the cymbals always get hit by a limiter.... but there's something that falls short of "it really sounds exactly the same". (To be candid, I've heard recordings of vocalists where I probably couldn't tell the difference, and perhaps a few horns, although many horns seem to lose that "sharp tearing sound" in recordings, but the cymbals never sound exactly right to me.)

Therefore, my assertion is simply "something isn't perfect yet" - so let's find out what it is. (And, since ultrasonic components are a known characteristic of cymbals, and cymbals seem to be a prime example of "something we haven't got perfectly right yet", until all the nit-picking disputes started, that seemed like an easy thing to actually rule out - or fail to rule out.)

And, yes, I'm perfectly willing to concede that the difference may turn out to be something that's bad for your hearing... but that's not really relevant to the question at hand. (Standing five feet from the cymbals at a live performance probably is bad for your hearing.)

My sense is that the main difference between live sound versus recordings played back on sound systems is in the acoustics, with respect to how we localize sounds, attenuation of frequencies, etc. to construct an 'auditory scene'. The live experience will always be quite different from anything played back on a sound system. That doesn't mean the sound system can't sound really good, maybe even be rated by a listener as 'better than live', but I just don't think we can replicate the live experience.

My *guess* is that ultrasonics aren't a significant factor in the perceived difference between live vs sound system (maybe not a factor at all), though I definitely see how it could be tempting to think so, since the high frequencies we can definitely hear (say 5-20 kHz) seem to have a different character live as compared to with sound systems. There might be a fallacy along the lines: "the difference in highs really matters (true), so maybe the difference in the ultrasonic highs is the last bit that really matters too."

 

[KeithEmo]

I'm pretty sure that, if you were to ask a neuroscientist, his or her response would be something like "any situation where a vibration carried through the atmosphere causes a measurable response in one of the areas of the brain dedicated to auditory perception". (In other words, anything that causes one or more neurons in your auditory cortex, or any area associated with it, to "light up" on an MRI.)

Not only does this complicate the issue because it adds another definition, but also because our brains are not only incredibly complicated, but incredibly interconnected. For example, since our brains are filled with connections between different sections, I wouldn't bet that being exposed to a bright flashing light wouldn't activate a few "auditory neurons".

To pick a slightly different example..... When struck on the head, most of us "see stars". (The proper term is "phosphene" - which includes any situation where "you see light for any reason other than light actually entering your eye".) Does that count as "vision" or not? And, when you see stars, after being struck on the back of the head, are you simply "seeing" the club that hit you in an unusual way? The answer would seem to depend simply on the definition of "see" that you prefer to use.

To me, in the context of "listening to music", I would use: "any situation where sound, defined as an airborn vibration, produces a result that is consciously perceived as hearing sound". (So for example, if a subwoofer vibrates your foot, but you consciously perceive and report that you heard the vibration, then it counts as hearing.)

From Wikipedia:

Hearing, or auditory perception, is the ability to perceive sounds by detecting vibrations,[1] changes in the pressure of the surrounding medium through time, through an organ such as the ear.​

From Merriam Webster:

the process, function, or power of perceiving sound specifically : the special sense by which noises and tones are received as stimuli​

From Brittanica:

Hearing is the process by which the ear transforms sound vibrations in the external environment into nerve impulses that are conveyed to the brain, where they are interpreted as sounds.
​

That doesn't help! What counts as perceiving or detecting? Does the organ have to be the ear? Does feeling bass count as hearing? Does any nerve impulse from the ear to the brain count as hearing? What's involved in 'interpreting' a nerve impulse as sound?

Seems like there may not a standard operational definition of hearing?

 

[Zapp_Fan]

I don't know exactly what's missing; maybe it's those ultrasonic components; maybe it's just that the first hit actually registers 165 dB, and neither the microphones or the speakers can handle it accurately, or maybe, when it comes to commercial recordings, it's just that the cymbals always get hit by a limiter.... but there's something that falls short of "it really sounds exactly the same". (To be candid, I've heard recordings of vocalists where I probably couldn't tell the difference, and perhaps a few horns, although many horns seem to lose that "sharp tearing sound" in recordings, but the cymbals never sound exactly right to me.)

I know exactly what you mean, but I think 99% of this effect has got to be due to things other than ultrasonics.

For one thing, the sound from a live band is coming from several sources around the stage and the directionality is totally different than loudspeakers. This alone - even if SPL and dynamics were somehow the same in both the recording and the live event (another big source of the difference I'd wager) - should be enough to tell live from recorded. The sound radiates around the space in a totally different way, and our ears are pretty good at picking up the directional source of a sound.

And no matter how well a given performance is mic'd, the directionality of the live band can't be fully reproduced in a recording you're listening to over loudspeakers. (except certain binaural recordings.)

I think this goes back to a point that @gregorio has been making, which is that multi-mic mixes are just as much an artistic creation as a simulation of a live performance.

 

[KeithEmo]

That is an excellent point.

There is a huge gap between when our sensory organs detect inputs and when our brains perceive something. This is especially complex when we talk about music because the connections themselves are quite complex. For example, when you hear a violin, what does your brain "perceive"?

The way our brains process input is IMMENSELY complicated..... so, for example, you may feel something, or taste something, or "see something in your mind" when you hear a certain sound. And, to make matters even worse, the details of this process vary wildly between individuals.

A casual listener might perceive "a violin playing", while a musician perceives the printed score the musician is playing, a mathematician perceives a sequence of numbers, and a scientist might perceive an image of what the spectrum would look like on a graph. And, inside their brains, the musician might see finger placements, or a printed musical score, while the mathematician sees equations printed on a page, an art student might even see the field of flowers the composer was thinking of when she wrote the piece, while Charlie might smell the perfume of the girl he was with the last time he heard it. And ALL OF THOSE ARE VALID RESPONSES.

(And, if there's a flaw in the recording, the mathematician may "see" an error in an equation, the musician might see fingers in the wrong place, the artist might notice that the flowers in her image seem a bit fuzzy, and it may FAIL to evoke feelings of his first love in Charlie - because it's a poor match for the pattern required to do so. And, unfortunately, none of that stuff can be measured.)

I'm thinking that the root of the problem is actually somewhat philosophical.

If I want to measure blood pressure, I hook up a meter to my arm and get some numbers. Lots of things can be measured or at least objectively observed. But when it comes to anything involving perception, we can't forever ignore the issue that perception, as subjective experience, occurs in minds, which aren't really considered to be the same as brains, i.e. we wouldn't describe an observable and measurable pattern of neuron firing in a brain as being the same kind of thing as the sound subjectively perceived by the person who has that brain.

That kind of perception isn't really observable or measurable in a scientific sense, not even by the person who experiences the perception - the best we can do is to try to correlate things happening in the brain or reported by the person with that perception. If we stick to the scientifically measurable and observable, we're not directly dealing with hearing as perception of sound. But if we sidestep subjective perception and stick to things like neurons firing and people's reports, there's an incompleteness and/or unreliability involved.

Then when you put conscious vs subconscious aspects in the model, it gets even more complicated, because things that are perceived subconsciously have a sort of more vague and distant character than what's perceived consciously.

So … I'm not sure how I want to define 'hearing'. There are lots of possible ways to scientifically operationalize the concept, but all of them are correlates of subjective perception of sound, never the same thing as that subjective perception, and even these correlates won't always line up (e.g., what SPL do we set as the cutoff to say someone can 'hear' a particular high frequency?).

 

[james444]

So I double-checked myself. Apparently, some humans can hear down to 12 hz under ideal laboratory conditions.

https://en.m.wikipedia.org/wiki/Hearing_range

This is a long way from proving that you or any human can hear pitch at 15 hz over IEMs, but it’s a start.

IEMs should be pretty much equivalent to ideal laboratory conditions for that purpose. With a perfect seal, you have high isolation against environmental noise and optimum coupling to the tympanic membrane.

Since I don't think my hearing is anything special, I would assume that many humans can hear 15 hz with IEMs. Don't you know someone you can borrow IEMs from, to try for yourself? All you need is you smartphone / tablet / pc, an online tongen and a pair of perfectly sealing IEMs. If all else fails, I could send you a pair of IEMs to try, no problem.

 

[KeithEmo]

But why would you guess that?

At least one published test has apparently proven that "under certain laboratory conditions some humans can hear frequencies as low as 10 Hz". Therefore, the "established bottom limit of 20 Hz" seems most likely to simply be wrong, or to be correct, but only under some conditions, rather than under all conditions.

Could just it be harmonic distortion off of the 15 hz tone? Just a layperson’s guess here. If you hear it as a tone rather than just low low low (to paraphrase REM) I’d guess it’s harmonic distortion. 15 hz is pretty much a lot lower than people generally hear as a tone, if I understand correctly. I don’t know how you’d check for distortion v. fundamental tone. Someone else might. Interesting observation. Thanks. I assume the tone generator generates sine waves with no harmonics. I would also guess some source equipment distorts at 15 hz so there’s that too. Just throwing stuff out there as a curious layperson.

 

[analogsurviver]

I know exactly what you mean, but I think 99% of this effect has got to be due to things other than ultrasonics.

For one thing, the sound from a live band is coming from several sources around the stage and the directionality is totally different than loudspeakers. This alone - even if SPL and dynamics were somehow the same in both the recording and the live event (another big source of the difference I'd wager) - should be enough to tell live from recorded. The sound radiates around the space in a totally different way, and our ears are pretty good at picking up the directional source of a sound.

And no matter how well a given performance is mic'd, the directionality of the live band can't be fully reproduced in a recording you're listening to over loudspeakers. (except certain binaural recordings.)

I think this goes back to a point that @gregorio has been making, which is that multi-mic mixes are just as much an artistic creation as a simulation of a live performance.

That is precisely why I prefer binaural - over anything else. It can be reproduced over the speakers, to a great effect, exceeding even surround 5.1 - properly processed, of course.

And that is precisely why @gregorio & Co. is so against the binaural - because, ultimately, all the multimiking is going to be remembered in history for is artistic creation and simulation of a live performance - and not as an accurate reproduction of one. The timing errors and bandwidth limitations for multimiked multichannel recording session just can not be brought to a similar level for just two mics.

Taken further, any improvement DSD has over PCM is grossly masked by the multimiking - look at random chosen 10 videos of symphony orchestra videos on YT, estimate the difference among the closest and farthest mic you can see in each, input that sound travels roughly 340 metres per second ( depending on temperature, pressure, humidity - but in that ballpark ) - and whatever computation you end up with, time difference(s) will be orders of magnitude greater than a few - or even tenths under best possible conditions/highest sample rates - microseconds that separate DSD and PCM.

No wonder that then they claim no difference heard between DSD and PCM - one can't measure the thickness of a sheet of paper with a 3 foot log.

 

[Zapp_Fan]

If I jack up the output of my headphone amp, a lot of IEMs can create some perceptible effect at 15hz. To me it basically sounds like a rapid flapping / whooshing noise. I think it's actually just periodic pressurization of my ear canal and not what might be (if any such sound can be) perceived as a tone.

I think 20hz is a practical lower limit because it's roughly the threshold where most things stop sounding like continuous tones and start sounding like periodic distinct sonic events.

It reminds me of the supposed fact that a lot of "haunted" houses are actually just plagued by infrasound. Places that somehow create a lot of 18-19hz tones (I dunno, from the wind or something) apparently are often "haunted" because those frequencies are supposed to create a sense of unease, and the human eye even supposedly resonates at that range, which supposedly can create visual hallucinations. Not to mention that a space plagued by that much infrasound will also have various stuff moving, doors opening and closing... etc.

It does speak to the difficulty of hearing, in a normal sense, anything that low-frequency. If you are experiencing ghosts instead of sound, I assume you aren't consciously hearing a darn thing.

I think there is, however, a very obvious benefit to being able to reproduce frequencies below 20hz, which is that if your system can do it, then typically audible sub-bass will tend to be a lot better, transients will be better, etc. But I think perceptible "notes" in that range are very rare if not totally nonexistent.

 

[KeithEmo]

Practical science is a subset of science as a general subject.
And, yes, in many cases "practical science" is both more useful and "more than good enough".
(Although I should point out that not everyone agrees on the diving line between the two.)

And, in fact, there are no such thing as "scientific laws".
That's just a word we use as shorthand for "really well established theories".
You are attempting to erect a bright line where none exists.

To use an example that is often quoted in books about probability and quantum theory.

The movement of individual gas molecules in an enclosed space is random. This suggests that, one day, you could suffocate because all of the gas molecules in the room where you're sitting could randomly decide to move to the other side, leaving you with no air to breathe. As far as we know this has never happened. And, as it turns out, the odds of this happening are tiny; so tiny that it is highly unlikely to happen any time during the life of our universe. HOWEVER, TECHNICALLY, IT IS POSSIBLE, AND IT COULD HAPPEN..... it is merely very very unlikely.

Math is different because it is an abstract.
We can safely say that the math associated with Fourier's theorem is valid.
We could even say that we have never observed a sound wave that failed to comply with it.
That makes it a very good model which so far has never been found to be wrong.
And it means that it is a very safe assumption that it will be correct the next time.
However, it is STILL a model, which is not the same as a fact.

I agree that it would be foolish to carry around an oxygen mask "just in case all the air jumps away".
But that is NOT the same as saying that it is IMPOSSIBLE that it could happen.

I absolutely agree that we should all note the difference between practicality and pure science.
For example, it would be totally impractical for me to try to turn lead into gold in my basement.
However, anyone with access to a nuclear reactor can do so rather easily.
Therefore it would be UNTRUE to say "you cannot turn lead into gold".
(But it would be quite reasonable to say that "it would be totally impractical to make gold from lead".)

This is the root of so many of the evils we run into here:
Firstly and most importantly, there's the massive issue of what is "uncertain" in the first place. Much of what is categorised as "uncertain" by audiophiles is not in fact uncertain and when challenged, the more sophisticated and apparently scientific response is along the lines of: Science is all about theoretical models of reality based on observations, models which are imperfect and evolve over time in response to new observations, new evidence and/or a failure of prediction. However, this is only "apparently" scientific rather than actually being scientific because while this assertion is often true/applicable to many scientific theories, it is also sometimes NOT true/applicable and even when it is, it often has no affect on the practical application of the science. Furthermore, it ignores the fact that we're often not dealing with scientific theories but also with proven scientific theorems and laws.
For example, we might describe Fourier's discoveries and proofs as a "model" of what sound waves are (comprised of), however, it has not followed the path of many theories (such as the theory of evolution for example), it has NOT evolved over time in response to new observations, evidence and/or failures of prediction because in the 200 years or so since Fourier's mathematical proof there have been no failures of prediction and no new observations or evidence to even hint that it might in some way be wrong or incomplete. It's the same story with digital audio/communication theory, certainly the engineering practicalities of applying the theory have evolved but the theory itself has not, there have been no failures of prediction and no evidence which even hints that it might be incorrect in the 70 years since the proof was published, despite the fact that every digital device on the planet puts the theory to the test hundreds of millions to trillions of times per second. A similar but slightly different example demonstrates another part of my statement above, that even when a theory is incomplete and "evolves" it often still doesn't make any practical difference: By about 170 years ago electricity had been fully defined mathematically by Maxwell, Ohm and others but starting around the 1920's, it became clear our understanding (scientific model) of electricity was not entirely complete, it did not include quantum mechanical effects for example. However, this incompleteness only affects what happens in certain extreme conditions (such as at absolute zero for example), outside those specific extreme conditions, Maxwell's, Ohm's and other's mathematical definitions/proofs of electricity still ALWAYS hold true and there's been no evidence in the intervening 150 years to suggest otherwise. And (hopefully) most realise that the recording and reproduction of music doesn't involve anywhere near the extreme conditions required for the basic classical model of electricity to no longer be ENTIRELY applicable.
These 3 "certainties" cover most of the recording and reproduction of music/sound and yet audiophiles (and those who sell to them) still routinely misrepresent them as "uncertainties"! As far as the audiophile community is concerned, a far more pertinent "challenge" than "dealing with uncertainty" would be to gain a far better grasp of what is certain and uncertain in the first place!

Secondly, there are definitely some areas of uncertainty, particularly if we're talking purely about science in say the field of human perception but even here we have to be careful what we mean by "certainty"/"uncertainty". Do we mean we have no idea at all? Do we mean we've got a pretty good idea, for example a "certainty" that a particular perception is a combination of several well defined and accepted theories? Or, do we mean that we actually have an extremely high degree of certainty in how perception works/affects us (and therefore how we can manipulate it) but relatively little science which explains the physical/biochemical processes within the brain which accomplishes this task? For example, centuries of musicology/composition and nearly a century of film sound has given us a very good understanding of how hearing perception works and how it can be manipulated. Again though, many audiophiles are partially or entirely ignorant of all this. This is good example;

Most of that isn't a "what if", it's very well known and has been tested exhaustively over the course of more than 6 decades. Why, for example, do you think we record orchestras with multiple mics (and have done since the 1950's), when just two mics can capture all the sound waves that a member of the audience (in the ideal listening position) would hear?



And it would be even more foolish to not believe the science/facts that ARE correct, and then make-up false assertions entirely based on that foolishness! Yet this is exactly what we see time and again, even from some posters in this sub-forum, let alone the other sub-forums. Ultimately, what you believe and whether you personally are convinced or not is irrelevant, the science/facts do not depend on and are not affected by your belief, understanding or lack thereof.

G

 

[KeithEmo]

I agree entirely....

I would also point out that the degree of certainty we are each willing to be satisfied with varies.

I am reasonably confident that the lunch I eat today will not have been accidentally contaminated with poison.
In fact I am confident enough that I'm not at all worried about eating it.
However, it could happen.... and does happen to a few people every year.

However, from what I've read, when the first atomic bomb was detonated:
"Most scientists were reasonably certain it wouldn't set the Earth's atmosphere on fire by a chain reaction."
Now, years later, many people find that degree of certainty to be "not really good enough".

I this case, odds are that the entire planet won't be reduced to a flaming cinder, even if one of us is wrong.

But isn't this largely semantics? Sure, in an absolute sense we can't be absolutely certain of anything, we can't be absolutely certain that pigs can't fly, that unicorns don't exist or that the Earth isn't flat. But if we've got a mathematically proven theorem that's demonstrated trillions of times per second, by billions of devices for many years, with no evidence or even hint that in some way it be incorrect/incomplete and has therefore never evolved or been refined, how much more certain of anything can we ever be? And yes, as I stated, the model of electricity has been refined and likely will be more refined in the future but none of that affects Ohm's Law (for example) as it pertains to home stereo systems. Now if one day we're all listening to Michael Jackson's Thriller while sitting on a singularity inside a black hole, then I'll not be nearly so entirely certain that Ohm's Law is applicable but until then ...

G

 

[KeithEmo]

I absolutely agree....

What I suspect is that we are far more able to resolve far smaller differences in timing and direction of acoustic waves than seems to be widely accepted. Inside a room, sounds from each instrument, and even each part of some instruments, are launched in different directions, and at different times. This is far different than attempting to launch all those sound waves from a few speakers at specific locations.

And, even outside a small window on the sidewalk, the sound waves from all those separate instruments will arrive from a variety of directions, after bouncing around the room inside. And those reflections will be far different than if the same sound waves had originated at a few distinct speakers.

For an analogy with light, imagine a room with multiple people moving around, waving an assortment of flashlights and lanterns, and an observer outside on the sidewalk. Light would be passing through the window from a wide variety of directions and in a wide variety of different patterns. Now imagine if we were to put a shade in the window, film the light striking the inside of the shade, then project an "equivalent" two-dimensional image on the shade. The pattern of light at the plane of the shade would be identical, but the directional information would be removed, and replaced with new and different, and incorrect, directional information.

It is generally accepted that the only sense of the directionality of sound we humans have comes from our stereophonic hearing - from timing and phase differences. (Many insects can actually "hear the direction of a sound directly" - but we humans cannot.)

Here is my THEORY. If you were to stand perfectly still outside the window you probably wouldn't be able to tell the difference. However, if you move your head, by interpreting the patterns of sound your purely directionless ears pick up, your brain is able to partially reconstruct some of the directional information that you cannot hear directly, and so synthesize at least a sense of "three dimensional sound".... which is going to be far different when the source is multiple instruments with different launch patterns than when it is a small number of speakers at fixed locations.

One way to test this experimentally would be to see it the ability to tell the difference between a live band and a reproduction played through speakers "collapses" when the listener is unable to move their head. (Compare the experience of someone with their head clamped in a "dentist chair" to someone free to move around.)

My sense is that the main difference between live sound versus recordings played back on sound systems is in the acoustics, with respect to how we localize sounds, attenuation of frequencies, etc. to construct an 'auditory scene'. The live experience will always be quite different from anything played back on a sound system. That doesn't mean the sound system can't sound really good, maybe even be rated by a listener as 'better than live', but I just don't think we can replicate the live experience.

My *guess* is that ultrasonics aren't a significant factor in the perceived difference between live vs sound system (maybe not a factor at all), though I definitely see how it could be tempting to think so, since the high frequencies we can definitely hear (say 5-20 kHz) seem to have a different character live as compared to with sound systems. There might be a fallacy along the lines: "the difference in highs really matters (true), so maybe the difference in the ultrasonic highs is the last bit that really matters too."

 

[gargani]

To me, this all illustrates that auditory perception is quite complex, and we can't really isolate it from other senses. Humans evolved to take in information in a multisensory way, not to listen to IEMs.

I think this very much applies to music listening and enjoyment also. Two examples:

- A weakness of headphones is that they lack the visceral bass impact of speakers. We can feel a lot of bass energy through our bodies that we can't feel through headphones. That presents a challenge for headphone design, to simulate and create a perception of suitable amount of bass without being able to produce the visceral impact. Headphones that increase the bass to do that seem to typically suffer from some reduction in clarity.

- When I watch concert videos on youtube with my headphones plugged in to the computer, I'm often impressed with how good the sound quality is. When I then close my eyes, the sound quality seems to get worse and I notice 'flaws' in the sound quality more. The difference seems to be that, when I see the video, I'm pulled into the experience in a multisensory way and I pay less attention to the sound quality - that makes it easier for the sound quality to be 'good enough'. A possible implication here is that when we struggle to simulate live sound quality with our gear, that perceived gap may not mainly be due to the sound quality falling short, but rather due mostly to our not seeing the performers, the music unfolding in real time, presence of an audience around us, etc. I suppose we can somewhat fill the gap by imagining that we're there live, but that of course requires a mental effort where we bring something to the music which isn't there in the physical sound, a sort of 'imposed placebo effect'.

There's a saying that I've heard. I can't remember if it was a singer or a musician; but it was used to describe the audience's perception of a performance: "The better you look, the better you sound. "

 

[bigshot]

It's hard to hear something as low as 15Hz as a tone, if you just listen to that single frequency. But if you start at, say, 30Hz and decrease the frequency step by step, you can discern the pitch change quite easily.

That's interesting. Can you hum the tone at a higher pitch and figure out what the musical note is? I can't do that with anything anywhere close to that frequency. Down low, I can detect a difference between one frequency and another, but not the musical pitch. Are you a musician or do you have perfect pitch? That might explain it.

In any case, frequencies that low probably don't exist at audible levels in most recorded music. I think a pipe organ is the only instrument that goes that low. And the main benefit of sound that low in movies is to create the kinesthetic thump in your chest along with explosions and stuff like that. You wouldn't get that at all with IEMs. I find with my subwoofer, the main purpose of super low frequencies is to just provide a rumble or thump. It gets the air vibrating so you can feel it. It's more feeling than hearing. Perhaps when you eliminate the air and space with IEMs you can discern sub bass frequencies a bit better. (I don't have IEMs, so I don't know.)

Maybe when the 20Hz figure was established they were talking about sound conducted through space in a room. They hadn't considered piping the sound directly into the ear canal.