No! 20Hz----20kHz is NOT the range of human hearing!

[rasputin1963]

......or so some new thinkers would have us believe.

 

 

Forget WIKI for a moment: What are YOUR personal convictions about the human frequency range spectrum? Would you agree that 20Hz---20kHz pretty much covers it....

 

.... or do you think evidence exists to suggest that there are some "magical" frequencies that exist above and below this range, which we hear "subliminally" or "kinesthetically" or "viscerally" or "clairvoyantly" or whatever audio buzzword-du-jour.

 

Denude a recording of frequencies outside the usual zone-- so the thinking goes-- and we start to strip a song of its "presence"....."brilliance"......"sparkle"........"thrust"......."viscerality".......

"boom"...."crispness"..."verve"... whatever.

 

What say you on this score, SSS'ers?

[DevilRaysFan]

......or so some new thinkers would have us believe. Forget WIKI for a moment: What are YOUR personal convictions about the human frequency range spectrum? Would you agree that 20Hz---20kHz pretty much covers it.... .... or do you think evidence exists to suggest that there are some "magical" frequencies that exist above and below this range, which we hear "subliminally" or "kinesthetically" or "viscerally" or "clairvoyantly" or whatever audio buzzword-du-jour. Denude a recording of frequencies outside the usual zone-- so the thinking goes-- and we start to strip a song of its "presence"....."brilliance"......"sparkle"........"thrust"......."viscerality"....... "boom"...."crispness"..."verve"... whatever. What say you on this score, SSS'ers?

 

Isnt there a black hole that is emitting a low sub Bb out there? This must make saxophone players everywhere in the universe happy......

[rasputin1963]

This must be the "music of the spheres" that the Good Book refers to....?

[DevilRaysFan]

 

This must be the "music of the spheres" that the Good Book refers to....?

 

 

I dont know, but I know a girl that can sing "I Want To Kiss You All Over" by Exile in one long burp after a few beers.......

[blue2blue]

......or so some new thinkers would have us believe. Forget WIKI for a moment: What are YOUR personal convictions about the human frequency range spectrum? Would you agree that 20Hz---20kHz pretty much covers it.... .... or do you think evidence exists to suggest that there are some "magical" frequencies that exist above and below this range, which we hear "subliminally" or "kinesthetically" or "viscerally" or "clairvoyantly" or whatever audio buzzword-du-jour. Denude a recording of frequencies outside the usual zone-- so the thinking goes-- and we start to strip a song of its "presence"....."brilliance"......"sparkle"........"thrust"......."viscerality"....... "boom"...."crispness"..."verve"... whatever. What say you on this score, SSS'ers?

Ras

 

[unless noted, everything below refers to sounds in free air, not bone conduction.]

 

I don't think any authoritative voices are suggesting that no humans can hear above 20 kHz -- because there's solid evidence that some young children and a few adults can hear as high as 22 kHz. There are a few somewhat credible reports of people being able to hear a little higher. As far as I know, there's no credible evidence that any human can hear 25 kHz or higher -- but those folks might be out there in very tiny numbers (one in many millions)... it's hard to rule out very anomalous extremes in something as fuzzy as human perceptions.

 

But it is certainly true that it is the very rare adult who can hear 20 kHz or above and that most adults of middle age probably have ranges topping out in the mid teens or lower.

 

Now, you will sometimes get audiophile or other self-identified "golden ears" try to claim that even if one can't perceive a given very high frequency, that its absence will affect the quality of that person's perception of the sound. Unfortunately for those claims, there is absolutely no evidence (that I'm aware of) that people can differentiate between two otherwise identical sounds, one of which has had signal content removed which the person could not perceive directly. (IOW, if you can't hear it, you can't hear its absence.)

 

On this last, some audiophilia true believers have dug up a study on bone conduction of audio done for a hearing aid implant research study and, as far as I know, not peer-reviewed (that may have changed) that does seem to suggest that, when special bone conduction transducers are used (surgery anyone?), that subjects were able to perceive such missing 'supersonic' frequencies.

 

But in normal free-air/headphone testing, there's no evidence to suggest that one can differentiate between signals containing components above one's hearing and otherwise identical signals that have had those frequencies removed. (If you can't hear it, you can't hear its absence.)

 

 

Is 20-20 kHz an adequate model for the nominal adult human range? I think so. Is it a good stopping place in the quest for higher fidelity? I think that's a harder case to make, at least to those of us who like to see a little 'headroom.'

 

The current CD-Audio standard of 44.1 kHz affords the ability to capture frequencies up to 22.05 kHz -- but anything at or above that frequency must be filtered out or alias error in the form of possibly noticeable patterned and random noise will occur. Since it's difficult to create a true brick wall filter that allows everything right up to the cut off frequency and then closes down completely at the cut-off, we generally allow for some roll-off range, and we've generally taken the old hi-fi grail of 20-20 kHz as a reasonable target. (When I was a kid, a great -- really expensive -- hi fi might be counted on delivering some kind of sound from around 30 to 18 kHz, but certainly not with anything close to truly flat response.)

 

 

If we were looking for a truly optimal sample rate, it's been suggested by some leading lights (Dan Lavry among them) that a sample rate of about 60-70 kHz would afford all the headroom we would reasonably need in order to cover well above the highest frequencies any human has ever been tested as able to perceive (in free air) and afford adequate time in order for the sampling mechanism to create an accurate measure of the signal. (It's important to realize that level measurement is accomplished by an extremely rapid series of comparisons of known voltages to the incoming signal. The less time one devotes to those comparisons, the less accurate the measure. For that reason, converter designers like Lavry argue that there is a distinct trade-off and that there is simply no point whatsoever in designing, building and selling "quad-rate" converters (192 kHz samping rate) -- except for the marketing charade of claiming that "more is better."

 

Instead, Lavry suggests that we should simply settle on the existing 88.2 kHz 96 kHz 'double-rate' standards as a practical compromise.

 

Of course, the prevailing wisdom is that consumers simply don't care and that most of them seem perfectly content listening to noticeably lower fidelity 128 kbps meda -- like that which made the iTunes store a top music retailer. Amazon introduced much higher fidelity 256 kbps Mp3 sales (the original iTunes format was DRM-protected AAC, an arguably advanced format that many folks feel offers somewhat better fidelity than an mp3 of the same bitrate -- so it's not possible to make a direct comparison) but the media focused not on the higher fidelity which, if mentioned at all, was a passing reference, but simply on the fact that the Amazon sales were not DRM-protected and that iTunes finally had a serious competitor. Indeed, Apple responded by introducing limited sales of similar 256 kbps non-DRM Mp3s (not AACs) for premium prices.

[slight-return]

 

Forget WIKI for a moment

 

 

I usually do!

[nat whilk II]

The only comment I can recall hearing on this topic that seemed to hang together was something along these lines:

 

no, humans can't hear the actual frequencies above the 20khz mark or closely thereabouts.

 

but the presence of those frequencies in a given sound does interact with the other frequencies in the audible range, performing as it were a bit of frequency modulation on them, which has the result of creating resonant bands of additional frequencies that "fill out" the sound in the audible range.

 

But this is just for me armchair speculation - I have no handle on the actual science. But of one thing I'm convinced - psycho-acoustics is a young science that has proven to be full of surprises, and the smart money is on the assumption that further surprises are in store as the field develops.

 

nat whilk ii

[blue2blue]

While it gives me serious pause to contradict a guy whose avatar is as scary as that, I'd respectfully suggest that's kind of backwards. (I go through it at some length above -- and was no doubt still adding to and tinkering my post above when your post hit the board.)

 

But there is science to suggest that the young and some adults can hear somewhat above 20 kHz. (I've seen an upper threshold of 22 kHz given as a nominal range for very young children. Some would be expected to be higher.)

 

But there's no evidence to suggest that humans can differentiate (in free air, with statistical significance) between two otherwise identical sounds, one of which contains frequencies above that listener's tested hearing range.

[Ethan Winer]

Agreed with blue on the scary avatar.

 

the presence of those frequencies in a given sound does interact with the other frequencies in the audible range, performing as it were a bit of frequency modulation on them

 

IM products are created only in the presence of nonlinearity. Air and room acoustics are linear, so no such effect occurs as you describe.

 

Guys, this stuff has been tested scientifically many times, always with the same results. We can't hear above about 20 KHz, and we aren't "affected" by those frequencies either. The real questions in my mind are 1) why does this topic keep coming up over and over again, and 2) why do some people want so badly to believe there's more to hearing than the established known science? It's like the X-Files.

 

--Ethan

[Jeff da Weasel]

We can't hear above about 20 KHz, and we aren't "affected" by those frequencies either. The real questions in my mind are 1) why does this topic keep coming up over and over again, and 2) why do some people want so badly to believe there's more to hearing than the established known science? It's like the X-Files.

 

Let me ask you something, Ethan: if you had your choice of two products that were impacted by frequency range -- perhaps a headphone amp -- and one had a filter with a sharp cut-off at 20Hz and 20kHz, while the other had a range of 10Hz-120kHz, and both were the same price, would you give any consideration to the one with the expanded frequency range? Based on your philosophy in the above statement, it would appear that it wouldn't make any difference.

[slight-return]

guys, this stuff has been tested scientifically many times, always with the same results. We can't hear above about 20 KHz, and we aren't "affected" by those frequencies either.

-Ethan Winer

 

 

Let me ask you something, Ethan: if you had your choice of two products that were impacted by frequency range -- perhaps a headphone amp -- and one had a filter with a sharp cut-off at 20Hz and 20kHz, while the other had a range of 10Hz-120kHz

 

 

given the statement Ethan made was on +20Khz, I'd suggest just changing the upper frequency range in the question as opposed to the upper AND lower ranges as the lower range isn't addressed in the statement

[Jeff da Weasel]

Heh heh, yeah, true. But there's not much controversy over the low end, other than the notes that might make you have to change your tighty-whities.

 

I'm interested in what Ethan has to say in this regard. Given his statement, there should be no reason he'd want a headphone amp that would go above 20kHz in any case, since he'd never have any perception of those frequencies, if they were represented at all, even in an overtone series.

 

Right, Ethan?

[slight-return]

 

Heh heh, yeah, true. But there's not much controversy over the low end, other than the notes that might make you have to change your tighty-whities.

 

 

we've injected a quality into unit B that could potentially make it more/less desirable that doesn't have to do with the +20khz boundary

It's not a good control

 

sort of a "would you rather have wooden voodoo doll NOT enchanted by witch-doctor or a golden voodoo doll that WAS enchanted by a witch-doctor" riff

[Jeff da Weasel]

True. I'm not a good scientist. But rarely in life do we have the luxury of true 1:1 comparisons anyway.

[slight-return]

True. I'm not a good scientist.

 

Eh, not to worry just part of my background (ugh, I learned the hard way when I was dating Bubba not to QA her experiments...it's similar to tandem kayaks...we call em "divorce generators")

 

But rarely in life do we have the luxury of true 1:1 comparisons anyway.

 

hence the need for careful experiment design! to get closer to that opportunity

[otherwise we wind up with apples to oranges ]

[MikeRivers]

I'll tell you what I have to say about this (and I'm correct, of course). There is sound above 20 kHz. We can't hear it directly, but under certain circumstances, it can affect what we perceive in the audible range. I don't mean something obvious like 23 kHz and 24 kHz mixing to create an audible 1 kHz beat frequency, it's more complicated than that. I'll leave it to the scientists and crackpots, if we have any of those here, for the explanation. I can relate, though, that Bob Katz tried to study this out a few years back. He created a set of brick wall filters to progressively chop off the top end that he was listening to in his mastering suite. He was quite surprised at how low he had to go before he considered the sound to be degraded, or even that he could hear a difference with and without the filter.

 

There was Rupert Neve's classic demonstration that it was possible for him (and others, presumably) to hear the difference between an 8 kHz sine wave and 8 kHz square wave, but apparently that was ultimately attributed to something oscillating (or maybe it was EMI pickup) in the console under test, and when that was fixed, the sine and square wave sounded alike.

 

Now as far as Jeff's specific question about headphone amplifiers, I wouldn't be impressed with a 120 kHz spec. If choosing between two amplifiers, that's probably the last thing I'd look at. I'd certainly look at the manufacturer and the weight before I'd worry about frequency response above 20 kHz. I'd probably want to check out both of them out to see what happens above 20 kHz. It's quite possible that the one specified to 20 kHz can pass 100 kHz, but frankly, I'd prefer that it be band-limited so that crap getting into it didn't get out to my headphones.

[MrKnobs]

You can learn to create a pitch higher than 20kHz with your throat, but you can't hear it. Not with your ears, not through bone conduction, you just can't. Few things have been so thoroughly tested.

 

Most (but not all) audiology is about interacting with the patient through his or her perception (i.e. the audiologist creates a sound and the patient indicates in some way whether they heard it or not). The test is very carefully administered to control for guessing.

 

If you can hear tones (much) above 20 kHz, all you need do is report to an audiologist and they can very easily confirm (or deny) that.

 

Heck, you can do it at home. Generate a random sequence of 25 kHz sine waves in your DAW and play them back (looping, so you don't know where the "play head" is at) through a very good speaker, earphones (or a cheap piezo will probably work).

 

Without looking at the screen, see if you can tell when the tone is playing and when it isn't.

 

As for artifacts, consider that most speakers (not all) are mechanical, so if you crank enough level of a high frequency tone through them you will get audible artifacts (and possibly visual ones as well!) but they will be created by the speaker not inherent in the signal.

 

Terry D.

[nat whilk II]

Agreed with blue on the scary avatar. IM products are created only in the presence of nonlinearity. Air and room acoustics are linear, so no such effect occurs as you describe. Guys, this stuff has been tested scientifically many times, always with the same results. We can't hear above about 20 KHz, and we aren't "affected" by those frequencies either. The real questions in my mind are 1) why does this topic keep coming up over and over again, and 2) why do some people want so badly to believe there's more to hearing than the established known science? It's like the X-Files. --Ethan

 

 

I concede as to modulation effect (it was just something I heard anyway).

 

My only remark is that "established known science" obviously doesn't know everything or no progress would ever be possible.

 

Surely there's more to hearing than the current state of science understands?

 

the Were-Pumpkin asks....

[blue2blue]

Certainly, there's much to learn about the psychoacoustic processing within the nervous system/brain continuum. We're continuing to learn fascinating information about how our hearing is used for the mapping of personal environmental space. (Think about the amazing ability of many blind people to navigate an unfamiliar area by what we might call adaptive echolocation, listening to the echoes/reverberation of their cane tapping or other sounds.)

 

But the frequency range of human hearing has been tested with increasing thoroughness and redundancy for the better part of a century. It has been studied from a number of approaches. And the findings tend to remain frustrating for the I want to believe crowd.

 

 

Speaking of which, the thing that sends me into conniptions is when true believers in the goldenness of their own ears try to deny the efficacy of double blind perceptual/preference testing. I have literally seen such folks argue in print that not knowing which of two sources one is listening to invalidates the testing. [And no, I'm not making that up. People are... amazing.]

[Jeff da Weasel]

I have literally seen such folks argue in print that not knowing which of two sources one is listening to invalidates the testing .

 

Well, that's just insane. "But Susie, how can I tell which cup I like if you don't have the Coke or Pepsi label on there???"

 

Sheesh.

[blue2blue]

Yeah... I don't think that party was a trained scientist.

 

 

It's funny, I spend a lot of time at GearSlutz, where there is a real diverse community of everyone from complete, utter newbs (sometimes they seem pretty new to the whole written communication thing) to deeply experienced recordists with both a great aesthetic but also a solid and sometimes expert grounding in various scientific disciplines.

 

But it can be shocking just how many folks do seem to be completely incapable of using even the simplest logical reasoning. I mean... zip. And that logical discourse-challenged group sometimes includes some folks who appear to be experienced recordists with seemingly well-equipped commercial studios.

 

I think that there are those who "play" the studio like an instrument -- without knowing precisely how it works or why. And that is great. Where things sometimes get sticky is when those folks conflate their aesthetic success with an actual scientific understanding of how things work...

[Anderton]

Dudddits can hear up to about 40kHz. So there.

 

I can't over 20kHz any more, although I could as a kid - the "ultrasonic" burglar alarms in some stores were physically painful.

[UstadKhanAli]

 

 

 

A loooooooong time ago, one of my university professors told our class of this appalling test conducted by a bulletproof vest company with sheep. The experimental group were composed of sheep wearing the vests; the control group were sheep with no vests. I have no proof that this actually happened, and a quick Google search produced nothing, but regardless, I'd say that it qualifies as a poor design for an effective test on numerous accounts, wouldn't you agree?

[UstadKhanAli]

But it can be shocking just how many folks do seem to be completely incapable of using even the simplest logical reasoning. I mean... zip. And that logical discourse-challenged group sometimes includes some folks who appear to be experienced recordists with seemingly well-equipped commercial studios.

 

I know that you and I have experienced that here on SSS just in the past several days in a couple of threads!!

[Anderton]

Some people believe that the small hairs on your body react to frequencies higher than 20kHz, transmit the vibrations to your skin, and there's a sensation although not an audible one. Who knows? I don't.

 

All I know is that a system that goes up to 20kHz sounds fine to me

 

But I've been doing a lot of mastering lately, and one band sent in files some of which were recorded at 96kHz and some at 44.1kHz. I do think the 96kHz ones sounded better, but not because they reproduced higher frequencies - my assumption is that something about the 96kHz recording caused the audible frequencies to reproduce better. This wouldn't surprise me given my experience with amp sims, which sound night-and-day better when run at 96kHz than 44.1kHz. I'm not talking subtle improvement, but something even the tin-eared would perceive.