24 bit in and around, 16 bit out?

[ofajen]

Something missing when we discuss sound is how humans detect it beyond hearing. We all know the 20 - 20 kHz hearing range (hopefully), but I don't see much analysis about our sense of feel in the perception of music. We know of course that we feel infrasonic sound, though the ear cannot “hear” it. These bass frequencies rattle our bones, so to speak. What's the impact, if any, of ultrasonic frequencies on our bones I wonder?

I don’t have any idea myself. I’ve always been agnostic when it comes to frequencies above human hearing. That’s not the reason I go with higher resolution and higher sampling rates… or analog. Everything we discuss concerns audibility. What about feelability of these high frequencies?

Any thoughts?

~Tim

Tim:

Like you, I don't feel I know for sure. I would suspect the answer is: those high frequencies don't have any physiological effect on the rest of our bodies.

I surmise this for two reasons: one, there is far less energy present in that spectrum, like orders of magnitude less energy. Second, the wavelengths are such that any affects would be superficial (purely on the surface) rather than invasive (penetrating through the entire body). Thus, if you were wearing clothes, they would surely absorb much of what little energy there is in that spectrum. I will make no suggestions concerning experiments in listening where the amount of skin coverage is varied!

Also bear in mind, as I pointed out earlier in this thread, that our perception of localization at high frequencies is gained not through relative phase information, but merely through volume differences caused by the shadowing effects of the head, so it seems unlikely that the presence or absence of small amounts of energy above our actual hearing range would meaningfully alter the perception of sound locality.

Cheers,

Otto

 

[SouthSIDE Glen]

What's the impact, if any, of ultrasonic frequencies on our bones I wonder?
...
Everything we discuss concerns audibility. What about feelability of these high frequencies?

I've never heard a dog whistle that didn't automatically make me wince and cringe. And the frequencies leading up to that (say, in the >15k range) tend to be pleasant only in very low doses (e.g. a little "air" or "edge").

As far as the true ultrasonic stuff, I had a battery of medical tests run on me last winter, including an ultrasonic cardiogram. This uses the same kind of machine like the ultrasounds they do for pregnant women checking out the bun in the oven, except this one checks out your heart volume and valve function. Lots of rib cage up there, and I felt nothing in my bones or any of my organs (other than a slight little twinge in one organ when I saw the cute little Asian nurse who was going to administer the test; but that was purely a visible frequency thing )

I have also spent many nights either in back yards or at campsites with plenty of bats flitting around taking care of the bugs for us, and have never felt their sonar chirping in my bones or in any other part of my body.

But I'd also point out that "ultrasonic" is a very loose term, and can represent frequencies anywhere from 20 kilohertz to 20 megahertz. This is the same order of magnitude as the difference between 20 and 20kHz. Kind of hard to make a single blanket statement about either frequency range, except to say that one is audible and the other is not.

G.

 

[Ethan Winer]

We know of course that we feel infrasonic sound, though the ear cannot “hear” it.

Right.

What's the impact, if any, of ultrasonic frequencies on our bones I wonder?

I assume none. We don't hear it because our ear drums can't vibrate that fast. And we don't feel it as we do with very low frequencies because, again, our bodies can't vibrate that fast. There was one semi-famous study published in the AES Journal that claimed to show some people perceiving ultrasonic frequencies. That was a long time ago, and nobody was ever able to duplicate their results in subsequent tests. So most researchers have concluded the original test was flawed and ultrasonics are not perceived.

The real issue for me is, even if it's possible for some people to just barely perceive the presence of ultrasonic energy, who cares? What relevance does it have for recording engineers?

I think some people want it to be true, so they can justify the need for high sample rates.

--Ethan

 

[Waltz Mastering]

OP: 10 bucks says no one can pick out the song that was recorded at 96k from the nine others tracked at 44.1k

First response: I'm gonna say "Who You Know"...

OP: Hmmm, you are good. Correct.

Let me pick your brain.

1) Is it that noticeable? Will the consumer hear a difference?
2) What was it that gave it away?

Remind me to record everything at the higher resolution from now on.

Send me a paypal link and I will forward you a 10 spot.


First Response:
Well here's what I did. I listened to about 30 seconds of each track...starting at #1. The 2nd one, I noticed...there was SOMETHING different. Couldn't put my finger on it but it just came across as different. I think - hmm...maybe it's just how the mastering is designed to flow. Move on to track three...and so...on....and so on...

All the other tracks are very consistient...but there was still something about that 2nd one. So I start over at track one...same as the final track...then I get to 2 again and the difference is there again. I studied it for a while to see what it was. The difference, in the best way I can describe it is this:

ALL the songs were beautifully mixed...the mastering was superb. All the songs had plenty of space, depth, width, bottom, ect. HOWEVER, all the other tracks seemed slightly (and I emphasise SLIGHTLY) more congested and smaller than #2 (again, none of the tracks lacked anything). It just seemed that #2 was a LITTLE bigger...the bottom seemed deeper somehow....thicker...rounder. I tried to convince myself that they all sounded the same - that I was fooling myself into hearing a difference just because you said there was one - so I gave some of the other tracks a quick listen. Nope...the difference is still there.

Now let me say this...I SERIOUSLY doubt the average listener will be able to tell the difference. I would even go so far as to say that MANY "expert" listeners wouldn't hear it either. I don't think recording an entire project at 96khz would be significantly benificial to the project as a whole. It definately won't change weather anyone buys it or not - if they love it at 96khz, they'll love it EQUALLY at 44.1khz.

I'm not saying that you shouldn't do it, but to do so would only please yourself and other highly analyitical listeners, which is not necessarily a bad thing. If your system can handle it and you have enough storage space, I say go for it. But I just can't see your audience going "woah...the sound of THIS one blows the other one away".

As for the 10bucks, I commend you for honoring your word, but I really didn't expect to receive any reward and it's really not necessary. Thanks, anyway and thanks for the opportunity for the listening exercise. I had been waiting for a completely non-biased opportunity to see if I could really hear a difference. Now I see that I definitely can..

 

[noisewreck]

I surmise this for two reasons: one, there is far less energy present in that spectrum, like orders of magnitude less energy. Second, the wavelengths are such that any affects would be superficial (purely on the surface) rather than invasive (penetrating through the entire body).

Not necessarily. Otherwise medical ultrasound imaging wouldn't work. It is also possible to turn these ultrasounds into heat, so you can't categorically say that these higher frequency sounds are of less energy. Now, if you are talking about higher harmonics of sounds in the human hearing range, then I agree. But as someone suggested earlier, bats communicate in the ultrasound range.

 

[Farview]

Not necessarily. Otherwise medical ultrasound imaging wouldn't work.

But ultrasound imaging only works when the thing is in direct contact with the patient. Now we are kind of getting into the definition of sound, but the ultrasound machine does not work when transmitting through the air. The thing is a high speed vibrator. The 'sound' that it makes isn't the mechanism that makes it work. (sound being the air vibration that we would hear if we could hear that high)

 

[SouthSIDE Glen]

And like many of the "ultrasonic" sources we're talking about, there's ultrasound, and there's ULTRAsound. The medical ultrasound machines are usually working at frequencies well above 1 MHz. I'm not sure if I remember this right, but I believe that bat sonar is in the hundreds of kHz range (somewhere around 150-500kHz *if* I remember right...I'll let someone else Bing it if they want ). But it's all *well beyond* the capabilities of even a 192k sample rate.

On the low end of the scale we have dog whistles, which tend to be not all that ultrasonic, usually somewhere in the 17k-23k range. That leaves a huge gap between dog whistles and bat or dolphin sonar about which we hear very little (pun not intended).

We read all about how dogs and cats can hear up to like 40k or 50k or something like that, indicating that if the ear is designed right (with it's low pass filtering set higher than us humans), these near-ultrasonic frequencies that theoretically could be covered by 88.2k or 96k sample rates remain frequencies that have "sonic" characteristics and not necessarily any other sixth sense-ish type of effect on our organs, the only reason they are "ultrasonic" to us is because our ears are tuned to not receive them.

It would be like if we were all walking woofers speculating about what 10kHz must be like. There's nothing mystical about 10k, it's just beyond our range as woofers and therefore impossible for us to properly comprehend as a "sound".

G.

 

[Beck]

Good responses so far.

I should have put the word "Bones" in quotes since I was really thinking how ultra freqs could affect us in any way. I probably also should have put a high limit of say, 100 kHz. I know some synths can produce frequencies approaching 50k. I don't know of anything else... certainly nothing acoustic.

I was reminded of this today after watching police use an “audio cannon” against protesters in NY at the G20 summit. You can hear it, but I’m wondering if anything above 20k is employed, or if it’s all in audible range. It’s sort of strange to think of music while watching people get attacked by sound. No one dies though, I’m sure.

~Tim

 

[SouthSIDE Glen]

I was reminded of this today after watching police use an “audio cannon” against protesters in NY at the G20 summit. You can hear it, but I’m wondering if anything above 20k is employed, or if it’s all in audible range. It’s sort of strange to think of music while watching people get attacked by sound. No one dies though, I’m sure.

Here's an article talking about the LRAD "sonic canon" used in Pittsburgh. They describe it as emitting a tightly-focused "shrill beep" that, if you listen to it long enough, and too closely, can cause hearing damage. Sounds like most live gigs I've been to .

And click here for the actual company website describing the LRAD. Depending upon which model you get, the thing puts out 145-151dB SPL at 1 meter of an (I love this quote ), "attention-getting and highly irritating deterrent tone for behavior modification."

They mention in the first article that the device can be defeated by wearing proper earphones; I assume they mean headphones. Either way it would seem to mean that, because ear protection can mute it's effects, that it's doing nothing but emitting extremely loud and annoying *audible* sounds, and not anything for any extra physiological effect beyond that.

Interestingly enough, it appears the LRAD can also be used for point-to-point audible *communication* at up to 500 yards.

I have read about other devices that the military has developed that uses (I believe) extremely LOW frequency pulses. One kind was used to physically repel - as in a kind of shock wave - another was designed to actually make the person it was pointed at feel physically ill, but only while it was pointed their way and they were within range. Whether they were the same device with different settings, or different weapons altogether, I'm not sure.

G.

 

[Bob Ross]

And yet another observation about ultrasonics that may help support the contention that they have no discernible effect on our physiology:

The absorption coefficient of air rises with frequency.

At 20kHz the absorption coefficient is twice what it is at 10kHz. At 40kHz it's nearly three times what it is at 20kHz. And at 100kHz it's over twice again what it is at 40kHz.

So in order for these ultrasonic sounds [sic] to even reach our bodies (much less be perceived by them) they'd have to be at an extremely high amplitude and/or eminating from an extremely close source.

Bats won't cut it. Unless we're talking about a 40-ton Giganto-Bat-asaurus that's screaming at you from 2" away.

 

[noisewreck]

Bats won't cut it. Unless we're talking about a 40-ton Giganto-Bat-asaurus that's screaming at you from 2" away.

And by definition, you still can't hear it

 

[Bob Ross]

And by definition, you still can't hear it

Right, that point was conceded a while back. I was just pointing out that for ultrasonics to even to have some discernible non-audiated effect on our physiology, it's unlikely anything occuring in nature would be able to overcome the medium's limitations.

 

[SouthSIDE Glen]

Right, that point was conceded a while back. I was just pointing out that for ultrasonics to even to have some discernible non-audiated effect on our physiology, it's unlikely anything occuring in nature would be able to overcome the medium's limitations.

Which is at least partly why ultrasonic body imaging requires the transducer to be pressed hard against the body to work.

What I love about this thread is how sharply it illustrates just one example of how often when people look for something "beyond today's science" as explanations for something, it's usually born in a completely inadequate understanding of just what "today's science" actually knows. There are so many *known* scientific reasons and so many *truly* scientific studies and experiments behind scientists and engineer's reasons for setting 20khz as the upper limit to human hearing (whether by ear or some other "unknown" mechanism) that one does not need to evoke the paranormal to try and go beyond that.

Of course the standard response is that science is not always right about everything, that we are always learning new stuff. That's absolutely true, of course, but once again, how that argument is used strongly implies a lack of understanding about what science does and does not know. What it does *know* (meaning 100% certainty) it definitely knows with 100% certainty.

Relativity may have surpassed Newtonian mechanics, but relativity had not suddenly make Newton's laws of motion incorrect. they are still exactly as correct as they were when Newton came up with them. They are still exactly what's used in the programming that guides today's interplanetary spacecraft.

And we know the physics of sound and the physiology of the human body well enough to know that a (for example) 33Khz sound at normal levels may be audible to or sensed by some cats and dogs, but has absolutely no significant effect on human beings in any sense (pun intended), and that any new science that comes down the pike will not change that fact.

G.