supposed hearing limit of 20khz is b.s., just saying

[Speakeasy]

you can proof it if you can record that 25kHz sound..
and then lowcut anything below 20kHz ... so then we dont have any lower harmonics on that sound present!

then people can try to listen it anywhere they are....

[Doug1978]

Hey guys, I just ran a 4 minute mile. Prove me wrong.

You have already accepted that you are wrong, having written about it in that last sentence.

[UltraJv]

I guess we are done here then. To sum up - some people can hear above 20khz, most cant. At the other end of the scale - some can hear the TAOS hum, some cant. Some people can see higher than visible spectrum, some cant. Nothing to see here

http://en.wikipedia.org/wiki/The_Hum

[JJBiener]

I have just created the first true perpetual motion machine. It has been running for 10 minutes with no signs of slowing. Of course at some point, the hamster might get tired, but I think I have proved my point.

[Bhan]

I used to work with Ultrasound transducers too. We did occasionally operate as low as 25Khz. You can get listenable audio from a 25Knz transducer.... and certainly the majority of it's power output will be at 25 khz. But it no where near pure and you can hear and see lots of different artifacts from a transducer. It doesn't mean you are hearing 25 khz tones though. Radial modes depending on the physical characteristics can operate all over the place and there are lots of harmonics generated with any transducer.

[rifftrax]

http://www.amazon.com/Master-Handbook-A ... 0071360972

This book covers a few basics on the human ear and our hearing mechanism. I suggest you read it to learn the basics before making biased hypotheses on how the world works. Static tones are always louder and more easily perceived. And the Equal Loudness contour is based on the perception of static tones. These days, engineers use noise because the material is multi-octave. The point is that we only receive so many frequencies for a given power level, and the static tone is king. It will be heard, but is not relevant to music. Try analyzing noise centered around 25.1 khz and measure the power, as this would be far more interesting.

Again, I'm not talking about music. I'm talking about sound. If all you're testing is hearing capability... all you need to use are sine tones. I don't see what is so hard about this.

Also, I've had that book for a very long time. I've read it a number of times.

Most of them don't speak in terms of limits but the expected passband.

I have no idea what you mean by that... passband? The ear has a specific passband? I don't think the ear operates like a typical filter. Pretty sure it doesn't at all actually.

rifftrax, you have the test equipment. Why not do some experiments at a safe SPL and tell us how noise at these frequencies is perceived? For equal power from noise through to static tone, the perception should vary considerably.

Again, why would I be testing broadband noise? That's inherently non-targeted to finding specifics that I'm interested in. I'm going to test just sine tones. Today was extremely busy or else I would have gotten some meaningful measurement and tests done. The other issue is sneaking out the spectrograms/waveform views/level measurements/etc. (all email and computers are monitored of course). Technically everything is proprietary so it's kind of tough but next week I can probably work something out.

I used to work with Ultrasound transducers too. We did occasionally operate as low as 25Khz. You can get listenable audio from a 25Knz transducer.... and certainly the majority of it's power output will be at 25 khz. But it no where near pure and you can hear and see lots of different artifacts from a transducer. It doesn't mean you are hearing 25 khz tones though. Radial modes depending on the physical characteristics can operate all over the place and there are lots of harmonics generated with any transducer.

Nope, I checked the waveform output at the single sample scale, it's definitely a undistorted sine wave with only the slightest harmonic at twice the frequency (easily -80db down in power). So... not applicable here.

I guess we are done here then. To sum up - some people can hear above 20khz, most cant.

Every single person in my office can hear the 116db 25khz tone to varying degrees. That would be 9 people with an average age of around 35 (I literally went from person to person and double-checked just today). Not a single person can't hear the 25khz tone. So, you're kinda wrong but maybe everyone in my office just has super-human hearing... but I'm kinda betting not.

@rifftraxs

I don't think many people here doubt that our hearing range probably varies quite a lot and that some people more likely than not can hear above 20khz. It has also been pointed out that science has never put a 20khz absolute limit on human hearing.

See my findings above. Also I'm not saying that "science" has put an absolute threshold on human hearing (well except for the f**king graph I pasted in my first post which it appears every single person has ignored, so I guess I won't even bother to count that) ... I understand that, but when you specify that "human hearing ranges from x to z" and then say that over and over and over in so many ways then a lot of people take that to mean "oh! that's totally a limit!". GOD I cannot tell you how many of those people I have met. Many of them are on this board. Wouldn't you know? lol

You guys COULD believe that our hearing rolls off similarily as a lowpass filter at those frequencies? I think so, as the cilia are only a certain size (as a group) and therefore will only transfer so much power to the nerves at higher frequencies. Boosting the volume in this range is similar to boosting an EQ where your ears are damaged and cannot hear as well. The wrong idea is to try transferring power to where the receiver is inefficient, because it will also vibrate other cilia in the vicinity and 'hog' their excursion. As a static tone, the ear WILL transfer this signal because there is a range they can move. But a complex multi-octave signal will eventually rise in volume and transfer enough power to not make a difference. Anything after this point is the sensation of actual movement of the ear's surrounding structures, and unfortunately too high to be enjoyed as it will damage the inner ear.

As far as ultrasonics are concerned, think about the actual wattage of the force of vibration. It is only so high because of this inefficiency of the cilia at this frequency. Hence the lowpass filtering mechanism of our hearing. Getting rid of ineffective frequencies will guarantee more range for the ear, and boosting into the cold will only serve to limit the dynamic range.

Wow, there are some serious inaccuracies here about what you're positing concerning how the ear works. I mean, dang.

Hey man don't bother. You'll be ridiculed here whenever you try to shake old dogmas and viewpoints. Nothing new for KVR.

I wanted to point out that i am in no way skilled to make graphs or whatever but from my experience with everything i am very convinced and sure that people i mean majority can hear over 20khz. I think it is sort of training of your perception (going in to moot zone). I believe all people sense more then what they think they do. Be it visually or via hearing.

Good luck with burning that witch anyway

Right? F**k, you'd think I told people their mom was a whore or something. I'm trying to share what I've found here and people act like I told them Santa Claus wasn't real. You people are unbelievable sometimes. It's not like KVR has to be a god-damn vampire acting as if I just buried a sharpened garlic clove with silver extract into it's heart. Honestly.

[Tony Ostinato]

i'd wait for some peer reviewing by known qualified people before claiming victory.

you know, like real scientists do.


smarter people than you have been wrong, being wrong is always a possibility and often the more someone is sure they're right is the more indication that they missed something.

now if you do all that and come out right after all you'll get a "good job" from me, but ill say it as high as i can.


or maybe get someone to do it for me, anyone know what leo sayer is doin now?

[Meffy]

Right? F**k, you'd think I told people their mom was a whore or something. I'm trying to share what I've found here and people act like I told them Santa Claus wasn't real. You people are unbelievable sometimes. It's not like KVR has to be a god-damn vampire acting as if I just buried a sharpened garlic clove with silver extract into it's heart. Honestly.

"If you think you can prove this, great -- provide some evidence" is not a witch hunt. Histrionics will only get the thread locked sooner. Do the science and convince people.

[trimph1]

Good Grief.


ANY audiologist I've worked with, and, believe me I've worked with a lot of them, never said that this whole 20 Hz to 20 kHz thing was the TRUTH, in the singular and with a capitol T.

[rifftrax]

"If you think you can prove this, great -- provide some evidence" is not a witch hunt. Histrionics will only get the thread locked sooner. Do the science and convince people.

Hey, fair enough - I'll get as much data as I can to post up here come monday when I'm back at work.

[Meffy]

Excellent. Progress! Excelsior! Testing, measurements, that's where the fulfilling fun is.

[Aleatoriac]

"If you think you can prove this, great -- provide some evidence" is not a witch hunt. Histrionics will only get the thread locked sooner. Do the science and convince people.

Hey, fair enough - I'll get as much data as I can to post up here come monday when I'm back at work.

I believe you.

When I was 26 I bet I could hear up there too. Not now. 13 khz maybe now.

[rifftrax]

Excellent. Progress! Excelsior! Testing, measurements, that's where the fulfilling fun is.

LOL, I already have all the actual data. Question is are people going to believe me when I post the spectrograms and say "you see that line? That's the sound I'm hearing". Still won't technically "prove" anything to a typical naysayer.

[camsr]

rifftrax, All I am trying to say to you is, of course you can hear 25khz at that volume. 116 DB!!! Try that at 1khz and your ears will not like it for very long. Or white noise. The reason the volume is so high, is because there is damping and less mechanical coupling at the cilia. I'm sure you could figure a roll off slope by trying the same thing the guys that made the Equal Loudness Contour did, and use your perception to judge the loudness of different tones. Would it matter in a musical context?

[camsr]

And on harmonics, metallic tweeters generate all kinds of ultrasound via non-linearity. It's not as appearent because it's not boosting, it's natural.