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

[Meffy]

Not that I rate Wikipedia as the font of all knowledge, because obviously any eejit can post any shite they want on it, but often it gives a decent idea of a subject. I suspect the OP is maybe mistaking the idea of"threshold of hearing" with "can't hear". Medically, hearing is tested at set volumes. For an audiologist to say you can't hear above X Hz doesn't actually mean you can't hear anything above X Hz, it means that at a useful volume you can't hear anything useful. Completely different from you saying the medical world says nobody can hear above 20 kHz - because they never said that. I rather think you inferred that of your own volition.

Absolute threshold of hearing
From Wikipedia, the free encyclopedia

The absolute threshold of hearing (ATH) is the minimum sound level of a pure tone that an average ear with normal hearing can hear with no other sound present. The absolute threshold relates to the sound that can just be heard by the organism.[1][2] The absolute threshold is not a discrete point, and is therefore classed as the point at which a response is elicited a specified percentage of the time.[1] This is also known as the auditory threshold.

The threshold of hearing is generally reported as the RMS sound pressure of 20 µPa (micropascals) = 2×10−5 pascal (Pa). It is approximately the quietest sound a young human with undamaged hearing can detect at 1,000 Hz.[3] The threshold of hearing is frequency dependent and it has been shown that the ear's sensitivity is best at frequencies between 1 kHz and 5 kHz.[3]

http://en.wikipedia.org/wiki/Absolute_t ... of_hearing

I think you finally mentioned that 116dB is pretty loud. For 25 kHz it's fuckin loud. So basically, at normal hearing levels in a normal environment probably very very few people can actually hear 25 kHz as the medcial world accept. But not you apparently...you can hear that tone from across the room at normal volume levels can you?

Most of the time I can't hear much above 16 or 17kHz (probably less nowadays). But it's entirely possible if blast your sound thingummy in my earhole that I might feel it as pain or something - possibly even not hear it at all. I suspect if you detonate a grenade inside my earhole I might even hear below 20Hz briefly. No bleedin' use to me though, and I doubt the medical world would call that useful hearing...

Yes, this. Zigactly.

[HTBoogie]

In accordance with the KVR corollary to Internet rule 32, please post links to a sample pack, preferably in kontact or wusik format.

[kritikon]

And the real question is which synth can produce a 25kHz sine wave most musically. Diva or a real analogue?

[whyterabbyt]

And the real question is which synth can produce a 25kHz sine wave most musically. Diva or a real analogue?

needs moar ultrasonic heat shimmer.


and smartarse aliasing.

[Kriminal]

how many ppl have speakers/headphones that can actually play this frequency ?

[Meffy]

Not I. The transducers I work with these days are more often in the low to middle megahertz region. Basically single-frequency devices, nothing you could call a "speaker."

[rockstar_not]

Wow, lot's of negative energy flowing in this thread unnecessarily.

Some of the reason is the attribution of past research as being total crap.

Let's keep some things in mind:

1. Equal loudness contour graphs have been around for some time. Harvey Fletcher did this long ago; much longer ago than microphones and test equipment were able to precisely measure out to such high frequencies.

2. These curves are a generalization, not an absolute. That 20 kHz is considered the upper frequency limit of most person's hearing is also a generalization. That generalization is very well established through decades of research. That said, if you've done the tests properly with mics sensitive well out past 25 kHz, don't see and subharmonics of 25 kHz in the spectra, then I have no doubt that you can hear such a loud sound at 25 kHz. I would caution you as to the safety aspect of running such experiments. You might find that you won't hear that frequency for much longer At a previous place of employment, we used ultrasonic transmitters and receivers to check for leaks in window seals. I never checked the frequency content of the transmitted signal, but I could hear it easily when placed close enough to my ear. It wasn't so much as a pitched sound, as it was an irritation of sorts. I'm also one of the folks that could detect a failed flyback transformer from across a room, causing me to stay out of the room altogether until the CRT was turned off. Most people thought I was just weird, because they couldn't hear it.

3. We can also hear infrasound. The 20 Hz lower frequency 'limit' is also not an absolute. That we talk about it that way isn't total crap either, it's an accepted generalization that has worked well for music production, PA system design, etc. etc. etc. If there's meaningful information that can be conveyed to humans via acoustic transmission below 20 Hz, then there's a market that hasn't been fully exploited yet.

4. Someone back in the thread acquiesced that yes, some can hear that high, but does it really mean anything to humans perception of any acoustic content; whether speech, music, sounds of nature, etc.? I can hear some bats in the summer when they are clicking to find flying insects. Only when they are in relatively close proximity - say within 4-6 meters, but that's probably not really ultrasonic. It conveys no meaning to me, either. Whether or not it's useful to reproduce or create acoustic energy above 20-25 kHz remains to be seen - though since we now have the signal generating capability - again, some entity would certainly exploit this for financial gain in some way.

So, to the OP - I fully believe you can hear that high of an SPL at that high of a frequency. Persons that have a true understanding of audiology and psychoacoustics would not doubt you and if you ever engaged them in conversation about this, they would be right there by your side. However, you have called out those people as propogating a myth. That is not nor has ever been the case. What you have taken from graphs and curves to try to explain a general case, you have taken as an absolute. That is the flaw in your position.

[Meffy]

BTW, if anyone has a spare million lying around, I'd really like to get back to that project so don't feel shy about investing it with us. Audio and video and Web jobs are fun but some substantial cash would be awfully nice about now.

So remember: Got a million dollars you don't need? Contact Meffy today.

[spaceman]

The butler did it.

[rifftrax]

Ok looks like this is the point we are at currently.

Camp One believes I'm full of it and can't actually hear a 25khz tone at 116db (which is not an unrealistic level by the way for stuff like machinery and certain musical instruments to produce so why you all feel that db level @ that frequency is astronomical or whatever is certainly beyond me).

Camp Two is spaceman with brilliant graphs and lots of fun jokes or people who think hearing up to level is "useless anyway" and "why the hell do we care where are the free vsts and shit"

Camp Three are people who actually agree and say "well this has been known for a while" and tend to not care about getting into an internet pissing match for the sake of being "teh coolest internet brosef evar"

This will make it easier to respond to people as I'm not going to defend my findings to every single last person and their smart-ass posts.

Camp One:
Why don't you look at the "accepted" standard graph outlined in my original post for the reference of what I'm 'fighting' against. What you will see is the typically "accepted" (hell, at least by most people I've known and certainly plenty of you guys here also prove it) outline of what the estimated sensitivity of the human ear looks like. Do you see how that graph accounts for db ratings up to 130db? OK then. Thank you for looking.

Camp Two:
I laughed pretty hard at spaceman's graph. Two points. Everyone else can go back to not caring about anything but 20hz to 20khz and writing dubstep music I guess. Maybe I'm not talking about music... I'm talking about "sound". Really novel concept here but stay with me for a second - believe it or not there's an entire field/industry actually dedicated to just "sound" and not "music". It's called (ready?): Acoustical Engineering ("ooh, aaah"). Fascinating right? Glad to help blow your mind.

Camp Three:
Thanks for being as cordial as kvr is capable of being. But at the same time 99% of the producers and audio engineers and audiophiles I have ever known take the 20khz-is-the-limit-of-human-hearing-end-of-story school of thought to the grave. I'm glad you people have a more open mind but remember you don't represent the majority of people (by a long shot).

What I'm thinking is that maybe Camp Three and Camp One get together and you guys can duke it out. Ready set go.

However, you have called out those people as propogating a myth. That is not nor has ever been the case. What you have taken from graphs and curves to try to explain a general case, you have taken as an absolute.

Did you look at the graph?

DID ANYONE LOOK AT THE EFFING GRAPH IN MY FIRST POST?

Dear god. LOOK AT THE GRAPH. Then consider that (as I mentioned) pretty much everyone in my office up to the age of 50 is able to detect a 25khz tone. Crazy? No, that's just what it is. I am not describing a "I am the only person who can hear this tone so the graph is wrong", I am describing a "every person I have EVER had check the ultrasonic transducers we use can hear this so the graph is wrong" kind of scenario. BIG difference.

The graph is totally misleading. How do I make it simpler?

IT'S WRONG. Generally/absolute/whatever I don't care it's TOTALLY MISLEADING.

The "estimated" portion of the curve has no basis in reality. Does that sound better? I can keep rewording this if needs be.

how many ppl have speakers/headphones that can actually play this frequency ?

Probably very few to zero which is another one of my points.

[Meffy]

What I'm thinking is that maybe Camp Three and Camp One get together and you guys can duke it out. Ready set go.

The old "hey, let's you and him fight"? That's not the way to keep a thread unlocked.

Besides, what's to argue? The thread title refers to a "supposed" limit on hearing but no qualified person I know has ever "supposed" that to be the case. If you happen to know people who will insist on believing non-scientific non-facts, your time would be better spent educating them than preaching to the choir, wouldn't it? Or taking that series of measurements that would provide some actual hard evidence to bolster your case better than "I know what I heard, so you must believe it"?

[Kriminal]

i liked spacemans graph

it shows that anyone can make a graph, so it made me feel good inside

i can probably hear 37mHz, but no company is willing to make a speaker that reproduces that sound, that makes me sad inside

[spaceman]

@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.

But some other good points have been raised as well:

1) anything around 20khz sounds pretty annoying already, anything higher is plain irritating
2) what musicality is there to be found in that range?
3) would my graph look better with different colours?

Some questions have been raised about your proof as well.

1) how can you be sure that, what people experience in their ear canal is 25khz? Your measuring devices are not in their ears. With the frequencies and energy involved -i.e. no musical or human interpretable sounds at all- who can tell what they experience?
2) does my graph need more cow bell?

As you can see, a lot of food for thought.

[camsr]

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.

[kmonkey]

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