Poll: Can you hear sound over 20kHz?
Jan 3, 2013 at 7:58 AM Post #376 of 551
Anywhere to test this? I can give it a whirl. Its generally easier for me to hear even lower in comparison to the very very high frequencies.
 
Jan 3, 2013 at 9:49 AM Post #377 of 551
When testing the audibility of very low frequencies, it is important to keep the THD of the transducer low enough that the harmonics do not become audible. Dynamic speakers and headphones often have high distortion when playing a low frequency tone at a high level, so it is best to keep the volume reasonably low, and use headphones that have good bass extension and not too high (especially high order) THD.
 
Jan 3, 2013 at 5:22 PM Post #379 of 551
Quote:
Yes I can.
 
And I cant hear lower than 10 hz as my headphones hit the limit (I have to put them really high volume to come near)

 
Read again:
Quote:
When testing the audibility of very low frequencies, it is important to keep the THD of the transducer low enough that the harmonics do not become audible. Dynamic speakers and headphones often have high distortion when playing a low frequency tone at a high level, so it is best to keep the volume reasonably low, and use headphones that have good bass extension and not too high (especially high order) THD.

 
Jan 3, 2013 at 7:33 PM Post #380 of 551
I'm extremely sensitive to 12-20Hz...can hear it pretty easily. I'm thinking many people can hear lower than 20 and they just don't know what it sounds like when exposed to it.

One more thing.
If there are people who can hear higher than 20kHz. How about 10Hz?
 
Jan 3, 2013 at 7:36 PM Post #381 of 551
Agree

That stinks.  I would be hesitant to trust the test if your sound card isn't properly emitting the tones.  You really need everything to be fully capable of the frequencies to know if you can in fact hear them.  Otherwise, you might be able to and not even know it. :p
 
Jan 3, 2013 at 10:19 PM Post #382 of 551
Keep in mind with any of these tests, you may be able to "hear" a frequency, but you should keep the volume at the reference level, and that shows your "equal loudness" curve.  Basically, assuming all of your equipment can reproduce everything accurately, which is really important, keeping the volume at reference will show how "well" you hear each frequency.  You might be able to hear 20khz at four times the volume, but when it is playing back from a song that means it will be four times quieter than the other frequencies and you may not really "hear" it.  Just a thought...
 
Jan 4, 2013 at 12:34 PM Post #383 of 551
Quote:
You might be able to hear 20khz at four times the volume, but when it is playing back from a song that means it will be four times quieter than the other frequencies and you may not really "hear" it.  Just a thought...

 
This exactly. This is why at Audiocheck, they added white noise to the blind test; makes it MUCH harder to hear the high frequencies when there's a full range of other frequencies in there. 
 
Jan 9, 2013 at 12:37 AM Post #384 of 551
I was a high school physics teacher for a while, and I would do this test with HP 203A oscillators, amps, and lab transducers - bear in mind that I did this with hundreds of students:
 
1.  HP203A set to 25kHz - I can't hear this at all - in fact, nobody can.  Have a mic and a scope to prove we are putting out sound, and confirm sufficient amplitude around the room.  There will be variations, there will be nodes.
 
2.  Before school starts, increase the volume level and begin decreasing frequency to the point where all female faculty on the hall begin to scream - this will be around 19kHz, usually minus a bit. The male students and faculty will be unable to hear it. These waves are highly directional, so bear that in mind.  Expect weird directional anomalies.
 
3.  Bring frequency down another 1  kHz, and up the volume a bit more - male students will now be impacted, and female faculty are now ready to kill you.  Lower the frequency a bit more until I can hear it, then raise the frequency just above my ability to hear (15kHz).  One in a hundred male faculty may detect a bit of sound, but all students will hear it now.  Crank up the volume, apologize to your colleagues, convince them that it is in the name of science and will be over soon - but please don't blow my cover.  Oh, also don't melt the transducer.
 
4.  Leave this on while class comes in - I can't hear anything - and watch the reactions.  It is quite amazing.  What do you mean there is a sound?  I can't hear it!  Works great until word gets around about Mr. C's class - by third period the whole school knows, and your room will be mobbed by the curious.
 
Once you admit to the sound, lower frequency to 10kHz or so - have all the kids raise hands, then slowly raise the frequency. Have them drop hands when they can no longer hear the sound.   The first hand (male) will drop at about 18 to 18.5kHz.  At a bit below 19 kHz, plus or minus, all male hands are gone, and about half the female hands are down, every time (hundreds of kids).  One female student per class can usually detect to right about 20kHz.  One student once swore that she could go to nearly 21kHz - tried a few times with as blind a test as I could manage, and it seemed to be true.  Remember that this was hundreds of kids, over years, and real lab equipment.  Nobody ever detected the sound above 21kHz except for that one. Show the kids the scope output so they can see the sound detected by the mic to prove it.  Boy, do they ever try to hear it.  Always the same, with small variations.  The class always feels bad for me when I say I still can't hear it.  Let the kids do it themselves - they love analog dials because old equipment is not part of life anymore so it's new.  Every kid - nerds, jocks, stoners, artists - loves test equipment.  They can play with scopes, mics, and oscillators for days.
 
There were issues with the test - who knows how many nodes were present in the room due to reflections, and it was unscientific in many respects.  The kids loved it, the female faculty hated it.  Even in the teens, there is a difference between male and female hearing - try it yourself next time you have a party.  With faculty age subjects, the difference is huge, spanning several kHz.  Loads of fun.  The internet auction sites have all the equipment you need, just make sure you have very good equipment or you'll be wasting your time.  I would not use sound cards - get an actual audio oscillator that is good to 60kHz or more.  The 203A is nice due to the variable phase output - you can do some way cool stuff with that.
 
Teaching sound is fun - put salt on a vibrating plate and watch the nodes - faces just light up.  I would use sugar on my Chladni plates beacuse the sound was just that much sweeter, and it made a good, but very old joke.
 
To make this scientific, you would need calibrated headphones, probably a booth, a much better way to read the frequency than the HP dials of yore, and a bunch of time to test and validate the experiment.
 
Jan 9, 2013 at 1:52 AM Post #385 of 551
Quote:
I was a high school physics teacher for a while, and I would do this test with HP 203A oscillators, amps, and lab transducers - bear in mind that I did this with hundreds of students:
 
1.  HP203A set to 25kHz - I can't hear this at all - in fact, nobody can.  Have a mic and a scope to prove we are putting out sound, and confirm sufficient amplitude around the room.  There will be variations, there will be nodes.
 
2.  Before school starts, increase the volume level and begin decreasing frequency to the point where all female faculty on the hall begin to scream - this will be around 19kHz, usually minus a bit. The male students and faculty will be unable to hear it. These waves are highly directional, so bear that in mind.  Expect wierd directional anomalies.
 
3.  Bring frequency down another 1  kHz, and up the volume a bit more - male students will now be impacted, and female faculty are now ready to kill you.  Lower the frequency a bit more until I can hear it, then raise the frequency just above my ability to hear (15kHz).  One in a hundred male faculty may detect a bit of sound, but all students will hear it now.  Crank up the volume, apologize to your colleagues, convince them that it is in the name of science and will be over soon - but please don't blow my cover.  Oh, also don't melt the transducer.
 
4.  Leave this on while class comes in - I can't hear anything - and watch the reactions.  It is quite amazing.  What do you mean there is a sound?  I can't hear it!  Works great until word gets around about Mr. C's class - by third period the whole school knows, and your room will be mobbed by the curious.
 
Once you admit to the sound, lower frequency to 10kHz or so - have all the kids raise hands, then slowly raise the frequency. Have them drop hands when they can no longer hear the sound.   The first hand (male) will drop at about 18 to 18.5kHz.  At a bit below 19 kHz, plus or minus, all male hands are gone, and about half the female hands are down, every time (hundreds of kids).  One female student per class can usually detect to right about 20kHz.  One student once swore that she could go to nearly 21kHz - tried a few times with as blind a test as I could manage, and it seemed to be true.  Remember that this was hundreds of kids, over years, and real lab equipment.  Nobody ever detected the sound above 21kHz except for that one. Show the kids the scope output so they can see the sound detected by the mic to prove it.  Boy, do they ever try to hear it.  Always the same, with small variations.  The class always feels bad for me when I say I still can't hear it.  Let the kids do it themselves - they love analog dials because old equipment is not part of life anymore so it's new.  Every kid - nerds, jocks, stoners, artists - loves test equipment.  They can play with scopes, mics, and oscillators for days.
 
There were issues with the test - who knows how many nodes were present in the room due to reflections, and it was unscientific in many respects.  The kids loved it, the female faculty hated it.  Even in the teens, there is a difference between male and female hearing - try it yourself next time you have a party.  With faculty age subjects, the difference is huge, spanning several kHz.  Loads of fun.  The internet auction sites have all the equipment you need, just make sure you have very good equipment or you'll be wasting your time.  I would not use sound cards - get an actual audio oscillator that is good to 60kHz or more.  The 203A is nice due to the variable phase output - you can do some way cool stuff with that.
 
Teaching sound is fun - put salt on a vibrating plate and watch the nodes - faces just light up.  I would use sugar on my Chladni plates beacuse the sound was just that much sweeter, and it made a good, but very old joke.
 
To make this scientific, you would need calibrated headphones, probably a booth, a much better way to read the frequency than the HP dials of yore, and a bunch of time to test and validate the experiment.

 
I would agree that those stats sound reasonable.  I don't want to sound boastful, but my audiologist this year said I had the best hearing he had tested.  And I'm 30.  All of my friends and family know me as the guy who can hear everything. haha.  I once heard the mail truck coming from the end of a long road in a wooded area.  I said "here comes the mail guy".  Everyone said "what do you mean?" I said that the truck is at the end of the road. They all stopped dead and listened carefully.  It took them almost 30 seconds before they heard any sign of the truck, but sure enough it came. haha.  It was pretty funny.  That is when I got my official reputation in the family. lol.
 
However, one thing that is interesting is that I have trained my ear, and I believe that some people might be able to hear more than they think, including the higher frequencies (if they haven't technically lost any hearing) if they were trained to listen a certain way.  What I mean is that as a kid I used to listen to songs and replay parts over and over until I could pick out every not on the piano and play it back.  That is essentially how i became a pianist.  Then I did it with the guitar, and then even more instruments later on when I would try to record famous songs exactly the same.  I have done it so much that I have developed the ability to pick out very minute sounds distinctly from other sounds.  It is sort of a focus thing.  So in tests like these, while no one may have heard the sound, they were probably hearing other sounds that were louder and had their attention, and they didn't "focus" on the high frequency sounds.  Even if they "tried" to hear it, they didn't have a certain targeting ability needed. Granted many probably had technical hearing loss anyhow, but some probably could have heard more if they were able to listen a certain way.
 
My audiologist said I could detect .5db changes and that I didn't miss a single test to the lowest tone.  I think this was possible because I was listening a certain way for the sound.  It may sound odd, but it's the same way you can pick out a conversation even when you're in a crowd.  I simply practiced more variation of that sort of listening throughout my life.  Anyway, my point is that i can probably hear to roughly 21khz because i have zero hearing loss and i have a trained ear.  I think most people either have hearing loss or simply don't know what to listen for or how and are distracted by prominent sounds, even when doing a quiet test believe it or not.  Breathing, heartbeat, etc. can all affect their hearing, and sometimes a tone might be lower than their ambient sounds.  And when you are targeting a certain frequency in your mind in just the right way, it helps block out other sounds.  For instance, for my audiologist test I literally had a hard time hearing the quietest sounds because my heart was so loud when I was focusing.  So, I "targeted" the higher frequencies, because we do know what high frequencies sound like right?  And that helped me ignore my heart sound.  Just some thoughts. :)
 
I don't believe you can learn this in a day and test it.  I really have developed my "ear" over the last 25 years.  I also mix and produce music, so that continues today.  Anyhow, as a test, when you're at work, sit and really try as hard as you can to focus on one individual thing and then skip to every different thing you hear and see how many unique sounds you can count.  I bet you'd be surprised at how much you hear, when really you don't normally "hear" anything but the typical humbug and talking.  Do this often enough and you'd be surprised again how much you grow in the ability to hear more things.
 
I'm curious if anyone else hear has any similar hearing history?  Any musicians perhaps?  I would guess as tested, 1 out of a lot of people can hear past even 18khz.  I commonly hear annoying sounds.  Buzzing, squeals, hums and such that others my age don't.  It's kind of fascinating.  Ironically, I lack stereo vision due to an amblyopia in my left eye.  So everyone else is probably seeing better 3d life than I am.  I have 20/20 vision, but no true depth perception like most.  I couldn't catch a baseball as a kid.  I've adapted to it so no one would probably even know, but I always wonder what it would be like to see true 3d life, or even just a 3d movie. haha.  Perhaps that heightened my hearing as a kid in some way too.  I bet some people's hearing is like my vision.  I can't even imaging not hearing above 18khz.  When I listen to certain things in nature I can't imagine what it would sound like without that hearing.  From my music mixing I know how high frequency cutoff affects my hearing, but in real life it would be like a veil or a muffle on the world.  Again, like my vision.  It's so interesting to think of these things.
 
O.k. it is 1:51 so I am probably rambling and boring everyone and not making sense.  I'm going to bed now.  I hope this wasn't too long or obnoxious. haha.  goodnight!
 
Jan 10, 2013 at 2:11 AM Post #386 of 551
Fascinating anecdotes both; thank you both for sharing :)
 
Jan 10, 2013 at 7:55 AM Post #387 of 551
my hearing drops off fast after 17. Im 35.

If I crank it up i can hear 19. I now know my very slight tinnitus sits somewhere around 17.5 to 18.5 :frowning2:


Many automatic sliding doors seem to have a very high pitched sound to them. Don't know what this is, but I hear this and it hurts my head. Its very noticeable. Anyone else hear this?
 

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