lee730
Headphoneus Supremus
- Joined
- Jan 9, 2011
- Posts
- 16,804
- Likes
- 452
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.
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)
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.
One more thing.
If there are people who can hear higher than 20kHz. How about 10Hz?
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.
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...
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 can hear till 22000hz with ease 14
i am using loudspeaker on my Galaxy S2 instead of actual earphones.
impressive !