Thus, I falsify the claim that "there is no physical mechanism that would prevent a human from hearing higher frequencies."
That's all I set out to do.
That's a different question. There are some pretty obvious ways to find people who can hear frequencies above 20 KHz. One is to simply jack up the intensity, and another is to use young people whose ear structures are simply smaller.
I read in sci.electronics.design that William Sommerwerck wrote (in ) about 'Speakers for High Frequency Sound', on Fri, 11 Feb 2005:
Some young children can hear at least up to 40 kHz. I've done the tests.
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I read in sci.electronics.design that George Gleason wrote (in ) about 'Speakers for High Frequency Sound', on Sat, 12 Feb 2005:
The normal audiometry test measures your hearing sensitivity at threshold level. You can see from the Fletcher-Munson (Robinson/Dadson) curves, that the sensitivity of even an unimpaired ear varies with sound pressure as well as frequency.
This means that you can hear LOUD sounds at much higher frequencies that you would expect from your threshold sensitivity curve.
-- Regards, John Woodgate, OOO - Own Opinions Only. The good news is that nothing is compulsory. The bad news is that everything is prohibited. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
-- Yes, but we're talking airborne sound here, aren't we?
I suspect that for the LCD screens what you are hearing are the power supplies for the backlight, and not the screen itself. Many of these have switching frequencies in the approx. 20kHz range, so when you light up the screen, you hear the squeal.
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Several posts have told you the frequency. To confirm that it is the TV generating the sound, turn it off and observe that the sound goes away.
J
You are probably hearing the backlight of the LCD. Some of them can be quite loud. Now that digital watches always use Indiglo backlights, I can hear them, and I actually had to get rid of a caller ID unit that lit up every day at 2am because the phone company reset the line. It kept waking me up.
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What was the name of the most tedious self absorbed, wanker tour ever. George
I knew I would be compared to Sir George Martin some day. :-) george
You can find headphone frequency response graphs for various brands with Google : there are hi-fi equipment reviews on the Net.
For detetecting that high frequency limit, any headphone will work because the ear response drops so sharply at the upper point that the variations in headphone response don't influence the upper point you will detect. You can get some mid-price headphones if you want something nicer, but you will get the same result. Even a cheap loudspeaker will do - recently I put a cheap speaker on my audio generator and compared my upper frequ with my son's - I was 13KHz vs his 18KHz.
If you want to plot your frequency response rather than just find your upper limit, then you need to reduce the generator output at each frequency to find the point where the sound just becomes inaudible. To do that you need a generator with an accurate attenuator or meter, and you plot the output level at each frequency on a graph. A $200 generator won't have this kind of accurate attenuator or output meter, so it will just give you an upper limit. To plot a response graph you will want headphones with a decent response.
Roger
Well i got the looks for it :-) A face meant for a career in radio G
[snip]
Must all perceived airborne sounds pass through the eardrum? I don't believe so. I know that nerve conduction is sometimes explained as physical contact through the skull, but I have always taken that as an example, not as a limitation.
I think we can hear airborne sounds (especially if they are intense) without the eardrum.
-- >>But, what are the limits of the cochlear cilia? Certainly there >>are animals that can hear higher frequencies, and they use >>the same basic equipment as humans do.
It sounds like a defect in his hearing, imagine if someone could see outside one octave of visual information that would also be considered abnormal, and actually possibly harmful to their existence if the sound of the tv whine drowns out normal conversation , you have a problem George
No, you would be falsifying a claim that there is no upper limit. But, that wasn't the statement you were challenging. You were challenging the statement that there is no physical mechanism preventing humans from hearing higher frequencies. These are not equivalent statements.
Congratulations.
It's the same question. Someone said that humans cannot hear above 20 kHz. I said there is no physical mechanism that prevents them from hearing higher frequencies. You were not addressing the same subject as we had been discussing.
So, there are people who can hear above 20 kHz. That is the point I am making.
You are probably corrrect. The sound of my Olympus C-3040 LCD display is not terribly high-pitched, but it is faint.
That is interesting. I have read that a newborn baby can hear the sound of a mosquito on the other side of a closed window. I've also read that ultrasounds on the fetus might harm the unborn child's hearing. But, I do not recall having read that some children can hear 40 kHz.
How likely is it that a TV produces sound at more than one frequency?
Going from memory (because I don't feel like looking it up right now)...
Most humans can see in 3 basic colors. This is because most humans have
3 basic color receptors. However, there are some women (and it must always be a female human who is so affected) can see in 4 basic colors. This is a fairly rare deviation.I saw something just the other day about some people seeing outside the usual spectrum. I didn't take the time to read the articles, though.
I thought they hummed because they did not know the lyrics.
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That would be a drag!
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