Shoutbox

Hello. My friend yesterday said that on the news people in shops were using high frequencies to deter people who are younger than 20 (because only people younger than 20 can hear these sounds). I did some research and found a website with diferent frequencies the frequencies are 18-20kHz. Could you listen to these sounds and vote and tell me wether you are over 20 and can her it or can't or if your younger than 20 and can or can't hear it. I have found that you may need to turn up the volume on your speakers.

The site is here:
German origional


The site is in german so if you can't read german please go here for the english:
English Translation

Important note:

This test is useless when you do this on a set of normal computer speakers. You need very special speakers in order to do this test properly (and maybe a couple of different sets to get the whole frequency range).

Normal computer speakers simply can not produce the wide range of frequencies in this test. This has two causes:

1) The speakers simply can't produce the frequency. So if you say you can't hear the sound, it might simply be that there is no sound to begin with.

2) The speaker can't produce the frequency, but is triggered so fast on and off that you hear clicking sounds instead. This clicking sound can be so fast it seems to be a single frequency, but in fact it is not. Therefor what you hear is not the intended frequency, but simply your speakers triggering.

3) The MP3 format is not a good and proper soundformat to do these tests with!!!

Conclussions: such tests are almost impossible todo on a home computer. And totally impossible if you have only a basic standard set of computer speakers.

Making a poll out of this, and thus comparing the result in a way, is totally useless as each individual uses a different kind of speakers (and in almost all cases, not a proper set to do such testings to begin with).

The test on the linked page is useless as it does not give you a right and proper view of the spectrum you can hear.

Cookie, do you thing that an old Amstrad computer might be able to do it?
We have one (8mhz, 4colour monitor, around 648kb of ram), and there is an application named hearing.exe (not the same with the one i posted earlier) that plays various frequencies from the pc speaker and by doing various tests, it displays the average frequency you can hear.
I remember the speaker making (really?) high frequencies that I could just hear (dont remember the frequency range).
Do you think that these old speakers could produce high frequencies? (lets not forget that the old computers could only make music from the speaker, so they might needed some more frequency ranges)
Also, I don't remember hearing any clicking sounds...

I might try and fetch that application, but the problem is, that that computer supports only 5" ( not sure about the size, but you know, they are the "big" ones ), so I dont know where I could find that type of drive nowdays...

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Originally posted by Mike
that computer supports only 5" ( not sure about the size, but you know, they are the "big" ones )

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5¼"

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Originally posted by raceprouk

quote:

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Originally posted by Mike
that computer supports only 5" ( not sure about the size, but you know, they are the "big" ones )

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5¼"

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Well, I was close...

I found that i can here when computer monitors and TV are turned on or off by a particular frequency they put out.  I also remember my brother playing some game on the PS2 and they had the choice of 50Hz or 60Hz for the graphics and i could hear a difference in the pitch of the TV when he was testing between the two (the 60Hz was a higher pitch and also louder i think), funny thing is that he is younger and couldnt hear it so I dont think it relates directly to age, it depends more on how much loud noise a person has heard in there life and the damage that as been caused to their hearing.

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Originally posted by Mike
Cookie, do you thing that an old Amstrad computer might be able to do it?

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No...

To do such tests, you must have specialized speakers able to produce very low and very high frequencies. Such speakers are expensive and can only be found in the top range of audio equipment.

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Originally posted by Mike
I remember the speaker making (really?) high frequencies that I could just hear (dont remember the frequency range). Do you think that these old speakers could produce high frequencies? (lets not forget that the old computers could only make music from the speaker, so they might needed some more frequency ranges)

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In general a speaker can often produce a somewhat "high" frequency, but for the low frequencies you need a different speaker. In general, the smaller the speaker (in dimensions) the worse it is to produce low frequencies. To produce a good low frequency you need a relative large speaker cone and a very big air volume to move (aka: big air chamber).

As for old speakers compared to new ones. It is the newer ones which can produce, again in general, lower frequencies than the old PC speakers. But this lower frequency is almost always produced by electronical alteration of the signal (eg: "Bass Boost"), in other words, although the frequency range is lower, the signal isn't a pure frequency anymore, but an altered signal again a reason why such tests aren't accurate on such speakers).

The bigger and more expensive the speakers are, the better result such tests will produce. Though it will still be inaccurate though.

quote:

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Originally posted by Mike
Also, I don't remember hearing any clicking sounds...

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The "clicking" is mostly heared at the beginning or end of a sound. If you do hear clicking, the speaker can't decently cope with the signal and you reached (almost) the end of the range the speaker can produce.

However, this clicking can also happen during the played frequency and can be so fast that it appears to be a pure signal. But in fact it is the on and off clicking you hear from the speaker instead of the frequency itself. (eg: this happened while I played that "new" high-freq ringtone with my speakers. I indeed could "hear" the high frequency, but in fact what I heared was the extremely rapid clicking of my speakers (I know it was the clicking because the thing I heared was too low in frequency to be that high frequency they talk about; and frankly I thinnk many people will report that they hear it, while in fact they hear the clicking and not the pure frequency).

Also the fact that MP3's are used for this test, is not good. MP3's are (like JPGs) compressed. It is exactly the fact that certain frequencies and amplitudes etc can be replaced by others that you can compress MP3's. In other words, an MP3 is the worst audio format you could use for something like this.

If you are interested in all this, such home-made tests are fun to do, and interesting. But they do not produce accurate results and it extremely highly depends on the equipment used.

If you're very serious about testing the range you can hear, I'd suggest to contact your doctor, an ear specialist, or an medical institute where they have the correct equipment for this study.

i tested.. i can hear 18kHz but 19 & 20 i cant 

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Originally posted by hardc0re
i tested.. i can hear 18kHz but 19 & 20 i cant 

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To statr with, make sure your speaker set can actually play up to 20KHz frequencies. The only way to determine this is to look up the specs of your speakers (or to measure the sound played by it, but I recon you don't have a calibrated frequency analyzer at hand)...

Some speakers simply will not play anything of a certain high frequency. So you might think you can't hear the frequency, while in fact the speaker isn't producing any sound at all...

Well it's still pretty cool. If you want to piss of some one just play the 10kHz one, even if you have bad speakers, it still hurts.