Most people’s hearing drops off in adulthood, with higher frequencies being the first to go. Apparently shopkeepers in the UK exploited this as a way to ward off rowdy teens. The device they made emits a 17 KHz audio signal, which teens can hear, but most people over thirty cannot.
Teens apparently have caught on to this idea, and turned it against the adults, by creating a ring tone out of it. Teachers and other adult authority figures can’t hear calls or messaging, allowing stealth communication among their peers. Clever.
There is a demo on the site linked. I can still hear it, so I must have young ears. There is a similar issue with detecting the flyback transformers on older NTSC televisions, which is 15 KHz, or thereabouts. Most people lose the ability to hear them at a certain age.
7 thoughts on “Young Hearing”
I have been cursed with dog hearing my whole life. I can barely pass a hearing test in most ranges, but when the frequencies get high I never miss. Trust me on this, old cars will make you nuts when you are the only one that can hear the symptom. :)
What’s it supposed to sound like? I just hear a buzzing/tingling noise. I don’t know if that means it is working.
I hear a pop at the beginning and the end but not really anything in between.
You should hear a very high pitched tone.
Well, I hear a tone with my speakers turned all the way up (on an iBook), but it’s not that annoying. I could probably stand a couple of hours of it. Maybe the store owners had louder speakers.
Alcibiades: If you can only borderline hear, it sounds much softer.
On this page, below the graph, there’s links for several different sounds of varying high pitch. I can hear the first three, with the third being very faint. However, my wife can hear the first four very clearly (and finds them annoying). The third doesn’t particularly bother me because it’s so soft. So I think finding it of minimum volume and not annoying is probably a sign that you’re just on the border of being able to hear that one.
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