The so-called "Mosquito" device emits high-frequency noise which is audible — and annoying — to young ears, but generally not heard by people over 20.OK, so I've seen stories about these for a while. I would really hope that shop owners don't really buy this idea that only people under 20 can hear them. I'm almost 30 and these things drive me batty. Insta-headache.
I just think it's funny that for more than a year now kids have been using the exact same technique to secretly notify each other on cellphones.
Want to make your own Mosquito tone? Fire up Sound Forge (or any editor with a tone generator), and create a tone over 17KHz. I can hear up to 18KHz in my left ear, so I tend to push even higher. You can test yourself, just keep increasing the frequency until you can't hear it anymore. Then just edit the tone (I prefer a series of quick pulses to help differentiate from random noise), and there you have it. A ringtone guaranteed to give me a migraine!
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