Frequency-wise, our hearing ability ranges from 20 Hz up to 20,000 Hz (please refer to our High Frequency Response Hearing Test
to give your hearing ability a test).
As we get older, the 20 kHz upper limit
decreases: this phenomenon is medically
known as presbycusis. Therefore, it is possible
to generate high frequencies that
are audible only to teenagers. Since these high pitched sounds are
uncomfortable to withstand, they can be used - for example -
to repel loitering teenagers in the street.
The test files
|Mosquito Tone 1
|Mosquito Tone 2
A -3dbFS steady sine tone at 17.4 kHz and its modulated version,
oscillating between 17 kHz and 20 kHz, 3 times per second.
If you hear any of these two mosquito sounds, you will then be
repelled by security products like the Mosquito. Lucky you!
This indeed means you either are young or your ears are still
in very good condition!