I know this is old news to many people, but I just saw this article about ring tones that only kids can hear on another blog and decided to listen to the ring tone. The interesting thing about the article is there are two mp3 files: one is the actual ring tone and the other is a sound file at the same frequency.
I would like to think my hearing is quite good as I sing and play the piano and guitar as well. When I was working on embedded systems, I could hear when power was applied to many of the components simply by listening to the sound they made. Also, my old Dell laptop power supply used to make a nasty noise before it had to be replaced due to exposed wires!
The two sound files are quite different and I found the second mp3 that used the same frequency to be highly annoying but not quite as bad as fingers scratching a chalk board. The ring tone is much different and uses an oscillating tone that peaks at the same frequency as the other sound file. The volume level is much lower though and I had to turn up the volume on my speakers as I usually keep it quite low. The bottom line is that I can hear the mosquito sound but it has a low