A story was doing the rounds some time ago about a new “adult-proof” ringtone that was at a pitch only children and teenagers could hear.
Simply put, the human ear has a standard range of hearing from birth which slowly deminishes as we get older; research in the UK showed that by the time people reached their 20’s they generally couldn’t hear a frequency of 17 kHz or more.
The scientific finding was hijacked and the ‘Teen Buzz’ ringtone was created (which according to the Wikipedia is at 14.4 kHz); the point of the ringtone is to allow students in a classroom to be alerted to incoming text messages without being caught by teachers.
This website has a useful list of mp3 links set at different frequencies (scroll down), from 10 kHz to 25 kHz; I’m aged 21 and I can hear as far as 17 kHz; anything above that is completely without sound for me. I recommend people check out the site and see what age their ears are; be warned that the sounds are very annoying however.
So, as a variant to the question posed by the superb Nintendo Brain Training game; how old are your ears?