Ever heard of the Mosquito Ringtone? Its a ring tone only children and young adults can hear. As people grow older, their ability to hear higher pitched sounds diminish. How these ring tones work is by creating a steady, high pich noise which only younger folks can hear. Its great at schoo and so on when you don't want to tip off the teacher, parents or anyone else that you have a phone call or text message and such. At any rate, I found a website that offer these ring tones as a free download for various age groups. 8khz Everyone 10khz 60 & Younger 12khz 50 & Younger 14khz 49 & Younger 15khz 39 & Younger 16khz 30 & Younger 17khz 24 & Younger 17.4khz 24 & Younger 18khz 24 & Younger 19khz 24 & Younger 20khz 18 & Younger 21khz 18 & Younger 22khz 18 & Younger Now the point of this topic is to listen to these sound files and see what the highest pitch (khz) you can hear and post the results here. You may need decent speakers/headphones to be able to play such high pitch noises. Heres the site: http://www.freemosquitoringtones.org/ The sound files come in OGG, MP3 and WAV files.