http://blahblahblahblog.quickdfw.com/archives/2008/04/-associated-press-in-thursdays.html
But here's the interesting part, they do it by sound. I didn't realize even in young people there are different levels of hearing.
Click on the link following and look for Free Ringtones. You can listen them, and see where your hearing level is. I would say this is unofficial until you go to an audiologist. http://www.teenbuzz.org/ I can hear from 8-14kHz; too many rock concerts in my past.
