test your hearing here
http://www.jimmyr.com/blog/hearingloss.html

"For most adults, hearing loss progressively clips off the higher frequencies starting at 18kHz-20kHz after the age of 19."

I could hear the 17Khz fine, 18kHz weakly, but I couldn't really hear the 19Khz one at all. Could be my cans and soundcard, but I doubt it. Guess it's about time for geritol, pants up to my chest and an oxygen tank.