So, either my sound card is broken, or...
You are a dog
Or maybe you are a mosquito, you certainly can't be human.
The highest pitched ultrasonic mosquito ringtone that I can hear is 21.1kHzFind out which ringtones you can hear!
(Probably a soundcard issue - on leapylees's computer, I can only hear up to about 16ish kHz... but, of course, it's hard to know if this is due to her speakers not reproducing sound well at higher frequencies, or my soundcard downsampling tones for some reason...)