Sound quiz

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 21.1kHz

Take the mosquito ringtones hearing test

Is it cheating that I happen to be using headphones? >_> For the 19.9kHz one, I definitely heard the high tone mixed with the lower pitched undertone, and I'm fairly certain I heard it for the 21.1kHz as well. Beware if you take this test, however, because the 22.4kHz one is apparently just an intentionally empty file.

From here, I'm pretty sure I heard the high tone in the 22000 Hz one mixed with the undertone, and I think that I was able to hear the 23000 Hz high tone amidst the undertone, but I'm not sure. For 24000 Hz I strangely heard nothing at all, not even an undertone, and for 25000 Hz I heard only the undertone. All of those seem to be legitimate sound files anyway, at least according to GoldWave.