Can anyone hear more than 20Khz, or less than 20Hz?

Answer 1

The 20hz to 20Khz is just an average range of hearing. The younger you are, the more likely you are to be able to hear beyond those ranges. But it also depends upon your upbrining. If you listened to loud music all the time, went to rock concerts etc, then chances are that your hearing is somewhat diminished from that range.

Once you get below 20hz it isn't so much "hearing" as it is "feeling". You can sense ultra-low frequencies and feel them vibrate you.

I can also hear the silent dog whistles. It is more of an annoyance than something which I would desire to hear.