I Can't Hear!

ME: Owen, please sing quietly to yourself.
OWEN: (Whispering) Like this?
ME: Yes, thank you.
OWEN: But I can't hear it.
ME: Yes you can.  I can still hear you, so you can hear yourself.
OWEN: No I can't.  My ears are taking a break, so I can't hear. 

I had no response to that.