I searched, and I saw that Travis E. had posted a topic about WILDs, and how he felt when he WILDed, he got that humming, vibrating feeling when he yawned. I don't know if this has been posted before, but screw it:

When I had a problem WILDing the other day, I felt that the WILDs were like a change in pressure in my ear canals, like when I yawned, or when my ears popped ascending/descending a mountain. I've been up for a long time now, so I have been yawning perhaps every 15 seconds or so. My ear canals really started to feel joggled and almost started to hurt... like my WILD experience...

It got me wondering... what is this feeling in the ears that one experiences during these two phenomena? Has pressure changes got to do with sleep? Perhaps the body closes its ears during a WILD so it is easier to sleep. When I yawn, I tend to hear better.
Any thoughts? This might explain the mystery of the yawn.

Also, I tried mastering WILDing at will... all I got was yawning at will. Seriously.