My friend who does free diving would kill to be able to do it! She can't learn it.

My mum taught me the ear popping thing, while we were traveling by air, to relieve the ear pressure.

I can do it on command but never paid attention to how before.

It's basically "yawning manually". There's a couple different muscles activating at the same time, most irrelevant to the popping, I can't control them individually yet. (Probably learnable, if I practiced I could probably get the pop more efficiently.)

But yeah, just yawn real wide, that should do it.

A lot of stuff is learnable, like I couldn't move my ears but taught myself how to do it because I was bored.

I'm not a diver but I suspect it can be learned. I have allergy issues that cause my ears to not equalize when allergies are hitting and I think I just learned how to do this. its just sort of muscle that can sort of be lightly controlled. Controlling one side vs the other I can't really manage.