So basicall it is "voluntary control of the Tensor tympani muscle", Ok I'm just gonna bump this one again https://en.wikipedia.org/wiki/Tensor_tympani_muscle
I've been able to do this for as long as I can remeber, since very early chiildhood... every time I asked someone if he can do it too, they looked at me weirdly, like I had voices in my head lol. But I was indeed always fascinated with it. It's something to do with either vibrating eardrum or pressure, I'm not sure, but I sure can hear thunder on command. Even more than 20 seconds, I did noc count I would if it werent for this awful feeling of lightheadedness I get after doing it for longer but then something inside the ears feels tired and the intesity slowly diminishes, but I can do it again right away on command. I've been using it for rhythm, like you're immagining a melody then you do this to add drums or base to your immaginary sound :) How cool.
IM SO GLAD I DECIDED TO LOOK THIS UP. I've been able to do this my whole life (I'm currently 14) although about 4 years ago I found out I have Eustachian tube dysfunction, I am deaf in primarily one ear but slightly in the other and I wear a hearing aid, I've had tubes put in but that procedure failed as the only tubes that would fit in my ears, were to small. This has not effected my ability to make this sort of humming sound in my ears for about 5-10 seconds but thought I'd share! so glad I've finally looked it up :)
I can do something similar but its like a deep humming sound almost exactly like wind is passing your ear and I can do this for 40 seconds
Not sure if this is at all linked, but i noticed that when i stopped consuming aspertame, the urge to compulsively flex this muscle stopped. maybe it's completely unrelated, but it's been a few months now and the urge still hasn't resurfaced. I'll post an update after a few months.
Not the same as "popping" open your eustachian tube. Instead you are just creating the sensation of a rolling thunder sound, not a thunder clap, which might have lead you to think this was ear popping. Ear popping is usually produced by swallowing or chewing. The noise being talked about here is produced by tensing the muscles around your ears, such as pulling your ears back with these muscles. I've been able to do it for as long as I can remember. Never met anyone else who could.