Here’s what I know:
For whatever reason, it’s impossible to breathe while doing this.
it’s much easier to do it with your eyes closed.
I’m pretty sure the roar isn’t blood because I can’t hear a heartbeat or any real change in the sound.
Finally, whatever I’m doing makes my closed eyes vibrate.
I suspect what is happening is somehow I’m making my sinuses expand while my throat is closed.
Sorry if I sound insane.
Heh! Yes! I’ve done this all my life. I just “clench” some muscles in my head, close to the jaw-hinge, and there is a rushing/roaring sound.
I’ve always figured it had something to do with the eustachian tubes.
Yes I can, I can still breathe while doing it, and my eyes are uninvolved.
I can also wiggle my nostrils individually. 
I can do it. My eyes kinda vibrate too. It also makes me yawn sometimes.
:eek:
I’ve always done it, and I’ve called it “thundering.” With me, the left side is a little louder than the right. And it’s independent of eyes, breathing, etc.
I can blow air through my eustachean tubes, which makes a roaring sound. That’s all I’ve got.
Back when I used to play the trumpet, my eustachian tubes would sometimes inflate suddenly. I could also blow air out through the inner corners of my eyes!
(Yes, my head is hollow…)
USCDiver: thanks! That’s stuff I never knew!
I can get it where the eyes aren’t involved but absolutely cannot breath out or in. Weird.
I also have never had a brain freeze. I may not be put together right.
I don’t know why you can’t do it while breathing. I’ll admit it’s harder to switch directions while doing it (breathing out to in or vice versa), but it took just a couple tries to do it.
This roaring is also how I “unpop” my ears. So I always thought I was vibrating the muscle that keeps the Eustachian tubes open.
The “ice cream headache?” Lucky! I hope you never do! It’s extremely painful! I first discovered the effect while slurping my first Slurpee. It took me decades to try another one!
I can make my ears roar too. I can also make them roar when I blink so it’s like I can hear myself blink.
Yeah. Sometimes I play “music” with the sound. I can’t change the pitch or anything but I can keep a beat going pretty well, so it’s easy to imagine actual notes.
I can only do it for about 10 seconds continuously before having to relax to reset it.
I thought I was the only freak who does this. I never knew how to even describe it.
I can roll my tongue into a tube, I can turn my tongue upside down, wiggle my ears, and cross my eyes.
Why couldn’t I have useful unusual traits?
Sure. It seems to involve putting pressure on the upper palate as well as clenching muscles, though.