Ditto! Very useful for relieving ear pressure at altitude.
> "[...] relieve your ear pressure without moving anything else"
With controlling the muscles in the ear, one can do it without a nose clip. It's called BTV (or VTO sometimes in English)[2], and instead of forcing air in to open the eustachian tube, you just open it by muscles.
[1]: https://en.m.wikipedia.org/wiki/Ear_clearing [2]: https://www.freedivinginstructors.com/article/204
To me, it "feels" kind of like moving the base of my tongue sideways and tensing my bottom jaw (in the same way I would pre-yawn).
I've known how to do the basic BTV/VTO for many years, but it wasn't quite enough for me to equalize pressure while diving (without descending very slowly, I suppose). Just a few minutes with the techniques on that page has already improved my ability dramatically.
But for freediving with the air going towards the stomach and much faster descent it's still a bit tricky. One thing is if I'm not equalizing quickly enough, no amount of force I can muster will open the tubes again without actually doing a more classic pinch nose technique. Doing a classic equalize you will often "overblow" air in and can descend a bit before needing to equalize again. But with VTO you're only equalizing to a perfect balance so will need to make sure to keep equalizing to not get under pressure. But of course not as much hassle hands free, I try to just do click-click-click continuously, almost every kick down to remind myself to keep it open. But yeah, if I get too much under-pressure I'm not able to open it again hands free.
I also feel head angle matters a lot, so trying to not bend the neck too much to look down, but instead swim down while looking "straight ahead" instead of where you're actually going helps for me.
There is, however, a simple trick anyone can do to equalize the pressure both ways: swallow. Works wonders with babies and toddlers.
It's one of those things where trying to describe it to someone who physically can't do it or doesn't know how to may make them question your judgment and/or sanity.
Of course, one might not be able to distinguish what muscles one is contracting, so it might be that most people actually tense both the tvp and the tympani at the same time, getting both the roaring sound from the tympani and the clicking sound from the tvp when the tubes open. Hence it's two different, but connected, things.
tensor tympani rumble = deep continuous rumbling sound you may hear when yawning
Eustachian tube clicking = a single slightly wet click you hear when you move your soft palate to block off your nasal cavity from your throat (via the tensor veli palatini muscle)