Deep, rapid breaths. They need to suck oxygen into their body as quickly and efficiently as possible to maintain consciousness, because the g-forces forces blood away from their heads and towards their legs and feet.
Here's a "classic" video of a pilot successfully evading an unbelievable number of SAMs over Iraq. The rapid breathing might make you think he's panicking. Nope, he's got it 100% under control and is following training perfectly. Though I'm sure he certainly needed a drink after making it home.
https://www.youtube.com/watch?v=qUjX1RntqVw
There's also sort of a method of flexing their thighs that they learn. Restricts blood flow to the legs, so there's more blood for the rest of the body. That's a bit of an athletic endeavor in and of itself. Try flexing your thighs... now hold them that way for 5, 10, 20 minutes. Yikes.
Anyway, how the hell could you even bark out voice commands while doing that sort of breathing!?!?
Second, given how shitty voice interfaces are, I'm shocked they would use them at all. I assume the military funds a lot of EEG research- that would be ideal here.
Given how finicky they are I can't say I'm surprised. Maybe with modern pseudo-AI systems they could be reliable enough to depend on, but none of that is in military hardware specced out 20 years ago.
No, and no. Just good, old-fashioned microphones and speakers. If you're lucky, you have a set of "communication ear plugs" wired up to your helmet so the speakers in your earcups aren't trying to compete with engine noise and your ear plugs.