By virtue of having the loudest voice, they are able to command greater attention and to further assert their dominance even when what they are saying doesn't really make much sense.
You probably already know that you're not supposed to talk with your mouth full of food and of course you want to avoid making loud smacking noises or chewing with your mouth open, so you bother other diners.
It's very powerful. And I have to admit, it feels a bit spooky to walk down to the ice in the nights, changing batteries in my sound recorder while being surrounded by these loud, strange sounds.
And please, fairly obviously, do not inflate your lovely life jacket until you've actually left the aircraft, at which point toggle up, inflate away and whistle all you like.
By virtue of having the loudest voice, they're able to command greater attention and to further assert their dominance even when what they're saying doesn't really make much sense.