Honestly, IMO, when I first saw it, I didnt know what to make of it lol.
At first, I thought maybe it was actually a joke and the meter is actually a clever visual disguise, and we are actually supposed to be paying attention to the noises because those noises come from distinct dinosaurs that are dangerous. Like maybe the threat level 1 was disguising the called of some small dinosaur. And the threat level 3 was actually the cry of a Spinosaurus or something big. Because we know the dinosaurs in the game make noises. Maybe like how in original Jurassic Park trilogy a big dinosaur would have audio cues like a stomp, and the small raptors would make those paw noises in the background and show that they are nearby, then maybe this was the games way of letting players know which big guy was on the way.
My other thought was that this was the mangle dino cries to signify wave levels and sizes of hordes before they rush at you. Like how in COD zombies you can always hear the zombies cry out before they approach and start attacking your defenses, but imagine if they were amped up depending on how big the waves were getting.
But those are just some initial thoughts from when I first heard it lol.