why do people talk/yell over each other when scared?

Because when you get scared you get worked up so much that you don't really notice how loud you're being.^_^

Hmm, idk xD But the way I'm thinking about it, it could just be an evolutionary trait that yelling and flailing makes you look more threatening. Like a dog barking is more scary than a dog cowering even if both dogs are scared :P So, if you're against something scary and threatening, yell and flail and the other animal might not take the chance to attack xD IDK....

My dog does that.