Noise as a status symbol

Why is it that some people are so freaking loud? I'm not talking about yelling and screaming here; I'm talking about how they talk in their everyday conversation. Talking louder doesn't make you more important and it doesn't make you more persuasive. It does annoy the hell out of those around you and make them want to pelt them with tennis balls. It makes you dread being around people you might actually like if they weren't so freaking loud.