No child could drown you out in school, so you were always the one getting in trouble for talking. Naturally it landed you detention more often than not. 

You never had the same teacher twice in detention, since they would always trick one another into staying with you.

They can't handle your loud voice. They have shushed you so many times they passed out. 

You yell when you're happy, you yell when you're sad, you yell when you're angry. Since you're only one volume, it's impossible for people to tell what emotion you're feeling.

It's impossible for anyone to win against an opponent who completely drowns out their argument. 

They just want a quiet park bench to nap on, and then you come along....

They're so focused on the fact that you are breaking their ear drums, they don't actually listen to the words pouring out of your mouth. 

How can there ever be a time when noise isn't happening? You have the unkillable urge to fill that silence...

You've been told to shut up so many times that you start to assume someone changed your birth certificate when you weren't looking. 

For you, whispering is like learning French. It would take 5+ years of classes. In other words, it ain't gonna happen anytime soon. 

No one can talk through the latest gossip with you, because you'd leak it 10 seconds later with that big mouth of yours.