gabby-mouth
A 'gabby-mouth' is a person who talks so much and so loud, it feels like they’re trying to steal your brain.
My sister is a gabby-mouth. She talks about her crush so much, I think I’ve heard it a thousand times.
My classmate is a gabby-mouth. He talks so much, he interrupts the teacher every time.
My mom is a gabby-mouth. She talks about her day even when I'm trying to sleep.