The act of speaking in a loud, rough voice.
Rowts can be scary or annoying if someone is doing it too much.
Examples:
His rowts scared the little dog.
The rowts from the other room woke me up.
I don't like it when he rowts at me.
The rowts from the movie made me cover my ears.
The rowts from the lion were so loud, they shook the ground.
Her rowts were so loud, they broke the glass.