Someone who is unable to control the volume or tempo of their voice.
girl: what is wrong with your voice?
Will Ferrell: I have Voice Imogilation Syndrome (V.I.S.), because of this I am unable to control the volume or tempo of my voice.
She is probably a weeb. Doesn't say much when talking to friends, and willsimp for any and all guys in anime. You don't know much about her home life, or anything else. She is a nice person, but will easily judge.