Kids half her age are loud and talkative. Babies rely on mimicking. It's how we learn and develop our vocal cords. You should talk to a newborn/infant constantly: while changing them, explain the steps you're going through. Show them things and explain what they are etc. It's also possible to teach infants basic sign language so they can better communicate their needs until they're able to form words. Granted, Rozy isn't seen much, so perhaps she does vocalize more, but she should definitely be making loud vocalizations (that aren't just crying) that can be heard while the ragepig streams.