i have littermates they are about three months old. the girl will make meep sounds, not quiet meows. the boy does not make the same noise. they have this werid purr sound when they can not see the other after a while. when do they normally start to be chatter boxes. they love to purr and can for long periods of times. we go to the vet in a few weeks so i can ask them to make sure nothing is to wrong.