There are definitely differences in a dogs personality and amount of barking. Also, you said this puppy is only a month old, and that is very young to be taken away from its parents, so that might be a good reason that she is so quiet. Most puppies are or weaned and rehomed until they are more like two months old, and being such a young puppy, she is probably not going to bark around older dogs. Once she gets to be several months old, and is playing more, she may start barking as she plays.
If the older dogs are not barkers, she may not be a barker either, since dogs learn the best from other dogs, especially older dogs that they are submissive to.
