Tatum does the very low, quiet growl thing also. I really wish she would bark. She does bark to get back inside so I know she knows how to do it.
The first year of her life we were living at my MIL's while our house was being built. Can't tell you how many times she peed on the rug in front of the back door because we didn't know she was back there waiting for someone. You couldn't see the back door from other rooms though. At our house, you can see and hear her better, thank goodness.