My daughter's almost one year old cavalier Belle never barks. that was one of the reasons i thought i could get away with having a cavalier in my apartment. when belle was here for a visit, she was so quiet. She was playful and curious and exploring and excitable, but she didn't bark. Like if people were walking up the stairs outside, or if someone came to the door and knocked, she just never barked. Lisa says she continues not to bark. I've seen her--when she was in her crate and wanted to get out, she wouldn't bark or cry out or whine. She just dug at the door of the crate with her front feet and you could hear her toenails, but nothing vocal at all.
I was hoping to get a dog that doesn't bark too, but Zack does bark. but not excessively. He barks if he hears a squirrel or sees a possum in the backyard. He's overall quiet and will stop barking when i tell him to stop.
One other thing he does thought that i haven't seen other dogs do, is when we are walking to the dog park, he gets excited and emotional and he starts going "arf arf arf arf" over and over in an excited way, and once or twice at the dog park, he's been so excited that he arfs while he's playing or running around with the other dogs, he's just so emotional about it. Other dog owners look at him and laugh, none of the other dogs are making a racket but zack is arfing, it's kind of high pitched and grates on my ears when it's nonstop, but a couple of times when i told him to stop, other dog owners said to let him keep doing it, it wasn't bothering them. It's not a barking sound, it's kind of like a crying sound but not exactly. It's like hysterical excitment.