When a human chatters with a dog the same thing happens. "Good girl" or "atta boy" elicits a tail wag or butt wiggle. We love that during training sessions. The dog does something great, the human gives copious praise and the dog dances about. We especially love when we call out gleefully to our dogs and they come charging to us from afar.
Causing this excitement can also work against us in many ways. If we are looking for calm, well-mannered, or sedentary behavior in our dogs it may be detrimental to call out "who's here?" when the doorbell rings - especially if you have a dog that jumps on guests or barks at them incessantly. We probably won't get our anxious dog to settle down at the veterinarian's office by squeaking out "it's okay" over and over again. I have repeatedly seen dog-reactive dogs being pulled back by their leashes and getting barraged with high-pitched, "Oh, that dog doesn't want to say hello to you" or some other statement that has no value or meaning to the dog. And the more that the human speaks the harder the dog pulls.
If you want a calm dog, act calmly.