I like for my dogs to know it is good that they bark when they hear something but that it's time to stop when I am alerted. I use "Good Job. I got this. No barking." He knows "no barking" and it just took consistency to teach him the other part. My Yorkie follows his lead a lot. I'm still working with her on it, but she's getting better.
I just don't want them to think they "shouldn't" bark initially, ya know? I like having watch dogs