I don't think I heard Riley bark until he was about 8-months old.....
and even now, he very Rarely Barks.
He will occasionally bark if he hears someone out in the hallway....
When he started doing that.... I would bang on my glass coffee table
and put my finger up to my lips and say "No Bark"! He would stop and
then I say... "Good No Bark" and we both go running into the kitchen for
a little treat... usually a piece of a green bean.
So now if he barks at the door, he will only bark a couple of times, and
then he will stop and look back at me.....