False alarm?

Because of the nice weather, we have all of the windows open. This drives the dog crazy, because he can hear people and cars and other dogs walking by WITHIN HIS EARSHOT!

So, he barks. He barks to inform those people and cars and other dogs that they are invading his territory, which naturally consists of everything within his earshot.

And I tell him, "Shhh! It's okay!"

But how can I be so sure? Maybe, just this once, there really is a robber or a monster walking by. I feel guilty for responding so hastily.

Until he barks again.