Some dogs are barkers, some aren't. This is a matter of individual dogs as much as breeds, although some breeds are worse than others. Shock collar? If you actually electrocuted a Shih Tzu, his very bones would rise up and bark.

A dog develops a very specific idea of their own "turf," and will bark the hell out of a stranger who "violates" it. Our dog scared the crap out of endless delivery people. Even though she was confined in her little fenced yard, the yard was connected to the house by a dog door, so she would shoot out of the dog door like a submarine-launched missile and start jumping up on the fence barking her little head off. I had to clean up as much FedEx guy crap as dog crap. There's a theory going around the neighborhood that a delivery guy is still living somewhere up on top of one of the live oaks out front.

But take her to the park on a leash, and strangers? Meh. Who cares? She'd sit there enjoying the sun, and ignore other people, and even other dogs. Away from home, barking wasn't her job any more.