I've spent a lot of time studying and working with dog behavior, mostly as a result of adopting damaged dogs.
My advice, unsolicited: Be very careful about loud noises and especially attaching anything to the collar; we tried a simple mild vibrator on a dog once (with remote, as mild as a typical cell phone vibrator), designed just to get the dogs attention, and it scared her to death. Dogs can be very vulnerable that way and sometimes will never get over certain sounds/actions.
Also be aware that using a buzzer/whatever could make the dog wary of all similar sounds. These things are super variable depending on individual dog and its history. It's really complicated.
Ours are very highly trained and don't get on furniture, never go through a door while with us until given permission, but I've never been successful keeping them out of certain rooms of the house when they're not being watched, good luck with that! :-)
I design lift-off gates for rooms like that, or we use child gates.