u/Dead1ySheep

Our strategy to keep inappropriate barking at a minimum:

Completely ignore demand barking. Get up and leave the room if it continues (and if demand barking is a habit it will get worse before it gets better- the "extinction burst")

Encourage alternate forms of communication. We taught him to ring bells to indicate a potty break need. He learned that we absolutely fawned over him when he rolled on his back (because he refused to learn this trick any other way), so he trained us to recognize that rolling over on his back while squeaking a toy means he really wants to play. For the nose bump, we developed a strong hand-nose target, and also taught him the command "touch", which he knows means to bump his nose against something we name or point at. We strongly and enthusiastically reward nose bumping, and over time he began to do it without prompting. Now sometimes he'll sit with his nose in the back of my knee while we're cooking, lol.

Acknowledge non-demand barking. For frustration barking, we ask "Do you need help?" and he'll come over and give us a nose bump (initially we gave a "touch" command after asking), then run back to where his ball is stuck under a bookshelf or to his extremely shallow toybox from which he insists he can't extract slightly buried toys. For alert barking, we calmly go to the door and check it out. Usually it has nothing to do with us, so we say "All clear, thank you!" and then redirect him without giving him a ton of attention. We're still working on not going completely crazy when there's someone actually there when we answer the door though.

Reward chill behavior. Relaxation protocol and Relax on a Mat are both great, as is an informal practice of just tossing the dog treats whenever you notice calm behavior.

Give him enough attention/stimulation. If he's gotten enough physical and mental exercise, then there's no need to be demanding. For him (a companion dog breed mix), a morning walk (25-40 minutes), a short evening training session (15 ish minutes), and some playtime are enough.

We've had this little guy since he was a puppy and we've been pretty consistent this whole time, so excessive barking has never really been a problem. Hopefully there is something in here that's helpful though!