
Depending on why he gets frustrated......use that.
Taught Zuma to 'talk' (couldn't use speak as when he heard the 's' he sat!)
I used a bit of carrot and held it under his nose but wouldn't let him have it, eventually got a VERY little whine - click and treat

Then over a few weeks worked up to a series of proper barks doing exactly the same - noise = click and carrot till I got what was wanted.
just read your 2nd post - we had a Rott who believed 'why keep a dog and bark yourself' She only barked if the other two had been taken out and she was the only dog in the house