I wouldn't reccomend yelling at bears they may get pissed. I'd rather back away quietly avoiding eye contact.
The technique you are mentioning, of making youself look big and yel, works better with cougars.
You're joking right?
Definitely yell at bears and make yourself look big. Black bears such as interior BC blacks bears are predatory, and will stalk/eat you.
A startled bear is also never a good thing so you're suppose to make noise moving through the bush. Most people don't know, but the best noise to make is actually breaking as many sticks, etc as you can. A study watching black bear response actually found that the most effective way to get a black bear to check out it's surroundings/respond/inform that you are coming is the sound of branches breaking (they set up recorders with various noises (people talking, branches breaking, etc).
Best thing to do if you see one (especially up there) is keep your eye on it and try to move it away (make yourself not look like an easy meal) especially if it's moving towards you or standing in plain sight "ignoring you" and slowly moving closer. As said before, bear spray is a very good defence once the bear is close as well, but it's always good to carry a sturdy walking stick, etc in bear country because there are a fraction of bears that are not effected. If you do get attacked (very rare), fight back and don't let it knock you down (black bears only).
To be honest, no black bear on the Vedder though will come after you, there is enough fish and the like to go around...
But saying to not make noise is just silly.
You did hit the cougar point though, same thing. Cats are very smart and will weigh the benefits of an attack vs the risk. The bigger and more aggressive you look, the more the cat with think twice about going after you because of the greater chance of injury to the cat (and a hurt cat in the bush is a dead cat or severely inhibited cat in the way of catching prey).