Sorry for back-tracking a few days, but I've just returned from 4 days holiday. [As an aside, Australia virtually stops for a horse race (The Melbourne Cup), which was yesterday (Tuesday). Aus$70 million (~US$35m, and heading south?!) plunged on the ONE race. Melbourne residents get a public holiday, and many people take the Monday as well for that great Aussie tradition "the long weekend".]

why do so many Americans ... pronounce herb and herbal as 'erb and 'erbal.

Somewhere in the last few weeks - and my fruitless search of this board suggests it wasn't here - I read a funny piece about a visitor to the US who was offered "urban cheese roll". She was expecting some kind of metropolitan answer to country cooking.

Many seem to say yuman instead of human.

I, too, have heard people pronounce human as yuman, although I can't recall whether it's a national thing. More common, though, is the proununciation of the name Hugh as Yoo rather than (my preference of) Hyoo. Tends to lead to some ridiculous misunderstandings along these lines:
"Who did that? Was it Hugh?"
"No, it wasn't me, it was Hugh!"
"Was it you, Hugh?"

Have others experienced this Hugh/You pronunciation and is it confined to Americans?