I've been thinking about "job" and "Jar" and I think it's the way an American ear hears the words as compared to a UK ear. In the UK we say "job" but in America it sounds more like "jaarb", so to a U.S ear jar would sound like jaarb without the b!
This of course works the other way round and i always listen to U.S cd's with the lyrics in front of me. In another hundred years will we have a common language?
No criticism intended by the way. I'm just hypothesising as i try hard not to sing with that awful mid-Atlantic accent so beloved of English pop artists from Elton John to whoever.