OK, you must have a different accent than I do. I would pronounce the "u" in undirected the same as the "u" in "um" or "sun". I also pronounce the "h" in "historic"...

I guess I can see where you would get the "y" sound, since if you say "a undirected", you are forced to say "a yundirected", but that's the whole reason we have "an", isn't it?