Usually, popstars' vocal abilities are scoffed at, and I think rightfully so, but Michael has always been something of an exception to many. Most pop music sounds manufactured, and while it's true that some of Michael's does as well, it's not necessarily a bad thing. What matters is how it's manufactured. People like Kanye West regularly auto-tune their vocals because, well, they really don't have any; not worth hearing anyway. How many mainstream artists have albums like
Off the Wall and
Dangerous to compare to each other? How many popstars can go from a flawless live performance of "Gone Too Soon" at a presidential inauguration (sung in hopes to make a difference no less), to something raw like "Can't Let Her Get Away"? Michael desired to be the best he could be, which is why
Bad didn't amount to a random assortment of cover songs, and ultimately what he owed his success to.
Anyway, regarding his voice. Naturally it was much lower than what he generally spoke in, but preferred the higher tones and pitches, making him a high tenor. I imagine that's partially why he was able to maintain the range that he did, which is something like three and one half octaves. It's not really powerful in say, an operatic sense, but more so in his precision and control.
Probably my favorite live performance:
4:27 - 4:51 = ecstasy.