His voice was not "weird". You guys really underplay the uniqueness of his voice. Michael was experimenting with different sounds for his upcoming album (in this case the album would be "Bad"), if you listen to all of Michael's demos in between and after different eras, you will notice that he sounds like a mix between whichever era came before and the era that came after. Simply put, Michael always had the same voice, he just learned how to sing differently as time passed, which is why he sounds different on Thriller than he does on Bad. Michael could always sing like he did on Thriller even when he was in his 40's. I believe "Chicago 1945" was simply a way to experiment with the "Bad" era singing style.