She barely has a 5 octave range. It's not impossible to have an 8 octave range which is currently the guiness world record for largest vocal range held by Georgia Brown. G2-G10 is her range but I've only heard G2 since her G10 is actually able to be heard and sounds more like a B8 or B9. Nicola Sedda actually has the largest vocal range that I know of which I only remember his highest as A9. The fact is that Mariah has only displayed a range of Bb2-G#7 which is very close to a full 5 octaves. Bb2 has only been displayed in an interview and G#7 has been hit twice in live performances of Emotions and seemed fairly easily done. Besides Bb2 she has hit C3 numerous times. Emotions, My All, You And I(live performance), and other songs have C3 as their lovest. Besides G#7, F#7 is her highest in the studio version of All In Your Mind.