15 Things You Might Not Know About Mariah Carey - http://www.buzzfeed.com/mariash...
"5. Mariah has a five octave range. Her voice is an alto; she can cover all the octaves between an alto and a soprano. According to the BBC, "Such a range is so unusual because the human voice is very limited and we use only a small part of it. This makes it very difficult to expand the vocal range and articulate such high notes. Exploiting the range we do have comes down to physical aspects, like body structure and the length of vocal cords, technique and psychological attitude." - Franc, a rememberer