Ariana has no where near a 6 octave range. She may have the ability to sing in the whistle register (which is the sixth octave) but the ability to sing in the sixth or even seventh registers does not mean you have a six octave range. Interestingly, among pop singers, Axl Rose actually has the greatest range (using studio recordings) followed by Mariah Carey (again based purely on studio recordings). Each can hit notes in a range of around five octaves. For some reason, when people hear singers high notes they automatically assume it means they have vast ranges. People also tend to assume that great singing means singing or having the ability to sing in many octaves, however greater range does not equal a greater voice. One of my favourite singers of all time Karen Carpenter had a modest two and a half octave range, but could convey so much emotion through her voice that wailing through the heavens in the sixth and seventh octaves wasn't necessary.
edit - I would like to point out I am in no way disparaging or hating on high singing - in fact a quick glance at my profile will show you that my favourite artist of all time is Mariah Carey. I just wanted to point out that range or lack doesn't define or determine whether a singer is good or not. That anybody here did that! I was just musing about things I'd heard. Just to clarify! :)
