In reply to skyfall.

I heard the nodules were also the part of her vocal chords that helped her do the whistle register.
The problem is, Mariah has such a large vocal range and the whistle register is an impressive feature of that, but it is basically straining and damaging her vocal chords (which is why she has to lip-sync to the high notes on a lot of her songs) - with a voice like this, as amazing as it is, her singing voice will be non-existent after she hits 50