A new study led by psychologists from UNSW Sydney has provided the strongest evidence yet that auditory verbal hallucinations – or hearing voices – in schizophrenia may stem from a disruption in the brain’s ability to recognise its own inner voice.

That's pretty interesting. Schizophrenic voices sound like they can be pretty different from a typical internal monologue, I wonder how that comes about. (And if it's related to how dreams end up being like dreams, I always wonder how I could be manufacturing those myself)

There's also the noted tendency for them to be negative or bullying in the first world, while people in poorer regions have neutral or friendly voices.