Not to offend anyone.
But in psychiatry, when a person thinks he hears voices that are not actually there, that's called a psychotic episode.
So, if a person thinks he hears voices from other people (not actually there), we call him a psychotic. But if a person thinks he hears the voice of God, we call him a person of faith.
Again, my intention is not to offend anyone. I am just pointing out the obvious incongruities between science and faith. I talk to myself in my mind all the time, mostly when I think about stuff, but never out aloud.