Why do people hear voices in their head?

[Liberty and Linguistics]

Generally, scientists presume that it's caused by psychosis. However, other diseases and or environmental conditions can cause voices in one's head. These voices may be temporary, or occur often. Psychosis is a leading cause of auditory hallucinations, but excessive stress, anxiety, and many environmental conditions can cause them.

[Margno]

Well, you've got self talk, also known as thinking. If you have OCD, like I do, sometimes you don't control your thoughts, they just repetitively say "you have aids" or something, but it's still in your voice. Then you've got the basic auditory hallucinations most people get, like hearing a million different voices saying your name. Then there are the extreme hallucinations schizophrenics get, and the ones from hallucinogenic drugs like salvia and LSD. Then there's that other thing, but we don't talk about that.

[Kuango]

That would be the lord talking to them.

[Kryozerkia]

Unfortunately our society glorifies mental health. Instead of committing suicide like they normally would (yes SAD, but less sad than school shootings and the like!!), we try to treat broken people that can't be fixed, they BREED, and now it's gotten to the point where apparently hearing voices is considered normal. Back fifty years ago we used to at least neuter these people, but liberal softies put a stop to that, so now they've bred and we all seem to think mental health problems are normal...

THEY'RE NOT.

I also admit that the poisons in our environment and pharmaceuticals have a lot to do with the world literally going crazy as well

If you'd left out your comment about mentally-ill people being "broken"and can't be "fix", you wouldn't be *** warned for trolling. ***

[Jute]

I heard that if you accept the voices (that is, if you have any), they will stop being jerks and awful and instead give helpful advice where they can, like relatives.
At least that's what I'm getting from this study here:

Differences in voice-hearing experiences of people with psychosis in the USA, India and Ghana: interview-based study

Method - An anthropologist and several psychiatrists interviewed participants from the USA, India and Ghana, each sample comprising 20 persons who heard voices and met the inclusion criteria of schizophrenia, about their experience of voices.

Results - Participants in the USA were more likely to use diagnostic labels and to report violent commands than those in India and Ghana, who were more likely than the Americans to report rich relationships with their voices and less likely to describe the voices as the sign of a violated mind.

Source

I don't have voices in my head?

Seems like you aren't actually sure about it.