This was taken from a medical journal pertaining to voices that schizophrenics hear:
Many times the voices simply comment on what the individual is doing at the time. If the individual is speaking with a supervisor, a voice may comment on what the supervisor is saying, or even be quite nasty about him/her. Sometimes the voices will actually give instructions to the individual, but they usually aren’t psychotic as portrayed in movies and books. Sometimes they will “take care” of the individual, instructing him or her to take a shower or eat a meal. It can be any number of things.
What do these voices sound like? Well, there are many different ways for them to appear. Sometimes they will sound like an echo in the back of the mind. Many people experience them as thoughts that are sudden and unexpected, which are out of context and not something they would normally think. Most times people wouldn’t even recognize this as a voice if they didn’t believe in it. Sometimes voices will come from outside the head, and then they will usually be unintelligible. On occasion, they will appear as block print inside the head. However they appear to one individual, they will usually appear the same way all the time.
Some of these individuals are capable of having a conversation with these voices. Some voices may even have names if they speak to the person often. On occasion they may even have personalities. However, people who claim most of this are labeled as insane, as getting into voices this deeply is not part of most cultures. It is a much disputed fact over whether these voices actually exist. The argument could go back and forth forever. However, it usually ends with simple insanity as the explanation.