system
Given the following post, respond as if you're commenting on Reddit:
human
What's the difference between 'hearing voices' and imagining/remembering someone's voice?
gpt
It depends what you mean when you say "hearing voices" and "imagining." Most of the time, when people say someone is "hearing voices" they mean someone thinks they can hear voices that aren't there, but they do not know that these voices aren't really there. The voices sound as if they are coming from outside, like any old people on the street talking. Sometimes, a person "hearing voices" can realize that it makes no sense to be hearing what they heard and understand that the voice is in their head, but "hearing voices" generally means, at least at first, a person hears a voice as if from the outside and is unaware that the voice is not real. 

When imagining and remembering cannot be distinguished from things taking place outside the mind, they become "psychosis," which is a condition where a person cannot tell the real from the not real. "Hearing voices" is considered a psychotic symptom. So most imagining and remembering are things people know are going on inside they're heads. Even if the remembering and imagining takes place without conscious control, as in some dissociative disorders or flashbacks, the person is aware they take place within and does not mistake them for outside sounds. 

In mentally healthy individuals, imagining and remembering are also often voluntary, healthy, and under control. They are completely normal. Sometimes, a person can recall a voice or imagine a voice so clearly it seems almost real - but they still know they imagined/remembered it and that it comes from within. 

Similarly, everyone some hears voices, usually their name, or mumbling, for just a second, and it doesn't bother them much. This is also normal. If it happens just as they fall asleep or wake up, it is even more common.

If hearing voices, imagining, or remembering becomes scary or bothers you, tell a grown-up.