i have experienced both external and internal voices...more internal...but the outside stuff i noticed was more related to when i was under a lot of stress. it also sometimes included seeing things or shadows of things. i have also heard other external (or maybe not) things like music when none is being played. my psychiatrist told me years ago that when i heard whispering behind me (externally) or thought someone was saying my name (externally) it was more how my brain processed sound (but was also during times of high distress).

as for my internal voices, i got to know them unlike the external things that were kind of just not really there long term and nothing i could grasp so to speak. but even those have changed over the years, so i can 'forget' they exist until they come up again or not just the voices but other things linked to them.

what feels real to you IS real...at least that is what i have learned for myself.