system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can we "hear" auditory hallucinations?

What causes auditory hallucinations in the brain? For example, when you are sleep deprived, it is possible to hear things very clearly as if they were real. For example, voices of people talking, which some people with schizophrenia experience commonly in their daily lives. But of course there is no input from the ears. So what exactly is happening and how is that possible?
gpt
Normally, when you hear something, the soundwaves travel through your ear and eventually creates signals in your nerves. That signal travels to the brain, gets processed, and you hear it. So, while the ears are how you sense sounds, your brain is doing the actual hearing.

In any hallucination (auditory or otherwise), it's the brain perceiving something despite no actual signal of the thing from your senses.