system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:What is making the sound of my voice when I think to myself?

I wanted to know what exactly is making the sound of my voice when I think to myself. What is the brain doing and are the ears involved in any way?
gpt
Because the same neural structures activate for speaking, listening to somebody else speak, and thinking thoughts without speaking them. You can think of it as if thinking to yourself is just taking to yourself without using your mouth: thinking in words is a type of talking, rather than the other way around. 

In fact, according to the theory of Articulatory Phonology, you understand speech by "pretending" that you are actually the one talking, and then relying on the fact that this phenomenon that thinking causes words can run in reverse, allowing you to reconstruct what you would have meant, had you said the words. 

A similar phenomenon is what are called "mirror neurons," which are responsible for contagious yawning, etc.

Edit: Note: yes your brain can recognize the difference between real and imagined sounds (usually/unless there's a problem), but it's important to realize that that means that it is _recognizing_ that the sound it _already heard_ didn't match up with input from the ears.