Magic

Read this to yourself. Read it silently. 
Don't move your lips. Don't make a sound.
Listen to yourself. Listen without hearing anything. 
What a wonderfully weird thing, huh?

NOW MAKE THIS PART LOUD!!
SCREAM IT IN YOUR MIND!! 
DROWN EVERYTHING OUT
Now, hear a wisper. A tiny wisper.

Now read this next line in your best crotchety-old-men voice: 
"Hello there, sonny. Does your town have a post office?" 
Awesome! Who was that? Whose voice was that? 
It sure wasn't yours!

How do you do that?
How?!
Must be magic.