Magic lyrics

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 whisper. A tiny whisper.

Now read this next line with your best crotchety-old-man 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.