Have you ever been into this situation where you talk to the phone and then you hear your voice comng back from the speaker? This is enough to block your brain activity for good! A temporary blue screen occurs and you try again and again to start and finish your phrase, usually in vain for the first seconds.
What happens is simple: The brain requires a feedback from your senses to confirm that everything is normal. Thus, when you speak, your brain awaits to hear what you've spoken. But when you hear your voice again, the brain sings a red alert! It assumes that you said something that you shouldn't have, so it restarts!