"As you scream for your favorite sports team, special brain cells kick in to protect your auditory system from the sound of your own voice, a new study suggests.
These cells dampen your auditory neurons' ability to detect incoming sounds. The moment you shut up, the inhibition signal stops and your hearing returns to normal, so you can then be deafened by the screams of the guy next to you.
Scientists call this signal a corollary discharge. In crickets, on which the study was done, it's sent from the motor neurons responsible for generating loud mating calls to sensory neurons involved in hearing. The signal is sent via middlemen called interneurons."