Roosters have built-in earplugs, so they don’t deafen themselves when they crow. Anyone who’s ever spent a night outside the city knows one thing, and that’s the fact that roosters are loud! Researchers measured how loud roosters do crow and found them to be as loud as 140 decibels – well over the amount needed to cause permanent ear damage and even deafness. When they studied what happens when roosters crow, they discovered that in opening their jaw to crow, their outer ear canals close up, essentially giving them natural earplugs.