They lack external ear flaps but their hearing is very sensitive

Penguins lack external ear flaps, much as other birds. On either side of the skull, in holes with feather coverings, are the ears. As every SCUBA diver is aware, diving's pressure shifts may harm the ear's delicate internal components. King penguins' middle ears are shielded from pressure fluctuations when diving by a specific organ comprised of cavernous tissue, according to research on the creatures' ears. The tissue stretches into the middle ear to maintain constant pressure when ambient pressure rises.

A returning parent may distinguish their kid from the rest of the colony based on its distinctive cry among the noise of hundreds of penguins on land. According to one research, African penguins have a hearing range of 100 to 15,000 Hz, with maximal sensitivity falling between 600 and 4,000 Hz. In contrast, humans have a hearing range of 20 to 20,000 Hz.

Penguins may use their extreme sensitivity to sound as a kind of defense against predators like orcas and leopard seals. According to one research, king penguins could discern between predatory and non-predatory noises even when they were asleep. When an orca calls, penguins awaken and immediately take flight. Like migratory birds, penguins may only use one-half of their brains while the other half remains alert and continually scans the environment for potential hazards.