An owl can hear sounds 10 times fainter than the human ear can even detect. Several features of an owl's ear make it so sensitive. Its extra large ear openings, surrounded by deep, soft feathers, help to funnel sound. Also, the feathers over the ear, or auriculars, have no barbules, the parts of the feather that zip together to make it wind resistant, making the owl's feathers loose and airy. A movable flap of skin, controlled by muscles around the ear opening, protects the ear and concentrates sound waves coming from behind.
Many owls also have asymmetrical ear openings.
The opening in one ear will be higher than in the other ear. A sound coming from above will sound slightly louder in the ear with the higher ear opening. This allows the owl to pinpoint its prey accurately. Finally, the owl's entire face acts as an outer ear. The face is shaped like two parabolic curves or satellite dishes that funnels sound to the ears.