Each ear of a cat has 30 muscles. These muscles let cats change the orientation of their ears so they can clearly hear what's happening around them. The ears swivel to help cats pinpoint the direction of sounds, and specific positions of cats' ears display a variety of emotions.
When cats are alert and curious, their ears are upright and face forward. When a cat begins to feel upset, annoyed or afraid, the ears flatten out, almost like airplane wings. If the ears flick or vibrate, the cat is becoming increasingly aggravated. Cats that are fully frightened or angry flatten their ears to their heads. This protects the ears in case of an attack.