Sense of Hearing.

Like your other sense organs, your ears are extremely well-designed. In fact, they serve two very important purposes. Do you know what they are? You were probably able to figure out that your ears help you to hear sounds, but what you probably did not know is that your ears also help you to keep your balance.
How You Hear
When an object makes a noise, it sends vibrations (better known as sound waves) speeding through the air. These vibrations are then funneled into your ear canal by your outer ear. As the vibrations move into your middle ear, they hit your eardrum and cause it to vibrate as well. This sets off a chain reaction of vibrations. Your eardrum, which is smaller and thinner than the nail on your pinky finger, vibrates the three smallest bones in your body: first, the hammer, then the anvil, and finally, the stirrup. The stirrup passes the vibrations into a coiled tube in the inner ear called the cochlea.