Yours ear do several different things. They detect sounds, but part of your ‘inner’ ear also helps you to keep your balance.
The visible outside part of your ear is called your ‘pinna’ and helps your inner ear to ‘collect’ sounds (made up of pressure waves) from the outside world. Because you have two ears each side of your head and sounds reach them at slightly different times - your ears help you localize where sounds come from.
Part of the job of your ears is to change sound pressure waves from the outside world into a signal of nerve impulses that go to your brain where these nerve impulses are interpreted as different sounds. This done by the inner part of your ear called the cochlea.
Another part of your inner ear called the labyrinth is a sense organ that is sensitive to the effects of both gravity and motion and helps you with your balance. It is this function of your labyrinth which is upset when you are car sick, air sick or sea sick.