What makes the eardrum vibrate?

The sound waves are gathered by the outer ear and sent down the ear canal to the eardrum. The sound waves cause the eardrum to vibrate, which sets the three tiny bones in the middle ear into motion. The motion of the three bones causes the fluid in the inner ear, or cochlea, to move.

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The sound waves go through the ear canal into the middle ear, which includes the eardrum (a thin layer of tissue) and three tiny bones called ossicles. The sound causes the eardrum to vibrate. The ossicles amplify these vibrations and carry them to the inner ear.