Our ear consists of three parts :-
The vibrations reach our pinna then strikes the ear drum. Then the three bones namely anvil,stirrup and hammer. Then it goes to the cochlea in which fluid and hair like structures are present to amplify the vibrations. Then these vibrations go to the auditory nerve which carries these vibrations to the brain and brain converts these vibrations into sound which the brain after processing sends again to the ear. This is how we hear.