We call those big flaps on each side of our heads “ears”; so where is the middle ear? “Middle ear” refers to the medical terminology in which there are three parts: The external ear, the middle ear – a space bordered on the outer side by the tympanic membrane (ear drum) and the inside by the inner ear. Eustachian tubes lead from this space into the naso-pharynx. Hearing is accomplished when sound waves travel through the external canal and move the eardrum. The drum cannot move freely without letting air escape through these tubes. The slightest movement is magnified through three little bones connecting the ear drum to the inner ear. The inner ear looks like a snail. It is a marvelous design, consisting of a coiled fluid-filled tube, with a membrane of its own attached to the little bones, and hair-like nerve cells of varying length projecting into the fluid. When a pulse of fluid causes movement of the hair cells, mechanical energy is converted into electrical signals. These nerve cells send their electrical signals through the auditory nerve. The different lengths of their hairs vibrate in response to different sound wave lengths. The semicircular canals that control balance share this space but only rarely suffer the same sort of problems. Read More.