The most apparent structure of hearing is the external ear or pinna , a structure that partially blocks sounds from the rear of the head. Its function of directing sounds toward the inner structures is demonstrated by a person who may cup a hand around the ear to focus on a sound.
Sound enters the ear canal or meatus and vibrates the ear drum or tympanum .
The vibrations of the ear drum are transmitted to a set of three bones or ossicles which transmit the sound energy to the oval window of the cochlea. The cochlea contains the receptor end organs which generate the neural impulses corresponding to sound. The middle ear is connected to the throat by the eustacian tube and this structure allows regulation of pressure on the ear drum and the oval window of the cochlea. Ossicles Think of the three bones as a lever system with three components. The hammer muscle or tensor tympani is able to pull the mallues away from the ear drum.