The ear consists of three main parts:
The Outer Ear
The Pinna is the visible portion of the outer ear. It collects sound waves and channels them into the ear canal where the sound is amplified. The sound waves travel toward a flexible, oval membrane at the end of the ear canal called the tympanic membrane, or eardrum. The eardrum begins to vibrate.
The Middle Ear
The vibrations from the eardrum set the ossicles into motion. The ossicles are three tiny bones (the smallest in the human body), the Malleus (hammer), Incus (anvil) and Stapes (stirrup), which further amplify the sound vibrations. The stapes attaches to the oval window that connects the middle ear to the inner ear. The Eustachian tube, which opens into the middle ear, is responsible for equalizing the pressure between the air outside the ear to that within the middle ear.
The Inner Ear
The sound waves enter the inner ear and then into a snail-shaped organ called the cochlea. The cochlea is filled with a fluid that moves in response to the vibrations from the oval window. As the fluid moves, thousands of nerve endings are set into motion. These nerve endings transform the vibrations into electrical impulses that travel along the auditory nerve to the brain, where the sounds are interpreted. The inner ear also contains the vestibular organ that is responsible for balance.