| The human ear is far more than an odd-shaped | | | | contains a membrane that is attached to the hair-like |
| appendage that we hang our eyeglasses and earrings | | | | nerve endings of the "hearing" nerve, or eighth cranial |
| on. It's a complex system that changes sound waves | | | | nerve. |
| into mechanical energy, then into fluid energy, and finally | | | | But how does all this work? How do we hear, really? |
| into electrical energy. | | | | The auricle and ear canal funnel sound waves toward |
| The human ear is divided into three parts, which are | | | | the eardrum. The eardrum vibrates in response to the |
| known as the outer ear, the middle ear, and the inner | | | | sounds, setting in motion the bones of the middle ear. |
| ear. The outer ear is comprised of the auricle, which is | | | | As the foot of the third bone moves in and out of the |
| the visible part, and the ear canal. Dividing the outer | | | | oval window, the vibrations make waves in the fluid of |
| and middle ears is the tympanum, or tympanic | | | | the cochlea - something like dropping a stone in a still |
| membrane or eardrum. This is a delicate, | | | | pond. The membrane inside the cochlea moves in |
| tightly-stretched, pearly-gray membrane that vibrates | | | | response to these vibrations, stimulating the hair-like |
| when sound waves are delivered to it via the ear | | | | nerve endings. The nerve endings send the impulses to |
| canal. | | | | the brain for interpretation. |
| The middle ear is the second section of the ear. It is a | | | | As you can see, the chain of systems for delivering |
| cavity that houses a chain of three tiny bones. These | | | | sound information to the brain becomes more and |
| bones are called the malleus or "hammer," the incus or | | | | more complex as it moves inward toward the brain. |
| "anvil" and the stapes or "stirrup." These bones are | | | | There are many conditions that can reduce hearing. |
| named for objects that they resemble. The foot of the | | | | Some of these conditions prevent or disrupt sound |
| malleus rests on the eardrum, and it picks up the sound | | | | waves from reaching the cochlea, causing what is |
| vibrations from the movements of the eardrum. The | | | | called conductive hearing loss. Conditions that prevent |
| malleus is connected to the incus, which in turn is | | | | or disrupt sound transmission in the inner ear and |
| connected to the stapes. The foot of the stapes rests | | | | beyond it cause what are called neural or |
| on a structure called the oval window. The stapes | | | | sensorineural hearing losses. |
| delivers sound to this window by moving in and out like | | | | In future articles, learn how hearing aids and cochlear |
| a piston. | | | | implants work and what results might be possible with |
| The third section of the human ear is the inner ear. It | | | | these devices. |
| has parts designed for hearing and parts designed for | | | | If you or someone you know has had a hearing loss, |
| balance. The cochlea, which is the part dedicated to | | | | there are many resources available. For assistive |
| hearing, is a structure that looks something like a snail's | | | | equipment, technology devices, and deaf products, |
| shell. The oval window mentioned above is situated in | | | | please click the link in my resource box. |
| a wall of the cochlea. The cochlea is fluid-filled and | | | | |