The human Body (Home)
Did you know..
..when you spin around and feel dizzy, it is because of the liquid in your ears?
When this liquid stops moving, the dizziness stops also. Our ears are not only the organs with which we hear, but also help us keep our balance.
Outer Ear: This is what collects the sound waves in the air and directs them towards the inner ear. It is made up of the pinna, which is the part we can see, the auditory canal, and the tympanic membrane, which separates the outer and middle ear.
Pinna: This is simply a flap of elastic cartilage covered with skin. It is this part of the ear that some people get pierced with earrings.
Auditory canal: (or ear canal) Sound waves travel through this tube, which is about 2.5cm long and ends at the tympanic membrane. Near the external opening of the auditory canal are hairs, and glands that secrete cerumen (ear wax). Both hairs and cerumen help prevent foreign objects from entering the auditory canal.
Middle ear: This is a small chamber which contains three tiny bones called the auditory ossicles. These are the malleus (hammer), incus (anvil) and stapes (stirrup). These three bones are joined together and transfer the vibrations from the tympanic membrane to something called the oval window.
Inner ear: This consists of a complicated series of canals, and for this reason it is also known as the labyrinth. We will be looking at the semicircular canals and cochlea.
Semicircular canals: These are three looped canals, which are all roughly at right angles to each other. These canals are filled with a fluid called endolymph, and it is this fluid that moves around when you spin around quickly.
Cochlea: Within the cochlea is the organ of Corti, which is the actual organ of hearing. Lining this are tiny hair-like protrusions, and when these move, sound is heard.
So how do we hear?
Sound is produced by vibrating objects. Have you noticed how guitar strings vibrate when they are plucked? It is the same with all sound, be it music, a person's voice, thunder, etc. From these vibrations, soundwaves are produced which move in all directions of the vibrating object. When these soundwaves reach the ear, they are collected by the pinna, and directed into the auditory canal. After travelling down the auditory canal, it reaches the tympanic membrane, which vibrates. The movements of the tympanic membrane causes the malleus to move back and forth, which is passed on to the incus and stapes. The oval window is then moved in and out by the movement of the stapes, which eventually bring about movement in the endolymph of the cochlea. The hair cells in the organ of Corti are stimulated and nerve impulses are passed onto the brain via the auditory nerve.
If a person is exposed to excessive loud noise, the hairs in the organ of Corti become damaged. This results in them no longer being able to vibrate, and therefore these damaged hairs can no longer pass on the message to the brain.