How Does
What Makes Ears Work?
By CLehman
eHow Contributing Writer
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Ear Function and Anatomy
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The ear has several parts, each of which is responsible for an essential part of the hearing process. Hearing relies mainly on vibrations created within the air from waves generated from a sound source. Loss of hearing can be caused by injury to any of the vital parts of the ear or can occur when the parts of the ear become less efficient with age.
The ear has three sections: the outer ear, the middle ear and the inner ear. The outer ear is the portion of the ear visible to us all. It consists of the pinna, which is the cartilaginous fleshy part of the ear, and the outer ear canal. At the ear canal, a thin membrane called the tympanic membrane serves as the external boundary for the middle ear. The middle ear contains three small bones, the malleus, the incus and the stapes (which are, incidentally, the smallest bones in the body). These bones are connected to the inner ear, which consists of the fluid-filled cochlea and the semicircular canals, through an opening called the oval window. While the cochlea is vital in the hearing process, the function of the semicircular canals is primarily that of maintaining balance.
Collecting and transmitting sound waves
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Sound waves travel through the air, are collected by the pinna and travel down the ear canal to the tympanic membrane. These sound waves cause the tympanic membrane to gently vibrate which, in turn, causes the three bones in the middle ear to vibrate against one another. The last bone of the three, the stapes, transmits the vibrations to the cochlea. Wax found in the ear canal generally does not impede the hearing process (and actually helps keep pathogens out of the ear) unless it builds to a thickness where it impedes the vibration of the tympanic membrane.
Perceiving and processing sound waves
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Once the vibrations from the stapes have been received by the cochlea, the fluid within this structure begins to vibrate as well. Thousands of tiny sensory hairs that line the cochlea receive these vibrations, which vary slightly depending on the intensity and frequency of the noise. These hairs, when triggered, send small impulses up to the auditory nerve, which is the large nerve that leaves the ear and is responsible for transmitting the sound from the ear to the brain. Once these impulses reach the brain, sound is perceived.
eHow Article: What Makes Ears Work?
