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The structure of the human ear
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Read：432 Date：2009-4-9 13:22:54 |
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The structure of the human ear can be divided into three parts: outer ear, middle ear and inner ear. Sound transmission from the natural environment to human brain in the process of the three parts of the human ear has a different role.
Refers to the human body from the external ear external ear to see part of the auricle and external auditory canal. Auricle symmetrical on both sides at first, the main structure of cartilage. Ear has two main functions, which both ranked Royal external objects in order to protect the external auditory canal and tympanic membrane, but also play a collection of voices from the natural environment and into the role of the external auditory canal. Will be on hand for the cup our ears, it is easy to understand the effect of ear, because the hands than the ear, and to collect more voices, so when you hear the voices ring will feel better.
When the sound transmission to the eardrum, the sound can enhance the external auditory canal, in addition, the external auditory canal with tympanic membrane to protect the role of the curved shape of the ear canal is difficult to make direct foreign body into the tympanic membrane, ear canal hairand Cerumen secreted into the ear canal can also prevent the membrane of small objects touched.
External auditory canal of the average length of 2.5cm, tympanic membrane and middle ear to control the environment, warm and humid to keep the ear canal, the external environment can not be affected and damage to the middle ear and tympanic membrane.
Outside of the external auditory canal 2 / 3 is composed of cartilage, near the tympanic membrane of the 1 / 3 surrounded by the skull.
Second, the middle ear 
Middle ear by the eardrum, middle ear and ossicular chain composition. Ossicular chain, including the malleus, incus and stapes, spinning in the middle ear cavity. The basic function of the middle ear is to transmit sound to the inner ear.
Voice to sound vibrations through the external auditory canal tympanic membrane, tympanic membrane ramp at the end of the external auditory canal, was concave, the normal for the pearl white, the vibration of air particles the pressure changes generated by the vibration of tympanic membrane, so that the structure of the sound through the middle ear into mechanical energy. Since the tympanic membrane before and after ossicular vibration so that the piston shape for mobile, membrane surface area of the stapes footplate than good times, the sound amplification in the here and transmitted to the middle ear. Due to differences in surface area, the received acoustic membrane on the concentration of the smaller space, sound waves transmitted from the tympanic membrane of the vestibular window energy conversion process, making the voice of Ossicular increased the intensity of 30dB.
In order to effectively transfer drum sound, both inside and outside the membrane must be made on both sides of the same pressure. Among ear cavity pressure and atmospheric pressure changes in vitro the same, normal tympanic membrane in order to play a role. Eustachian tube connecting the middle ear cavity with the mouth, the physical structure of this natural balance has played the role of internal and external pressures.
Third, the inner ear 
The structure of the inner ear is not easy to separate, which is located within the petrous bone cavity of a series of pipes, we can be seen as three separate inner ear structure: semicircular canals, vestibule, cochlea. Vestibule is a small oval window, irregular-shaped cavity, is a semi-regulated stapes footplate, the confluence of the cochlea. Semicircular canals can sense movement in all directions, play a role in regulating the body balanced. Cochlea is surrounded by the skull, like a snail as the structure of the inner ear to ear from here will be converted into mechanical energy of the electrical nerve impulses sent to the brain.
In order to facilitate the understanding of cochlear function, we use the right to display the stapes footplate and the vestibular cochlear connection window. Cochlea is filled with the basement membrane and separated from the basement membrane is located at the top of the spiral organ, which is the collection of nerve electrical pulse structure, the cochlea shows the helix cross-section's structure.
When the stapes footplate in the vestibular Department before and after the exercise window, cochlea also with the mobile liquid. Cochlear fluid back and forth movement of the basement membrane occurs leading to displacement, the movement of basement membrane-embedded in the plastic film so that the hair cell cilia bending, and the hair cells and auditory nerve fibers connected to peripheral, when the hair cells when bending to the auditory nerve fibers in the central transmission electrical pulse, the brain receives this electrical pulse, we heard the "voice." |
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