Hearing
Hearing(The ちょ う like this),Outer ear、Middle ear、Inner ear、Acoustic nerve、Auditory adrenal cortexAnd so on organ is used, the signal of sound is converted to the information of nervous activity, intensity of sound, the sound high, timbre, direction of the sound source, to the ability function which recognizes the rhythm and language etc. points. Generally known senses.
- Like above it is defined, but when to tell the truth it pierces finely and stuffs there is an insufficient point. Under " hearing ".
Audible limits
With the person usually from 20Hz, there is a personal equation, but to be able feel the sound of 15000Hz or 20000Hz, as sound this frequency zoneAudible limitsWith you say. As for sound of the frequency which exceeds the audible limits ultra wave. It is less than the audible limits, or near the audible limits lower limit it is low frequency sound is observed noise damage of the type which is not known so far (low frequency noise) as those which are pulled up, (It is low frequency soundReference).
MusicCD sampling frequency44100Hz is adopted, but because as for this because it can reproduce to with respect to 22050Hz theory, the audible limits of the person were thought that it can cover sufficiently. In addition picture tube televisionScanning lineAs for frequency of scan 15750Hz (525 x 30 frames/second,NTSC) is depending upon the person noise of the high frequency which it occurs entering inside the audible limits, attendant upon scan exceeds listening.
Dissection of auditory system
Outer earEar mediating/helping (to be), it consists of the external auditory meatus direct.Ear mediating/helpingLike the parabolic antenna you called top and bottom front and back & left and right by the fact that acoustic transfer characteristic changes not only it has the function which increasing the sound pressure of the sound which is transmitted, collection sound does in the air, from the complicated form, with the direction of the sound sourceSound source normal positionIt has been useful. The external auditory meatus approximately 20? We have the length of 30mm, end with the tympanic membrane.
Middle earThree ossicular chains of tympanic membrane, malleus, incus and stapes (the じ it does and ょ う secret) consists of. The occasion where the vibration of the tympanic membrane with the aerial vibration is transmitted to the lymph the inner ear, three ossicular chains by the fact that it is transmitted, pressure rises in approximately 22 times with the relationship of area ratio of the tympanic membrane and the stapes and the principle of the lever. In other words natural physics transformer is carried out. Beethoven the movement of the ossicular chain becomes badEar muscardineIt is said that you had contracted a disease.
Inner earIt is located in the side skull, at diameter 1cm 2 turning half has wound the snail which does the shape like the snail (the key ゅ う), the semicircular canal, it consists of the front yard. As for the snail inside is designed to be 3 layer system, (from above the front yard floor, it is filled up in the snail tube and the tympanic cavity floor) the respective lymph etc.. Vibration of stapes entrance of snail small window (egg bull's-eye window: Viewing it is to obtain so) to be transmitted, it vibrates the lymph inside,Corti's organIt placedBasilar membraneIt vibrates. Position of the basilar membrane which this time vibrates most strongly it differs depending upon the frequency of sound, high sound near the entrance, vibrates the basilar membrane of the position where bass is more distant from the entrance. This vibration deforms the firm hair of the inside pilose cell among the Corti's organ, opens the ion channel and is excited the cell electrically, is conveyed to the inner ear nerve.
We from first stage of audio acknowledgment, it has converted to the information which calls frequency information nerve cell excitation in addition to the physical frequency characteristic of this kind of basilar membrane, with the living thing element which is called "tuning" to the frequency of specification of the inside pilose cell. Frequency characteristic of the basilar membrane was discoveredベケシー(Georg Von B 駝 駸 y) you have been awarded the Nobel medical physiology prize 1961 with the achievement.
After that、Inner ear nerveAs for the nervous excitation which was transmitted passing the back side and the ventral snail nervous nucleus, as for the majority it is relayed () by the upper olive nucleus of part same side of anti- side, the outer part hair band, the lower hill, passes the inside geniculate body and is transmitted to the auditory adrenal cortex of cerebrum.
The topic which it is related to hearing
Tympanic cavity formation technique When function of the ossicular chain is lost by the chronic otitis media and the like, the middle earImpedance matchingStops going well, the hearing impairment becomes. In place of ossicular chain artificial boneSurgeryThe hearing impairment lightens by the fact that you install in the mark.
Artificial inner ear
Vis-a-vis the patient who because there is an obstacle on the inner ear becomes the hearing impairment,Artificial inner earThere are times when you can do the operation which imbeds. As for this microphone small size computer, inserts in the inner ear according to the pitch of sound is stimulated.
Auditory adrenal cortexトノトピー
In the basilar membrane the inner ear, when sound is disassembled frequency, in order to correspond, regarding the auditory adrenal cortex, corresponds to the unevenness of sound being the arrangement which from the time beforeElectric physiologyTo be known in the mark, recent years brain functional imaging research. Arrangement of the central nervous system which corresponds to this frequency "トノトピー"(Tonotopy <- tono:Topos: of soundThe place) with you say.
About the definition of hearing
"Hearing, the outer ear, the middle ear and the inner ear, uses the organ of the acoustic nerve and the auditory adrenal cortex, etc. converts the aural signal to the information of nervous activity, intensity of sound, the sound high, timbre, direction of the sound source, points to the ability function which recognizes the rhythm and language etc.", that it defined with beginning.
But to tell the truthAs a definition the insufficient pointIs included 2 points below.
- The ability to recognizeWith you wrote, but not yet elucidation it is the part whether recognition some part of the brain does. Because it is thought that "" audio information the thing equal consciousness which is converted to the excitation of the cell of the primary auditory area "to feel sound as sound recognizing" is not.ConsciousnessThat it means that the serious theme which you say whether it is borne somewhere of the brain participates. As for this brain science.
- "The outer ear, the middle ear and the inner ear, you used the organ of the acoustic nerve and the auditory adrenal cortex and etc." wrote, but there is a possibility of using also the organ other than that. For example, it is said as the maneuverability Broca's area it does and to acknowledgment of word that and others the Broca field which the れ て is participates. ThereforeTerritory of brain other than auditory adrenal cortexIt means to have participated in hearing. In addition, in acknowledgment of direction of the sound source, like the antenna moving ear mediating/helping it has been useful partly for example the dog and it is good e.g., with. With the person as for ear mediating/helping it does not move usually, but it has participated in sound source normal position with the fact that among other things direction of the face is changed delicately. Therefore, muscle and the like of cervixEar compared to organ of peripheryIt can do also to have participated in hearing.
Related item
- Auditory psychology
- Acoustooptics - acoustics
- The nose and ears science
- auditory handicapped person - Hearing impairment
