Ear

Menschliches Ohr
human ear
the ear (lat. auris) a sensory organ , a sensor , is with that acoustic signals, sound, tones, noises as the normal air pressure overlaid Schallwechseldruck as acoustic perceptions to be thus taken up.

Table of contents

ears generally

many animals having ears, structure and placement of the ears are with the different kinds howeverdifferently.

With grasshoppers the ears sit at the abdomen or the legs, with cicadas at the legs and with mosquitoes at the feelers. Some lizards - and Salamanderarten hear with thorax and lung. Always outside ears are missing, if that Sense of hearing available is, for example with queues and unites kinds of seal.

The audio range (hearing zone) of the human ear is enough from approximately 16 Hertz to maximally 20,000 Hertz at the age of 2-5 years, whereby at the age the aural acuity for high Frequencies leaves. Among other things elephants can notice still deeper frequencies, the Infraschall in such a way specified, while a set of animals, for example dogs, Delfine and bats still substantially higher frequencies ( the ultrasonic) to hear to be able.

A task of the earsorientation in the area is to thus locate acoustic sources i.e., to determine whose direction and distance. Laterally incident sound reaches the turned ear rather as the turned away and is there louder, there the turned away ear by the headone shades. These run time differences and differences in level between both ears are evaluated by the brain and used for direction regulation.
Beyond that the cap produces specific spectral changes of the frequency response, which are evaluated likewise and used for the direction regulation depending upon direction.

ManyOrganisms, like also humans, can locate existing acoustic sources, need however for orientation still the sense of face. Opposite use in particular Delfine and bats the sense of hearing to a completely developed orientation system. Both discharge high frequency tones (to 200 kHz) andorient themselves on the basis the echo. One calls this active procedure for orientation detection. With the bats the hearing replaced the eyes practically, which are in the darkness from no large use.

the ear of theHumans

the ear is divided for structure cross section

by the human ear with humans into three ranges:

  • The external ear covers the cap (3), the Ohrläppchen and the outside Gehörgang (2). It does not only serve the capture of the sound,but also, in order direction of arrival of the sound determined code by spectral minima and maxima. The numerous collections and recesses of the cap form acoustic in each case resonators, which become lively with sound idea from a certain direction in each case. Thereby direction-controlled minima developand maxima in the spectrum of the ear signal, which are used above, down, in front or in the back from the hearing to the determination of the directions of arrival.
  • The interior ear consists of the hearing snail (10), in that the soundinto nerve impulses one converts, and the labyrinth (9), which serves as organ of equilibrium. Hearing snail and labyrinth are similarly built: Both are filled with a liquid (endolymph) and possess hair cells, with which fine villi are enough into the liquid. ThroughMovements of the liquid are bent the villi and release thereby nerve impulses. These hair cells are cylindric and have their name of approximately 30 to 150 hair-like extensions at the upper end of the cell, consisting of Stereozilien. At the lower end is a synapse with a sensory neuron. This pays already in a state of rest neurotransmitters. Now by idiom or acceleration if the hair extension is expenditure-steered toward the longest Stereozilie, the quantity of the neurotransmitters increases. The hair extensions in the organ of equilibrium are with oneIt is supported kind Gallertschicht covered, on the calcium carbonate whereby the effect of movements is to be strengthened. From the hearing snail the hearing nerve ( 11) goes toward brain.

The perception of acoustic signals is substantially determined of it, like acoustic vibrations on theirAway by the external ear over the tympanic cavity to the nerve cells of the interior ear to be in each case transformed and converted.

characteristics

the human hearing can acoustic events only within a certain frequency and sound pressure level range notice. Between the auditory threshold and that Pain threshold lies the sensation area. The sensitivity of the ear is extraordinary. But likewise the tolerance in relation to noise.

The quietest perceptible sound pressure is about 20 micro Pascal (2·to 10 -5 Pa), L p = 0 corresponds dBSPL to sound pressure level. These sound pressure changes Δ p are transferred over the drum skin and changed in the ear brain system to the impression of the sound. Because the drum skin has the characteristics of a sound pressure receiver as sensor with the ear system, the sound pressure level describes the strength of the impression of the sound at the best one as sound field size. The loudness J in W/m 2 is however not to be described as sound energy size been suitable the impression of the sound; due to the complex impedance of the outside and tympanic cavity with same sound pressure level. Same applies in a general manner to the acoustic velocity.

The sound power, which takes up the human hearing, is extremely small. The quietest perceptible sound produces an achievement of less than 10,-17 W in the interior ear. Within a tenth second, which needs the ear to convert around this signal into nerve impulses it becomes by an energy of approximately 10,-18 joulesalready a sensory impression produces. To it becomes clear how sensitive this sensory organ is actually.

The pain threshold is with over 120 dBSPL, that is the millionfold sound pressure of the smallest audible. Nevertheless or straight therefore is the ear very sensitively, above all thatInterior ear takes damage with loud sound pressure.

When natural hearing and with the headphone Stereofonie plays the ear distance [1] a role.

those

can get sick to diseases the human ear in each case for the part concerned of the ear specifically in different ways,are.

  • The external ear is sensitive by its relatively thin skin in the Gehörgang and in the cap to infections with bacteria or mushrooms. These lead to the frequently observed ear inflammation or Otitis. By weakened defense and unsatisfactory treatment the infection can upthe bone, which surrounds the Gehörgang, spreads and its Vereiterung causes. One speaks then of a Cholesteatom, which can be treated only operationally.
  • Also the tympanic cavity can be affected by an inflammation and a Vereiterung. These often produce a positive pressure inTympanic cavity, because the Eustachi tube swells and the inflammation products cannot flow off. From the positive pressure a painful stretch results at the drum skin. Also the auditory ossicles can be attacked and destroyed by the infection. The tympanic cavity can further by large sound pressures damagedbecome, as they develop with explosions. Together with the other damage developed from this one speaks of bang trauma.
  • The most frequent illnesses of the interior ear arise in connection with durable noise pollution and bang traumata. Here first the outside become and later alsothe internal hair cells damaged. The transformation of the mechanical attractions into nerve impulses is then no longer possible and a Schwerhörigkeit adjusts itself. In this connection Tinnitus also often arises. Further the interior ear is a goal of above all viralen infections,like Meningitis, masers and Mumps. Also different medicines (e.g. Gentamicin) can damage the interior ear.

See also: Otosklerose.

To the diagnostics of illnesses of the ear stand apart from the generally usual methods of the medicine such as x-ray examinations, serologischen and visualInvestigations also a multiplicity from hearing tests to the order. The techniques for the investigation of the audition are summarized under the term audiometry. A result of a hearing test, which examines the aural acuity with different frequencies, calls itself audiogram. From this mostly leaves itselfthe auditory threshold read off.

direction hearing when natural hearing

around directions to notice, evaluates the hearing differences in level and run time between both ears. Additionally when natural hearing the spectral changes are evaluated, which produces related to the direction by the own external earbecome. For the estimation of distances spectral characteristics of the sound and (in areas) the relationship between direct sound and reflected sound are evaluated.

In order to test and examine around acoustic signals for the effects for lateral direction deflection the direction hearing,both ears different Test-Signale over headphones are often offered. One calls this Lateralisation. The subject of the investigation is here mostly the influence of run time differences (ITD = Interaural Time Delay) and differences in level (ILD = Interaural level Delay)on the direction hearing.

Localization applies against it to the direction and distance allocation of a hearing event when natural hearing and when loudspeaker hearing. The maximum run time difference ITD between the ears corresponds for instance to Δ t = 0.63 ms = 630 µs, which the ear distance, thus cm with a speed of sound of C = 343 m/s with 20 °C corresponds to a sound distance of D = Δ t/C = 21.6.

see also

Wiktionary: Ear - word origin, synonyms and translations
Wikiquote: Ear - Quotations

Web on the left of

Wiktionary: Ear - word origin, synonyms and translations
 

  > German to English > de.wikipedia.org (Machine translated into English)