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Hearing

Moving and soudarjajas, objects vibrate and create the fluctuations transferred by air. Fluctuations are perceived by an ear and will be transformed to sounds of various intensity.

We hear, because our ears react to sound waves or on the slightest changes of pressure of air. They will transform these waves to electronic impulses and transfer them in a brain where those are transformed to sounds.

The Ear of the person includes three branches - an external, average and internal ear. The external ear consists of a skin fold with a cartilage and the acoustical pass conducting to its latent part.


As we hear

The Visible part of an ear is called as an auricle. It operates as an intake of sound waves which then get into a middle ear through acoustical pass and force to vibrate an eardrum which is on an input in a middle ear.

On the sizes the middle ear in eight times less external also represents a small cavity in a skull. The eardrum Here settles down, and the opposite part of a middle ear is connected to a nose a narrow tube which is called the Eustachian tube. It allows to level pressure of air on the average an ear in relation to an environment. If pressure changes, our ears should adapt to it that sometimes causes "§ыюяъш" in ears.

In a middle ear cavity there are three stones, each of which has the characteristic form: a hammer, an anvil and stremechko. The fluctuations of air reflected by an eardrum pass from a hammer to stremechku and further through the oval window of a threshold connecting an average and internal ear.

In an internal ear the labyrinth - three tubes filled by a liquid thanks to which we feel the counterbalanced pressure settles down. Also there there is the tiny spiral tube (snail) consisting of two channels and channels. These channels and a channel are filled by a liquid. In a channel also are tiny voloskovye the touch cages covered narrow membrannoj with a film. These cages and a membrane make kortiev body.

It is the present acoustical center. Fluctuations, passing through a snail, force a membrane to move back and forth. Moving, the membrane pulls voloskovye cages and they send electric signals through an acoustical nerve to a brain. The brain deciphers signals and perceives them as sounds.


Noise levels

Loudness - energy level in a sound - is measured in decibels. Whisper is equated approximately to 15 db, the rustle of voices in a student's audience reaches approximately 50 db, and street noise at intensive traffic - nearby 90 db. Noise above 100 db can be intolerable for an ear of the person. Noise of an order 140 db (for example, a sound of the flying up jet plane) can appear painful for an ear and damage an eardrum.

At the majority of people sensory acuity becomes dull with the years. This results from the fact that ear stones lose the primary mobility in this connection fluctuations are not transferred in an internal ear. Besides, infections of organs of hearing can damage an eardrum and negatively be reflected in work of stones. At occurrence of any problems with hearing it is necessary to address immediately to the doctor.

The Reason of some kinds of deafness is damage of an internal ear or an acoustical nerve. Hearing deterioration can be caused also constant noise influence (for example, in factory to shop) or sharp and very loud sound splashes. It is necessary to use very cautiously personal stereoplayers as excessive loudness of sounding also can lead to deafness.