Middle section of the ear. The structure of the hearing organ

26.04.2020

The ear is considered the most complex organ of the human body. It allows you to perceive sound signals and controls the position of a person in space.

Anatomical structure

The organ is paired, and it is located in the temporal part of the skull, in the area of \u200b\u200bthe pyramidal bone. Conventionally, the anatomy of the inner ear can be divided into three main areas:

The inner ear, consisting of several dozen elements.
Middle ear. This part includes the tympanic cavity (membrane) and special auditory ossicles (the smallest bone in the human body).
Outer ear. Consists of an external auditory canal and auricle.

The inner ear includes two labyrinths: membranous and bone. The bony labyrinth consists of hollow elements inside, connected to each other. The labyrinth is perfectly protected from external influences.

A membranous labyrinth, identical in shape but smaller in size, is placed inside the bone labyrinth.

The cavity of the inner ear is filled with two fluids: perilymph and endolymph.

Perilymph is used to fill the interlabyrinth cavities.
Endolymph is a thick, transparent liquid that is present in the membranous labyrinth and circulates through it.

The inner ear consists of three parts:

snail,
vestibule;
semicircular canals.

The structure of semicircular canals begins with the center of the maze - this is the vestibule. In the back of the ear, this cavity is connected to the semicircular canal. On the side of the wall there are "windows" - the internal openings of the channel of the cochlea. One of them is connected to the stepladder, the second, having an additional eardrumcommunicates with the spiral channel.

The structure of the snail is simple. The spiral bone plate is located along the entire length of the cochlea, dividing it into two sections:

drum ladder;
vestibule staircase.

The main feature of the semicircular canals is that they have legs with ampoules expanding at the end. Ampoules closely adjacent to the pouches. In front of the fused front and rear channels. The vestibulo-cochlear nerve serves to transmit nerve impulses.

Functions

Scientists have found that the structure of the inner ear has been modified with the evolution process. In organism modern man the inner ear will perform two functions.

Orientation in space. The vestibular apparatus located inside the auricle helps a person navigate the terrain and keep his body in the right position.

Here, the district channels and the vestibule will be involved.

Hearing. The processes responsible for the perception of sound signals by the brain occur inside the cochlea.

Perception of sounds and orientation

Eardrum shocks are caused by the movement of the endolymph. Perelymph that moves up the stairs also affects the perception of sound. Oscillations irritate the hair cells of the organ of Corti, which converts audible sound signals directly into nerve impulses.

The human brain receives information and analyzes it. Based on the information received, a person hears a sound.

For the position of the body in space, the vestibular apparatus is responsible. Roughly speaking, it acts like a building level used by workers. This organ helps maintain body balance. The vestibule and semicircular canals have a very complex systematic structure, inside them there are special receptors called scallops.

Scallops perceive head movements and react to them. In this they resemble the hair cells found in the cochlea. Irritation occurs due to the presence of a jelly-like substance in the scallops.

If necessary, orientation in space, receptors in the vestibule sacs come into activity. The linear acceleration of the body causes the endolymph to move, which causes irritation of the receptors. Then, information about the beginning of movement enters the human brain. Now there is an analysis of the information received. In the event that the information received from the eyes and from the vestibular apparatus is different, the person experiences dizziness.

For proper functioning of the inner ear, hygiene is essential. It is the timely cleaning of the ear canal from sulfur that will allow you to keep your hearing in good condition.

Possible diseases

Diseases of the auricle lower a person’s hearing, and also interfere with the vestibular apparatus to function properly. In the case when damage is caused to the cochlea, sound frequencies are perceived, but incorrectly. Human speech or street noise is perceived as cacophony from different sounds. This state of affairs not only impedes the normal functioning of hearing, it can also lead to serious injury.

The ear snail can suffer not only from sharp sounds, but also from the effect of an airplane take-off, sharp immersion in water and many other situations.

In this case, damage to the eardrum and. Thus, a person can lose hearing either for a long period, in more severe cases - for life. In addition, other troubles associated with the inner ear can happen.

Dizziness can have both independent causes, and possible.

This disease not fully investigated and its causes are unclear, but the main symptoms are considered periodic dizziness, accompanied by clouding of the auditory function.

Lop-eared. Despite the fact that this is a cosmetic nuance, many are puzzled by the problem of correcting deafness. In order to get rid of this ailment, plastic surgery is performed.

Due to damage to bone tissue (its proliferation), a decrease in ear sensitivity, the occurrence of noise, and a decrease in auditory function occur.

They call acute or chronic inflammation of the auricle, provoking a violation of its functioning.

Most “ear diseases” can be eliminated by observing. But, in the event of inflammatory processes, a consultation with the attending physician or ENT is necessary.

Video: Inner Ear

Everyone knows that the human ear has a complex structure: the outer, middle and inner ear. The middle ear plays an important role in the entire auditory process, as it performs a sound-conducting function. Diseases that occur in the middle ear are a direct threat to human life. Therefore, to study the structure, functions and methods of protecting the middle ear from infections is a very urgent task.

Organ structure

The middle ear is deep temporal bone and is represented by the following bodies:

tympanic cavity;
auditory tube
mastoid.

The middle ear is arranged as a collection of air cavities. Its central part is the tympanic cavity - the area between the inner ear and the eardrum. It has a mucous surface and resembles a prism or tambourine. The drum cavity is separated from the skull by the upper wall.

Anatomy of the middle ear involves the separation of its bone wall with the inner ear. There are 2 holes in this wall: round and oval. Each hole, or window, is protected by an elastic membrane.

The middle ear cavity also contains auditory ossicles, which transmit sound vibrations. Such bones include: a malleus, an anvil and stirrup. The names of the bones arose in connection with the features of their structure. Interaction mechanism auditory ossicles resembles a leverage system. The malleus, anvil and stirrup are connected by joints and ligaments. In the center of the eardrum is the handle of the malleus, its head is connected to the anvil, and it is connected by a long process to the head of the stapes. The stirrup enters the oval hole, behind which there is a vestibule - a part of the inner ear filled with fluid. All bones are covered with mucous membrane.

An important element of the middle ear is the auditory tube. It connects the tympanic cavity with the external environment. The mouth of the pipe is located at hard palate and opens into the nasopharynx. The mouth of the auditory tube is closed when there are no sucking or swallowing movements. There is one feature of the structure of the pipe in newborns: it is wider and shorter than in an adult. This fact facilitates the penetration of viruses.

The mastoid process is the process of the temporal bone, which is located behind it. The structure of the process is cavity, since it contains cavities filled with air. The cavities communicate with each other through narrow slits, which allows the middle ear to improve its acoustic properties.

The structure of the middle ear suggests the presence of muscles. The muscle straining the eardrum and the stirrup are the smallest muscles in the entire body. With their help, the auditory ossicles are supported on weight, regulated. In addition, the muscles of the middle ear provide accommodation for different sounds in height and strength.

Purpose and functions

The functioning of the organ of hearing without this element is impossible. The middle ear contains the most important components, which together perform the function of sound conduction. Without a middle ear, this function could not be realized, and a person could not hear.

The auditory ossicles provide bone conduction of sound and mechanical transmission of vibrations to the oval window of the vestibule. 2 small muscles perform a number of important hearing tasks:

maintain the tone of the eardrum and the mechanism of the auditory ossicles;
protect the inner ear from strong sound irritations;
provide accommodation of the sound-conducting apparatus to sounds of different strength and height.

Based on the functions that the middle ear with all its components performs, we can conclude that without it, the auditory function would be unfamiliar to a person.

Middle ear disease

Ear diseases are one of the most unpleasant ailments for humans. They carry a great danger not only to health, but also to human life. The middle ear, as the most important part of the auditory organ, is prone to various diseases. Leaving the middle ear disease untreated, a person runs the risk of becoming deaf and significantly reducing the quality of his life.

Among inflammatory diseases, there are:

Purulent otitis media refers to complex inflammatory processes. It is characterized by pronounced symptoms: shooting pains, purulent-bloody discharge from the ear, significant hearing impairment. With this disease, the tympanic membrane is affected, so it is extremely dangerous to delay purulent otitis media with treatment. The disease can go into a chronic stage.
Epitympanitis occurs when the tissue of the outer ear grows into the cavity of the eardrum. This process is dangerous because the bone structure of the inner and middle ear may be disturbed. On the good quality hearing in this case is not worth counting.
Mesothympanitis develops when the mucous membrane of the central part of the tympanic membrane is inflamed. The patient suffers from a decrease in hearing quality and frequent purulent discharge.
Cicatricial otitis media - restriction of the mobility of the mechanism of the auditory ossicles. With such otitis media, a very dense connective tissue. The main function of the ossicles - conducting sound - is significantly impaired.

Some diseases can lead to dangerous complications. For example, epithympanite can destroy top wall tympanic cavity and expose hard meninges. Purulent chronic otitis media is dangerous in that complications can not only affect the area of \u200b\u200bthe temporal bone, but also penetrate deep into the cranial cavity.

A distinctive feature of middle ear infections is that getting to it is much harder, as the middle ear is deep. In addition, the conditions are very favorable for infection, so you cannot delay treatment. If you experience any strange, unpleasant sensations in your ear, you must urgently consult an otolaryngologist to exclude the risk of a danger to life and health. Doctors categorically do not recommend self-medication. The treatment of hearing diseases without qualified help can adversely affect the entire auditory process.

Disease Control

The main source for the appearance and development of infections is reduced immunity. To reduce the risk of middle ear infections, it is necessary to take vitamins, exclude hypothermia. Everything must be done so that the immune system provides maximum resistance to any disease. It is useful to use decoctions from healing herbs for the prevention of inflammatory diseases.

A regular visit to a specialist will reveal any changes in the structure of the auditory organ and prevent the development of certain diseases. To study the condition of the middle ear, the doctor uses a special device - an otoscope. It is impossible to penetrate the middle ear with improvised means, therefore any unskilled intervention in the ear is dangerous - there is a risk of mechanical damage.

The disease must be cured before its complete disappearance. Otherwise, even ordinary otitis media can lead to dangerous complications.

In general, otitis media can be treated effectively and quickly, the main thing is to see a doctor on time, not to self-medicate and monitor general condition your health.

The middle ear is an integral part of the ear. It occupies the space between the external auditory organ and the eardrum. Numerous elements that have certain features and functions are involved in its structure.

Structural features

The middle ear consists of several important elements. Each of these components has structural features.

Drum cavity

This is the middle part of the ear, very vulnerable, often exposed inflammatory diseases. She is behind the eardrum, not reaching the inner ear. Its surface is covered with a thin mucous membrane. It has the shape of a prism with four irregular faces, inside it is filled with air. Consists of several walls:

The outer wall with a membranous structure is formed by the inner part of the eardrum, as well as the bone of the ear canal.
The inner wall at the top has a recess in which there is a vestibule window. It is a small oval hole that is covered by the lower surface of the stapes. Below it is a cape along which a furrow passes. Behind it is a funnel-shaped dimple, in which the snail window is placed. From above it is limited by a bone roller. Above the window of the cochlea there is a tympanic sinus, which is a small depression.
The upper wall, which is called the tympanic, as it is formed by a solid bone substance and protects it. The deepest part of the cavity is called the dome. This wall is necessary to separate the tympanic cavity from the walls of the skull.
The lower wall is jugular, as it participates in the creation of the jugular fossa. It has an uneven surface, as it contains drum cells necessary for air circulation.
The posterior mastoid wall contains an opening that leads into the mastoid cave.
The front wall has a bone structure and is formed by substance from the channel carotid artery. Therefore, this wall is called carotid.

Conventionally, the tympanic cavity is divided into 3 sections. The lower one is formed by the lower wall of the tympanic cavity. Medium is most of, the space between the upper and lower bounds. The upper section is the part of the cavity corresponding to its upper boundary.

Hearing bones

They are located in the region of the tympanic cavity and are important, since without them it would be impossible sound perception. This is a malleus, anvil and stirrup.

Their name comes from the corresponding form. They are very small and lined with mucous membranes on the outside.

These elements are connected to each other, forming real joints. They have limited mobility, but allow you to change the position of the elements. They are connected to each other as follows:

The hammer has a rounded head that connects to the handle.
The anvil has a rather massive body, as well as 2 processes. One of them is short, rests in a hole, and the second is long, directed to the handle of the malleus, thickened at the end.
The stirrup includes a small head, covered with articular cartilage from above, serves to articulate the anvil and 2 legs - one straight and the other more curved. These legs are attached to the oval plate contained in the vestibule window.

The main function of these elements is the transmission of sound impulses from the membrane to the oval window of the vestibule. In addition, these vibrations are amplified, which makes it possible to transfer them directly to the perilymph of the inner ear. This is due to the fact that the auditory ossicles are articulated in a lever manner. In addition, the size of the stapes is many times smaller than the eardrum. Therefore, even minor sound waves allow you to perceive sounds.

Muscle

The middle ear also has 2 muscles - they are the smallest in the human body. Muscle abdomen located in the secondary cavities. One serves to tension the eardrum and is attached to the handle of the malleus. The second is called stapes and is attached to the head of the stapes.

These muscles are necessary to maintain the position of the auditory ossicles, regulate their movements. This provides the ability to perceive sounds of varying strength.

Eustachian tube

The middle ear connects to the nasal cavity through the Eustachian tube. It is a small channel, about 3-4 cm long. On the inside, it is covered with a mucous membrane, on the surface of which there is a ciliated epithelium. The movement of his cilia is directed to the nasopharynx.

It is conditionally divided into 2 parts. The one that is adjacent to the ear cavity has walls with bone structure. And the part adjacent to the nasopharynx has cartilaginous walls. In the normal state, the walls are adjacent to each other, but when moving with the jaw they diverge in different directions. Due to this, air freely flows from the nasopharynx into the organ of hearing, providing the same pressure within the organ.

Due to the close proximity with the nasopharynx, the Eustachian tube is prone to inflammatory processes, since the infection can easily enter it from the nose. Its patency may be impaired with colds.

In this case, the person will experience congestion, which brings some discomfort. To deal with it, you can do the following:

Inspect the ear. An unpleasant symptom can be caused by an ear plug. You can delete it yourself. To do this, drop a few drops of peroxide into the ear canal. After 10-15 minutes, the sulfur will soften, so it can be easily removed.
Move the lower jaw. This method helps with mild congestion. Need to put forward lower jaw forward and move it from side to side.
Apply the Valsalva method. Suitable in cases where stuffy ears do not go away for a long time. It is necessary to close the ears and nostrils, take a deep breath. You need to try to exhale it with your nose closed. The procedure should be carried out very carefully, since during it can change arterial pressure and speed up your heartbeat.
Use the Toynbee method. It is necessary to fill the mouth with water, pinch the ear holes and nostrils, take a sip.

Eustachian tube is very important, because thanks to it is observed normal pressure in the ear. And when it is blocked various reasons this pressure is disturbed, the patient complains of tinnitus.

If after the above manipulations the symptom does not disappear, you must consult a doctor. Otherwise, complications may develop.

Mastoid

This is a small bone formation, convex above the surface and in shape resembling a papilla. Located behind the auricle. It is filled with numerous cavities - cells connected to each other by narrow slots. The mastoid process is necessary to improve the acoustic properties of the ear.

Main functions

The following middle ear functions can be distinguished:

Sound conduction. With it, the sound is transmitted to the middle ear. The outer part picks up sound vibrations, then they pass through the auditory canal, reaching the membrane. This leads to its vibration, which affects the auditory ossicles. Through them, vibrations are transmitted to the inner ear through a special membrane.
Uniform distribution of pressure in the ear. When atmospheric pressure is very different from what occurs in the middle ear, it is leveled off through the Eustachian tube. Therefore, when flying or when immersed in water, ears are temporarily blocked, as they adapt to new pressure conditions.
Safety function. The middle part of the ear is equipped with special muscles that protect the organ from injuries. With very strong sounds, these muscles reduce the mobility of the auditory ossicles to a minimum. Therefore, the membranes do not burst. However, if strong sounds are very sharp and sudden, the muscles may not have time to fulfill their functions. Therefore, it is important to guard against such situations, otherwise you can partially or completely lose your hearing.

Thus, the middle ear performs very important functions and is an integral part of the auditory organ. But it is very sensitive, so it should be protected from negative influences.. Otherwise, they may appear. various diseasesleading to hearing loss.

The human hearing organ is necessary for the natural functioning of man. Ears are responsible for the susceptibility of sound waves, processing into nerve impulses and the sending of converted decibels to the brain. In addition, the ear is responsible for performing the equilibrium function.

Despite the external simplicity of the auricle, the design of the organ of hearing is considered incredibly complex. In this material, the structure of the human ear.

Ear organ has a paired structure and is located in the temporal part of the cerebral cortex. The ear organ is characterized by the constant performance of several tasks.

However, among the main functions considered receiving and processing sounds of different frequencies.

Subsequently, they are transmitted to the brain and send signals to the body in the form of electrical signals.

The hearing aid perceives both low-frequency sounds and high-frequency sounds up to 2 tens of kHz.

A person accepts frequencies above sixteen Hertz. However the highest threshold human ear does not exceed twenty thousand hertz.

Only the outer region is open to the human eye. In addition, the ear consists from two departments:

the average;
internal.

Each section of the hearing aid has an individual structure and certain functions. The three sections are connected in an elongated auditory tube, which is directed to the brain. For visualization of this picture view the sectional photo of the ear.

The composition of the human ear

An exceptional organ in the structure of the body is the organ of hearing. Despite the external simplicity, this area has a complex structure. The main function of an organ is the distinction between signals, noise, tones and speech, their conversion and increase or decrease.

The following elements are responsible for maintaining all tasks in the ear:

The outer part. The structure of this area includes the external shell, which passes into the auditory tube.
Next is the tympanic region that separates the outer ear from the middle region.
The cavity located behind the tympanic region is called the middle ear, which includes the auditory bones and the Eustachian tube.
Next is the inner region of the ear, which is considered one of the most intricate and intricate in the structure of the described organ. The main task of this cavity is to maintain equilibrium.

In the anatomy of the ear are the following structural elements:

curl;
- This is a bulge on the outer part of the ear, located on the outer part;
the paired organ of the tragus is an antihelix. It is located on the top of the lobe;
earlobe.

Outdoor area

Outer earthat a person sees is called the outer area. It consists of soft tissues and a cartilaginous membrane.

Unfortunately, due to the soft structure of this area,

This leads to severe pain and prolonged treatment.

Mostly, young children and people who are professionally engaged in boxing or martial arts suffer from broken cartilage and bones of the ear.

In addition, the auricle is susceptible to numerous viral and. Most often this happens in the cold season and with frequent contact with the hearing organ with dirty hands.

Thanks to the outdoor area, man has the ability to hear sounds. It is through the outer part of the auditory organ that sound frequencies pass to the brain.

Interestingly, unlike animals, the human organ of hearing is immobile and, in addition to the described functions, does not have additional capabilities.

When sound frequencies enter the outer ear, decibels enter the middle part through the auditory canal. To protect and maintain the functioning of the middle region of the ear, it is covered with skin folds. This allows you to further protect your ears and process any sound frequencies.

The human ear can detect sounds at various distances: from one centimeter to twenty or thirty meters, depending on age.

Sulfur cork.

Hearing the described sound vibrations to the outer ear helps auditory tube which at the end of the passage is converted into bone tissue. In addition, the auditory tube is responsible for the functioning of the sulfur glands.

Sulfur is a yellow mucous substance necessary to protect the hearing organ from infections, bacteria, dust, foreign objects and small insects.

Sulfur is usually excreted independently. However, with improper cleaning or lack of hygiene, a sulfur plug is formed. Self-removal of the cork is prohibited, as you can push it further along the auditory canal.

To eliminate such an unpleasant problem, consult a specialist. He will wash his ear with specialized tinctures. If it’s not possible to go to a qualified doctor, get a “” or “”. These funds gently remove sulfur and cleanse the ear. However, the use of drugs is allowed with a small accumulation of sulfur.

Outer ear goes into middle area. They are separated by an eardrum. After processing the sounds in this area, the sound goes into the middle part. For visualization, see the photo of the outer shell below.

The structure of the outer area

You can clearly see the structure of the outer ear of a person with a description in the diagram below.

Auricle consists of twelve elements of varying complexity of structure:

curl;
rook;
darwin's tubercle;
cavity of the auricle;
anti-tragus;
the lobe;
curl leg;
tragus;
bowl of the sink;
lower leg antihelix;
triangular fossa;
upper leg antihelix.

The base of the outer ear includes elastic cartilage. The upper and outer edge of the ear is converted into a curl. The paired organ of the curl is closer to the aisle. It goes around the outer hole and forms two protrusions:

Prototype tragus located in the back.
Tragus, located in front.

Earlobe represents soft cloth in which there are no bones and cartilage.

Darwin's hillock has a pathological structure and is considered an anomaly of the body.

The structure of the middle ear of man

Middle ear the person is located behind the drum region and is considered the main structure of the organ of hearing. The volume of the middle part is about one cubic centimeter.

The middle region falls on the temporal part of the head, in which following items:

Drum area.
An auditory tube that connects the nasopharynx and the drum.
Next is a portion of the temporal bone called the mastoid process. It is located behind the outside of the auditory tube.

From the presented elements, it is necessary to analyze the structure of the drum part in more detail, since the main functions of processing sound frequencies pass in this area. So, the drum area is divided into three parts:

Adjacent to the eardrum the first part is the hammer. Its function is to receive sound waves and transmit them in the following areas.
After the malleus is an anvil. The main function of this area is the initial processing of sounds and the direction to the stirrup.
Directly in front of the internal area of \u200b\u200bthe organ of hearing and after the malleus is a stapes. It processes the received sound and translates the cleared signals further.

The main function of the auditory ossicles - This is the conversion of signals, noise, low or high frequencies and transmission from the outside to the inner ear. In addition, the malleus, anvil and stapes are responsible for following tasks:

maintaining the tone of the tympanic region and supporting its functioning;
softening too high sounds;
increase in low sound waves.

Any trauma or complications after lead to dysfunctions stirrups, anvils and a hammer. This can provoke not only hearing impairment, but also a loss of visual acuity forever.

It is important to understand that sharp sounds, such as explosions, can cause reflex contraction, thereby damaging the structure of the hearing organ. This will result in partial or total hearing loss.

Inner ear

The inner ear is considered one of the most complex component of the described organ. Due to its complex construction, this area is often referred to as webbed labyrinth.

The inner part is located in the stony area of \u200b\u200bthe temporal bone and connects to the middle ear with small windows of various shapes.

The structure of the inner ear of a person includes the following elements:

vestibule of the maze;
snail;
semicircular channels.

The composition of the last element includes form liquids two types:

Endolymph.
Perilymph.

In addition, in the inner ear is vestibular system. She is responsible for the equilibrium function in space.

As mentioned above, the labyrinth is located inside the bony skull.

The inner ear is separated from the brain by a space filled with a viscous fluid. She is responsible for conducting sounds.

The snail is located in the same area.

Snail It looks like a spiral channel, which is divided into two parts. This spiral channel is responsible for the conversion of sound vibrations.

Conclusion

Having become acquainted with what the ear consists of and with its structure, it is important to monitor the health of the ears daily. Important to maintain the immune system and at the slightest sign of a disease, consult a specialist.

Otherwise, the main function of the organ of hearing may be impaired and lead to serious complications in the form of loss of sensitivity of sounds and noises forever.

Remember that the organ of hearing must perform its functions without interruption. Inflammation of the ears entails severe consequences, and any disorders seriously affect the life of a person.

And morphologists call this structure organelukha and balance (organum vestibulo-cochleare). It distinguishes three departments:

external ear (external auditory meatus, auricle with muscles and ligaments);
middle ear (tympanic cavity, mastoid appendages, auditory tube)
(a membranous labyrinth located in the bone labyrinth inside the bone pyramid).

1. The outer ear concentrates sound vibrations and directs them into the external auditory opening.

2. In the auditory canal conducts sound vibrations to the eardrum

3. The eardrum is a membrane that vibrates when exposed to sound.

4. The hammer with its handle is attached to the center of the eardrum using ligaments, and its head is connected to the anvil (5), which, in turn, is attached to the stapes (6).

Tiny muscles help transmit sound by regulating the movement of these bones.

7. The Eustachian (or auditory) tube connects the middle ear to the nasopharynx. When the ambient pressure changes, the pressure on both sides of the eardrum is equalized through auditory tube.

Theortic organ consists of a number of sensitive cells equipped with hairs (12), which cover the basilar membrane (13). Sound waves are captured by the hair cells and converted into electrical impulses. Further, these electrical impulses are transmitted through the auditory nerve (11) to the head. Auditory nerve consists of thousands of the thinnest nerve fibers. Each fiber starts from a specific area of \u200b\u200bthe cochlea and transmits a specific sound frequency. Low-frequency sounds are transmitted along the fibers emanating from the top of the cochlea (14), and high-frequency sounds are transmitted through the fibers associated with its base. Thus, the function of the inner ear is the conversion of mechanical vibrations into electrical ones, since the brain can only receive electrical signals.

Outer ear is a sound pickup device. The external auditory canal conducts sound vibrations to the eardrum. The eardrum that separates the outer ear from the tympanic cavity, or middle ear, is a thin (0.1 mm) septum, shaped like an inwardly directed funnel. The membrane fluctuates under the influence of sound vibrations that have come to it through the external auditory canal.

Sound vibrations are captured auricles (in animals, they can turn to the sound source) and are transmitted along the external auditory canal to the eardrum, which separates the outer ear from the middle. Sound capture and the whole process of listening with two ears - the so-called binaural hearing - is important for determining the direction of sound. Sound vibrations coming from the side reach the nearest ear a few ten thousandths of a second (0.0006 s) earlier than to the other. This insignificant difference in the time of arrival of sound to both ears is enough to determine its direction.

Middle ear is a sound conducting device. It is an air cavity that connects through the auditory (Eustachian) tube to the nasopharynx cavity. Fluctuations from the tympanic membrane through the middle ear are transmitted by 3 auditory ossicles connected to each other - a malleus, anvil and stapes, and the latter, through the membrane of the oval window, transmits these vibrations of the fluid located in the inner ear - the perilymph.

Due to the peculiarities of the geometry of the auditory ossicles, the vibrations of the tympanic membrane of reduced amplitude but increased strength are transmitted to the stapes. In addition, the surface of the stapes is 22 times smaller than the tympanic membrane, which increases its pressure on the oval window membrane by the same amount. As a result of this, even weak sound waves acting on the eardrum can overcome the resistance of the membrane of the oval window of the vestibule and lead to fluid oscillations in the cochlea.

With strong sounds, special muscles reduce the mobility of the eardrum and auditory ossicles, adapting the hearing aid to such changes in the stimulus and protecting the inner ear from destruction.

Due to the connection through the auditory tube of the air cavity of the middle ear with the nasopharynx, it becomes possible to equalize the pressure on both sides of the eardrum, which prevents its rupture with significant changes in pressure in the external environment - when diving, lifting to heights, shots, etc. This is an ear barofunction .

Two muscles are located in the middle ear: the straining eardrum and the stirrup. The first of them, shortening, increases the tension of the eardrum and thereby limits the amplitude of its vibrations with strong sounds, and the second fixes the stapes and thereby limits its movement. Reflex contraction of these muscles occurs 10 ms after the onset of a strong sound and depends on its amplitude. This inner ear is automatically protected from overload. With instant strong irritations (strikes, explosions, etc.), this protective mechanism does not manage to work, which can lead to hearing impairment (for example, for explosives and artillerymen).

Inner ear is a sound pickup device. It is located in the pyramid of the temporal bone and contains a cochlea, which in humans forms 2.5 spiral turns. The cochlear canal is divided by two partitions by the main membrane and the vestibular membrane into 3 narrow passages: the upper (vestibular staircase), middle (membranous canal) and lower (tympanic stairs). On the top of the cochlea there is a hole connecting the upper and lower channels into a single one, going from the oval window to the top of the cochlea and further to the round window. Its cavity is filled with a liquid - peri-lymph, and the cavity of the middle membranous canal is filled with a liquid of a different composition - endolymph. In the middle channel there is a sound-receiving apparatus, the Corti organ, in which there are mechanoreceptors of sound vibrations - hair cells.

The main way to deliver sounds to your ear is through the air. Approached sound vibrates the eardrum, and then through the chain of auditory ossicles, the vibrations are transmitted to the oval window. At the same time, air vibrations of the tympanic cavity arise, which are transmitted to the round window membrane.

Another way to deliver sounds to the snail is tissue or bone conduction . In this case, the sound directly affects the surface of the skull, causing it to vibrate. Bone path of sound transmission It is of great importance if the vibrating object (for example, the tuning fork leg) comes into contact with the skull, as well as in diseases of the middle ear system, when the transmission of sounds through the chain of auditory ossicles is disrupted. In addition to the airway, conducting sound waves, there is a tissue, or bone, path.

Under the influence of airborne sound vibrations, as well as when vibrators (for example, a bone telephone or a bone tuning fork) come into contact with the integument of the head, the bones of the skull begin to oscillate (the bone labyrinth also begins to oscillate). Based on the latest data (Bekesy-Bekesy et al.), It can be assumed that the sounds propagating through the bones of the skull excite the organ of Corti only if they, like air waves, cause a certain section of the main membrane to bend.

The ability of the skull bones to conduct sound explains why the person himself, recorded on tape, seems alien to him when playing a recording, while others easily recognize him. The fact is that the tape recording does not fully reproduce your voice. Usually, while talking, you hear not only the sounds that your interlocutors hear (that is, those sounds that are perceived due to air-liquid conduction), but also those low-frequency sounds, the conductor of which is the bones of your skull. However, listening to the tape recording of your own voice, you hear only what could be recorded - sounds whose conductor is air.

Binaural hearing . Man and animals have spatial hearing, that is, the ability to determine the position of the sound source in space. This property is based on the presence of binaural hearing, or hearing with two ears. For him, the presence of two symmetrical halves at all levels is important. The acuity of binaural hearing in humans is very high: the position of the sound source is determined with an accuracy of 1 angular degree. The basis of this is the ability of neurons of the auditory system to evaluate the interaural (inter-ear) differences in the time of sound arrival to the right and left ear and sound intensity on each ear. If the sound source is away from the midline of the head, the sound wave arrives in one ear somewhat earlier and has greater strength than on the other ear. The assessment of the distance of the sound source from the body is associated with a weakening of the sound and a change in its timbre.

When the right and left ears are separately stimulated through the headphones, a delay between sounds of as little as 11 μs or a difference in the intensity of two sounds by 1 dB leads to an apparent shift in the localization of the sound source from the midline to an earlier or stronger sound. In auditory centers, there is an acute adjustment for a certain range of interaural differences in time and intensity. Also found cells that respond only to a certain direction of motion of the sound source in space.