Hearing analyzer, structure, functions. Abstract: Auditory analyzer Structure and operation of the auditory analyzer

The auditory analyzer is the most important part of the human sensory system. The structure of the auditory analyzer allows people to communicate with each other through sound transmission, perceive, interpret and respond to sound information: when a car approaches, thanks to the sounds perceived through hearing, a person moves out of the road in time, which allows him to avoid a dangerous situation.

Sound waves are vibrations in a solid, liquid or gaseous medium that can be heard using the organ of hearing. Sound is defined in the audible range of the spectrum, just as light is defined in the visible part of the electromagnetic wave spectrum.

Vibrations of sound waves are the propagation of motion at the molecular level, which is characterized by the movement of molecules around a state of equilibrium. In the process of this movement, which is created mechanically, the molecules are subjected to acoustic pressure, which causes them to collide with each other and transmit these vibrations further. When the transfer of energy stops, the displaced molecules return to their original position.

The similarity between the visual and auditory analyzers is that they are both capable of perceiving specific qualities, selecting them from the general sound stream. For example, the location of the sound source, its volume, timbre, etc. But the physiology of the auditory analyzer functions in such a way that the human auditory system does not mix different frequencies, as vision does when different wavelengths of light are mixed with each other - and the ocular analyzer represents this as a continuous color.

Instead sound analyzer separates complex sounds into their component tones and frequencies so that a person can distinguish the voices of specific people in a general hum or individual instruments in the sounds of an orchestra. Features of hearing abnormalities make it possible to identify various audiometric methods for studying the auditory analyzer.

Outer and middle ear

The way the auditory analyzer is structured affects the functioning of its structures, parts of the ear, subcortical relay and cortical centers. The anatomy of the auditory analyzer includes the structure of the ear, stem and cortical parts of the brain. The sections of the auditory analyzer are:

• peripheral part of the auditory analyzer;
• cortical end of the auditory analyzer.

According to the diagram, the structure of the ear consists of 3 parts. The outer and middle ear transmit sounds to the inner ear, where they are converted into electrical impulses for processing by the nervous system. Thus, the functions of the auditory analyzer are divided into sound-conducting and sound-perceiving.

The outer, middle and inner ear are the peripheral parts of the auditory analyzer. The outer part of the ear consists of the pinna and the auditory canal. This passage closes with inside eardrum. The auditory analyzer, the structure and functions of which include the peripheral section of the auditory analyzer, acts as an acoustic antenna.

Sound waves are collected in a part of the outer ear called the pinna and travel through the ear canal. eardrum, causing it to vibrate. Thus, the outer ear acts as a resonator, which amplifies sound vibrations.

The eardrum is the end of the outer ear. Then the middle begins, which communicates with the nasopharynx through the Eustachian tubes. The age-related features of the auditory analyzer are that in newborns the middle ear cavity is filled with amniotic fluid, which by the third month is replaced by air that enters here through the Eustachian tubes. In the middle ear cavity, the eardrum is connected by a chain of three auditory ossicles with another membrane called the oval window. She closes the cavity inner ear.

The first bone, the malleus, vibrates under the action of the eardrum, transmits these vibrations to the incus, which causes the stirrup to vibrate, which presses on the oval window in the cochlea. The base of the stapes has mechanical pressure, amplified tens of times, onto the oval window, as a result of which the perilymph in the cochlea begins to fluctuate. In addition to the oval window, there is a round window, which also separates the cavity of the middle ear and the inner ear.

The ratio of the eardrum to the surface of the oval window is 20:1, which makes it possible to amplify sound vibrations twenty times. This is necessary so that the vibration of fluid in the inner ear requires much more energy than the average vibration of air.

Inner ear

The inner ear contains two different organs - the auditory and vestibular analyzers. Due to this, the schematic structure of the inner ear provides for the presence of:

• vestibule;
• semicircular canals (responsible for coordination);
• cochlea (responsible for hearing).

Both analyzers have similar morphological and physiological properties. Among them are hair cells and the mechanism for transmitting information to the brain.

The discrimination of sound frequencies begins in the cochlea of ​​the inner ear. It is designed in such a way that its different parts respond to different pitches of sound vibrations. High notes vibrate some parts of the basilar membrane of the cochlea, low notes vibrate others.

The basilar membrane contains hair cells, at the top of which there are entire bundles of stereocilia, which are deflected by the membrane located on top. Hair cells convert mechanical vibrations into electrical signals that travel along the auditory nerve to the brain stem. Thus, the conductive section of the auditory analyzer is represented by fibers auditory nerve. Because each hair cell has its own location in the basilar membrane, each cell transmits a different pitch of sound to the brain.

Structure of the cochlea

The cochlea is the “hearing” part of the inner ear, which is located in the temporal part of the skull. It gets its name from its spiral shape, reminiscent of a snail shell.

The cochlea consists of three channels. Two of them, the scala tympani and the scala vestibule, are filled with a fluid called perilymph. The interaction between them occurs through a small hole called helicotrema. In addition, between the scala tympani and scala vestibuli, neurons of the spiral ganglion and fibers of the auditory nerve are located on the inner side.

The third canal, scala media, is located between the scala tympani and scala vestibule. It is filled with endolymph. Between the scala media and the scala tympani on the basilar membrane there is a structure called the organ of Corti.

The cochlear ducts are composed of two types of fluid, perilymph and endolymph. Perilymph has the same ionic composition as extracellular fluid in any other part of the body. It fills the scala tympani and scala vestibule. The endolymph that fills the scala media has a unique composition intended only for this part of the body. First of all, it is very rich in potassium, which is produced in the stria vascularis, and very poor in sodium. It also contains virtually no calcium.

Endolymph has a positive electrical potential (+80 mV) relative to perilymph, which is rich in sodium. The organ of Corti in the upper part, where the stereocilia are located, is moistened by endolymph, and at the base of the cells by perilymph.

Using this method, the cochlea is able to carry out a very complex analysis of sounds, both in terms of their frequency and volume. When the pressure of sounds is transmitted to the fluid of the inner ear by the stapes, the pressure of the waves deforms the basilar membrane in the area of ​​the cochlea that is responsible for these vibrations. Thus, higher notes cause the base of the cochlea to vibrate, and lower notes cause its top to vibrate.

It has been proven that the human cochlea is capable of perceiving sounds of different tones. Their frequency can vary from 20 Hz to 20,000 Hz (approximately the 10th octave), in steps of 1/230 octave (from 3 Hz to 1 thousand Hz). At a frequency of 1 thousand Hz, the cochlea is able to encode the pressure of sound waves in the range between 0 dB and 120 dB.

Auditory cortex

In addition to the ear and auditory nerve, the auditory analyzer includes the brain. Sound information is analyzed in different centers in the brain as the signal is sent to the superior temporal gyrus of the brain. This is the auditory cortex, which performs the sound-processing function of the human auditory analyzer. Here is huge amount neurons, each of which performs its own task. For example, there are neurons that:

• react to pure tones (flute sounds);
• recognize complex tones (violin sounds);
• responsible for long sounds;
• react to short sounds;
• respond to changes in sound volume.

There are also neurons that can be responsible for complex sounds, for example, identifying a musical instrument or a word of speech. Connections between the auditory and speech motor analyzers allow a person to learn foreign languages.

Sound information is processed in various areas sound cortex in both hemispheres of the brain. For most people, the left side of the brain is responsible for the perception and production of speech. Therefore, damage to the left auditory cortex during a stroke can lead to the fact that although a person will hear, he will not be able to understand speech.

Primary path

Sound information is collected in the brain by two pathways of the auditory analyzer:

• The primary auditory pathway, which carries messages exclusively from the cochlea.
• The non-primary auditory pathway, also called the reticular sensory pathway. It conveys messages from all senses.

The primary path is short and very fast, since the speed of impulse transmission is provided by fibers with a thick layer of myelin. This pathway ends in the auditory cortex of the brain, which is located in the lateral sulcus of the temporal part of the brain.

The primary pathways of the auditory analyzer conduct nerve impulses from the sound-sensitive cells of the cochlea. At the same time, at each final point of the transmission link, decoding and integration of nerve impulses occurs by the nuclear cells of the cochlea.

The first switching nucleus of the primary auditory pathway is located in the cochlear nuclei, which is located in the brain stem. Nerve impulses travel along spiral gangliary axons of type 1. At this level of switching, nerve sound signals are deciphered, which characterize the duration, intensity and frequency of the sound.

The second and third switching nuclei of the primary auditory pathway play a significant role in determining the location of the sound source. The second switching nucleus in the brainstem is called the superior olivary complex. At this level, most auditory nerve synapses have crossed the central line. The third switching nucleus is located at the level of the midbrain.

And finally, the fourth switching nucleus is located in the thalamus. Here, significant integration of sound information occurs, and preparation for motor reaction(for example, making sounds in response).

The last neuron of the primary pathway connects the thalamus and the auditory cortex of the brain. Here the message, most of which was deciphered on the way here, is recognized, stored and integrated for further random use.

Non-primary paths

From the cochlear nuclei, small nerve fibers pass into the reticular formation of the brain, where sound messages are combined with nerve messages that come here from other senses. The next switching point is the nonspecific nuclei of the thalamus, after which this auditory pathway ends in the polysensory associative cortex.

The main function of these auditory pathways is the production of nerve messages that are subject to priority processing. To do this, they connect to the centers of the brain responsible for feelings of wakefulness and motivation, as well as to the autonomic nervous and endocrine systems. For example, if a person is doing two things at once, reading a book and listening to music, this system will direct attention to more important work.

The first transfer point of the non-primary auditory pathway, as well as the primary one, is located in the cochlear nuclei of the brain stem. From here, small fibers join the reticular tract of the brainstem. Here, as well as in the midbrain, there are several synapses where auditory information is processed and integrated with information from other senses.

In this case, information is filtered by primary priority. In other words, the role of the reticular formation of the brain is to connect nerve messages from other centers (wakefulness, motivation) to the processed sound information, so that there is a selection of nerve messages that will be processed in the brain first. After the reticular formation, non-primary pathways lead to nonspecific centers in the thalamus, and then to the polysensory cortex.

It must be understood that conscious perception requires the integration of both types of auditory neural pathways, primary and non-primary. For example, during sleep, the primary auditory pathway functions normally, but conscious perception is impossible because the connection between the reticular pathway and the centers of wakefulness and motivation is not activated.

Conversely, as a result of trauma to the cortex, conscious perception of sounds may be impaired, while continued integration of non-primary auditory pathways may result in autonomic nervous system responses to sound. In addition, if the brainstem and midbrain are intact, the startle and surprise response may remain, even in the absence of understanding the meaning of the sounds.

Sound waves are vibrations transmitted at a certain frequency in all three media: liquid, solid and gaseous. For human perception and analysis, there is an organ of hearing - the ear, which consists of outer, middle and inner parts, capable of receiving information and transmitting it to the brain for processing. This principle of operation in the human body is similar to that characteristic of the eyes. The structure and functions of the visual and auditory analyzers are similar to each other, the difference is that the ear does not mix sound frequencies, perceives them separately, rather, even separating different voices and sounds. In turn, the eyes connect light waves, thereby receiving different colors and shades.

Hearing analyzer, structure and functions

You can see photographs of the main parts of the human ear in this article. The ear is the main organ of hearing in humans; it receives sound and transmits it further to the brain. The structure and functions of the auditory analyzer are much broader than the capabilities of the ear alone; it is a coordinated work of transmitting impulses from the eardrum to the stem and cortical parts of the brain responsible for processing the received data.

The organ responsible for the mechanical perception of sounds consists of three main sections. The structure and functions of the sections of the auditory analyzer are different from each other, but they perform one general work- perception of sounds and their transmission to the brain for further analysis.

Outer ear, its features and anatomy

The first thing that sound waves encounter on the way to the perception of their semantic load is its anatomy is quite simple: it is the auricle and the external ear canal, which is the link between it and the middle ear. The auricle itself consists of a cartilaginous plate 1 mm thick, covered with perichondrium and skin, it is devoid of muscle tissue and cannot move.

The lower part of the shell is the earlobe, it is fatty tissue, covered with skin and penetrated by many nerve endings. The concha smoothly and funnel-shaped passes into the auditory canal, bounded by the tragus in front and the antitragus in the back. In an adult, the passage is 2.5 cm in length and 0.7-0.9 cm in diameter; it consists of internal and membranous cartilaginous sections. It is limited by the eardrum, behind which the middle ear begins.

The membrane is an oval-shaped fibrous plate, on the surface of which elements such as the malleus, posterior and anterior folds, umbilicus and short process can be distinguished. The structure and functions of the auditory analyzer, represented by such parts as the outer ear and the eardrum, are responsible for capturing sounds, their primary processing and transmission further to the middle part.

Middle ear, its features and anatomy

The structure and functions of the sections of the auditory analyzer are radically different from each other, and if everyone is familiar with the anatomy of the outer part firsthand, then more attention should be paid to studying information about the middle and inner ear. The middle ear consists of four air cavities connected to each other and an incus.

The main part that performs the main functions of the ear is the auditory tube, combined with the nasopharynx, through which the entire system is ventilated. The cavity itself consists of three chambers, six walls and which, in turn, is represented by the hammer, anvil and stirrup. The structure and functions of the auditory analyzer in the middle ear transform the sound waves received from the outer part into mechanical vibrations, after which they transmit them to the fluid, which fills the cavity of the inner part of the ear.

Inner ear, its features and anatomy

The inner ear is the most complex system of all three parts of the hearing system. It looks like a labyrinth, which is located in the thickness of the temporal bone, and is a bone capsule and a membranous formation included in it, which completely repeats the structure of the bone labyrinth. Conventionally, the entire ear is divided into three main parts:

• the middle labyrinth is the vestibule;
• anterior labyrinth - cochlea;
• posterior labyrinth - three semicircular canals.

The labyrinth completely repeats the structure of the bone part, and the cavity between these two systems is filled with perilymph, reminiscent in its composition of plasma and cerebrospinal fluid. In turn, the cavities in the cell itself are filled with endolymph, which is similar in composition to intracellular fluid.

Hearing analyzer, inner ear receptor function

Functionally, the work of the inner ear is divided into two main functions: transmitting sound frequencies to the brain and coordinating human movements. The main role in transmitting sound to parts of the brain is played by the cochlea, different parts of which perceive vibrations with different frequencies. All these vibrations are absorbed by the basilar membrane, covered with hair cells with bundles of stereolicia at the top. It is these cells that convert vibrations into electrical impulses that travel to the brain along the auditory nerve. Each hair of the membrane has different size and receives sound only at a strictly defined frequency.

The principle of operation of the vestibular apparatus

The structure and functions of the auditory analyzer are not limited to the perception and processing of sounds; it plays an important role in all human motor activity. The fluids that fill part of the inner ear are responsible for the functioning of the vestibular apparatus, on which coordination of movements depends. The main role here is played by the endolymph; it works on the principle of a gyroscope. The slightest tilt of the head causes it to move, which, in turn, causes the otoliths to move, which irritate the hairs of the ciliated epithelium. With the help of complex neural connections all this information is transmitted to parts of the brain, then its work begins to coordinate and stabilize movements and balance.

The principle of coordinated operation of all chambers of the ear and brain, the transformation of sound vibrations into information

The structure and functions of the auditory analyzer, which can be briefly studied above, are aimed not just at capturing sounds of a certain frequency, but at converting them into information understandable by the human consciousness. All transformation work consists of the following main stages:

1. Catching sounds and moving them along the ear canal, stimulating the eardrum to vibrate.
2. Vibration of the three auditory ossicles of the inner ear caused by vibrations of the eardrum.
3. Fluid movement in the inner ear and vibrations of hair cells.
4. Converting vibrations into electrical impulses for their further transmission along the auditory nerves.
5. Promotion of impulses along the auditory nerve to parts of the brain and converting them into information.

Auditory cortex and information analysis

No matter how well-functioning and ideal the work of all parts of the ear would be, everything would be meaningless without the functions and work of the brain, which converts all sound waves into information and guidance for action. The first thing a sound encounters on its way is the auditory cortex, located in the superior temporal gyrus of the brain. Here are the neurons that are responsible for the perception and separation of all ranges of sound. If, due to any brain damage, such as a stroke, these parts are damaged, the person may become hard of hearing or completely lose hearing and the ability to perceive speech.

Age-related changes and features in the functioning of the auditory analyzer

As a person ages, the operation of all systems changes; the structure, functions and age-related characteristics of the auditory analyzer are no exception. Older people often experience hearing loss, which is considered physiological, i.e. normal. This is not considered a disease, but only age-related changes called persbycusis, which does not need to be treated, but can only be corrected with the help of special hearing aids.

Highlight a whole series reasons why hearing loss is possible in people who have reached a certain age threshold:

1. Changes in the outer ear - thinning and sagging of the auricle, narrowing and curvature of the ear canal, loss of its ability to transmit sound waves.
2. Thickening and clouding of the eardrum.
3. Reduced mobility of the ossicular system of the inner ear, stiffness of their joints.
4. Changes in the parts of the brain responsible for processing and perceiving sounds.

In addition to the usual functional changes in a healthy person, problems can be aggravated by the complications and consequences of previous otitis media; they can leave scars on the eardrum, which provoke problems in the future.

After medical scientists studied such an important organ as the auditory analyzer (structure and function), age-related deafness ceased to be a global problem. Hearing aids, aimed at improving and optimizing the functioning of each department of the system, help older people live a full life.

Hygiene and care of human hearing organs

To keep your ears healthy, they, like the rest of your body, need timely and careful care. But, paradoxically, in half the cases problems arise precisely because of excessive care, and not because of its lack. The main reason is inept equipment ear sticks or other means for mechanical cleaning of accumulated sulfur, touching the tympanic septum, scratching it and the possibility of accidental perforation. To avoid such injuries, only clean the outside of the passage without using sharp objects.

To preserve your hearing in the future, it is better to follow the safety rules:

• Limited listening to music using headphones.
• Using special headphones and earplugs when working in noisy workplaces.
• Protection against water getting into your ears while swimming in pools and ponds.
• Prevention of otitis and colds of the ears during the cold season.

Understanding the operating principles of a hearing analyzer and following hygiene and safety rules at home or at work will help you preserve your hearing and not face the problem of hearing loss in the future.

The receptive part of the auditory analyzer is the ear, the conductive part is the auditory nerve, and the central part is the auditory zone of the cerebral cortex. The hearing organ consists of three sections: the outer, middle and inner ear. The ear includes not only the organ of hearing itself, with the help of which we perceive auditory sensations, but also an organ of balance, due to which the body is held in a certain position.

The outer ear consists of the pinna and the external auditory canal. The shell is formed by cartilage covered on both sides by skin. With the help of a shell, a person catches the direction of sound. The muscles that move the auricle are rudimentary in humans. The external auditory canal looks like a tube 30 mm long, lined with skin, in which there are special glands that secrete earwax. In the depths, the ear canal is covered with a thin oval-shaped eardrum. On the side of the middle ear, in the middle of the eardrum, the handle of the hammer is strengthened. The membrane is elastic; when struck by sound waves, it repeats these vibrations without distortion.

Middle ear represented tympanic cavity, which communicates with the nasopharynx through the auditory (Eustachian) tube; It is delimited from the outer ear by the eardrum. The components of this department are: hammer, anvil And stapes. With its handle, the malleus fuses with the eardrum, while the anvil is articulated with both the malleus and the stirrup, which covers the oval hole leading to the inner ear. In the wall separating the middle ear from the inner ear, except oval window There is also a round window covered with membrane.
Structure of the hearing organ:
1 - auricle, 2 - external auditory canal,
3 - eardrum, 4 - middle ear cavity, 5 - auditory tube, 6 - cochlea, 7 - semicircular canals, 8 - anvil, 9 - hammer, 10 - stapes

The inner ear, or labyrinth, is located deep in the temporal bone and has double walls: membranous labyrinth as if inserted into bone, repeating its shape. The slit-like space between them is filled with a transparent liquid - perilymph, cavity of the membranous labyrinth - endolymph. Labyrinth presented the threshold anterior to it is the cochlea, posteriorly - semicircular canals. The cochlea communicates with the middle ear cavity through a round window covered by a membrane, and the vestibule communicates through the oval window.

The organ of hearing is the cochlea, its remaining parts make up the organs of balance. The cochlea is a spirally twisted canal of 2 3/4 turns, separated by a thin membranous septum. This membrane is spirally curled and is called basic. It consists of fibrous tissue, which includes about 24 thousand special fibers (auditory strings) of different lengths and located transversely along the entire course of the cochlea: the longest are at its apex, and the shortest at the base. Overhanging these fibers are auditory hair cells - receptors. This is the peripheral end of the auditory analyzer, or organ of Corti. The hairs of the receptor cells face the cavity of the cochlea - the endolymph, and the auditory nerve originates from the cells themselves.

Perception of sound stimuli. Sound waves passing through the external auditory canal cause vibrations in the eardrum and are transmitted to the auditory ossicles, and from them to the membrane of the oval window leading to the vestibule of the cochlea. The resulting vibration sets in motion the perilymph and endolymph of the inner ear and is perceived by the fibers of the main membrane, which carries the cells of the organ of Corti. High-pitched sounds with a high vibration frequency are perceived by short fibers located at the base of the cochlea and transmitted to the hairs of the cells of the organ of Corti. In this case, not all cells are excited, but only those located on fibers of a certain length. Consequently, the primary analysis of sound signals begins already in the organ of Corti, from which excitation along the fibers of the auditory nerve is transmitted to the auditory center of the cerebral cortex in the temporal lobe, where their qualitative assessment occurs.

Vestibular apparatus. In determining the position of a body in space, its movement and speed of movement, it plays an important role vestibular apparatus. It is located in the inner ear and consists of vestibule and three semicircular canals, located in three mutually perpendicular planes. The semicircular canals are filled with endolymph. In the endolymph of the vestibule there are two sacs - round And oval with special lime stones - statolites, adjacent to the hair receptor cells of the sacs.

In normal body position, the statoliths irritate the hairs of the lower cells with their pressure; when the body position changes, the statoliths also move and irritate other cells with their pressure; the received impulses are transmitted to the cortex cerebral hemispheres. In response to irritation of the vestibular receptors associated with the cerebellum and the motor zone of the cerebral hemispheres, muscle tone and body position in space reflexively change. Three semicircular canals extend from the oval sac, which initially have extensions - ampoules, in which hair cells - receptors are located. Since the channels are located in three mutually perpendicular planes, the endolymph in them, when the body position changes, irritates certain receptors, and the excitation is transmitted to the corresponding parts of the brain. The body reflexively responds with the necessary change in body position.

Hearing hygiene. Earwax accumulates in the external auditory canal and traps dust and microorganisms, so it is necessary to regularly wash your ears with warm soapy water; Under no circumstances should you remove sulfur with hard objects. Overfatigue of the nervous system and overstrain of hearing can cause sharp sounds and noises. Prolonged noise is especially harmful, causing hearing loss and even deafness. Loud noise reduces labor productivity by up to 40-60%. To combat noise in industrial environments, walls and ceilings are lined with special materials that absorb sound, and individual noise-reducing headphones are used. Motors and machines are installed on foundations that muffle the noise from the shaking of the mechanisms.

Subject:"Hearing analyzer"

Plan

1. The concept of analyzers and their role in understanding the world around us

2. Structure and functions of the hearing organ

3. Sensitivity of the auditory analyzer

4. Hygiene of the child’s hearing organ

5. Identify deviations from the norm in the functioning of the auditory analyzer of children in your group

1. The concept of analyzers and their role in understanding the world around us

The body and the external world are a single whole. The perception of our environment occurs through the senses or analyzers. Aristotle described five basic senses: sight, hearing, taste, smell and touch.

Term "analyzer"(decomposition, dismemberment) was introduced by I.P. Pavlov in 1909 to designate a set of formations whose activity ensures the decomposition and analysis in the nervous system of stimuli affecting the body. “Analyzers are devices that decompose the external world into elements and then transform irritation into sensation” (I.P. Pavlov, 1911 - 1913).

The analyzer is not just an ear or an eye. It is a set of nervous structures, including a peripheral perceptive apparatus (receptors), which transforms the energy of stimulation into a specific process of excitation; the conductive part, represented by peripheral nerves and conduction centers, transmits the resulting excitation to the cerebral cortex; central part - nerve centers located in the cerebral cortex, analyzing the received information and forming an appropriate sensation, after which a certain tactic of behavior of the body is developed. With the help of analyzers, we objectively perceive the outside world as it is. This is a materialistic understanding of the issue. On the contrary, the idealistic concept of the theory of knowledge of the world was put forward by the German physiologist I. Muller, who formulated the law of specific energy. The latter, according to I. Muller, is embedded and formed in our senses, and we perceive this energy in the form of certain sensations. But this theory is not correct, since it is based on the action of stimulation that is inadequate for a given analyzer. The intensity of the stimulus is characterized by the threshold of sensation (perception). The absolute threshold of sensation is the minimum intensity of the stimulus that creates the corresponding feeling. Differential threshold is the minimum difference in intensity that is perceived by the subject. This means that the analyzers are able to give quantification increase in sensation in the direction of its increase or decrease. Thus, a person can distinguish bright light from less bright light, evaluate the sound by its pitch, tone and volume. The peripheral part of the analyzer is represented either by special receptors (tongue papillae, olfactory hair cells) or by a complex organ (eye, ear). The visual analyzer provides the perception and analysis of light stimuli, and the formation of visual images. The cortical department of the visual analyzer is located in occipital lobes cerebral cortex. The visual analyzer is involved in the implementation writing. The auditory analyzer provides perception and analysis of sound stimuli. The cortical section of the auditory analyzer is located in the temporal region of the cerebral cortex. Using an auditory analyzer, it is carried out oral speech.

The speech motor analyzer provides the perception and analysis of information coming from the speech organs. The cortical section of the speech motor analyzer is located in the postcentral gyrus of the cerebral cortex. With the help of reverse impulses coming from the cerebral cortex to the motor nerve endings in the muscles of the respiratory and articulation organs, the activity of the speech apparatus is regulated.

2. Structure and functions of the hearing organ

The organ of hearing and balance, the vestibular-cochlear organ in humans, has a complex structure, perceives vibrations of sound waves and determines the orientation of the body’s position in space.

The vestibulocochlear organ is divided into three parts: the outer, middle and inner ear. These parts are closely related anatomically and functionally. The outer and middle ear conduct sound vibrations to the inner ear, and are thus a sound-conducting apparatus. The inner ear, in which the bony and membranous labyrinths are distinguished, forms the organ of hearing and balance.

Outer ear includes the auricle, external auditory canal and eardrum, which are designed to capture and conduct sound vibrations. Auricle consists of elastic cartilage and has a complex configuration; the outside is covered with skin. There is no cartilage in the lower part, the so-called lobule or lobe. The free edge of the shell is rolled up and is called a helix, and the ridge running parallel to it is called an antihelix. At the anterior edge of the auricle there is a protrusion - the tragus, and behind it is the antitragus. The auricle is attached to the temporal bone by ligaments and has rudimentary muscles that are well expressed in animals. The auricle is designed to concentrate sound vibrations as much as possible and direct them into the external auditory opening.

External auditory canal It is an S-shaped tube that opens from the outside with the auditory opening and ends blindly in the depths and is separated from the middle ear cavity by the eardrum. The length of the ear canal in an adult is about 36 mm, the diameter at the beginning reaches 9 mm, and at the narrow place 6 mm. The cartilaginous part, which is a continuation of the cartilage of the auricle, makes up 1/3 of its length, the remaining 2/3 is formed by the bone canal of the temporal bone. At the junction of one part to another, the external auditory canal is narrowed and curved. It is lined with skin and is rich in fatty glands that produce earwax.

Eardrum- a thin translucent oval plate measuring 11x9 mm, which is located on the border of the outer and middle ear. It is located obliquely, forming an acute angle with the lower wall of the ear canal. The eardrum consists of two parts: a large lower part, the tense part, and a smaller upper part, the loose part. On the outside it is covered with skin, its base is formed by connective tissue, and on the inside it is lined with mucous membrane. In the center of the eardrum there is a depression - the navel, which corresponds to the attachment on the inside of the handle of the hammer.

Middle ear includes a mucous membrane-lined and air-filled tympanic cavity (volume about 1 cm3) and an auditory (Eustachian) tube. The middle ear cavity connects with the mastoid cave and, through it, with the mastoid cells of the mastoid process.

Tympanic cavity located in the thickness of the pyramid of the temporal bone, between the tympanic membrane laterally and the bony labyrinth medially. It has six walls: 1) the upper tegmental wall - separates it from the cranial cavity and is located on the upper surface of the pyramid of the temporal bone; 2) inferior jugular - the wall separates the tympanic cavity from the outer base of the skull, is located on the lower surface of the pyramid of the temporal bone and corresponds to the area of ​​the jugular fossa; 3) medial labyrinth - separates the tympanic cavity from the bony labyrinth of the inner ear. On this wall there is an oval opening - the window of the vestibule, closed by the base of the stapes; slightly higher on this wall there is a protrusion of the facial canal, and below is the window of the cochlea, closed by the secondary tympanic membrane, which separates the tympanic cavity from the scala tympani; 4) posterior mastoid - separates the tympanic cavity from the mastoid process and has an opening that leads into mastoid cave, the latter in turn connects with the mastoid cells; 5) anterior carotid – borders the carotid canal. Here is the tympanic opening of the auditory tube, through which the tympanic cavity is connected to the nasopharynx; 6) lateral membranous - formed by the tympanic membrane and the surrounding parts of the temporal bone.

In the tympanic cavity there are three auditory ossicles covered with mucous membrane, as well as ligaments and muscles. The auditory ossicles are small. Connecting with each other, they form a chain that stretches from the eardrum to the oval opening. All bones are connected to each other using joints and are covered with a mucous membrane. The hammer is fused with the handle to the eardrum, and the head, through a joint, is connected to the anvil, which in turn is movably connected to the stirrup. The base of the stapes closes the window of the vestibule.

There are two muscles in the tympanic cavity: one goes from the canal of the same name to the handle of the malleus, and the other, the stapedius muscle, goes from the back wall to the back leg of the stapes. When the stapedius muscle contracts, the pressure of the base on the perilymph changes.

Eustachian tube has an average length of 35 mm, a width of 2 mm, serves to allow air to enter the tympanic cavity from the pharynx and maintains pressure in the cavity equal to the external one, which is very important for normal operation sound-conducting apparatus. The auditory tube has cartilaginous and bony parts and is lined with ciliated epithelium. The cartilaginous part of the auditory tube begins with the pharyngeal opening on the side wall of the nasopharynx, goes down and laterally, then narrows and forms an isthmus. The bony part is smaller than the cartilaginous part, lies in the hemicanal of the pyramid of the temporal bone of the same name and opens into the tympanic cavity through the opening of the auditory tube.

Inner ear located in the thickness of the pyramid of the temporal bone, separated from the tympanic cavity by its labyrinthine wall. It consists of a bone labyrinth and a membranous labyrinth inserted into it.

The bony labyrinth consists of the cochlea, vestibule and semicircular canals. The vestibule is a cavity of small size and irregular shape. There are two openings on the lateral wall: the window of the vestibule and the window of the cochlea. On the medial wall of the vestibule there is a crest of the vestibule, which divides the cavity of the vestibule into two recesses - the anterior spherical and posterior elliptical. Through an opening on the posterior wall, the cavity of the vestibule is connected to the bony semicircular canals, and through an opening on the anterior wall, the spherical recess of the vestibule is connected to the bony spiral canal of the cochlea.

Snail– the anterior part of the bony labyrinth, it is a convoluted spiral canal of the cochlea, which forms 2.5 turns around the axis of the cochlea. The base of the cochlea is directed medially towards the internal auditory canal; the top of the cochlea's dome is towards the tympanic cavity. The axis of the cochlea lies horizontally and is called the bony cochlear shaft. A bone spiral plate wraps around the rod, which partially blocks the spiral canal of the cochlea. At the base of this plate there is a spiral channel of the rod, where the spiral ganglion snails

Bone semicircular canals They are three arcuately bent thin tubes that lie in three mutually perpendicular planes. On a transverse section, the width of each bony semicircular canal is about 2 mm. The anterior (sagittal, superior) semicircular canal lies above the other canals, and its upper point on the anterior wall of the pyramid forms an arcuate eminence. The posterior (frontal) semicircular canal is located parallel to the posterior surface of the pyramid of the temporal bone. The lateral (horizontal) semicircular canal protrudes slightly into the tympanic cavity. Each semicircular canal has two ends - bony pedicles. One of them is a simple bone pedicle, the other is an ampullary bone pedicle. The semicircular canals open with five openings into the cavity of the vestibule, and the adjacent legs of the anterior and posterior valves form a common bony pedicle, which opens with one opening.

Membranous labyrinth in its shape and structure it coincides with the shape of the bone labyrinth and differs only in size, since it is located inside the bone labyrinth.

The space between the bony and membranous labyrinths is filled with perilymph, and the cavity of the membranous labyrinth is filled with endolymph.

The walls of the membranous labyrinth are formed by a connective tissue layer, a basic membrane and an epithelial layer.

The membranous vestibule consists of two depressions: an elliptical one, called the utricle, and a spherical one, called the sac. The sac passes into the endolymphatic duct, which ends in the endolymphatic sac.

Both recesses, together with the membranous semicircular ducts with which the uterus is connected, form the vestibular apparatus and are an organ of balance. They contain the peripheral apparatus of the vestibule nerve.

The membranous semicircular ducts have a common membranous pedicle and are connected to the bony semicircular canals in which they lie through connective tissue cords. The sac communicates with the cavity of the cochlear canal.

The membranous cochlea, also called the cochlear duct, includes the peripheral apparatus of the cochlear nerve. On the basilar plate of the cochlear duct, which is a continuation of the bony spiral plate, there is a protrusion of the neuroepithelium, called the spiral or organ of Corti.

It consists of support and epithelial cells, located on the main membrane. Nerve fibers - processes of nerve cells of the main ganglion - approach them. It is the organ of Corti that is responsible for the perception of sound stimuli, since the nerve processes are receptors of the cochlear part of the vestibulocochlear nerve. Above the spiral organ is a covering membrane.

3. Sensitivity of the auditory analyzer

The human ear can perceive a range of sound frequencies over a fairly wide range: from 16 to 20,000 Hz. Sounds of frequencies below 16 Hz are called infrasounds, and sounds above 20,000 Hz are called ultrasounds. Each frequency is perceived by certain areas of the auditory receptors, which respond to a specific sound. The greatest sensitivity of the auditory analyzer is observed in the mid-frequency region (from 1000 to 4000 Hz). Speech uses sounds within the range of 150 – 2500 Hz. The auditory ossicles form a system of levers that improve the transmission of sound vibrations from air environment auditory canal to the perilymph of the inner ear. The difference in the size of the base area of ​​the stapes (small) and the area of ​​the tympanic membrane (large), as well as in in a special way articulations of bones that act like levers; the pressure on the membrane of the oval window increases 20 times or more than on the eardrum, which enhances the sound. In addition, the auditory ossicular system is capable of changing the strength of high sound pressure. As soon as the pressure of the sound wave approaches 110–120 dB, the nature of the movement of the ossicles changes significantly, the pressure of the stapes on the round window of the inner ear decreases, and protects the auditory receptor apparatus from prolonged sound overloads. This change in pressure is achieved by contracting the muscles of the middle ear (muscles of the malleus and stapes) and reducing the amplitude of vibration of the stapes. The auditory analyzer is capable of adaptation. Long lasting sounds leads to a decrease in the sensitivity of the auditory analyzer (adaptation to sound), and the absence of sounds leads to its increase (adaptation to silence). Using a hearing analyzer, you can relatively accurately determine the distance to the sound source. The most accurate assessment of the distance of a sound source occurs at a distance of about 3 m. The direction of the sound is determined thanks to binaural hearing; the ear that is closer to the sound source perceives it earlier and, therefore, more intensely in sound. At the same time, the delay time on the way to the other ear is determined. It is known that the thresholds of the auditory analyzer are not strictly constant and fluctuate within significant limits in humans depending on the functional state of the body and the action of environmental factors.

There are two types of transmission of sound vibrations - air and bone conduction of sound. In air conduction, sound waves are captured by the pinna and transmitted through the external auditory canal to the eardrum, and then through the perilymph and endolymph system of the auditory ossicles. A person with air conduction is able to perceive sounds from 16 to 20,000 Hz. Bone conduction of sound occurs through the bones of the skull, which also have sound conductivity. Air conduction of sound is better expressed than bone conduction.

4. Hygiene of the child’s hearing organ

One of the skills of personal hygiene - keeping one's face, in particular ears, neat - should also be instilled in the child as early as possible. Wash your ears, keep them clean, remove discharge, if any.

A child with suppuration from the ear, even a seemingly minor one, often develops inflammation of the external auditory canal. About eczema, the causes of which are often purulent otitis media, as well as mechanical, thermal and chemical damage caused during the cleansing of the ear canal. The most important thing in this case is maintaining ear hygiene: you need to clean it of pus, drain it in case of instillation of drops at medium purulent otitis, lubricate the ear canal with petroleum jelly, and the cracks with tincture of iodine. Doctors usually prescribe dry heat, blue light. Prevention of the disease mainly consists of hygienic maintenance of the ear during purulent otitis media.

You need to clean your ears once a week. First, drip a 3% hydrogen peroxide solution into each ear for 5 minutes. Sulfur masses soften and turn into foam, they are easy to remove. When “dry” cleaning, there is a great danger of pushing some of the sulfur masses deep into the external auditory canal, towards the eardrum (this is how sulfur plug).

The earlobe should only be pierced in beauty salons, so as not to cause infection of the auricle and its inflammation.

Systematic exposure to noisy environments or short-term but very intense exposure to sound can lead to hearing loss. Protect your ears from excessively loud sounds. Scientists have found that prolonged exposure to loud noise damages hearing. Strong, harsh noises cause the eardrum to rupture, and constant loud noises cause the eardrum to lose its elasticity.

In conclusion, it must be emphasized that hygienic education of the baby in kindergarten and at home, of course, is closely connected with other types of education - mental, labor, aesthetic, moral, i.e. with the education of the individual.

It is important to observe the principles of systematic, gradual and consistent formation of cultural and hygienic skills, taking into account the age and individual characteristics of the baby.

5. Identify deviations from the norm in the functioning of the auditory analyzer of children in your group

The method of pedagogical examination of the hearing of preschool children depends on whether the child can speak or not.

To examine the hearing of speaking children, test material available to them is selected. It should consist of words that are well known to the child and that meet certain acoustic parameters. Thus, for Russian-speaking children, it is advisable to use the words selected by L.V. Neiman (1954) for examining the hearing of children in a whisper and including an equal number of high-frequency and low-frequency words. All words (30 in total) are well known to preschool children.

For preschool children, from these 30 words we selected 10 low-frequency words (Vova, house, sea, window, smoke, wolf, ear, soap, fish, city) and 10 high-frequency words (bunny, clock, Sasha, tea, cone, cabbage soup, cup, bird, seagull, match), well known to all children over 3 years old.

It has already been mentioned that two lists are compiled from these words, each with 5 low-frequency and 5 high-frequency words:

bunny, house, Vova, cone, fish, clock, bird, ear, tea, wolf;

soap, smoke, cup, window, cabbage soup, Sasha, city, seagull, sea, match.

When examining children's hearing, the words of each list are presented in a random sequence.

Hearing examination of talking preschoolers

Situation A

To prepare the child for the examination, an auxiliary list of words is used, consisting of 10 names of toys that are well known to children, for example: doll, ball, ball, stroller, bear, dog, car, cat, pyramid, cubes. These words should not be included in the main word list. Corresponding pictures are selected for the words of the main and auxiliary lists.

The examiner tries to put the child at ease and calms him down if he is worried. The examination begins only after contact with the child is established. The adult moves 6 m away from him and says: “Listen to what pictures I (the doll, the bear) have. I will speak quietly, in a whisper, and you repeat loudly.” Covering his face with a sheet of writing paper, he whispers one of the words from the auxiliary list, for example, “ball,” and asks a child sitting or standing facing him to repeat the word. If he copes with the task (i.e. repeats the named word loudly or quietly), the adult (or toy) shows him the corresponding picture, thereby confirming the child’s correct answer, praises him and invites him to listen to the second word of the auxiliary list. If the child repeats this, it means that he understood the task and is ready for the examination.

Examination procedure

Rita stands sideways to the teacher. A cotton swab is inserted into the opposite ear, the surface of which is slightly moistened with some oil, for example, Vaseline. Rita is presented with words from one of two corresponding lists in random order. The words are pronounced in a whisper from a distance of 6 m. If she does not repeat the word after being presented twice, you should approach her at 3 m and repeat the word again in a whisper. If in this case Rita did not hear the word, it is pronounced in a whisper near the child. If in this case the word is not perceived, then it is repeated in a voice at conversational volume near her, and then in a whisper from a distance of 6 m. Similarly, the teacher offers Rita the next words of the list, which she pronounces in a whisper at a distance of 6 m from the child. If necessary (if the word is not accepted), the teacher approaches Rita. At the end of the examination, the names of the pictures that the child had difficulty perceiving are repeated in a whisper again from a distance of 6 m. Each time the control word is repeated correctly, the teacher confirms her answer with the corresponding picture.

Situation B

The teacher presents the word in a whisper from 6 m. If Dima does not give the correct answer, the same word is repeated in a voice at conversational volume. If the answer is correct, the next word is again pronounced in a whisper. The word that caused the difficulty is presented again after the child listens to the next two or three words of the list or at the end of the test. This option allows you to reduce the examination time.

Then Dima is asked to stand on the other side to the teacher, and the second ear is examined in the same way, using the second list of words.

Thus, together with the teacher, the children of the entire group were examined for the functioning of the auditory analyzer. Out of 26 children, it was possible to identify a deviation from the norm in one child. The remaining 25 children completed all tasks well the first time.

Note to parents.

Dear parents, protect your child’s hearing!

Every day, millions of people are exposed to noise levels that experts define as “harmful to hearing and harmful to health.” And indeed, regardless of whether you live in big city or a small village, you may be among the 87% of people who are at risk of losing some of their hearing over time.

Children are especially vulnerable to noise-related hearing loss, which is usually painless and gradual. Excessive noise damages the microscopic sensory receptors found in a baby's inner ear. There are 15 to 20 thousand of these receptors in the inner ear, and damaged receptors can no longer transmit sound information to the brain. The situation is worsened by the fact that hearing damage from excessive noise exposure is almost irreversible.

The importance of early diagnosis

Experts believe that the first few years of a child's life are the most important for his development. Poor hearing can significantly slow down a child's mental development. And if hearing loss is diagnosed late, critical time may be missed to stimulate the ear canals leading to the auditory centers of the brain. The child may experience delayed speech development, which will lead to slower communication and learning skills.

Unfortunately, most hearing problems are discovered quite late. It can take quite some time from the onset of hearing loss to the time you notice obvious signs of hearing loss in your child. There are several signs, depending on the age of the child, by which you can understand whether everything is fine with his hearing:

Newborn: Should flinch when you clap your hands 1-2 meters away and calm down at the sound of your voice.

From 6 to 12 months: must turn his head when hearing familiar sounds and raise his voice in response to human speech addressed to him.

1.5 years: Must speak simple, one-syllable words and point to body parts when asked.

2 years: must follow simple commands given by voice without gestures, and repeat after an adult simple words.

3 years: must turn his head directly towards the source of the sound.

4 years: must perform two simple commands in turn (for example, “Wash your hands and eat soup”).

5 years: must be able to carry on a simple conversation and have more or less articulate speech.

Schoolboy: Hearing impairment in schoolchildren often manifests itself in the form of inattention during lessons, lack of concentration, poor study, frequent colds and ear pain.

If you notice that your child is delayed in hearing and/or speech development, or has hearing problems, consult your doctor immediately.

Children living in cities are especially susceptible to the harmful effects of noise. The hearing is most often affected in children whose homes or schools are located near busy highways or railroads. But the home environment is no less important. Try to keep your child away from common sources of loud noise such as television, home cinema or stereo system at high volume. If there is an urgent need, such as working with a drill, it is better to put silent headphones on your child.

At home, the simplest techniques will help protect your child’s hearing from external noise:

Wall to wall carpeting.

Panels on the ceiling and walls.

Well-fitted and tight-fitting windows and doors.

Potentially harmful noises

According to medical data, prolonged exposure to noise levels greater than 85 decibels can cause hearing impairment. Below are some levels of different sounds that a child may hear in his environment:

High traffic highway: 85 decibels

Noise from a restaurant or cafe: 85 decibels

Music player at medium volume: 110 decibels

Snowmobile: 110 decibels

Ambulance siren: 120 decibels

Rock concert: 120 decibels

Loud musical toys: 125 decibels

Fireworks and firecrackers: 135 decibels

Drill: 140 decibels

organ hearing analyzer sound

REFERENCES

1. Agadzhanyan N.A., Vlasova I.G., Ermakova N.V., Torshin V.I. Fundamentals of human physiology: Textbook. Ed. 2nd, rev. – M.: RUDN Publishing House, 2005. – 408 p.: ill.

2. Anatomy and physiology of children and adolescents: Textbook. aid for students ped. universities /M.R.Sapin, Z.G.Bryksina. – 4th ed., revised. and additional – M.: Publishing Center “Academy”, 2005. – 432 p.

3. Batuev A.S. Physiology of higher nervous activity and sensory systems: Textbook for universities. – 3rd ed. – St. Petersburg: Peter, 2006. – 317 pp.: ISBN 5-94723-367-3

4. Galperin S.I. Physiology of humans and animals. Textbook manual for high fur boots and peds. Inst. M., “Higher. school", 1977. - 653 p. with ill. and table

5. N.A. Fomin Human physiology: Textbook. manual for students of the Faculty. physical culture ped. Institute, - 2nd ed., revised. – M.: Education, 1991. – 352 p. – ISBN 5-09-004107-5

6. I.N. Fedyukovich Anatomy and physiology: Textbook. – Rostov – n/a: publishing house “Phoenix”, 2000. – 416 p.

7. N.I. Fedyukovich Anatomy and physiology: Textbook. allowance. – Mn.: LLC “Polifact - Alpha”, 1998. – 400 pp.: ill.

8. Nekulenko T.G. Age-related physiology and psychophysiology / T.G. Nikulenko. – Rostov n/d: Phoenix, 2007. – 410, p. – (Higher education).

9. Sapin M.R., Sivoglazov V.I. Human anatomy and physiology (with age-related features) child's body): textbook aid for students avg. ped. textbook establishments. – 2nd ed., stereotype. – M.: Publishing Center “Academy”, 1999. – 448 p., ill. ISBN 5-7695-0259-2

Submitting your good work to the knowledge base is easy. Use the form below

Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.

Posted on http://www.allbest.ru/

Introduction

1. Hearing analyzer

1.1 Reception of sound stimuli

1.2 Function of the sound-conducting apparatus of the ear

1.3 Inner ear

2. Resonance theory of hearing

3. Conducting paths of the auditory analyzer

4. Cortical section of the auditory analyzer

5. Analysis and synthesis of sound stimulation

6. Factors determining the sensitivity of the auditory analyzer

Conclusion

References

Introduction

Sense organs, or analyzers, are devices through which the nervous system receives stimuli from the external environment, as well as from the organs of the body itself, and perceives these stimuli in the form of sensations. hearing analyzer ear

Indications from the senses are sources of ideas about the world around us.

The process of sensory cognition occurs in humans and animals through six channels: touch, hearing, vision, taste, smell, gravity. The six senses provide diverse information about the surrounding objective world, which is reflected in consciousness in the form of subjective images - sensations, perceptions and memory representations.

Living protoplasm has irritability and the ability to respond to irritation. In the process of phylogenesis, this ability especially develops in specialized cells of the integumentary epithelium under the influence of external irritations and intestinal epithelial cells under the influence of irritation with food. Specialized epithelial cells already in coelenterates are associated with the nervous system. In some areas of the body, for example on the tentacles, in the mouth area, specialized cells with increased excitability, form clusters from which the simplest sense organs arise. Subsequently, depending on the position of these cells, their specialization occurs in relation to stimuli. Yes, cells oral area they specialize in the perception of chemical irritations (smell, taste), cells on protruding parts of the body - in the perception of mechanical irritations (touch), etc.

The development of sense organs is determined by their importance for adaptation to living conditions. For example, a dog is sensitive to the smell of insignificant concentrations organic acids secreted by the body of animals (the smell of traces), and is poorly versed in the smell of plants that have no biological significance for her.

The increasing sophistication of analysis of the external world is due not only to the complication of the structure and function of the sense organs, but, above all, to the complication of the nervous system. The development of the brain (especially its cortex) is of particular importance for the analysis of the external world, which is why F. Engels calls the sense organs “tools of the brain.” Nervous excitations arising due to certain stimuli are perceived by us in the form of various sensations.

For sensations to arise, the following are needed: devices that perceive irritation, nerves through which this irritation is transmitted, and the brain, where it turns into a fact of consciousness. I. P. Pavlov called this entire apparatus necessary for the emergence of sensation an analyzer. “An analyzer is a device whose task is to decompose the complexity of the external world into individual elements.”

1. Hearing analyzer

In the process of evolution, animals have developed an auditory analyzer that is complex in structure and function. Hearing is the ability of animals to perceive and analyze sound waves.

The peripheral part of the auditory analyzer includes: 1. Sound-collecting apparatus - the outer ear, 2. Sound-transmitting apparatus - the middle ear, 3. Sound-receiving apparatus - the inner ear (cochlea with the organ of Corti).

1.1 Reception of sound stimuli

Organ of hearing. Most invertebrates do not have special tonoreceptors that are sensitive only to sound vibrations. However, specific auditory organs have been described in insects; they can be located in various places of the body and consist of a thin, stretched membrane that separates the outside air from auditory cavity. On the inside of the membrane there are auditory receptor cells. With the help of these organs, some insects can perceive sounds of very high frequency, up to 40 and even up to 90 thousand vibrations per second.

In lower vertebrates the peripheral auditory organ together with the vestibular apparatus, it differentiates from the anterior end of the lateral line organ, the receptors of which perceive vibrations in the aquatic environment. A blinded pike, provided that the lateral line organ is preserved, grabs a fish swimming past and moves without bumping into oncoming objects that reflect the vibrations of the water produced by the movements of the pike. Oscillations of pain frequency are perceived only by the sac developed from the anterior end of the lateral line organ and its blind outgrowth, called lagena. In amphibians (and especially reptiles), a special auditory area appears closer to the base of the lagena - a stretched membrane consisting of parallel connective tissue fibers. In mammals, due to the growth of this area, the blind process sharply lengthens. Curving, it takes the shape of a snail shell with a different number of turns in different animals. Hence the name of this organ - snail. Ear like peripheral organ The auditory analyzer consists not only of the receptor apparatus, hidden in the thickness of the temporal bone and forming, together with the vestibular apparatus, the so-called inner ear. Of essential importance are those parts of the ear that are associated with the capture of sounds and their conduction to the receptor apparatus.

The sound-conducting apparatus of all terrestrial animals is the middle ear, or tympanic cavity, which was formed due to the anterior gill slit. Already in reptiles, this cavity contains an auditory ossicle, which facilitates the transmission of sound vibrations. Mammals have three interconnected bones that help increase the strength of sound vibrations. The sound-receiving apparatus, or external ear, consists of the external auditory canal and the pinna, which first appears in mammals. In many of them, it is mobile, which allows it to be directed in the direction of the appearance of sounds and thereby better capture them.

1.2 Function of the sound-conducting apparatus of the ear

The tympanic cavity (Fig. 1) communicates with the outside air through a special canal - the auditory or Eustachian tube, the external opening of which is located in the wall of the nasopharynx. It is usually closed, but opens at the moment of swallowing. When there is a sudden change in pressure atmospheres, for example when descending into a deep shaft, or when an airplane is ascending or landing, a significant difference may occur between the outside air pressure and the air pressure in the tympanic cavity, which causes discomfort and sometimes damage to the eardrum. Opening the opening of the auditory tube helps equalize the pressure, and therefore, when the pressure of the outside air changes, it is recommended to make frequent swallowing movements.

Rice. 1. Semi-schematic representation of the middle ear:

1- external auditory canal; 2- tympanic cavity; 3 -- auditory tube; 4 -- eardrum; 5 -- hammer; 6 -- anvil; 7 -- stirrup; 8 -- window of the vestibule (oval); I am a snail window (round); 10- bone tissue.

Inside the tympanic cavity there are three auditory ossicles - the malleus, the incus and the stapes, connected by joints. The middle ear is separated from the outer ear by the eardrum, and from the inner ear by a bony septum with two holes. One of them is called the oval window or the window of the vestibule. The base of the stirrup is attached to its edges using an elastically ring ligament. The other opening - the round window, or window of the cochlea - is covered with a thin connective tissue membrane. Airborne sound waves entering the ear canal cause vibrations in the eardrum, which are transmitted through the system of auditory ossicles, as well as through the air in the middle ear, to the perilymph of the inner ear. The auditory ossicles articulated with each other can be considered as a lever of the first kind, the long arm of which is connected to the tympanic membrane, and the short arm is connected to the oval window. When transferring movement from a long to a short arm, the range (amplitude) decreases due to an increase in the force developed. A significant increase in the strength of sound vibrations also occurs because the surface of the base of the stapes is many times smaller than the surface of the eardrum. In general, the strength of sound vibrations increases by at least 30-40 times. With powerful sounds, due to contraction of the muscles of the tympanic cavity, the tension of the eardrum increases and the mobility of the base of the stapes decreases, which leads to a decrease in the force of transmitted vibrations.

Complete removal of the eardrum only reduces hearing, but does not lead to loss of it. This is explained by the fact that a significant role in the transmission of sound vibrations is played by the membrane of the round window, which perceives vibrations of the air in the middle ear cavity.

1.3 Inner ear

The inner ear is a complex system of canals located in the pyramid of the temporal bone and called the bony labyrinth. The cochlea and vestibular apparatus located in it form a membranous labyrinth (Fig. 2). The space between the walls of the bony and membranous labyrinths is filled with fluid - perilymph. The auditory analyzer includes only the anterior part of the membranous labyrinth, which is located inside the bony canal of the cochlea and together with it forms two and a half turns around the bone rod (Fig. 3). A process in the form of a helical spiral plate extends from the bone rod into the canal, wide at the base of the cochlea and gradually narrowing towards its apex. This plate does not reach the opposite, outer wall of the canal. Between the plate and the outer wall is the cochlear part of the membranous labyrinth, as a result of which the entire canal ends up with two floors, or passages.

One of them communicates with the vestibule of the bony labyrinth and is called the scala vestibule, the other starts from the window of the cochlea, bordering the tympanic cavity, and is called the scala tympani. Both passages communicate only at the upper, narrow end of the cochlea.

On a cross section, the cochlear part of the membranous labyrinth has the shape of an elongated triangle. Its lower side, bordering the scala drum, is formed by the main plate, which consists of thin elastic connective tissue fibers immersed in a homogeneous mass, stretched between the free edge of the spiral bone plate and the outer wall of the cochlear canal. The upper side of the triangle borders the scala vestibule, extending at an acute angle from the upper surface of the spiral bone plate and heading, like the main plate, to the outer wall of the cochlear canal. The third, shortest side of the triangle consists of connective tissue, tightly fused with the outer wall of the bone canal.

Rice. 2. General scheme bone and the membranous labyrinth located in it:

1 - bone; 2 -- middle ear cavity; 3 -- stirrup; 4 -- window of the vestibule; 5- cochlear window; 6 -- snails; 7 and 8 - otolithic apparatus (7 - sacculus or round sac; 8 - utriculus, or oval sac); 9, 10 and 11 - semicircular canals 12 - the space between the bony and membranous labyrinths, filled with perilymph.

Rice. 3. Schematic representation of the cochlea of ​​the inner ear:

A - bony canal of the cochlea;

B - diagram of a cross-section of part of the cochlea; - bone rod; 2 - spiral bone plate; 3 - fibers of the cochlear nerve; 4 - cluster of bodies of the first neuron of the auditory pathway; 5 -- staircase vestibule; 6-drum ladder; 7 - cochlear part of the membranous labyrinth; 8 - organ of Corti; 9 -- main plate.

Function of the organ of Corti.

The receptor apparatus of the auditory analyzer, or the spiral organ of Corti, is located inside the cochlear part of the membranous labyrinth on the upper surface of the main plate (Fig. 4). Along the inner part of the main plate, at some distance from each other, there are two rows of pillar cells, which, touching their upper ends, delimit a free triangular space, or tunnel. On both sides of it there are laughter, or hair cells, sensitive to sound vibrations, each of which on its upper free surface has 15-20 small, finest hairs. The ends of the hairs are immersed in the integumentary plate, it is fixed on the bony spiral plate and the free end covers the organ of Corti. The hair cells are located inward from the tunnel in one row, and outward in three rows. They are separated from the main plate by supporting cells.

The terminal branches of the fibers of bipolar nerve cells approach the bases of the hair cells, the bodies of which are located in the central canal of the bony core of the cochlea, where they form the so-called spiral ganglion, homologous to the intervertebral ganglion spinal nerves. Each of the three and a half thousand inner hair cells is associated with one, and sometimes two separate nerve cells. The outer fibers of the cell, the number of which reaches 15-20 thousand, can be connected to several nerve cells, but each nerve fiber gives branches only to hair cells of the same row.

The perilymph surrounding the membranous apparatus of the cochlea experiences pressure, which changes according to the frequency, strength and shape of sound vibrations. Changes in pressure cause vibrations of the main plate along with the cells located on it, the hairs of which experience changes in pressure from the integumentary plate. This, apparently, leads to excitation in the hair cells, which is transmitted to the terminal branches of the nerve fibers.

Rice. 4. Scheme of the structure of the organ of Corti:

1 -- main plate; 2 -- bone spiral plate; 3 -- spiral channel; 4 -- nerve fibers; 5 -- pillar cells forming a tunnel (6); 7 -- auditory, or hair cells; 8 -- supporting cells; 9- cover plate.

2. Resonance theory of hearing

Among the various theories explaining the mechanism of peripheral analysis of sounds, the resonance theory proposed by Helmholtz in 1863 should be considered the most substantiated. If you play a sound of a certain pitch near an open piano, a string tuned to the same tone will begin to resonate, that is, sound in response. Studying the structural features of the main plate of the cochlea, Helmholtz came to the conclusion that sound waves coming from the environment cause vibrations of the transverse fibers of the plate according to the principle of resonance.

In total, there are about 24,000 transverse elastic fibers in the main plate. They vary in length and degree of tension: the shortest and most tense are located at the base of the cochlea; the closer to its top, the longer and weaker they are stretched. According to resonance theory, various areas The bases of the plates react by vibrating their fibers to sounds of different pitches. This idea was confirmed by the experiments of L.A. Andes. After the dogs had developed conditioned reflexes to pure tones of different pitches, he completely removed the cochlea of ​​one ear, and partially damaged the cochlea of ​​the other. Depending on which part of the organ of Corti of the second ear was damaged, the disappearance of previously developed positive and negative conditioned reflexes to sounds of a certain vibration frequency was observed.

When the organ of Corti was destroyed closer to the base of the cochlea, conditioned reflexes to high tones disappeared. The closer to the apex the damage was localized, the lower were the tones that lost their significance as conditioned stimuli.

3. Conducting paths of the auditory analyzer

The first neuron of the auditory analyzer pathways is the cells mentioned above, the axons of which form the cochlear nerve. The fibers of this nerve enter the medulla oblongata and end in the nuclei where the cells of the second neuron of the pathways are located. The axons of the cells of the second neuron reach the internal geniculate body, mainly the opposite side. Here the third neuron begins, through which impulses reach the auditory area of ​​the cerebral cortex (Fig. 5). In addition to the main conducting path connecting the peripheral part of the auditory analyzer with its central, cortical part, there are other paths through which reflex reactions to irritation of the organ of hearing in an animal can be carried out even after the removal of the cerebral hemispheres.

Indicative reactions to sound are of particular importance. They are carried out with the participation of the quadrigeminal, to the posterior and partly anterior tubercles, which are collaterals of fibers heading to the internal geniculate body.

Rice. 5. Diagram of the conductive paths of the auditory analyzer:

1 -- receptors of the organ of Corti; 2 -- bodies of bipolar neurons; 3 - cochlear nerve; 4 -- nuclei of the medulla oblongata, where the bodies of the second neuron of the pathways are located; 5 -- internal geniculate body, where the third neuron of the main pathways begins; 6 -- upper surface of the temporal lobe of the cerebral cortex (lower wall of the transverse fissure), where the third neuron ends; 7 -- nerve fibers connecting both internal geniculate bodies; 8 -- posterior tubercles of the quadrigeminal; 9 - the beginning of the efferent pathways coming from the quadrigeminal.

4. Cortical section of the auditory analyzer

In humans, the nucleus of the cortical part of the auditory analyzer is located in the temporal region of the cerebral cortex. In that part of the surface of the temporal region, which represents bottom wall The transverse, or Sylvian fissure, contains field 41. The bulk of the fibers from the internal geniculate body are directed to it, and possibly to the neighboring field 42. Observations have shown that when these fields are destroyed, complete deafness occurs. However, in cases where the damage is limited to one sex, a slight and often only temporary hearing loss may occur. This is explained by the fact that the conductive paths of the auditory analyzer do not completely intersect. In addition, both internal geniculate bodies are interconnected interneurons, through which impulses can pass from the right side to the left and back. As a result, the cortical cells of each hemisphere receive impulses from both organs of Corti.

From the cortical part of the auditory analyzer, efferent pathways go to the underlying parts of the brain, and primarily to the internal geniculate body and the posterior colliculus of the quadrigeminal. Through them, cortical motor reflexes to sound stimuli are carried out. By irritating the auditory area of ​​the cortex, it is possible to cause an indicative alarm reaction in the animal (movements of the auricle, turning the head, etc.).

5 . Analysis and synthesis of sound stimulation

The analysis of sound stimulation begins in the peripheral part of the auditory analyzer, which is ensured by the structural features of the cochlea, and above all the main plate, each section of which vibrates in response to sounds only of a certain pitch.

Higher analysis and synthesis of sound stimuli, based on the formation of positive and negative conditioned connections, occurs in the cortical section of the analyzer. Each sound perceived by the organ of Corti leads to a state of excitation of certain cell groups of field 41 and its neighboring fields. From here, excitation spreads to other points of the cerebral cortex, especially to fields 22 and 37. Between different cell groups that repeatedly entered a state of excitation under the influence of a certain sound stimulation or a complex of successive sound stimuli, establishing increasingly strong conditioned connections. They are also established between the foci of excitation in the auditory analyzer and those foci that simultaneously arise under the influence of stimuli acting on other analyzers. This is how more and more new conditioned connections are formed, enriching the analysis and synthesis of sound stimuli.

The analysis and synthesis of sound speech stimuli is based on the establishment of conditioned connections between foci of excitation that arise under the influence of direct stimuli acting on various analyzers, and those foci that are caused by sound speech signals denoting these stimuli. The so-called auditory center of speech, i.e. that part of the auditory analyzer, the function of which is associated with speech analysis and synthesis of sound stimuli, in other words, with the understanding of audible speech, is located mainly in the left field and occupies the posterior end of the field and the adjacent area of ​​the field.

6. Factors determining the sensitivity of the auditory analyzer

The human ear is especially sensitive to the frequency of sound vibrations from 1030 to 4000 per second. Sensitivity to higher and lower sounds decreases significantly, especially as you approach the lower and upper limits of perceived frequencies. Thus, for sounds whose vibration frequency approaches 20 or 20,000 per second, the threshold increases 10,000 times if the strength of the sound is determined by the pressure it produces. With age, the sensitivity of the auditory analyzer, as a rule, decreases significantly, but mainly to high-frequency sounds, while to low-frequency sounds (up to 1000 vibrations per second) it remains almost unchanged until old age.

In conditions of complete silence, hearing sensitivity increases. If a tone of a certain pitch and constant intensity begins to sound, then, due to adaptation to it, the sensation of loudness decreases, first quickly, and then more and more slowly. However, although to a lesser extent, sensitivity to sounds that are more or less close in vibration frequency to the sounding tone decreases. However, adaptation usually does not extend to the entire range of perceived sounds. After the sound stops, due to adaptation to silence, the previous level of sensitivity is restored within 10-15 seconds.

Adaptation partly depends on the peripheral part of the analyzer, namely on changes in both the amplifying function of the sound apparatus and the excitability of the hair cells of the organ of Corti. The central section of the analyzer also takes part in the phenomena of adaptation, as evidenced by the fact that when sound affects only one ear, shifts in sensitivity are observed in both ears. The sensitivity of the auditory analyzer, and in particular the adaptation process, is influenced by changes in cortical excitability, which arise as a result of both irradiation and mutual induction of excitation and inhibition when irritating the receptors of other analyzers.

Sensitivity also changes with the simultaneous action of two tones of different heights. IN the latter case a weak sound is drowned out by a stronger one, mainly because the focus of excitation, which arises in the cortex under the influence of a strong sound, reduces, due to negative induction, the excitability of other parts of the cortical section of the same analyzer.

Prolonged exposure to strong sounds can cause prohibitive inhibition of cortical cells. As a result, the sensitivity of the auditory analyzer sharply decreases. This condition persists for some time after the irritation has stopped.

Conclusion

An auditory analyzer, a set of mechanical, receptor and nervous structures, the activity of which ensures the perception of sound vibrations by humans and animals.

In higher animals, including most mammals, the auditory analyzer consists of the outer, middle and inner ears, the auditory nerve and central departments(cochlear nuclei and superior olive nuclei, posterior colliculus, internal geniculate body, auditory cortex). The superior olive is the first formation of the brain where information from both ears converges. Fibers from the right and left cochlear nuclei go to both sides. The auditory analyzer also has descending (efferent) pathways that go from the overlying sections to the underlying ones (down to the receptor cells). In the frequency analysis of sounds, the cochlear septum is of significant importance - a kind of mechanical spectral analyzer that functions as a series of mutually mismatched filters. Its amplitude-frequency characteristics (AFC), i.e., the dependence of the amplitude of vibrations of individual points of the cochlear septum on the frequency of sound, were first experimentally measured by the Hungarian physicist D. Bekesi and later refined using the Mössbauer effect.

The external ear includes the pinna and the external auditory canal. The auricle is rupe-shaped and movable, which makes it possible to capture and concentrate sound in the ear canal.

The external auditory canal is slightly curved, narrow channel. The glands of the auditory canal secrete a secretion called “earwax,” which protects the eardrum from drying out.

The eardrum separates the outer ear from the middle ear. It is irregularly shaped and unequally tensioned, so it does not have its own period of oscillation, but oscillates in accordance with the length of the incoming sound wave.

The middle ear includes the auditory ossicles - the malleus, the incus, the lentiform bone and the stapes. These ossicles transmit vibrations from the eardrum to the membrane of the oval window, located on the border between the middle and inner ear.

The tympanic cavity communicates with the outside air through the auditory (Eustachian) tube in the nasopharynx during swallowing. As a result, the pressure on both sides of the eardrum is equalized. With a sharp change in external pressure in any direction, the tension of the membrane changes and a state of temporary deafness develops, which is eliminated by swallowing movements.

The inner ear consists of the bony and membranous labyrinths. The membranous labyrinth is located in the bony labyrinth. The space between them is filled with perilymph, and the membranous labyrinth is filled with endolymph. There are two organs located in the labyrinth. One of them, consisting of the vestibule and cochlea, performs the auditory function, and the second, consisting of two sacs and three semicircular canals, performs the balance function (vestibular apparatus).

hearing analyzer ear sound

References

1. http://slovari.yandex.ru/dict/bse/article/00072/11500.htm

2. http://analizator.ucoz.ru/index/0-7

3. http://works.tarefer.ru/10/100119/index.html

4. http://liceum.secna.ru/bl/projects/barnaul2007/borovkov/s_sens_sluh.html

5. http://meduniver.com/Medical/Anatom/513.html

6. http://www.analizator.ru/anatomy.php

7. http://ru.wikipedia.org/wiki/sens_sluh

8. Akaevsky A.I. \ Anatomy of domestic animals. Ed. 3rd, rev. And additional M., Kolos, 1975. 592 p. With ill. (Textbooks and teaching aids for higher agricultural educational institutions).

9. Anatomy of domestic animals\ I.V. Khrustaleva, N.V. Mikhailov, Ya.I. Schneiberg et al.; Under. ed. I.V. Khrustaleva. - 3rd ed., rev. - M.: KolosS, 2002. - 704 p.: ill. - (Textbooks and teaching aids for students of higher educational institutions).

10. Klimov A.F., Akaevsky A.E. Anatomy of domestic animals: Study guide. 7th ed., ster. - St. Petersburg: Publishing House "Lan", 2003. - 1040 pp. - (Textbooks for universities. Special literature).

Posted on Allbest.ru

...

Similar documents

The concept of analyzers and their role in understanding the surrounding world. Structure and functions of the human hearing organ. The structure of the sound-conducting apparatus of the ear. Central auditory system, information processing in centers. Methods for studying the auditory analyzer.

course work, added 02/23/2012


Location and functions of the outer, middle and inner ear. The structure of the bone labyrinth. Basic levels of organization of the auditory analyzer. Consequences of damage to the organ of Corti, auditory nerve, cerebellum, medial geniculate body, Graziole bundle.

presentation, added 11/11/2010


Area of ​​the cerebral cortex. The meaning of vision. The structure of the eye. Visual and auditory analyzer. Human receptors: visual, auditory, tactile, pain, temperature, olfactory, gustatory, pressure, kinetic, vestibular. Skin structure.

presentation, added 05/16/2013


Study of hearing acuity in children and adults. Function of the auditory analyzer. Criteria for frequency and strength (loudness) of tones. Peripheral auditory department sensory system person. Sound conduction, sound perception, auditory sensitivity and adaptation.

abstract, added 08/27/2013


Impedancemetry as a research method that allows you to determine the tone and mobility of the eardrum, the chain of auditory ossicles, and pressure in the middle ear. Purpose and methods of tympanometry. Test to assess the ventilation function of the auditory tube.

presentation, added 01/12/2017


Diagram of the ear sections; location of the vestibular and auditory apparatus. Sound wave propagation. Secretion of endo- and perilymph of the inner ear. "Strings" of the membrane of the organ of Corti. Prevocalization reflex; strong sound and reaction of the muscles of the middle ear.

presentation, added 08/29/2013


Physiology of the cerebral cortex and auditory analyzer. Influence electromagnetic radiation to the cerebral cortex. The relationship between the number of errors in response to a non-speech sound and the number of minutes during which a student uses a mobile phone.

course work, added 07/20/2014


Study of the structure of the retina, the sensitivity of the eye to the perception of light. Binocular and color vision. Auditory analyzer, structure of the middle and inner ear. Gustatory, olfactory, tactile and temperature analyzers, their characteristics and significance.

abstract, added 06/23/2010


The concept and functions of the sense organs as anatomical formations, perceiving the energy of external influence, transforming it into nerve impulse and transmitting this impulse to the brain. The structure and significance of the eye. Conducting path of the visual analyzer.

presentation, added 08/27/2013


External ear: parts, innervation and blood supply. External auditory canal: bone and cartilaginous parts, bends, crevices. Cochlea, cochlear duct, spiral organ: structure and function. Conducting pathways and centers of the auditory analyzer. Radiation anatomy of the ear.