The main method of hearing research is. How to transcribe an audiogram - a detailed guide from a doctor

The main task of hearing research is to determine the acuity of hearing, i.e. ear sensitivity to sounds of different frequencies. Since the sensitivity of the ear is determined by the hearing threshold for a given frequency, in practice, the study of hearing consists mainly in determining the perception thresholds for sounds of different frequencies.

The simplest and most accessible method is the study of hearing by speech. The advantages of this method lie in the absence of the need for special instruments and equipment, as well as in its compliance with the main role of the auditory function in humans - to serve as a means of verbal communication.

In the study of hearing by speech, whispered and loud speech is used. Of course, both of these concepts do not include exact dosage strength and pitch, however, there are still some indicators that determine the dynamic (power) and frequency response of whispered and loud speech.

In order to give whispered speech a more or less constant volume, it is recommended to pronounce words using the air remaining in the lungs after a calm exhalation.

In practice, under normal research conditions, hearing is considered normal when perceiving whispered speech at a distance of 6-7 m. the perception of a whisper at a distance of less than 1 m characterizes a very significant hearing loss. Complete absence the perception of whispered speech indicates a sharp hearing loss that makes speech communication difficult.

As mentioned above, speech sounds are characterized by formants of different heights, that is, they can be more or less "high" and "low".

By selecting words consisting of only high or low sounds, one can partly differentiate the lesions of the sound-conducting and sound-perceiving apparatuses. Damage to the sound-conducting apparatus is considered to be characterized by a deterioration in the perception of low sounds, while the loss or deterioration in the perception of high sounds indicates damage to the sound-perceiving apparatus.

To study hearing in whispered speech, it is recommended to use two groups of words: the first group has a low frequency response and is heard with normal hearing at an average distance of 5 m; the second - has a high frequency response and is heard on average at a distance of 20m. The first group includes words that include vowels y, o, from consonants - m, n, v, p, for example: raven, yard, sea, number, Murom, etc .; the second group includes words that include hissing and whistling sounds from consonants, and from vowels - a, and, e: hour, cabbage soup, cup, siskin, hare, wool, etc.

In the absence or a sharp decrease in the perception of whispered speech, they proceed to the study of hearing in loud speech.

First, they use speech of medium, or the so-called conversational volume, which is heard at a distance of about 10 times greater than whispered. To give such speech a more or less constant loudness level, the same technique is recommended that is proposed for whispered speech, i.e. use reserve air after a quiet exhalation. In cases where the speech of conversational loudness is distinguished poorly or does not differ at all, speech of increased loudness (cry) is used.

The study of hearing by speech is carried out for each ear separately: the ear under study is turned to the source of the sound, the opposite ear is muffled with a finger (preferably moistened with water) or a wet ball of cotton. When blocking the ear with a finger, do not press hard on the ear canal, as this causes noise in the ear and can cause pain.

When examining hearing in conversational and loud speech, the second ear is turned off using an ear ratchet. Plugging the second ear with a finger in these cases does not achieve the goal, since in the presence of normal hearing or with a slight decrease in hearing in this ear, loud speech will differ, despite the complete deafness of the ear being examined.

The study of speech perception must begin at close range. If the subject correctly repeats all the words presented to him, then the distance gradually increases until most of the spoken words are indistinguishable. The speech perception threshold is considered to be the greatest distance at which 50% of the presented words differ.

If the length of the room in which the hearing test is performed is insufficient, i.e. when all words are clearly distinguishable even at the maximum distance, then the following technique can be recommended: the researcher becomes his back to the researcher and pronounces the words in the opposite direction; this roughly corresponds to doubling the distance. When examining hearing by speech, it must be taken into account that the perception of speech is a very complex process. The results of the study depend not only on the acuity and volume of hearing, but also on the ability to distinguish in what is heard such elements of speech as phonemes, words, their combination into sentences, which, in turn, is due to how much the subject has mastered sound speech.

In this regard, when examining hearing with the help of speech, one must take into account not only the phonetic composition, but also the availability of the words and phrases used for understanding. Without taking into account this last factor, one can come to an erroneous conclusion about the presence of certain hearing defects where, in fact, these defects do not exist, but there is only a discrepancy between the speech material used for the study of hearing and the level of speech development of the subject.

For all its practical significance, the study of hearing by speech cannot be accepted as the only method for determining the functional ability of the auditory analyzer, since this method is not entirely objective both in terms of dosage of sound intensity and in terms of evaluating results.

A more accurate method is the study of hearing with the help of tuning forks. Tuning forks emit pure tones, and the pitch (oscillation frequency) for each tuning fork is constant. In practice, tuning forks are usually used, tuned to the tone C (do) in different octaves, including tuning forks Cp C, c, c ^ c2, c3, c4, c. Hearing studies are usually performed with three (C128, C32, C2048 or C4096) or even two (C128 and C2048) tuning forks.

With prolonged continuous sounding of the tuning fork, the phenomena of adaptation of the auditory analyzer occur, i.e., a decrease in its sensitivity, which leads to a shortening of the time of perception of the sound of the tuning fork. In order to exclude adaptation, it is necessary, when examining both air and inert conduction of time (every 2-3 seconds), to remove the tuning fork from the ear under study or from the crown of the head for 1-2 seconds and then bring it back.

A more advanced method is the study of hearing with the help of a modern device - an audiometer.

An audiometer is a generator of alternating electrical voltages, which, with the help of a telephone, are converted into sound vibrations.

To study auditory sensitivity during air and bone conduction, two different phones are used, which are respectively called “air” and “bone”. The intensity of sound vibrations can vary within very large limits: from the most insignificant, lying below the threshold of auditory perception, to 120-125 d (for sounds of medium frequency). The height of the sounds emitted by the audiometer can also cover a large range - from 50 to 12,000 - 15,000 Hz.

Measuring hearing with an audiometer is extremely simple. By changing the frequency (pitch) of the sound by pressing the corresponding buttons, and the intensity of the sound by rotating a special knob, the minimum intensity is set at which the sound of the length of the height becomes barely audible (threshold intensity).

Changing the pitch is achieved in some audiometers by smooth rotation of a special disk, which makes it possible to obtain any frequency within the frequency range of this type of audiometer. Most audiometers emit a limited number (7-8) of certain frequencies, either tuning fork (64,128,256, 512 Hz, etc.) or decimal (100, 250,500,1000,2000 Hz, etc.).

Like other methods based on the testimony of the subject, the study using an audiometer is not free from some inaccuracies associated with the subjectivity of these testimony.

However, by repeated audiometric studies, it is usually possible to establish a significant constancy of the results of the study and thus give these results sufficient persuasiveness. [ 1]

For the study of phonemic hearing, i.e. the ability to distinguish from each other separate acoustically similar speech sounds (phonemes), it is necessary, where possible, to use specially selected pairs of words that are accessible in meaning, which would differ from each other phonetically only by the sounds whose differentiation is being studied.

As such pairs, for example, such as heat - ball, cup - checker, dot - daughter, kidney - barrel, goat - braid, etc. can be used. Such pairs of words can also be successfully used to study the ability to differentiate vowel phonemes. Here are some examples: a stick - a shelf, a house - ladies, a table - a chair, a bear - a mouse, etc.

If it is impossible to select the appropriate pairs of words, the study of the distinction of consonant sounds can be carried out on the material of syllables such as ama, ana, ala, avya and others. Carrying out tuning fork and audiometric studies in children under 4-5 years old is practically impossible and succeeds only as a rare exception. In older preschoolers, in many cases, conduct a hearing test with tuning forks or an audiometer, which requires special training.

It should be emphasized that a single primary hearing test in children rarely gives completely reliable results. Very often, repeated studies are required, and sometimes a final conclusion on the degree of hearing impairment in a child can be given only after a long (six months) observation in the process of upbringing and education in a special institution for children with hearing impairment.

Methods of unconditioned reflexes. This group of methods is quite simple, but highly inaccurate.

The definition of hearing here is based on the occurrence of unconditioned reflexes in response to sound stimulation. According to these, the most diverse reactions (increased heart rate, pulse rate, respiratory movements, motor and autonomic responses) it is indirectly possible to judge whether the child hears or not. A number of recent scientific studies show that even the fetus in the womb from about the 20th week reacts to sounds by changing the rhythm of heart contractions. Very interesting data suggests that the embryo hears the frequencies of the speech zone. On this basis, it is concluded that possible reaction the fetus to the speech of the mother and the beginning of the development of the psycho-emotional state of the unborn child. The main contingent of application of the method of unconditioned reactions are newborns and children infancy. A hearing child should respond to sound immediately after birth, already for the first time in minutes of life. In these studies, various sound sources are used: sounding toys, pre-calibrated sound level meters, rattles, musical instruments, as well as simple devices, such as sound meters, sometimes narrow and broadband noise. The intensity of the sound is different.

Methods based on the use of conditioned reflex reactions.

For these studies, it is first necessary to develop an orienting reaction not only to sound, but also to another stimulus that reinforces the sound. So, if you combine feeding with a strong sound (for example, a bell), then after 10-12 days the sucking reflex in a child will appear only in response to the sound.

There are numerous methods based on this pattern. Only the nature of the reinforcement of the reflex changes. Sometimes pain stimuli are used as it, for example, the sound is combined with an injection or directing a strong air stream into the face. Such sound-reinforcing stimuli elicit a (rather stable) defensive reaction and are used primarily to detect aggravation in adults, but cannot be applied to children for humane reasons.

On examination, pay attention to the condition of the external auditory canal and the tympanic membrane. Carefully examine the nasal cavity, nasopharynx, upper Airways and evaluate functions cranial nerves. Conductive and sensorineural hearing loss should be differentiated by comparing the hearing thresholds for air and bone conduction. Air conduction is examined during the transmission of irritation through the air. Adequate air conduction is ensured by the patency of the external auditory canal, the integrity of the middle and inner ear, the vestibulocochlear nerve and the central sections of the auditory analyzer. To study bone conduction, an oscillator or tuning fork is applied to the patient's head. In case of bone conduction sound waves bypass the external auditory canal and middle ear. Thus, bone conduction reflects the integrity of the inner ear, cochlear nerve, and central pathways of the auditory analyzer. If there is an increase in air conduction thresholds at normal threshold values ​​of bone conduction, then the lesion that caused the hearing loss is localized in the external ear canal or middle ear. If there is an increase in the sensitivity thresholds of air and bone conduction, then the lesion is located in the inner ear, cochlear nerve, or the central parts of the auditory analyzer. Sometimes conductive and sensorineural hearing loss occur simultaneously, in which case both air and bone conduction thresholds will be elevated, but air conduction thresholds will be significantly higher than bone conduction thresholds.

In the differential diagnosis of conductive and sensorineural hearing loss, Weber and Rinne tests are used. Weber's test consists in placing the tuning fork leg on the patient's head along the midline and asking him if he hears the sound of the tuning fork evenly from both sides, or if the sound is perceived more strongly on one of the sides. With unilateral conductive hearing loss, sound is perceived more strongly on the side of the lesion. With unilateral sensorineural hearing loss, sound is perceived more strongly on the healthy side. The Rinne test compares the perception of sound through air and bone conduction. The branches of the tuning fork are brought to the ear canal, and then the stem of the sounding tuning fork is placed on the mastoid process. The patient is asked to determine in which case the sound is transmitted more strongly, through bone or air conduction. Normally, the sound is felt louder with air conduction than with bone conduction. With conductive hearing loss, the sound of a tuning fork mounted on the mastoid process is better perceived; with sensorineural hearing loss, both types of conduction are impaired, however, during the study of air conduction, the sound is perceived louder than normal. The results of the Weber and Rinne tests together suggest the presence of conductive or sensorineural hearing loss.

Hearing loss is quantified using an audiometer - an electrical device that allows you to study air and bone conduction using sound signals of various frequencies and intensities. Research is carried out in a special room with a soundproof coating. In order for the patient's responses to be based only on the sensations from the ear being examined, the other ear is screened using broad-spectrum noise. Use frequencies from 250 to 8000 Hz. The degree of change in auditory sensitivity is expressed in decibels. A decibel (dB) is equal to ten times the logarithm of the ratio of the sound intensity required to reach the hearing threshold in a given patient to the sound intensity required to reach the hearing threshold in a given patient. healthy person. An audiogram is a curve showing the deviations of hearing thresholds from normal (in dB) for different sound frequencies.

The nature of the audiogram in hearing loss often has diagnostic value. With conductive hearing loss, a fairly uniform increase in thresholds for all frequencies is usually detected. Conductive hearing loss with a massive volume effect, as occurs with transudate in the middle ear, is characterized by a significant increase in conduction thresholds for high frequencies. In the case of conductive hearing loss due to stiffness of the conductive formations of the middle ear, for example, due to fixation of the base of the stirrup on early stage otosclerosis, note a more pronounced increase in low-frequency conduction thresholds. With sensorineural hearing loss, in general, there is a tendency to a more pronounced increase in the air conduction thresholds of high frequencies. The exception is hearing loss due to noise trauma, in which the greatest hearing loss at a frequency of 4000 Hz is noted, as well as Meniere's disease, especially at an early stage, when the thresholds for low-frequency conduction increase more significantly.

Additional data can be obtained by speech audiometry. This method, using two-syllable words with a uniform stress on each syllable, examines the spondeic threshold, that is, the sound intensity at which speech becomes intelligible. The sound intensity at which the patient can understand and repeat 50% of words is called the spondeic threshold, it usually approaches the average threshold of speech frequencies (500, 1000, 2000 Hz). After determining the spondeic threshold, the discriminatory ability is examined using monosyllabic words with a sound volume 25-40 dB above the spondeic threshold. People with normal hearing can repeat 90 to 100% of words correctly. Patients with conductive hearing loss also perform well on the discrimination test. Patients with sensorineural hearing loss are unable to distinguish words due to damage to the peripheral auditory analyzer at the level of the inner ear or cochlear nerve. With damage to the inner ear, the discrimination ability is reduced and is usually 50-80% of the norm, while with damage to the cochlear nerve, the ability to distinguish words deteriorates significantly and ranges from 0 to 50%.

Speech intelligibility at a sound intensity of 25 to 40 dB above the spondeic threshold should then be analyzed to determine sensitivity to increased sound intensity. A decrease in speech intelligibility at a higher sound intensity indicates damage to the cochlear nerve or the central parts of the auditory dialyzer.

Tympanometry measures the acoustic impedance of the middle ear. The sound source and microphone are introduced into the ear canal and hermetically sealed with a valve. Sound passing through or reflected from the middle ear is measured using a microphone. With conductive hearing loss, sound is reflected more intensely than normal. The pressure in the ear canal can rise and fall depending on atmospheric pressure. Normally, the middle ear is most exposed to atmospheric pressure. With negative pressure in the middle ear, as happens in the case of blockage of the Eustachian tube, the moment of maximum stretching occurs when negative pressure occurs in the external auditory canal. Violation of the integrity of the auditory ossicles complex leads to the fact that the point of maximum stretch cannot be reached. Tympanometry is especially informative in the diagnosis of diseases of the middle ear, accompanied by the release of a significant amount of transudate, in children.

With tympanometry, an intense sound (80 dB above the hearing threshold) causes a contraction of the stapedius muscle. Contraction of the stapedius muscle reveals a change in the distensibility of the middle ear. The presence or absence of this acoustic reflex determines the localization of the lesion in case of paralysis facial nerve, and by the presence or absence of the disappearance of the acoustic reflex, a differential diagnosis of sensory and neural hearing loss is carried out. With neural hearing loss, the acoustic reflex decreases or disappears over time.

The minimum audiological examination required to evaluate a patient with hearing loss should include determination of air and bone conduction thresholds, spondeal threshold, speech intelligibility, sensitivity to increased sound intensity, tympanometry, acoustic reflex testing, and an acoustic reflex disappearance test. These data allow you to comprehensively evaluate the functions of the auditory analyzer and determine the need for further differential diagnosis sensory and neural hearing loss.

In addition to these tests, a study of the phenomenon of sound loudness leveling, a test for determining sensitivity to a fast small increment in sound intensity, a test for the disappearance of a threshold young, Bekesy audiometry, and auditory stem evoked potentials can provide significant assistance in the differential diagnosis of sensory and neural hearing loss.

Clinical evaluation of complaints of hearing loss. In patients with complaints of hearing loss, it is necessary to identify concomitant symptoms, such as tinnitus, systemic dizziness, earache, otorrhea, and ear swelling. In addition, you need to carefully re-sequence the process of hearing loss. Sudden onset of single-sided deafness with or without tinnitus may indicate a viral infection of the inner ear. Gradual hearing loss is characteristic of otosclerosis, schwannoma auditory nerve and Meniere's disease. In the latter case, intermittent tinnitus and dizziness usually occur. Deafness can develop with demyelinating lesions of the brain stem. hearing loss is hallmark some hereditary diseases. In some cases, it is noted from the moment of birth, in others it occurs in childhood or adolescence.

Tinnitus is the sensation of sound in the absence of it in the environment. It can be buzzing, roaring, ringing in character, pulsating (synchronous with the beating of the heart). Tinnitus is usually seen in association with conductive or sensorineural hearing loss. The pathophysiological mechanisms of tinnitus are not well understood. The cause of its appearance can be established by finding out the origin of the accompanying hearing loss. Tinnitus may be the first symptom of a serious illness, such as acoustic neuroma. With pulsating noise, it is necessary to examine vascular system head to rule out a vascular tumour, such as a jugular vein glomangioma, aneurysm, or stenosing lesion.

Most patients with conductive and unilateral or asymmetric sensorineural hearing loss require a CT scan. temporal bone. Patients with sensorineural hearing loss should be examined vestibular system using electronystagmography and caloric tests.

Impedancemetry is a research method based on measuring the acoustic resistance (or acoustic compliance) of the sound-conducting structures of the peripheral part of the auditory analyzer. AT clinical practice Two methods of impedancemetry are most commonly used - tympanometry and acoustic reflexometry.

Tympanometry allows you to assess the mobility of the eardrum and auditory ossicles. This is a fast and non-invasive method for diagnosing diseases such as exudative (secretory) otitis media, otosclerosis, etc.

Using acoustic reflexometry, it is possible to register the contraction of the intra-ear muscles in response to sound stimulation. The method is used for differential diagnosis of diseases of the middle and inner ear, as well as for determining the discomfort thresholds used in the selection and adjustment hearing aids.

Multifrequency acoustic impedancemetry is a precision technique that measures the resonant frequency of the middle ear. Has been successfully applied in complex diagnostics anomalies in the development of the auditory ossicles, differential diagnosis. The results of multifrequency impedancemetry are used during the operation cochlear implantation.

The study reveals the minimum level of sound that a person hears by measuring hearing thresholds for tones of different frequencies. Hearing thresholds are measured in decibels worse man hears, the more hearing thresholds in decibels it has.

There is also speech audiometry, in which words are presented and their intelligibility is assessed in different conditions (in silence, in noise and with other distortions). Currently, behavioral, psychophysical, electroacoustic and electrophysiological research methods are used to determine hearing in people.

All methods of studying the organ of hearing in young children are divided into 3 groups.

1. Unconditioned reflex methods of hearing research.
2. Conditioned reflex methods of hearing research.
3. Objective methods of hearing research.

All methods are informative when used correctly.

1. Unconditioned reflex techniques

In children under one year old, the state of hearing is checked by assessing unconditioned reflexes that occur without prior development. The informative orienting reactions of the child to sounds include the following:

• auropalpebral Bekhterev's reflex (blinking and activity of the eyelids);
• auropupillary Shurygin's reflex (pupil dilation);
• oculomotor reflex;
• sucking reflex;
• startle reaction, fright;
• freezing reaction;
• awakening reaction;
• turning the head towards or away from the sound source;
• facial grimace;
• wide opening of the eyes;
• the occurrence of motor movements of the limbs;
• change in the rhythm of respiratory movements;
• change in heart rate

These reflexes serve as a manifestation of a complex orienting reaction (motor defensive reaction) and the inclusion of an acoustic feedback loop. When using unconditional reflex techniques, the age-related features of the auditory function and the psychomotor development of the child are taken into account.

Psychoacoustic techniques based on the registration of various components of the congenital unconditioned orienting reflex allow us to get a general idea of ​​the presence of hearing in infants (up to a year).

Unconditional reflex techniques, due to their easy accessibility, can be widely used for the screening system for identifying young children with hearing impairment, but they have a number of disadvantages.

The negative aspects of the unconditioned reflex technique include:

• significant individual variation in behavioral responses;
• inconstancy, rapid extinction of the unconditioned reflex upon repeated presentation of the sound signal;
• the need to present an inadequately high threshold for the occurrence of a reflex response (70-90 dB), and therefore it is more difficult to detect hearing loss up to 50-60 dB, which, in turn, leads to an increase in false positive results.

Many authors believe that in young children (up to 2 years old) and especially in children with pathology of the central nervous system accompanied by a lag in motor development, along with psychoacoustic methods, it is advisable to use objective electrophysiological methods for studying hearing

At present, when conducting audiological screening in young children in Russia, OAE (otoacoustic emission) is used.

2. Conditioned reflex techniques

The second direction of children's audiometry is based on the development of conditioned reflexes. At the same time, the most biologically significant unconditioned reflexes are used as the basic ones - defensive, food and operant on game or speech reinforcement. Operant conditioned reflexes involve the performance of some action on the part of the subject - pressing a button, moving the hand, head.

The development of a conditioned reflex in response to a sound stimulus with repeated use of unconditioned reinforcement is explained by the laws of conditioned reflex activity according to Pavlov. When a temporary connection is established between the conditioned (sound) and unconditioned stimulus, one sound is able to cause one or another reaction.

Methods based on conditioned reflex connections also include:

• conditioned reflex pupillary reaction;
• conditioned reflex blinking reaction;
• conditioned reflex vascular reaction;
• conditioned reflex cochleocardial reaction (this reaction with reinforcement develops as a vegetative component to a number of stimuli;
• galvanic skin reaction - the use of an electric current that causes a change in skin potentials and others.

In children older than 3 years and younger than 1 year, the results were unsatisfactory, which was explained by the lack of interest in older children and the appearance of rapid fatigue in younger ones.

Negative moments conditioned reflex techniques are:

• impossibility exact definition hearing thresholds;
• rapid disappearance of conditioned reflexes during repeated studies;
• dependence of the results of the study on the psycho-emotional state of the child, difficulties in assessing hearing in children with mental disabilities.

3. Objective methods of hearing examination

One of the directions of modern clinical audiology is the development and improvement of objective methods for the study of hearing.

Objective research methods include techniques based on the registration of electrical signals that have arisen in various parts of the auditory system in response to the action of sound stimuli.

Objective methods for studying the functional state of the auditory system are progressive, promising and extremely relevant for modern audiology. Of the objective methods, the following are currently used: impedancemetry, registration of auditory evoked potentials (AEP), including electrocochleography, otoacoustic emission.

Let's dwell on each of the methods in more detail.

Acoustic impedancemetry

Acoustic impedancemetry includes several methods of diagnostic examination: measurement of absolute acoustic impedance, tympanometry, measurement of acoustic muscle reflex (A.S. Rosenblum, E.M. Tsiryulnikov, 1993).

The most widely used is the assessment of dynamic indicators of impedancemetry - tympanometry and acoustic reflex.

Tympanometry is a measurement of the dependence of acoustic conductivity on air pressure in the external auditory canal.

Acoustic reflexometry - registration of contraction of the stapedius muscle in response to sound stimulation (J. Jerger, 1970). The minimum sound level necessary to cause contraction of the stapedius muscle is considered as the threshold of the acoustic reflex (J. Jerger, 1970; J. Jerger et al., 1974; G.R. Popelka, 1981). The acoustic reflex is a reaction of the nervous system to counteract a strong sound, designed to protect the vestibulocochlear organ from sound overloads (J. Jerger, 1970; V.G. Bazarov et al., 1995).

The amplitude characteristics of the acoustic reflex of the stapedius muscle are widely practical use. According to many authors, this method can be used for the purpose of early and differential diagnosis of hearing loss.

The acoustic reflex, closing at the level of the nuclei of the brain stem and participating in complex mechanisms for processing sound information, can respond by changing its amplitude in case of violations of the functional state of the organ of hearing and the central nervous system. When studying the parameters of the AR amplitude depending on the violations of the functional state of the central nervous system according to EEG data, it was found that their decrease is more often observed with irritation of the cerebral cortex than its diencephalic-stem sections (N.S. Kozak, A.N. Golod, 1998) .

With damage to the brain stem, an increase in the threshold of the acoustic reflex or its absence may be noted (W.G. Thomas et al., 1985). If the acoustic reflex is realized in the auditory analyzer at a level lower than a certain pure tone threshold, the hearing loss is obviously functional (A.S. Feldman, C.T. Grimes, 1985).

The accumulated facts in the literature on tympanometry are almost exclusively based on the allocation of five standard types proposed back in 1970 by J. Jerger, while in young children there is a polymorphism of tympanograms that does not fit into this classification.

It should be noted the significant value of tympanometry in the diagnosis of lesions of the middle ear in children of all age groups.

Until now, the question of the value of the acoustic reflex for predicting hearing loss in children has been debated. In most works, the reflex threshold is reported as the main criterion for impedancemetry (S. Jerger, J. Jerger, 1974; M. McMillan et al., 1985), but it is known that in children of the first year of life, threshold responses are fuzzy and unstable. For example, G.Liden, E.R. Harford (1985) noted that half of the children with hearing loss in the range of 20-75 dB had a normal acoustic reflex (as well as in well-hearing children). On the other hand, only in 88% of children with normal hearing did the acoustic reflex correspond to the norm.

B.M. Sagalovich, E.I. Shimanskaya (1992) studied the results of impedancemetry in young children. According to the authors, in many children of the 1st month of life, the absence of an acoustic reflex was noted even at such an intensity of the stimulus at which the children wake up and a motion artifact appears in the recording (100–110 dB). Consequently, there is a reaction to sound, but it is not expressed in the formation of an acoustic stapedial reflex.

According to B.M. Sagalovich, E.I. Shimanskaya (1992), in screening diagnostics, it is inappropriate to rely on impedancemetry data in children during the first month of life. They note that at the age of over 1.5 months, an acoustic reflex appears, the reflex threshold ranges from 85-100 dB. All children aged 4-12 months recorded an acoustic reflex, so impedancemetry can be used as an objective test with a sufficient degree of reliability, subject to strict observance of some special methodological conditions.

The question of the use of sedatives to eliminate movement artifacts in children remains very difficult, especially in screening diagnostics (B.M. Sagalovich, E.I. Shimanskaya, 1992).

In this sense, their use is advisable, however, sedative drugs are not indifferent to the child's body, besides, the sedative effect is not achieved in all children, and in some cases changes the threshold value and amplitude of the above-threshold responses of the acoustic reflex (S. Jerger, J. Jerger, 1974; O. Dinc, D. Nagel, 1988).

Various drugs and toxic drugs can affect the acoustic reflex (VG Bazarov et al., 1995).

Thus, for a correct assessment of the results of impedancemetry, it is necessary, firstly, to take into account the patient's condition (the presence of pathology from the CNS; the use of sedatives), and secondly, to introduce an age-related correction, since in the process of maturation of the auditory system, some parameters of the acoustic reflex of the stapes muscle change (S.M. Megrelishvili, 1993).

The method of dynamic impedance measurement deserves to be widely introduced into audiological practice.

auditory evoked potentials

The objectivity of the SVP registration method is based on the following. In response to sound exposure, electrical activity occurs in various parts of the auditory analyzer, which gradually covers all parts of the analyzer from the periphery to the centers: the cochlea, the auditory nerve, the nuclei of the trunk, and the cortical sections.

The ABR recording consists of 5 main waves that appear in response to sound stimulation in the first 10 ms. It is generally accepted that individual ABR waves are generated by different levels of the auditory system: the auditory nerve, the cochlea, the cochlear nuclei, the superior olivar complex, the nuclei of the lateral loop, and the inferior colliculi. The most stable of the entire complex of waves is the V wave, which persists up to the threshold levels of stimulation and which determines the level of hearing loss (A.S. Rosenblum et al., 1992; I.I. Ababii, E.M. Prunyanu et al., 1995 and others).

Auditory evoked potentials are divided into three classes: cochlear, muscular and cerebral (AS Rosenblum et al., 1992). Cochlear SEPs combine the microphonic potential, the summation potential of the cochlea, and the action potential of the auditory nerve. Muscular (sensomotor) SEPs include evoked potentials of individual muscles of the head and neck. In the class of cerebral SEPs, the potentials are subdivided depending on the latent period. There are short-, medium- and long-latency SVPs.

T.G. Gvelesiani (2000) identifies the following classes of auditory evoked potentials:

• cochlear potentials (electrocochleogram);
• short-latency (stem) auditory evoked potentials;
• mid latency auditory evoked potentials;
• long-latency (cortical) auditory evoked potentials.

Currently, a reliable method of hearing research, which is becoming more widespread, is computer audiometry, including the registration of short-latency, medium-latency and long-latency evoked potentials.

Registration of ABR is carried out in the state of wakefulness of the subject or natural sleep. In some cases, with an overly excited state of the child and a negative attitude towards the study (which is more common in children with pathology of the central nervous system), sedation should be used (A.S. Rosenblum et al., 1992).

The dependence of the amplitude-temporal characteristics of SEPs and the thresholds for their detection on the age of the child (E.Yu. Glukhova, 1980; M.P. Fried et al., 1982) is explained by the process of maturation of glial cells, differentiation and myelination of neurons, as well as the functional inferiority of synaptic transmission.

The thresholds for recording short-latency auditory evoked potentials (SEPs) in one-year-old children approach those in adults, and long-latency (DSEP) - to the age of 16 (Z.S. Aliev, L.A. Novikova, 1988).

Therefore, knowledge of the exact quantitative characteristics of ABR, which are characteristic of healthy young children, is one of the conditions for diagnosing hearing impairment in children. childhood. ABRs can be successfully used in pediatric audiological practice with the obligatory consideration of the age values ​​of these parameters (I.F. Grigorieva, 1993).

The result of ABR depends on the state of receptors and centers in the brain stem. Abnormal curves may be due to damage to both.

G. Liden, E.R. Harford (1985) emphasize that using this method can give wrong results therefore, if an atypical CVSP record is obtained in infants, the study should be repeated after 6 months.

Despite the 30-year history of the issue, the problem of matching the results of registration of ABRs and subjective methods for determining hearing thresholds in deaf children still remains relevant (A.V. Gunenkov, T.G. Gvelesiani, 1999).

A.V. Gunenkov, T.G. Gvelesiani (1999), having analyzed the results of the survey in 81 children (from 2 years 6 months to 14 years), made the following conclusions.

First, in the majority of children with hearing loss, the subjective hearing thresholds are quite consistent with the ABR registration data.

Secondly, with mixed hearing loss, the discrepancy between objective and subjective thresholds is significantly higher than with sensorineural hearing loss. This is likely due to the fact that the conductive component not only increases the latency of the ABR peaks, but also worsens their visualization.

According to B.M. Sagalovich (1992), electrical responses supplement or clarify information about the nature of disturbances in the auditory system, but it is practically more correct not to turn them into an analogue of subjective processes. Widely using the registration of SVP, the author does not consider it correct to identify them with hearing. At best, they can be seen as the electrical equivalent of this sensation.

SEPs occur only in response to suprathreshold stimuli, while the aim of the study is to determine the minimum signal intensity at which a brain response can be registered. The problem is only in determining the relationship between subjective hearing thresholds and SVP thresholds.

To the greatest extent, the so-called long-latency SVPs correlate with the concept of “hearing” (K.V. Grachev and A.I. Lopotko, 1993). Unlike KSVP, DSVP, i.e. cortical potentials have thresholds close to the thresholds of audibility. But even this should hardly be regarded as an expression of hearing acuity (B.M. Sagalovich, 1992).

A.D. Murray et al. (1985), A. Fujita et al. (1991) also came to the conclusion that when using DSWP, the registration thresholds coincide with the hearing thresholds. Along with this, the authors clarify that the results of the study depend on the psycho-emotional state, the phase of sleep, therefore, in practice, the absolute values ​​of the latent periods of SEP are used, and not their ratio.

According to A.S. Rosenblum et al. (1992), DSEP allow assessing the state of auditory function in the entire range of speech frequencies, but show signs of "maturation", i.e. the process of growing up, and therefore, there are difficulties in identifying children under the age of 15-16 years.

DVSP have diagnostic value for the detection of central hearing loss. However, this technique has a number of disadvantages (K.V. Grachev, A.I. Lopotko, 1993; A.S. Feldman, C.T. Grimes, 1985):

1. their significant dependence on the physiological state of the subject;
2. his age;
3. the presence of difficulties associated with the influence of artifacts of biological and non-biological origin (long-latency potentials give a significant instability of reactions);
4. Preliminary medical sedation of children distorts the records of reactions from the cerebral cortex.

Therefore, it is extremely difficult to study hearing in mobile and negatively minded young children, since all types of anesthesia, with the possible exception of diphenhydramine and chloral hydrate, are unsuitable in these cases for one reason or another (K.V. Grachev, A.I. . Lopotko, 1993).

Thus, SVP-methods do not depend on the cooperativity of the subject, and can be used for the examination of hearing in a subject of any age. In this sense, they are objective, at least to the same extent as reflex techniques. However, they depend to a much greater extent on the qualifications of the researcher and, in this sense, only transfer the subjective factor of diagnosis from the patient to the doctor (K.V. Grachev and A.I. Lopotko, 1993).

K.V. Grachev and A.I. Lopotko (1993) also believe that common disadvantage SVP diagnostics, in addition to the need for unique equipment, is the duration of the study. And the possibility of a practical reduction in the time required to complete the tests does not yet have visible prospects.

Of course, ideally, it is advisable to combine several methods (registration of ABRs and impedance measurements), however, in practice this turns out to be very difficult for a number of reasons. Today, computer audiometry is used mainly in specialized centers, since registration of SVP requires rather complex expensive equipment and, more importantly, specialization of otorhinolaryngologists in the field of electrophysiology. Obviously, the recording of auditory evoked potentials will not become a screening method in the near future (B.M. Sagalovich, E.I. Shimanskaya, 1992).

Thus, the use of various registration options for SEPs and their characteristics in children of different age categories is currently the method of choice in the diagnosis of various hearing impairments and the most promising in terms of scientific research, which can provide more effective rehabilitation for this category of patients.

Electrocochleography

Electrocochleography data (registration of the cochlear microphone potential, summation potential, and total action potential of the auditory nerve) make it possible to judge the state of the peripheral part of the auditory analyzer.

Recently, electrocochleography (EcoG) has been used mainly for diagnosing labyrinth hydrops and as a basic technique for intraoperative monitoring. For diagnostic purposes, a non-invasive study option is preferable - extratympanic EcoG (E.R. Tsygankova, T.G. Gvelesiani 1997).

Extratympanic electrocochleography is a method of non-invasive recording of the induced electrical activity of the cochlea and the auditory nerve, which improves the efficiency of differential and topical diagnosis of various forms of hearing loss (E.R. Tsygankova et al., 1998).

Unfortunately, the method is used in children, as a rule, under general anesthesia, which prevents its widespread use in practice (B.N. Mironyuk, 1998).

Otoacoustic emission

The discovery of the OAE phenomenon was of great practical importance, allowing an objective, non-invasive assessment of the state of the micromechanics of the cochlea.

Otoacoustic emissions (OAE) are sound vibrations generated by the outer hair cells of the organ of Corti. The OAE phenomenon is widely used in studies of the mechanisms of primary auditory perception, as well as in clinical practice as a means of assessing the functioning of the sensory apparatus of the hearing organ.

There are several classifications of the UAE. Here is the most common classification (R. Probst et al., 1991).

Cspontaneous UAE, which can be registered without acoustic stimulation of the organ of hearing.

Caused by the UAE, including:

1) delayed UAE - registered after a short acoustic stimulus.

2) stimulus-frequency OAE - is recorded during stimulation with a single tonal acoustic stimulus.

3) OAE at the frequency of the distortion product - is recorded during stimulation with two pure tones.

The optimal time for this test is 3-4 days after birth.

It is known that the characteristics of VOAE change with age. These changes may be associated with maturation processes in the organ of Corti (i.e., at the site of generalization of VOAE) and / or age-related changes in the outer, middle ear. Most of the energy of the TEOAE in newborns is concentrated in a fairly narrow frequency band, while in older children it has a more even distribution (A.V. Gunenkov, T.G. Gvelesiani, G.A. Tavartkiladze, 1997).

In a number of works, the negative aspects of this method of objective examination were noted. The evoked OAE is physiologically extremely vulnerable, the amplitude of the OAE is significantly reduced after intense noise exposure, as well as after tone stimulation. In addition, middle ear dysfunction also leads to a decrease in amplitude and a change in the frequency spectrum of the OAE, and even to the inability to register it. Pathological processes in the middle ear affect both the transmission of the stimulus to the inner ear and the return path to the ear canal. For audiological screening of children in the first days of life, it is advisable to use the TEOAE registration method, and when examining hearing in children in premature wards, it is preferable to use the PTOAE test.

It is known that THROAE is characterized by a much less pronounced adaptation than ABR. Registration of TEOAE is possible only in relatively short periods of physical and "vocal" rest of the child.

Audiometry

The study reveals the minimum level of sound that a person hears by measuring hearing thresholds for tones of different frequencies. Hearing thresholds are measured in decibels - the worse a person hears, the greater the hearing thresholds in decibels he has.

As a result of tone audiometry, an audiogram is obtained - a graph characterizing the state of a person's hearing.

There is also speech audiometry, in which words are presented and their intelligibility is assessed in different conditions (in silence, in noise, and with other distortions).

The organ of hearing is one of the main analyzers that provide a connection between a person and the environment. Today, modern otolaryngology deals with the treatment of a number of different disorders of this sense organ. However, the correct therapy can be selected only after a complete and adequate examination, which is necessarily performed under the supervision of a highly specialized specialist.

The doctor begins the first diagnostic search simultaneously with the acquaintance with the patient's complaints, as well as with the history of the development of the disease. Ways of possible researches at different states are very diverse, which mainly depends on the specifics of the disease and the age of the patient.

There are two main directions in diagnostics - these are subjective and objective methods of hearing examination. They are equally used in people of different age groups, however, the examination of hearing in children has its own characteristics.

So, young children are prescribed unconditional and conditioned reflex research methods to assess auditory perception. In cases correct execution they are quite informative.

Unconditioned reflex way

A fairly common method for assessing hearing in newborns, which is based on the child's response to a sound stimulus. This reaction is formed without any preliminary preparations. These include reflexes:

• Ankylosing spondylitis - reacting to the sound, the child begins to blink intensively, the activity of the eyelids increases.
• Shurygin - in a child, against the background of the presence of a sound stimulus, the pupil expands.
• Sucking and oculomotor.
• Increased breathing and heart rate.
• Increased motor activity in the limbs.

In addition to the above reactions, in response to a loud sound, the baby can often experience fear, fading or awakening, and various grimaces appear on the face.

Despite the availability and ease of use, this technique has several disadvantages:

• Each baby has its own, individual reaction to the stimulus.
• When re-checking, a decrease in the reflex is noted.
• For the appearance of a reaction, it is necessary to act with a sufficiently high sound threshold, which worsens the detection of hearing impairment to 50 or 60 dB.

Such a diagnosis of hearing in children is not very informative if the child has concomitant pathology from the nervous system.

Conditioned reflex method

This method can be successfully applied only within the following limits of childhood - from one to three years, since in the older age group there is no longer that interest, and the smallest ones showed increased fatigue.

It is based on the formation of a conditioned reflex during the repeated repetition of a sound signal against the background of unconditioned reflexes - defensive, food (based on Pavlov's theory).

Most often, the child has pupillary, blinking and vascular reactions. Also, the method has its own list of shortcomings: when repeated, the reflex quickly fades away, it is impossible to accurately determine the threshold of hearing.

In children with mental disorders, this type of diagnosis is very difficult. Quite informative subjective methods also include pure tone audiometry, but since it is used in children older than seven years, distribution in junior group received play audiometry.

Play audiometry is a subjective hearing test in children from the age of three. The child is shown a toy or a picture, reinforcing this action with a sound accompaniment, as a result of which a reflex reaction to a sound signal is achieved.

To prevent the extinction of the resulting reflex, it is necessary to replace the used pictures or toys. The volume of the sound also needs to be reduced, which allows the analysis of hearing according to the full tone scale.

The data obtained is stored on an audiogram, a graphic image that shows the relationship between hearing acuity and sound intensity and gives an assessment of auditory conduction.

Diagnosis of central hearing changes in children

In many cases, in a child with a physiological hearing threshold and intellect, it is possible to identify the presence of impairments in the ability to distinguish between voiced and deaf consonants, memorizing the order of sounds, and in selective misunderstanding of oral speech. These signs are characteristic of the central disorders of the organ of hearing. To diagnose them, the following methods of hearing research are carried out:

• dichotic test. Has many variations. The basis of the method is the simultaneous exposure of both ears to two completely different speech signals. This allows you to identify violations from the cortical sections and determine the affected side.
• Monaural test. Unlike the dichotic test, the speech signal is given sequentially. A method is used to detect disorders of the brain stem.

Tests are also used that assess the perception of the temporal structure of the signal, which, in addition to identifying pathology from the cortical regions, allows you to determine the maturity of the auditory pathways.

Subjective assessment of the hearing organs

Already from the age of two, it is permissible to use the same approach in the examination for both adults and children to test hearing. However, this becomes possible only if the child by this time has begun to pass speech development- he is already able to repeat words or point to their visual image in the pictures. Thus, in addition to the above examinations, it is permissible to conduct subjective methods of hearing research in the form of whispered speech.

This diagnostic method is based on the ability of a person to recognize various speech signals, while being at a distance of six meters from the sound source. During the study, the subject is placed in a relatively soundproof room, positioned in such a way that one ear is directed towards the sound source, while the other is covered.

Usually, two-digit numbers or specially selected words are used for research, a list of which can be found in the table of V. Voyachek. The results obtained may indicate the level of detected violations. So, for example, violations on the part of the sound-perceiving apparatus can be detected if a person perceives whispered speech poorly, and conversational speech quite well.

If the subject has impaired perception of phrases, but a normal understanding of simple sounds is preserved, then one can judge the presence of disturbances in the zone of the auditory centers.

There are other subjective ways of examining the hearing of children and adults, which include the use of special tools - tuning forks. With their help, it is possible to assess the air and bone conduction of sound, which, in turn, makes it possible to judge the quality of the functional ability of the hearing organ. A quantitative assessment is given on the basis of the time during which the subject perceives sound signals from an irritated tuning fork.

It is this diagnostic method that makes it possible to clarify the cause of changes in the auditory function in the hearing impaired: whether it is a lesion of the sound-conducting (impaired perception of low tones) or sound-perceiving (impaired perception of high tones) apparatus.

Taking into account the period of adaptation and fatigue of the body, a working tuning fork is brought to the ear for no more than 5-10 seconds and carried away for the same time.

Otoacoustic emission

Despite the fact that subjective diagnostic methods are widely used, objective methods of hearing research have won high popularity due to their high information content and accuracy.

One of these types of this diagnostic, which is carried out for the purpose of mass screening and is used at the initial stages of the examination, is the method of otoacoustic emission (OAE).

A miniature microphone is placed in the area of ​​the external passage, registering a faint sound that occurs due to the motor activity of the outer hair cells of the organ of Corti. If audibility is reduced by more than 25-30 dB in accordance with normal values, then this weak sound cannot be registered during the study.

There are spontaneous OAE, which is recorded without acoustic stimulation, and OAE caused by an acoustic stimulus (short, single tone or two pure tone). The characteristics of the induced UAE change according to the age of the subject.

The study also has a negative side - the amplitude of the OAE decreases when exposed to high noise. However, this method allows you to establish only the very fact of hearing loss, and not to detail the level and extent of the damage that has occurred.

Acoustic impedancemetry

Acoustic impedance allows you to register pressure numbers in the middle ear, to identify the presence of fluid and damage in the eardrum, in the connection of the auditory ossicles. The method is based on the measurement of the resistance exerted by the external and middle departments ear in response to a sound signal.

The obtained low values ​​of acoustic impedance correspond to physiological indicators, any deviation from the norm always indicates the presence of disorders of the middle ear and tympanic membrane. In addition, the method includes dynamic measurement of tympanic membrane compliance (tympanometry), as well as registration of reflex contraction of the stapedius muscle.

If the acoustic reflex is in the range of 75-80 dB, this indicates the absence of violations from the sound-conducting system. Its negative values ​​are often detected in otitis, accompanied by accumulation of fluid, inflammation of the Eustachian tube.

To obtain reliable data, it is necessary to take into account the state of a person during the examination - the presence of disorders of the nervous system, the use of sedatives medicines, as well as give an assessment according to the age of the person.

Computer audiometry

All the previously described methods for diagnosing hearing impairment are inferior in their information content. this species research. They begin to conduct an examination with the introduction of the patient into a state of medical sleep, since the procedure lasts quite a long time. Such a diagnosis can be carried out in children who have reached the age of three.

The method is based on the registration of the electrical activity of the hearing system, which occurs in different parts of the hearing organ, as a reaction to a sound stimulus. There are four classes of recorded evoked potentials: brain stem, medium and long latency (cortical), as well as cochlear potential.

Electrocochleography assesses the state of the peripheral part of the hearing organ. Most often, this method is prescribed if there is a suspicion of labyrinth hydrops, and also as a basic examination during intraoperative observation. Cortical potentials reflect the reaction of the cerebral cortex to a sound signal, and short-latency potentials reflect the brainstem.

This method is actively used in the diagnosis pathological conditions organ of hearing in childhood. Electrical potentials significantly complement the information obtained in other ways about the features of disorders from the hearing aid.

Complexity this study consists only in the necessary preliminary sedation of the subject.

At the moment, this diagnostic method is used only in specialized centers, since it needs good equipment and the work of highly qualified specialists.

Objective hearing methods can be used from infancy. These include acoustic impedancemetry, auditory evoked potential (AEP) computerized audiometry, evoked otoacoustic emission (AOAE).

Russia has developed a unified system early detection hearing loss since the neonatal period. On the basis of the order of the Ministry of Health and Medical Industry of Russia dated March 23, 1996 No. N2 108 "On the introduction of audiological screening of newborns and children of the 1st year of life" at present, this system is being widely implemented in the regions of the Russian Federation.

A modern objective method for the study of hearing used for audiological screening (mass examination) is the registration of induced otoacoustic emission (TOAE) (O.A. Belov, I.V. Koroleva, A.V. Kruglov, Ya.M. Sapozhnikov, G. A. Tavartkiladze, V. L. Fridman and others).

The method of evoked otoacoustic emission. Otoacoustic emission is a very faint sound produced in the ear as a result of the mechanical movements of the outer hair cells in the cochlea, which can be detected by placing a miniature sensitive microphone in the external auditory canal. Currently, two classes of DOAE are used: delayed EOAE (3BOAE) and otoacoustic emission at the frequency of the distortion product (POAE).

3BOAE is registered in all children with normal hearing, starting from the first days of life. With hearing loss of more than 25-30 dB relative to normal hearing thresholds, 3VOAE is absent. It does not matter whether the hearing loss is a consequence of the pathology of the structures of the middle or inner ear. The absence of 3 VOAE indicates hearing loss and the need for referral to diagnostic examination. Thus, with the help of OAE registration, the presence of hearing loss is detected, but it is impossible to determine the degree of hearing loss and the level of damage using this method alone.

The study of the statistical and dynamic characteristics of the sound-conducting and partially sound-perceiving systems of the organ of hearing is carried out using an objective method - acoustic impedancemetry.

Acoustic impedancemetry . The technique allows using an acoustic impedance device to register pressure in the middle ear, the integrity and degree of mobility of the tympanic membrane and the ossicular chain, the presence of exudate (fluid) in the tympanic cavity, the degree of patency of the auditory tube, the acoustic reflex of the stapedial muscle (M.R. Bogomilsky,

L.D. Vasilyeva, M.Ya. Kozlov, I.V. Koroleva, A.L. Levin, Ya.M. Sapozhnikov, G.A. Tavartkiladze and others). The method is based on the measurement acoustic and impedance, those. resistance of the outer and middle ear in response to sound: when the sound reaches the tympanic membrane, part of the energy is transmitted through the middle ear to the inner ear, and part of the energy, due to resistance from the tympanic membrane and the ossicular chain, is reflected and can be measured. Normally, the human ear has a low acoustic impedance. With pathology of the middle ear, negative pressure in the tympanic cavity, thickening of the tympanic membrane, the passage of sounds through the middle ear is difficult.

The study includes conducting ty.mpano.meters, Those. dynamic measurement of tympanic membrane compliance with changes in air pressure in the external auditory canal (from +200 to -200 mm of water column) and acoustic reflectometry- registration of the acoustic reflex of the stapedius muscle.

The diagnosis is made on the basis of the analysis of the parameters of the tympanogram: the location of the peak of maximum compliance, its values, the shape of the tympanogram.

Additional information can be obtained from acoustic reflexometry- registration of changes in the resistance of the structures of the outer and middle ear during the contraction of the stapedius muscle, caused by loud sounds. This gives some information about hearing thresholds. it is known that a person with normal hearing has an acoustic reflex threshold of 75-80 dB. With an increase in hearing thresholds, the threshold of the acoustic reflex (a.p.) also increases. With a hearing loss of more than 60 dB, the acoustic reflex is not recorded. In children under the age of one year, the acoustic reflex with normal hearing is recorded to a sound with a level of 90 dB. The registered acoustic reflex can serve as a sign of the absence of damage to the sound-conducting apparatus of the middle ear.

In the process of conducting tympanometry, the researcher increases the air pressure in the external auditory canal (up to 200 mm of water column). In this case, the tympanic membrane is pressed into the cavity of the middle ear, which leads to a deterioration in its mobility and, as a result, a decrease in acoustic conductivity. Most of the energy of the probing tone is reflected, creating a relatively high sound pressure level in the cavity of the external auditory canal, which is recorded by the probe microphone.

Then the air pressure is reduced, the eardrum returns to its normal position, its mobility is restored, acoustic conductivity increases, and the amount of sound energy decreases. Maximum conductivity is observed at equal air pressure on both sides of the tympanic membrane, i.e. at atmospheric pressure. A further decrease in air pressure in the external auditory canal again leads to a deterioration in the mobility of the tympanic membrane and, accordingly, to a decrease in acoustic conductivity. Registration of tympanogram type BUT and an acoustic reflex is noted during normal functioning of the middle ear, and can also be observed with sensorineural hearing loss of I-IP degrees.

Some diseases (secretory otitis media, acute otitis media without perforation of the tympanic membrane) lead to the accumulation of fluid in tympanic cavity on the background of low intratympanic pressure. These factors cause a significant decrease in the mobility of the eardrum. Under these conditions, the peak of the tympanogram is shifted towards negative values ​​and is represented by a sharply flattened or completely smoothed curve. (rice. 3).

In violation of the aeration of the Eustachian tube, for example, as a result of inflammatory process, intratympanic pressure decreases. In this case, the balance of pressure on both sides of the tympanic membrane can be achieved only when the air is rarefied in the external auditory canal. The tympanic membrane is allowed to oscillate with maximum amplitude when the pressure in the external auditory canal becomes equal to the air pressure in the middle ear. As a result, the peak of the tympanogram is shifted towards negative pressure, and the magnitude of the shift corresponds to the value of the negative pressure in the tympanic cavity.

The main method for an objective quantitative assessment of hearing in children aged from birth to three years, as well as older children with pathology of the central nervous system, is the registration of auditory evoked potentials of the brain.

The method of computer audiometry by auditory evoked potentials (AEP).
This method is also known as "computer audiometry", "audiometry by auditory evoked potentials" (Z.S. Aliyeva, I.V. Koroleva, L.A. Novikova, N.V. Rybalko, Ya.M. Sapozhnikov, G. A. Tavartkiladze, V.R. Chistyakova and others).

The SVP method is based on recording the induced electrical activity of the auditory system. The main methods are: electrocochleography(acoustic nerve action potentials and cochlear microphone potentials are recorded), brainstem (short-latency) SEL, cortical(long-latency) SVP.

The study is usually carried out in a state of sedation, i.e. medical sleep, because a significant duration of the examination (when recording ABR about 1 hour) tires young children and makes it difficult to conduct the study.

The method of recording evoked auditory potentials, which is used with the use of a computer, allows the accumulation, summation and averaging of the recorded signals. The response to the action of a sound stimulus, starting in the hair cells, spreads sequentially to the cerebral cortex. There are three groups of components depending on the time of occurrence of the response in relation to the beginning of the sound stimulus (latent period): short-latency responses (from 1.5 to 12 ms), medium-latency (from 12 to 50 ms), long-latency (from 50 to 300 ms ).

For clinical purposes, registration of stem brain and cortical auditory evoked potentials is more often used. Long latency potentials(DSVP) reflect the electrical response of the cerebral cortex to the supply of a sound stimulus. brain stem, or short-latency, auditory evoked potentials(KSVP) - electrical potentials that occur mainly in the brain stem in response to a sound stimulus.

Analysis of the dependence of SEP on the intensity of the stimulus has a prognostic value in the process of treatment and correction measures and can help practitioners in choosing the most rational methods of treating identified diseases and monitoring its effectiveness.

In addition to objective audiological methods, subjective methods are used to diagnose hearing impairment in children: registration of an unconditioned orienting reflex, audiometry in a free sound field, threshold tone audiometry, speech audiometry, tuning fork tests, examination of conversational speech and whisper.

AT early age(before 1 of the year) apply studies aimed at identifying behavioral unconditional reflex reactions to acoustic stimuli. For this purpose, they use various sounding toys, jars of cereals, jars of shot, etc., previously calibrated with a sound level meter; sound-react tests that allow you to present sounds of a certain frequency (0.5; 2; 4 kHz) with an intensity of 90; 65; 40 dB.

Sound proof test method (3RT - 01) is based on the registration of unconditioned reflex reactions. The most informative and easily fixed are the following reactions of the child:

unconditioned orienting Moro reflex (extension, i.e., shuddering of the body and hugging movements of the hands); cochleo-palpebral reflex (closing or twitching of the eyelids under the action of sounds); changes in breathing, pulse, pupillary reflex, turning the head towards or away from the sound source, sucking movements, etc. The reaction is considered positive if the child responds 3 times to the same sound with one of the indicated reactions. Children suspected of having hearing loss are selected for observation and follow-up examination.

For the study of hearing in young children is also widely used sounding toy technique proposed by T.V. Pelymskaya and N.D. Shmatko. For examination, a set of sounding toys is used, which differ in the dynamic severity of frequencies from 500 to 5000 Hz: a drum, a whistle, an accordion, a pipe, a hurdy-gurdy, a rattle. A child (from 6-8 months old) behind his back is presented first with high-frequency sounds (for example, barrel-organs), then medium-frequency ones (pipes), and finally low-frequency ones (drum). A child with normal hearing should respond to all stimuli at the same distance (3 to 5 m). The distance from which all stimuli are perceived (from the barrel organ to the drum) is constant and depends on the age of the child: the younger he is, the closer acoustic stimuli are perceived from.

FROM l-th year to 3 years life for the study of hearing are also used various conditioned reflex techniques . Their essence lies in the initial simultaneous presentation of sound in a free sound field (sound speakers are used instead of headphones) and the display of a bright picture or toy laterally (on the side) from the child. After several simultaneous presentations of sound and picture, the child develops an orienting reaction in the form of eye movement or turning of the head towards the sound, but without visual reinforcement (Ya.M. Sapozhnikov).

Tone threshold audiometry is the main subjective method for studying hearing (V.G. Ermolaev, M.Ya. Kozlov, A.L. Levin, A. Mitrinovich-Modzhaevska, L.V. Neiman, etc.). It consists in determining the minimum (threshold) sound intensity, expressed in decibels (dB), at which sound is perceived as an auditory sensation. The frequency range used for audiometry, both in air and bone conduction, corresponds to 7 octaves: 125-250-500-1000-2000-40008000 Hz (for air conduction, 10-12 kHz are sometimes additionally used).

Tonal threshold audiometry is performed in children older 7 years. Used at a younger age play audiometry.

Play tone audiometry is based on the subjective report of the subject and is carried out in children aged 3-3.5 to 7 years. The method is based on the preliminary development of a conditioned reflex to sound in a child, which is achieved by using various bright electronic toys and pictures.

First, a sound obviously audible to the child is presented, and the assistant presses the answer button with the child's hand. Gradually, the intensity of the sound decreases. When the child understands the essence of the study, he begins to press the answer button on his own; When pressed correctly, a picture is displayed. By changing the intensity, as well as the frequency of stimulation, it is possible to obtain information about the state of the child's hearing on the entire tone scale (from 125 Hz to 8 (10) kHz). So that the reflex does not fade away, visual reinforcement changes. Initially, hearing acuity is detected by air conduction in each ear, and then by bone conduction. The results obtained are recorded on an audiogram.

Audiogram is a characteristic of the dependence of hearing acuity on the intensity of sound and its frequencies, which is depicted on the form in the form of curves reflecting the state of air and bone conduction. It is generally accepted to designate the air conduction curve as a solid line, and the bone conduction curve as a dotted line. Circles (0-0-0) are used to indicate the right ear (AD), and

for the left (AS) - crosses (x-x-x). The absence of an interval between the curves of air and bone conduction is characteristic of minimal sensorineural auditory disorders. The presence of a significant gap between the curves of air and bone conduction is typical for conductive hearing loss.

Screening audiometry with the help of microaudiometer-otoscope(type AtlClioScope 3, USA). This method consists in registering the child's conditioned reflex response (for example, "I hear") to tone signals.

An otoscope can be used to examine the outer ear and eardrum, which allows you to determine possible reasons hearing loss. The microaudiometer allows you to get ahead of the child's perception of tonal signals in the frequency range from 500 to 4000 Hz at a sound intensity of 20 to 40 dB. The child's lack of response to low-frequency and mid-frequency signals (500, 1000, 2000 Hz) at a given intensity of 20 dB suggests that he has a minimal conductive type hearing loss (impaired sound conduction). When registering reactions to low-frequency tones and the absence of a reaction to a high-frequency signal (4000 Hz), one can think of a minimal sensorineural hearing loss (impaired sound perception). The results of the examination are recorded in the "Hearing Passport" of the child.

The study of hearing by speech is carried out in a relatively soundproof room, the length of which should be at least 6 m. The quantitative assessment of the results of the study comes down to determining the distance, expressed in meters, from which the subject hears whispered or colloquial speech. An important circumstance for the reliability of the study is the muffling of the unexamined ear. During the examination, the child is located sideways to the experimenter, i.e. in the most convenient position for hearing perception.

If it is impossible to examine a child in a large room, you can put him with his back to the experimenter. This will halve the distance (3 m) from which the test words are spoken.

In the study of hearing by whispered speech, familiar words are pronounced at a normal pace, in reserve air, which helps to equalize the intensity of the whispers of different persons.

There are specially designed verbal tables that take into account the main physical indicators of speech: its amplitude response (acoustic power of sound), frequency response (acoustic spectrum), temporal response (sound duration) and rhythmic-dynamic composition of speech, as well as corresponding to different ages.
The subjective method of examining the state of hearing is tuning fork method . A tuning fork study makes it possible to conduct a presumptive "qualitative" and "quantitative" characteristic of the state of the auditory function. With the help of tuning forks, the perception of sounds through the air and through the bone is determined. The data obtained by air and bone sound conduction are compared, after which conclusions are drawn about the qualitative state of the auditory function. Quantitative evaluation of the results of the study of hearing with tuning forks is reduced to determining the time (in seconds) during which an irritated tuning fork is perceived by the subject through the air and through the bone.

The survey is best done with low-frequency tuning forks (C-128, C-256), because their sound is heard for a long time through the air, through the bone, and the child has time to adequately respond to test tasks.

When conducting differential diagnosis, Weber, Rinne, Schwabach, etc. tests are used.

The essence of the Weber test is that the sounding tuning fork is placed in the middle of the crown, and the subject answers whether he hears the sound of the tuning fork equally in both ears (in the middle of the crown) or only in one ear. With normal or equal hearing in both ears (even with a decrease in hearing acuity), lateralization (displacement of the sound image) does not occur. When the sound-conducting apparatus is damaged, the sound of the tuning fork is lateralized towards the worse hearing ear. When the sound-perceiving apparatus is damaged, the sound of the tuning fork is lateralized towards the normal (or better) hearing ear.

To clarify the results of the Weber test, Rinne's experiment is carried out, which consists in comparing air and bone conduction for the same ear. With a healthy ear or damage to the sound-perceiving apparatus, air conduction prevails over bone conduction (Rinne +). The predominance of bone conduction over air conduction is characteristic of a disease of the sound-conducting apparatus (Rinne -). If the air and bone conduction are the same, then there is a hearing impairment of a mixed nature.

Often in children with normal hearing thresholds and normal intelligence, there are impairments in distinguishing voiced and deaf consonants, perceiving a sequence of non-speech and speech sounds, memorizing sound sequences, automated word sequences (counting from 1 to 10, seasons, months, etc.), selective insufficiency of understanding oral speech (especially against the background of surrounding noise and a fast pace of speech). This is a sign central auditory disorders, in which the analysis, synthesis and differentiation of speech signals are not provided.

For the diagnosis of central hearing disorders in children I.V. The Queen gives the following comprehensive tests:

- dichotic tests(simultaneous presentation on the right and left ear 2 different speech signals: syllables, numbers, words of various structures, sentences). The tests are aimed at identifying the pathology of the cortical regions and interhemispheric interaction. In clinical practice, about 10 modifications of these tests are used, which make it possible to identify the pathology of the brain stem, cortical parts of the auditory system, corpus callosum (interhemispheric interaction is carried out through it), determine the side of the lesion (right - left hemisphere brain), as well as to assess the degree of maturation of the central auditory structures;

- tests to assess the perception of the temporal structure of signals(determination of the sequence of tones of different frequencies and different durations). These tests are sensitive to disturbances at the level of the cortical part of the auditory system, the corpus callosum, reveal the degree of maturity of the auditory pathways;

- monaural tests(presentation of signals in one ear). Tests for the presentation of distorted speech, compressed in time, are sensitive to subcortical and cortical disorders; - tests evaluating binaural interaction. In contrast to dichotic tests, in these tests, signals are presented to the right and left ears not simultaneously, but sequentially or with partial overlap (resynthesis effect). These tests detect hearing disorders at the level of the brainstem;

- electrophysiological methods(registration various kinds auditory evoked potentials). Analysis of various auditory evoked potentials makes it possible to determine the level of damage to the auditory system.

Most of these tests can be used in practice by different specialists, since their application requires only a tape recorder and magnetic recordings of tests. However, to work with them, you need the correct selection of test material, certain experience in conducting research and interpreting the results. The exception is electrophysiological research methods that are performed in specialized medical and speech centers.