Audiometry
Last reviewed: 23.04.2024
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This scientific term originated from two different words - audio - I hear (Latin) and metreo - I measure (Greek). Their combination very accurately determines the very essence of this technique. Audiometry is a procedure that allows you to assess the level of acuity of hearing.
After all, how well we hear is due to the presence or absence of abnormalities in the anatomical structure or biofunctional susceptibility of the auditory analyzer. Defining the threshold of sensitivity, the expert estimates how well the patient hears.
[Audiometry of hearing
Simple speech or whisper - an ordinary person with normal hearing hears it, taking it for granted. But due to various reasons (due to injury, professional activity, disease, congenital defect), some people begin to lose their hearing. To assess the sensitivity of the auditory organ to sounds of different tonalities use such a testing method as hearing audiometry.
This technique is to determine the threshold of sound perception. The advantage of this procedure is that there is no need to use additional expensive equipment to conduct it. The main instrument is the speech apparatus of the doctor. Used as audiometers and tuning forks.
The main criterion of the auditory standard is considered to be the perception of the ear of the person under study whisper, the source of which is six meters away. If the audiometer is used in the testing process, the result of the test is reflected in a special audiogram, which enables the specialist to get an idea of the level of sensitivity of the auditory perception and the location of the lesion.
So how do audiometry? The procedure is quite simple. In the test ear, the doctor gives a signal of a certain frequency and strength. Hearing the signal, the patient presses the button, if not hears - the button is not pressed. This is how the threshold of audibility is determined. In the case of computer audiometry, the subject must be asleep. Before that, electro sensors are fixed on his head, which fix changes in brain waves. The connected computer, through special electrodes, independently controls the brain's response to a sound stimulus, building a diagram.
Tonal audiometry
To determine the threshold of sound perception, the doctor tests the patient at a frequency range of 125 to 8000 Hz, determining from what value a person begins to hear normally. Tonal audiometry makes it possible to obtain both the minimum and maximum values (the level of appearance of the discomfort state) that are inherent in a particular researched person.
Tonal audiometry is performed using medical equipment such as an audiometer. With the help of headphones connected to the device, a sound signal of a certain key is sent to the ear of the researcher. As soon as the patient hears a signal, he presses the button, if the button is not pressed, the doctor raises the signal level. And so until the moment when a person hears it and presses a button. Similarly, the maximum perception is determined - the patient simply after a certain signal ceases to press the button.
Similar testing can be done for small patients, but in this case, playing audiometry will be more suitable. The result of this procedure is an audiogram reflecting the real picture of the pathology, exposed in the language of figures and curves.
Threshold audiometry
This study is conducted using an audiometer. The market of medical equipment for today can offer a wide enough choice of this equipment of different manufacturers, slightly different from each other. This unit allows you to change the annoying sound signal, from the minimum frequency at 125Hz and beyond 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 6000 and 8000Hz. Some manufacturers have extended this scale to 10,000, 12,000, 16,000, 18,000 and 20000 Hz. The switching step is typically 67.5Hz. Threshold audiometry, with the use of such medical equipment, makes it possible to carry out testing, both with the use of pure tones, and a narrowly focused noise curtain.
Switching the sound indicators begin with 0dB (threshold hearing threshold) and step in 5dB, the intensity of the sound load gradually begins to increase, reaching 110dB, some models of the device allow you to stop at 120dB. Apparatus of the latest generation, make it possible to obtain a smaller stepping range of 1 or 2 dB. But each model of the audiometer is equipped with a restriction on the intensity of the output stimulus on three parameters: 125Hz, 250Hz and 8000Hz. There are devices with overhead headphones, represented by two separate air phones, there are also with the ears phones that are inserted directly into the auricle. The device also includes a bone vibrator used to analyze bone sound, as well as a microphone and a button for the patient being examined. A recording device is connected to the equipment, which gives the results of the test to the audiogram. It is possible to connect the playback equipment (tape recorder) used for speech audiometry.
Ideally, the room where the testing takes place must be soundproofed. If this is not the case, when analyzing the audiogram, the audiometrist must make a discount to the fact that the external noise can influence the test data. Usually this is expressed in the growth of the differentiated boundary of sound recognition. At least partially to solve such a problem in-ear phones are capable. Their use makes it possible to increase the accuracy of audiometric studies. Thanks to this device, the total natural noise can be reduced by thirty to forty dB. This kind of accessories audiometer has a number of other advantages. With its use, the need for masking sounds is reduced, this is due to the growth of the inter-ear relaxation to a level of 70-100 dB, the comfort of the patient increases. The use of intra-ear phones allows to exclude the possibility of collapse of the external auditory canal. This is especially true when working with young children, namely with newborns. Thanks to such equipment, the level of repeatability of the study results increases, which indicates the reliability of the results obtained.
The deviation from the zero mark is not more than 15-20 dB - this result is normal. The analysis of the air conduction diagram makes it possible to assess the level of functioning of the middle ear, while the bone permeability diagram allows one to get an idea of the state of the inner ear.
If full hearing loss is diagnosed - deafness - it is difficult to localize the site immediately. To refine this parameter, extra-threshold tests are additionally carried out. Such refinement techniques include noise studies, tests of Langenbeck or Fowler. Such an analysis will make it possible to understand whether the lesion of the ear maze, the cells of the auditory or vestibule nerve is concerned.
Computer audiometry
The most informative and reliable method of research in this area can be called a procedure such as computer audiometry. In carrying out this study, using computer equipment, there is no need to actively use the patient under study. The patient can only relax and wait for the end of the procedure. Medical equipment will do everything automatically. Due to the high accuracy of diagnostics, low motor activity of the patient and high safety of the method, the use of computer audiometry is also allowed in case of necessity of this study in newborns.
Speech audiometry
This method of diagnosing the level of hearing is perhaps the oldest and simplest. After all, in order to determine how a person hears, you do not need anything other than a normal audiometrist's spoken device. But, strange as it may sound, the reliability of the research largely depends not only on the condition of the hearing aid of the subject, the correctness of his perception of the sound signal, but also on the level of his intellect and the breadth of the vocabulary.
Monitoring of this technique has shown that speech audiometry can show some excellent results if the doctor speaks individual words or speaks with sentences. In the latter situation, the threshold of perception of the audio signal is better. Therefore, in order for diagnostics to be more objective and accurate, the audiometrist uses in his work a universal set of simple sentences and words.
To date, this technique is not practically used to determine the sensitivity of auditory receptors. But the method is not forgotten. Speech audiometry in modern medicine has found its application in the selection and testing for a sick hearing aid.
Objective audiometry
This technique is particularly in demand in the forensic field or for determining the sensitivity threshold in newborns and young children. This is due to the fact that objective audiometry is based on the analysis of conditioned and unconditioned reflexes of the human body, triggered by sound stimuli of varying intensity. The advantages of this method are that the response is fixed regardless of the testee's will.
The unconditioned reflexes of the sound stimulus include:
- The cochlear-pupillary reaction is an expansion of the eye pupil.
- Auropalpebralny reflex - closing of the eyelids with a sudden impact of the sound stimulus.
- The inhibition of infants sucking reflections on decibels of different tonalities.
- The blinking reflex is the contraction of the circular muscle of the eye.
- Skin-galvanic reaction - the measurement of the electrical conductivity of the body through the skin of the palms of the hands. After the sound effect, this reflex reaction lasts for a long time, gradually fading out, and does not present any big problems when measuring. Painful impact is even more persistent. Applying together pain (cold or any other) and sound stimuli, the surdologist makes a conditioned skin-galvanic reaction in the tested patient. Such a recall of the organism also makes it possible to diagnose the level of the auditory border.
- Reaction of the vascular system - assessment of the direction and severity of changes in baseline hemodynamic parameters (heart rate and blood pressure). By the means of plethysmography the audiometrist can measure the degree of narrowing of the vessels - as a reaction to the sound of different tonalities. Measurement should be done immediately after the audio message, as this reaction fades very quickly.
Medicine does not stand still and modern scientists, together with physicians, have developed new, more progressive methods and equipment used to determine the sound sensitivity of a person, his threshold of perception. The modern methods of objective audiometry include:
- Acoustic impedance measurement is a set of diagnostic procedures that are performed to assess the condition of the middle ear. It includes two procedures: tympanometry and registration of an acoustic reflex. Conducting tympanometry allows simultaneously to assess the level of mobility of the tympanic-ossicular system of the middle ear and the chain of the bone component of the hearing aid (together with the muscular and ligamentous tissues). And it also makes it possible to determine the level of counteraction of the air cushion in the tympanic cavity with different metered injection microvibrations in the external auditory canal. Acoustic reflex is the recording of a signal from the ears of the ear, mostly in the stapedal, as the response to the eardrum.
- Electro-chloografy is the diagnosis of ear diseases, performed with artificial electrical stimulation of the auditory nerve, which causes the activation of the cochlea.
- Electroencephalaudiometry, when this procedure is performed, the evoked potential of the auditory zone of the brain is recorded.
This method of studying the auditory threshold of perception (objective audiometry) is widely used in modern medicine. Especially it is in demand in those cases when the tested can not (or does not want) communicate with the doctor-audiologist. To such categories of patients it is possible to carry newborns and children of small age, mentally sick patients, prisoners (at passage of judicial examination).
Game audiometry
This technique is most in demand when dealing with children. It is very difficult for them to sit for a long time in one place and simply tact to press ugly buttons. Where the game is more interesting. Game audiometry is based on the development of a conditioned motor reflex, which is based on the basic movements that the kid uses in his life. Fundamental in the technique is to interest a small patient not only with a trivial tool (toys and colorful pictures). The surdologist tries to stimulate the motor reflexology of the baby, for example, with a switch, light the lamp, press on the bright button, shift the beads.
When carrying out the game audiometry, a specific action, for example, pressing a bright key that lights a screen with a certain picture, is accompanied by an audible signal. On this principle of diagnostics, practically all modern methods for determining the threshold of the sound sensitivity of the human ear are based.
One of the most commonly used methods is the technique developed by Jan Lesak. He suggested using a baby tonal audiometer. This device is presented in the form of a children's toy house. The set includes operating mobile elements: humans, animals, birds, means of transport. This test takes 10-15 minutes to force, so as not to tire the baby.
High-precision equipment makes it possible to diagnose quite quickly the attainment of the threshold of auditory perception. The signal is fixed when a combination of the corresponding tones and associated meaning values of the game elements. A small man of two or three years is given a handle in the handle, made in the form of a mushroom. The kid is explained that if you press a key, he as a superhero can release from captivity various animals and little men. But you can do this only after they ask him about it. Hearing a squeak (the sound signal issued by the phone of the audiometer) the kid has to press the key, closing the contact, the little animal leaves - this signal to the audiometrician that the child has heard the sound of the tonality being given. There is also an option that if the sound is not fed to the device, and the baby presses the key - the little animal is not released. Interested in the baby, and having done several control tests, you can get a fairly objective picture of the disease with the definition of sound patency in the ear canal and determine the sensitivity threshold.
The frequency of the tested tones is taken in the range from 64 to 8192Hz. This technique is more acceptable, in contrast to the development of Dix-Hallpike, as testing is conducted in a bright room, so as not to frighten the baby.
Sufficiently actively used and the technique of AP Kosachev, which is perfectly adapted to determine the auditory threshold in children of two to three years. The mobility and compactness of the instrumentation makes it possible to conduct research under the conditions of a standard district polyclinic. The essence of the technique is akin to the previous one and is based on the conditioned motor response of the baby's body to the electric toys offered to him. In this case, the set of such toys is multicomplete, which allows the doctor - a surdologist to choose exactly the kit that will be of interest to a particular baby. As a rule, it takes 10-15 attempts to develop a child's reaction to a specific subject. As a result, everything (learning about the baby, working out the reaction and carrying out the test directly) goes not as much as two or three days.
Attention should be paid to the somewhat different, but based on similar reflex, methods of A. R. Kängesenn, VI Lubovsky and LV Neiman.
All these developments make it possible to diagnose a hearing defect in small children. After all, they do not require a verbal contact with the toddler under test. The whole difficulty of this diagnosis consists, first of all, in the fact that in children with hearing loss, there is often a retardation in the development of the speech apparatus. As a result, a small patient does not always understand what they want from him, ignoring the preliminary instructions.
Developing a conditioned reflex response to a sound stimulus in a child, the specialist determines not only the threshold of the susceptibility of the child, but also the individual feature of assimilation of the conditioned motor reflex, the so-called latent period value. It also establishes the power of perception, the duration of the child's stable memory for sound stimulation and other characteristics.
Supra-threshold audiometry
To date, quite a lot of methods have been proposed for the determination of supra-threshold audiometry. The most applicable is the technique developed by Lusher. Due to its use, the specialist receives a differential threshold of perception of the sound force, which is called by the physicians as an index of small intensity increments (IMPI), in international circles this term sounds and is written as a Short Increment Sensitivity Index (SISI). Subthreshold audiometry conducts to the balance of the sound power, using the Fowler technique (if the hearing loss affects one side of the hearing aid), the initial limit of discomfort is fixed.
The structuring of the auditory limit is diagnosed as follows: the subject receives a sound signal with a frequency of 40 dB above the auditory threshold. Modulation of the signal occurs in the intensity range from 0.2 to 6 dB. The norm of conductive hearing loss is the state of the human hearing aid, in which the conductivity of sound waves on the path from the outer ear to the tympanic membrane is impaired, the depth of modulation is then from 1.0 to 1.5 dB. In the case of cochlear hearing loss (non-infectious internal ear disease), when performing a similar sequence of actions, the level of recognizable modulation decreases significantly and corresponds to a figure of about 0.4 dB. The audiometrist usually conducts repeated studies, gradually increasing the depth of modulation.
Over-threshold audiometry, conducting a Sisi test, begins to determine this parameter by setting the handle of the device to 20dB above the auditory threshold. Gradually, the intensity of sound increases. This occurs at intervals of four seconds. For a short time, a gain of 1 dB occurs over 0.2 s. The patient being tested is asked to describe his feelings. After that, the percentage of correct answers is determined.
Before testing, bringing the intensity indicators to 3-6 dB, the audiometrist usually explains the essence of the test, only after that the study returns to the starting 1dB. In the normal state or in the case of a permeability defect, the patient can actually distinguish up to twenty percent of the increase in the intensity of the sound tone.
Hearing loss due to internal ear disease, defeat of its structures, pre-collar nerve (sensorineural hearing loss), appears together with a failure in the loudness factor. There have been occasions when, with an increase in the threshold of audibility of approximately 40 dB, there was an increase in the volume function by a factor of two, that is, by 100%.
Most often, Fowler loudness testing is performed if there is a suspicion of the development of Meniere's disease (internal ear disease causing an increase in the amount of fluid (endolymph) in its cavity) or a neurinoma of the auditory nerve (a benign tumor that progresses from the cells of the vestibular portion of the auditory nerve). Fowler's predominantly over-threshold audiometry is performed with suspicion of unilateral hearing loss, but the presence of bilateral partial deafness is not a contraindication to the use of this technique, but only if the difference (difference) in the auditory thresholds of both sides is not more than 30-40 dB. The essence of the test is that each ear receives a sound signal simultaneously, which corresponds to the threshold value for a given hearing aid. For example, 5dB on the left and 40dB on the right ear. After that, the signal arriving at the deaf ear makes 10dB more, while on the healthy ear the intensity is selected so that both signals, according to the patient's perception, have the same tonality. Further, the intensity of the tone on the affected earplug is increased by another 10dB, and again the leveling of loudness in both ears is provided.
Screening audiometry
Audiometer - medical device eotolaryngological focus for today is represented by three types of apparatus - it is polyclinic, screening and clinical. Each species has its own functional orientation and its advantages. The screening audiometer is one of the simplest devices, unlike a polyclinic apparatus, which gives the audiometrist great opportunities for research.
Screening audiometry makes it possible to carry out tonal diagnostics of the hearing state of the patient's ear by the air conduction. The device is mobile and its capabilities allow you to create various combinations of the strength and frequency of the sound tonality. The research procedure assumes both manual and automatic testing. In parallel with the testing, the eotolaryngological apparatus analyzes the obtained data, determining the level of audibility and sound comfort.
If necessary, with the help of a microphone, a specialist can contact a test person, the presence of a connected printer allows you to get an audiogram on a solid carrier.
The audiometry cabinet
To obtain objective test results, in addition to modern equipment, it is necessary that the audiometry cabinet should meet certain acoustic requirements. After all, monitoring of the conducted procedure showed that the general external sound background can significantly affect the final result of testing. Therefore, the audiometry cabinet must be well isolated from external acoustic noises and vibrations. It is required to protect this space from magnetic and electric waves.
This room should have a certain freedom, especially it is essential for speech audiometry, where a free sound field is necessary. Analyzing the foregoing, it can be stated that it is problematic to fulfill these requirements in an ordinary room. Therefore, special acoustic chambers are used for the research.
Cab for audiometry
The simplest of them are the failure of a small booth (akin to a pay phone) with well-insulated walls, in which the tested person sits. The audiometrist is located outside this space, communicating with the subject, if necessary, through the microphone. Such a cabin for audiometry allows you to mute the external background by 50 or more dB on the frequency range from 1000 to 3000 Hz. Before entering the booth, permanently installed in the room, in operation, the control testing of a person with a known normal hearing is carried out. After all, not only the booth itself should be isolated, but the general background of the room in which it is located must be low, otherwise it is impossible to trust the results of such studies. Therefore, if the threshold of the sound sensitivity of a person with normal hearing is established no higher than 3-5 dB from the norm, you can use such a booth for audiometry.
Audiometry standards
The result of the testing is an audiogram tape, which represents two signal graphs: one shows the severity level of the hearing of the left ear, the other - the right ear. There are audiograms on which there are four curves. Receiving such a printout, the doctor has the opportunity to evaluate not only the acoustic sensitivity of the auditory receptors, but also to receive bone conduction. The last parameter makes it possible to localize the problem.
Consider the accepted norms of audiometry, thanks to which the expert assesses the degree of receptivity of the auditory receptors, that is, the level of deafness. There is an international classification of this parameter.
- Perception is at a level of 26 to 40 dB - I degree of hearing loss.
- From 41 to 55 dB - II degree of hearing loss.
- From 56 to 70 dB - III degree of deafness.
- From 71 from 90 dB - IV degree of hearing loss.
- The figure above 90 dB is complete deafness.
Control points are taken as threshold values for air, determined for frequencies of 0.5 thousand, 1 thousand, 2 thousand. And 4 thousand. Hz.
The first degree of deafness is characterized by the fact that the patient normally hears a normal conversation, but experiences discomfort in a noisy company or if the interlocutor whispers.
If the patient has a second degree, then the ordinary speech he discerns in a radius of two to four meters, whispering no more than a meter or two. In everyday life, such a person constantly asks.
At the third stage of pathological changes a person can understand intelligible speech within a radius of not more than a meter - two from himself, and whisper practically does not differentiate. In this situation, the interlocutor has to raise his voice even while standing next to the victim.
A patient with a diagnosed fourth degree of hearing loss can clearly hear the words of conversational speech only if his interlocutor speaks very loudly while being near. In such a situation, without the use of gesticulation or the use of a hearing aid, it is very difficult to find mutual understanding with the respondent.
With total deafness of the patient, communication with the surrounding worlds without special equipment and auxiliary tools (for example, the exchange of notes) is impossible.
But it is not necessary to approach this division unequivocally. After all, the comparison of the audiogram occurs, starting from the averaged arithmetic number, which determines the starting level. But to make the picture more informative for a particular case, it is necessary to evaluate the forms of the audiometric curves. Such diagrams are divided into smoothly rising and ascending, sinusoidal, sharply ramping and chaotic forms, which are difficult to attribute to one of the above varieties. According to the configuration of the line, the expert assesses the level of unevenness of the fall in the sound perception at different frequencies, determining which of them the patient hears better and which one is not available to him.
Long-term monitoring of audiograms, when carrying out audiometry, shows that the curves are predominantly smoothly falling, maximum deafness falls on high frequencies. A normal audiogram of a healthy person is a line that is close to a straight line. It rarely exceeds 15-20 dB.
Equally important is the comparative analysis of indicators obtained by air and through bone. This comparison allows the doctor to determine the localization of the lesion, leading to hearing loss. Based on his data, physicians distinguish three types of pathology:
- Conductive changes, when there are violations of sound permeability.
- Sensory-neural defects, when there are violations of sound perception.
- And mixed type.
Decoding audiometry
An audiogram is two or four graphs plotted on a plane with two axes. The horizontal vector is divided into divisions, characterizing the tone frequency, determined in hertz. The vertical axis fixes the level of sound intensity, determined in decibels. This indicator has a relative value, compared with the figure of the accepted average normal perception threshold, which is taken as the zero value. Advantageously, the diagram of the curve with the cups denotes the characteristic of the sound perception of the right ear (usually it is red, with the designation AD), and with the crosses the left one (preferably the blue curve with the designation AS).
International standards determine that the continuous line on the audiogram is applied to the curves of air conduction, the dashed line to bone conduction.
Analyzing the audiogram, it is worth remembering that the axis of the vector is at the top, that is, the numerical value of the level increases from the top down. Therefore, the lower its index, the greater the deviation from the norm shows the graph, and, consequently, the person under study hears worse.
The interpretation of audiometry allows the surdologist not only to determine the threshold of audibility, but also to localize the pathology site, suggesting a disease that provoked a decrease in sound perception.
How to cheat audiometry?
Many respondents are interested in how to deceive audiometry? It is worth noting that it is almost impossible to influence the result of computer audiometry, because this process is based on conditioned and unconditioned human reflexes. In the case of diagnosing with the help of speech audiometry, when the doctor, having moved a certain distance, says test words, and the patient needs to duplicate them, in such a situation, it is quite possible to feign a bad ear.
Where to make audiometry in Kiev?
If a person needs to undergo a specific research, he tries to find the institution where he is being held, as close to his home as possible, but meeting all modern requirements. For example, where to make audiometry in Kiev?
In the capital of Ukraine, there are a lot of such centers. Here are some of them
- The medical center "DoctorLor", which is located at: ul. Lomonosov 56.
- Private clinic "Stomatel", which is located at: ul. Dimitrova 5-B
Where to make audiometry in Moscow?
If the patient lives in the Russian capital, or it is more convenient for him to study here, then to the question of where to make audiometry in Moscow? You can offer such clinics:
- The multifield medical center "Stolitsa", which is located near the Prospect Vernadsky metro station at the address: Leninsky prospect, 90.
- SM-Clinic, which is located near the metro Tekstilshchiki at: Volgogradsky Prospect, 42 bldg. 1
- Medical Center MEDSI, which is located near the metro Paveletskaya at: Derbenevskaya nab., 7
Where to make audiometry in St. Petersburg?
Many similar clinics in North Palmyra, so the question is, where to make audiometry in St. Petersburg? For the inhabitants of this beautiful city is not worth it.
- Center for the correction of hearing and speech "Melphon-St. Petersburg", located near the metro station Moskovskie Vorota at: Moscow Avenue, 117A.
- SM-Clinic, which is located near the metro station Ladozhskaya at the address: Udarnikov Avenue, 19, building 1.
Where to make audiometry in Nizhny Novgorod?
Answering the question where to make audiometry in Nizhny Novgorod? Can offer:
- The multifaceted clinic Alfa - Health Center, located on the street. M. Gorky 48/50.
- Medical Center "Privolzhsky District", address: st. M. Gorky, 113/30.
Where to make audiometry in Yekaterinburg?
Medical Center "DOCTOR PLUS" gives an affirmative answer to the question of where to make audiometry in Yekaterinburg? It is located at: ul. Sheynkman, 90.
To pass this examination it is possible and in the medical center "Panacea" to the address: st. Factory, 32/2.
Where to make audiometry in Volgograd?
Where to make audiometry in Volgograd? This testing can be carried out at the Clinical Hospital of Emergency Care No. 15 at: ul. Andijan, 1a.
Where to make audiometry in Kazan?
Answering the question, where to make audiometry in Kazan? Can offer:
- Medical Center for Cosmonauts. Address: st. Astronauts, 41b (office center).
- Medical Center "Mart-M", address: st. Adela Kutuya, 16/30.
Cost of Audiometry
Before you go for testing, it's not superfluous to clarify the cost of audiometry. The price of this procedure is very different and depends on the region, the city and the level of the clinic in which the study is planned. For example, if in Kazan this procedure costs from 190 rubles, then in Moscow this study will cost from 1000 rubles.
To ensure that your hearing is always sharp, it is necessary to take care of the hearing aid. But if you started to notice that you often began to ask again from the interlocutor, do not be lazy to go through hearing diagnostics. Audiometry is a safe but informative procedure that will answer the tormenting question whether there are pathological changes in your hearing aid.