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Tuning forks

The study of hearing with tuning forks can be made taking into account the duration of their sound in seconds - quantitatively and qualitatively based on a comparison of their perception through air and bone, as well as from the patient and the doctor.

An accurate quantitative assessment of the duration of tuning forks requires quite a lot of time, therefore, in conditions of the military unit and otolaryngologists, quality tuning fork tests are used in outpatient practice. Together, they are of importance as a method of differential express diagnostics of violations of the mechanism of sound conduction and sound perception. When performing these tests (experiments), one bass tuning fork C128 or A105 is used.

Weber's experience - evaluation of lateralization of sound (Weber E., 1829). A tuning fork is placed on the crown of the head with a patient’s foot and asked to say with which ear he hears a louder sound. With unilateral damage to the sound-conducting apparatus (sulfuric plug in the ear canal, inflammation of the middle ear, perforation of the tympanic membrane, etc.), lateralization of sound in the affected ear is observed; with bilateral lesions - to the side worse than the hearing ear. Impairment of sound perception leads to lateralization of sound into a healthy or better hearing ear.

Rinne's experience is a comparison of the duration of perception of bone and air conduction (Rinne A., 1855). The low-frequency tuning fork is installed by the foot on the mastoid process. After the perception of sound on the bone ceases, it is brought in by branches in the auditory canal. Normally, a person hears a tuning fork longer in the air (the Rinne experience is positive). In case of disturbance of sound perception, bone and air conduction deteriorate proportionally; therefore, the Rinne experience remains positive. If sound conduction with normal function of the auditory receptor suffers, then sound on the bone is perceived longer than through the air (negative Rinne experience).

The Schwabach experiment is an assessment of the duration of the tuning fork for bone (Schwabach D., 1885). The duration of perception of a tuning fork with a mastoid process in a patient and a normally hearing doctor is compared. In case of disturbance of sound perception, the doctor hears the tuning fork longer (shortening of bone conduction in the Schwabach experiment). Violation of sound conduction leads to the opposite effect - a patient with reduced hearing perceives a tuning fork longer than a doctor (lengthening bone conduction in the Schwabach experiment).

The experiments of Weber, Wrynne, and Schwabach are considered to be classical with a qualitative tuning fork study of hearing. Their results are normal, in violation of sound conduction and sound perception are given in table. 1.2.1.

Table 1.2.1

Quality tuning fork test results

In the Rinne experiment, it is advisable to compare not the duration of the tuning fork perception, but the intensity of its sound. This significantly saves research time and with a convincing result allows you to limit yourself to just two tests. The first of these is a modified Rinne experiment - a comparison of the intensity of perception of a tuning fork from the mastoid process and at the external auditory meatus, and the second is the Weber experiment, the result of which is compared with lateralization of ultrasound. No more than one minute is spent on such a tuning fork differential diagnostic diagnosis of impaired sound conduction and sound perception.

In addition to these experiments, others were proposed, of which the experiments of Federichi and Bing are most often used.

Experience Federici (Federici F., 1933) - a comparison of the duration of perception of tissue conduction from the mastoid and tragus during obstruction of the external auditory canal. The experiment is carried out similarly to the experiment of Rinne. After the tuning fork has stopped sounding on the mastoid process, it is placed with the foot on the tragus. Normally, and with a violation of sound perception, Federici's experience is positive, i.e. the sound of the tuning fork from the tragus is perceived longer, and if the sound conduction is disturbed, it is negative.

Bing's experiment (Bing A., 1891) is a comparison of the intensity of perception of bone-tissue conduction from the mastoid process with the open and closed tragus of the external auditory canal. Normally, and with a violation of sound perception, obstruction of the external auditory canal leads to increased uptake of the tuning fork (Bing’s positive experience), but this does not occur with impaired sound conduction (Bing’s negative experience).

The improvement in the tuning of the tuning fork for the skull tissues in the Bing experiment is normal and in case of disturbance of sound perception due mainly to the absence of the influence of external noise and resonant amplification of sound in the closed ear cavity. Violation of sound conduction in the outer and middle ear in itself creates an obstacle to the release of sound energy to the outside, so the closure of the external auditory canal by the tragus does not cause additional amplification of sound.

Along with tuning fork tests, which serve to differentiate lesions of sound conduction and sound perception, a special Jelle test is used to diagnose otosclerosis.

The experience of Jelle (Gelle M., 1881) - ii? Aaaeaiea iiaae? Iinoe iiaii? Iie ieanoeiee no? Aiaie a iaaeuiii ieia. The external auditory meatus is densely obstructed by the olive of Politzer’s balloon and with its help the air pressure on the eardrum and the auditory ossicles periodically increase and decrease. The maximum sounding low-frequency tuning fork is installed on the mastoid process.
If the stapes is still in the oval window, the sound volume does not change due to pressure changes in the external auditory canal (the Jelle experiment is negative), while normally, with increasing pressure, the sound is perceived more quiet (the Jelle experiment is positive).

A quantitative study of hearing tuning forks, proposed by Bezold (Bezold F., 1897), is intended for a more accurate differential diagnosis of hearing impairment at various levels of the auditory system. It consists in determining the time of perception of the sound of tuning forks. For a detailed analysis of auditory function, a complete set of Bezold-Edelman tuning forks with a Galton whistle is required. With the introduction of tonal audiometry, the use of such a set of tuning forks has lost its significance. Currently, V.I.Voyachek uses two tuning forks in the clinic. Typically used tuning forks C128 (low) and C2048 (high) or close to them in tone - A105 and C1024. Determine the duration of the perception of the treble tuning fork through the air, and the bass - through the air and tissues of the skull.

In the study of air conductivity, a number of rules are observed.

1. The tuning fork is excited according to the principle “iaeneiaeuiiai oaa? A”,? Oi ainoeaaaony oaa? Ii aai i oaii? eaaiie, eeai by hitting it with a rubber mallet or by pinching. In these cases, the initial vibrations of the tuning fork will be the greatest, and the duration of the sound will be approximately the same.

2. Time is counted by the stopwatch from the moment the tuning fork is excited.

3. The sounding tuning fork is held by the foot with two fingers at a distance of 1 cm from the ear so that the branches oscillate in the plane of the axis of the ear canal.

4. To exclude adaptation, the tuning fork is periodically removed from the ear for 3-5 s.

Bone-tissue conduction is examined with a bass tuning fork, setting it on the base of the mastoid process in the projection area of ​​the antrum. The time of perception of the tuning fork by the right and left ears is noted, and then the tuning fork is excited again, set it in the middle of the crown with branches in the sides and the lateralization of sound is checked.

Tuning forks with a biological method is annually certified. For this, the average duration of the perception of the sound of tuning forks in ten healthy people with normal speech and tonal hearing at the age of 20 to 25 years is established. These indicators are applied to the foot of the tuning fork, for example, on a strip of sticky patch. The month and year of testing is also noted.

The results of a tuning fork study, together with the results of a hearing test, are recorded in a speech into the auditory passport of the medical history, which was proposed by V.I. Voyachek and N.F. Bohon (1935). It also notes the norm of the tuning forks, with which indicators are compared in patients.

According to the auditory passport, primary differential diagnosis of various forms of hearing loss is carried out: impaired sound conduction, sound perception or mixed type. Particular attention is paid to those diseases in which the eardrum is intact and often has a normal appearance (sensorineural hearing loss, otosclerosis, Meniere's disease, tubootitis, serous otitis media, adhesive middle otitis media, nerve neurinoma VIII, etc.). With purulent otitis media or perforation of the eardrum, the cause of hearing loss is more understandable.

In case of violation of the sound conduction mechanism (Table 1.2.2), the air perception of a predominantly bass tuning fork deteriorates. When examining bone conduction, it is heard longer than normal, and its sound is lateralized in the sore ear.

Table 1.2.2

Auditory passport (with damage to sound conduction)

Conclusion: hearing loss in the right ear in a sound-conducting type.

Legend: SS - subjective ear noise (+ available, 0 no); SR - whispering speech; PP - colloquial speech; Cr. - a cry with the muffling of the opposite ear by the thrashka Barani (+ perceived, 0 no); A105, N2048 - aicaooiay i? Iaiaeiinou; Ak105 - bone conduction.

Violation of the mechanism of sound perception (table. 1.2.3) is accompanied by a pronounced deterioration in air perception of a treble fork. The duration of the bass tuning fork sounding in the air and skull tissues is proportionally reduced (their ratio, as in the norm, is approximately equal to 2: 1). There is lateralization of sound in a better hearing ear.

Table 1.2.3

Auditory passport (in case of violation of sound perception)

Conclusion: hearing loss in the right ear according to the sound pickup type.

Mixed hearing impairment (Table 2.3) is characterized by the absence of a predominance of disturbance in the perception of bass or treble tuning forks through the air and a change in the normal ratio of the duration of perception of a bass tuning fork through air and bone (normal 2: 1), as well as fuzzy lateralization of sound.

Table 2.3

Hearing passport

(when hearing loss is mixed)

Conclusion: hearing loss in both ears is mixed.
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Tuning forks

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