RU2552099C1 - Method for examining ear-drum state - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: polyharmonic audio signal of each frequency is supplied into an acoustic analyser through an ear plug hermetically jointed to a wave guide tip, the other end of which is equipped with a loud speaker connected to a generator. Three frequencies (f_i), whereat a responsive component of eardrum complex impedance is equal to zero are measured. Absorption (α_i) and resistance (R_i) factors are calculated for each frequency. If K>10, the eardrum state requiring no in-depth examination is stated. The polyharmonic audio signal is generated by a set of audio signals at a frequency pitch of 20 Hz and supplied in the range of 340 Hz to 3300 Hz.

EFFECT: method enables providing more reliable examination ensured by determining responsive component frequencies of the eardrum impedance and calculating the absorption and resistance factors.

4 cl

Description

The invention relates to methods for audiometric studies.

The eardrum, being the main link in the auditory system, undergoes slight elastic vibrations under the influence of vibrations of the sound-conducting environment, the dynamic characteristics of which make it possible to evaluate its condition.

A device for assessing the condition of an eardrum (patent for invention RU No. 2332164, published on 08.27.2008) containing a sound frequency generator with head phones and a frequency meter, characterized in that an ultrasonic frequency, ultrasonic emitter is integrated into the head phones, is known from the prior art. a sensor and a frequency meter, and the heads of the headphones are made of dynamic broadband. The disadvantages of this device is the low accuracy due to the fact that the vibrational velocity of the eardrum at the sound frequency is small, and as a result, the level of the reflected signal will also be small, that is, even in the absence of pathology of the eardrum, the difference in the frequencies of the ultrasonic and sound signals will be minimal . To increase the objectivity of assessing the condition of the eardrum using the above-mentioned device, it is necessary to strengthen the power of sound vibrations. However, at high levels of sound pressure, an acoustic reflex is manifested, the degree of tension of the eardrum is enhanced, which leads to a decrease in vibrational velocity and, accordingly, to a decrease in the objectivity of assessing the condition of the eardrum.

The technical task of the invention is the ability to diagnose the condition of the eardrum with the help of sound frequency signals.

The solution to the technical problem is achieved by the fact that for each frequency of the polyharmonic sound signal supplied to the human auditory analyzer through an earmold, hermetically articulated with the end of the waveguide, the other end of which is equipped with a loudspeaker connected to the generator of such a signal, three frequencies are determined (f _i ), which the reactive component of the complex impedance of the tympanic membrane is zero, for each frequency calculated values of the absorption coefficient (α _i), and Resistance (R _i), based on which races ityvayut assessment of the tympanic membrane of the ear of the test (K)

K = 0.01 (| f ₁ -430 | + | f ₂ -980 | + | f ₃ -2300 |) +

+10 (| α ₁ -0.9 | + | α ₂ -0.2 | + | α ₃ -0.8 |) +0.5 (| R ₁ -2 | + | R ₂ -20 | + | R ₃ -2.6 |),

and at K> 10, an eardrum pathology is diagnosed, requiring in-depth examination.

The frequency range of the signal used for diagnosis is, as a rule, from 340 Hz to 3300 Hz.

The polyharmonic sound signal used for diagnostics, as a rule, is formed by a set of tonal signals with a frequency step of 20 Hz, which ensures the accuracy of the diagnosis of the condition of the eardrum, which meets the requirements of otolaryngological practice.

The procedure for diagnosing the condition of the eardrum of one ear, as a rule, is no more than 15 seconds.

The technical result provided by the given set of features is to simplify and reduce the time for diagnosing the condition of the eardrum.

In terms of the set of essential features, the claimed method differs significantly from the analogue, since:

1) there is no need to create excessive pressure in the external auditory canal, which eliminates the pronounced interference factor;

2) there is no need to radiate ultrasound and high-intensity sound into the external auditory canal, adversely affecting the auditory analyzer;

3) provides a direct measurement of the impedance of the auditory system in the audio frequency range with any step.

Diagnosis of the condition of the eardrum using the proposed method is as follows.

1) The patient is seated on a chair (on a stool, in a chair, etc.), an ear insert is installed in his ear, hermetically articulated with the end of the waveguide, the other end of which is equipped with a loudspeaker connected to a sound frequency polyharmonic signal generator, and at two points The side surface of the waveguide is equipped with measuring microphones so that:

the distance from any microphone to the end of the waveguide exceeded 10 waveguide diameters;

the distance between the microphones L satisfied the ratio

0,025λ _max <L <λ _min / 2,

where λ _min , λ _max - the minimum and maximum length of the sound wave emitted by the loudspeaker when diagnosing the condition of the eardrum, m

2) Through the loudspeaker, a polyharmonic sound signal formed by a set of tonal signals is supplied to the waveguide; simultaneously, information from two measuring microphones is transmitted to the computer through an analog-to-digital converter.

3) Processing the registered information, for each frequency of the polyharmonic signal, it is determined:

- sound pressure levels at two points of the waveguide (P ₁ and P ₂ ) and the phase difference of the signals recorded by the measuring microphones at each frequency (φ);

- module of the complex reflection coefficient (r) of sound vibrations for each frequency:

, $$r=\frac{\sqrt{\left[\left(N^2-\mathrm{one}\right)+\mathrm{four}{N}^2\left({\cos }^{2}kL+{\cos }^2\varphi \right)-\mathrm{four}N\left(N^2+\mathrm{one}\right)\cos \varphi \cdot \cos kL\right]}}{\left(N^2+\mathrm{one}-2N\cos \left(kL+\varphi \right)\right)}$$

,

where N = P ₁ / P ₂ is the ratio of sound pressure levels in the measuring microphones at each frequency, k = 2π / λ is the wave number (spatial frequency), L is the distance between the measuring microphones;

- absorption coefficient

α = 1-r ² ;

- complex impedance of the eardrum for each frequency

Z = R + jY,

where R is the resistance (active component of the impedance), Y is the reactance (reactive component of the impedance):

, $$Y=\frac{-2r\sin \theta }{1+r^2+2r\cdot \cos \theta }$$

, $$R=\frac{\mathrm{one}-r^2}{\mathrm{one}+r^2+2r\cdot \cos \theta }$$

, $$Y=\frac{-2r\sin \theta }{\mathrm{one}+r^2+2r\cdot \cos \theta }$$

,

where θ is the angle of reflection of sound vibrations,

θ = arctg [(2NsinkL · (NcoskL-cosφ)) / (N ² -1-2NcoskL (NcoskL-cosφ))].

4) Determine the frequencies at which the reactance (Y) changes sign, taking into account that there are three of the physiological characteristics of the auditory analyzer with an increase in the frequency of the sound signal:

f ₁ is the first frequency at which the reactance becomes zero when the sign changes from negative to positive, and in its absence, the arithmetic average of two adjacent frequencies of the sound signal, at the lower of which the reactance sign is negative, and at the greater - positive;

f ₂ is the frequency at which the reactance becomes zero when the sign changes from positive to negative, and if it is absent, the arithmetic average of two adjacent frequencies of the sound signal, the smaller of which the reactance sign is positive, and the larger is negative;

f ₃ is the second frequency at which the reactance becomes zero when the sign changes from negative to positive, and in its absence, the arithmetic average of two adjacent frequencies of the sound signal, at the lower of which the reactance sign is negative, and at the larger - positive.

The impossibility of determining at least one of the frequencies f ₁ ... f ₃ indicates a leak in the articulation of the earmold with the end of the waveguide or the mismatch of the diameter of the earmold with the diameter of the ear canal of the patient. In this case, it is necessary to repeat the measurements, eliminating the revealed violations of the conditions for their implementation.

5) For each frequency f ₁ ... f ₃ calculate the values of the absorption coefficient (α _i ) and resistance (R _i ) and taking into account that normally f ₁ = 430 Hz, f ₂ = 980 Hz, f ₃ = 2300 Hz, and the corresponding values of α ₁ = 0.9, R ₁ = 2.0, α ₂ = 0.2, R ₂ = 20.0, α ₃ = 0.8, R ₃ = 2.6, calculate the assessment of the state of the drum membranes of the studied ear (K) as

K = 0.01 (| f ₁ -430 | + | f ₂ -980 | + | f ₃ -2300 |) +

+10 (| α ₁ -0.9 | + | α ₂ -0.2 | + | α ₃ -0.8 |) +0.5 (| R ₁ -2 | + | R ₂ -20 | + | R ₃ -2.6 |),

A higher K value corresponds to the worst condition of the eardrum; at K> 10, its pathology is diagnosed, requiring in-depth examination.

The proposed method should be used in otorhinolaryngology to study the condition of the eardrum, which will optimize the treatment and rehabilitation of patients. The method can be implemented by enterprises (organizations) of the medical industry in the production and modernization of audiometric equipment.

Claims (4)

A method for studying the condition of the eardrum, characterized in that for each frequency of the polyharmonic sound signal supplied to the human auditory analyzer through an earmold sealed to the end of the waveguide, the other end of which is equipped with a loudspeaker connected to the generator of such a signal, three frequencies are determined (f _i ), on which the reactive component of the complex impedance of the tympanic membrane is equal to zero, for each frequency the values of the absorption coefficient (α _i ) and the resistance a (R _i ), based on which the assessment of the condition of the eardrum of the studied ear (K) is calculated

and at K> 10 determine the condition of the eardrum, requiring in-depth examination. 2. The method according to p. 1, characterized in that the frequency range of the polyharmonic sound signal is from 340 Hz to 3300 Hz. 3. The method according to p. 1, characterized in that the polyharmonic sound signal is formed by a set of tonal signals with a frequency step of 20 Hz. 4. The method according to p. 1, characterized in that the procedure for examining the condition of the eardrum of one ear is not more than 15 seconds.