JP2579848B2 - Impedance audiometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impedance audiometer, and is particularly suitable for use in an air system for injecting air into an ear canal of a subject.

[0002]

2. Description of the Related Art Conventionally, an impedance audiometer may be used in the examination of the middle ear. The impedance audiometer outputs a sound wave of a specific frequency toward the subject's eardrum while changing the pressure in the ear canal of the subject, and detects an attenuation amount of the sound wave energy from the sound wave reflected on the eardrum. A device that measures and displays changes in acoustic compliance in the middle ear corresponding to changes in pressure in the outer ear.

[0003] The measurement result is usually displayed using a graph, and it is known that the displayed graph has a characteristic peculiar to the state of the middle ear of the subject, whereby the examiner can use the graph. It is possible to diagnose the subject's illness from the situation. As shown in FIG. 6, the measurement result of the impedance audiometer described above can be represented by a graph in which the horizontal axis indicates the pressure in the ear canal of the subject and the vertical axis indicates the equivalent compliance of the eardrum with air. .

The graph of FIG. 6 (a) shows a normal ear type, and the graph of FIG. 6 (b) shows an exudative otitis media type.
The graph of (c) shows the otitis media type, the graph of FIG. 6 (d) shows the fixed ossicle type, and the graph of FIG. 6 (e) shows the ossicle detached type.

[0005]

By the way, in the conventional impedance audiometer, as shown in FIG. 7, the ear canal 30 of the subject is hermetically sealed by the ear plug 5, and the air pipe is connected to the variable pressure device 4 having an air pump. By sending air into the ear canal 30 through 50, the pressure in the ear canal 30 can be changed.

Here, the broken line 2 indicates the air system of the conventional impedance audiometer, and the data S1 measured by the pressure sensor 3 is thereafter supplied to an arithmetic circuit. However, such a method tends to cause air leakage. For example, when air leakage occurs, the measured value of the pressure sensor 3 and the actual pressure in the external auditory canal 30 may not match.

That is, the air system of the conventional impedance audiometer shown in FIG. 7 can be represented as an electrical equivalent circuit by acoustoelectric conversion in FIG. 8, where V0 is the pump pressure, and V1 is the pressure measured by the pressure sensor 3. , V3
Indicates the pressure in the ear canal 30 of the subject, R0 indicates the air resistance of the pump and the piping in the main body, R2 indicates the air resistance of the air pipe 50, and R3 indicates the air leak resistance between the ear canal 30 and the earplug 5. . Here, the pressure V3 in the ear canal 30 of the subject is
Next formula

(Equation 1) It is represented by

Accordingly, as R3 decreases (the leakage increases), the pressure V1 measured by the pressure sensor 3 increases.
Thus, the pressure V3 in the external auditory canal 30 of the subject does not match, and thus, when air leaks, it is difficult to accurately measure the pressure in the external auditory canal 30.

The present invention has been made in view of the above points, and when a middle ear is examined using an impedance audiometer, the examination is performed regardless of whether or not air leaks from the ear canal. It is intended to propose an impedance audiometer capable of accurately measuring the pressure in the ear canal of a person.

[0010]

According to the present invention, to solve the above-mentioned problems, an air resistance 20 formed in an air passage 52 for injecting air into an external auditory canal 30 of a subject, Based on the first and second pressure sensors 21 and 22 coupled to both sides and the pressure data S21 and S22 in the air passage 52 supplied from the first and second pressure sensors 21 and 22, Means 8 for detecting pressure.

[0011]

The pressure sensors 21 and 22 are formed on both sides of the air passage 52, and the pressure in the ear canal 30 of the subject can be detected based on the pressure data in the air passage 52 supplied from the pressure sensors 21 and 22. By providing the means 8, the pressure in the external auditory canal of the subject can be accurately detected, and thus the usability of the examiner and the performance of the impedance audiometer can be remarkably improved.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

In FIG. 1 in which parts corresponding to those in FIG. 7 are assigned the same reference numerals, 1 denotes an impedance audiometer as a whole, and outputs an output signal S2 of a predetermined frequency from an oscillator 6 to an earphone 7. Supply and earphones 7
Converts the output signal S2 into sound energy, and then emits the sound energy into the external auditory meatus 30 of the subject through the communication path 51.

At this time, the inside of the ear canal 30 of the subject is supplied from the pressure variable device 4 having an air pump to the air pipe 5.
2 so that the pressure in the ear canal 30 sealed by the earplug 5 is +
It can change continuously in the range of about 200 to -200 dapa.

Here, an external auditory canal pressure detecting section 8 is formed in the air pipe 52 so that the pressure in the external auditory canal 30 of the subject can be measured. The sound wave energy emitted into the external auditory meatus 30 of the subject is reflected by the eardrum 32 and collected by the microphone 9 through the communication path 53 as reflected sound wave energy.

Further, the reflected sound energy is converted into an electric signal in the microphone 9 and supplied to the compliance detector 10 as a reflected sound pressure signal S4. In the compliance detector 10, the reflected sound pressure signal S 4 is amplified by the amplifier 11, noise other than a predetermined frequency equal to the output signal S 2 is removed by the bandpass filter 12, and rectified into a DC signal by the rectifier 13.

The rectified output is converted from an analog signal to a digital signal by an analog-to-digital converter 14, converted to compliance by a compliance converter 15, and supplied to a storage device 16 as a compliance signal S 5.

Here, the storage device 16 temporarily stores the compliance signal S5 together with the internal auditory canal pressure signal S3 supplied from the external auditory canal detecting unit 8, and then stores the compliance signal S5.
The equivalent compliance of the air in the eardrum 32 corresponding to the pressure change within 0 is supplied to the display unit 17 as a display signal S6.

The display unit 17 includes a monitor 18 and the printer 1
9 and the monitor 1 based on the supplied display signal S7.
The measurement result can be displayed as a graph by the printer 8 and the printer 19.

In this embodiment, in addition to the above-described configuration, the internal auditory canal pressure detecting section 8 connected to the air pipe 52 accurately detects the pressure in the external auditory canal 30 of the subject regardless of whether or not air leaks. It is made to be able to do.

That is, as shown in FIG. 2, a part of the external auditory canal pressure detector 8 is connected to the air pipe 52 by a diameter of 0.4.
[Mm] and 10 [cm] long tubes 20 are connected to form an air resistance.

A pressure sensor 21 and a pressure sensor 22 are respectively connected to the left and right sides of the thin tube 20, so that the internal pressure of the air pipe 52 at both ends of the thin tube 20 can be measured.

When the air system of FIG. 2 is represented as an electrical equivalent circuit by acoustoelectric conversion, as shown in FIG. 3, the pressure V1A can be measured by the pressure sensor 21 and the pressure V1B can be measured by the pressure sensor 22. Can be measured, the air resistance due to the thin tube 20 is R1, and the air resistance due to the air pipe 52 is R1.
Assuming 2A, the pressure V3 in the ear canal 30 of the subject is given by the following equation:

(Equation 2) Can be calculated by

Here, the air resistance R1 of the thin tube 20 and the air resistance R2A of the air pipe 52 are values that can be measured in advance, and thus, regardless of the magnitude of the air leakage resistance R3 between the external auditory canal 30 and the earplug 5, the resistance to air leakage is small. The pressure V3 in the ear canal 30 of the examiner can be accurately detected.

By the way, in the case of this embodiment, the above calculation is performed in the pressure detecting device 23. That is, FIG.
As shown in (1), the value measured by the pressure sensor 21 is input to the multiplexer 25 via the sample hold circuit 24 as a pressure signal S21, and the value measured by the pressure sensor 22 is input to the multiplexer 25 as a pressure signal S22.

The multiplexer 25 alternately inputs the two input signals to the analog-to-digital converter 26, converts the signals into digital signals in the analog-to-digital converter 26, and supplies the digital signals to the microprocessor 27 as pressure digital signals S24. . In addition, microprocessor 2
7 is based on the pressure digital signal S24, the above (2)
The pressure in the external auditory canal 30 of the subject is calculated by the calculation of the formula, and the calculated pressure is supplied to the storage device 16 (FIG. 1) as the external ear canal pressure signal S3.

In the above configuration, the output signal S2 of a specific frequency of, for example, 226 [Hz] output from the oscillator 6
Is converted into sound wave energy in the earphone 7 and is emitted into the external auditory meatus 30 of the subject through the communication channel 52.
At this time, air is sent into the external auditory canal 30 from the pressure variable device 4 through the air pipe 52, and the pressure in the external auditory canal 30 is detected by the internal auditory canal pressure detector 8 and stored in the storage device 16.

The sound wave energy emitted into the ear canal 30 is thereafter reflected by the eardrum 32, collected as reflected sound energy by the microphone 9 and reflected by the reflected sound pressure signal S4.
Is converted to

Further, the reflected sound pressure signal S4 is converted into compliance by the compliance detection unit 10, and after being input to the storage device 16, a graph is displayed on the display unit 17 as an equivalent compliance of the air of the eardrum 32 corresponding to the pressure change in the external auditory canal 30. Will be displayed as

Here, conventionally, the pressure in the ear canal 30 of the subject has been measured using one pressure sensor 3, but air leaks from the gap between the earplug 5 and the ear canal 30. As a result, it was difficult to accurately detect the pressure in the ear canal 30. On the other hand, in this embodiment, by using two pressure sensors, it is possible to detect an accurate pressure in the external auditory canal 30 of the subject regardless of the presence or absence of air leakage.

That is, in the external auditory canal pressure detecting section 8, the pressure sensor 21 and the pressure sensor 22 measure the pressure at both ends of the thin tube 20 formed in the air pipe 52, and obtain a pressure signal S21 and a pressure signal S22. 23. Further, in the pressure detecting device 23, the microprocessor 27 outputs the pressure signals S21 and S2.
The pressure in the external auditory canal 30 of the subject is detected by calculating the equation (2) based on the equation (2).

According to the above configuration, when examining the middle ear using the impedance audiometer 1, the external auditory canal 30
Even when air leaks from the gap between the inner wall of the earplug 5 and the earplug 5, it is possible to accurately detect the pressure in the external auditory canal 30 of the subject, and thus the usability of the examiner and the performance of the impedance audiometer 1. Can be significantly improved.

In the above embodiment, the oscillator 6
Although the case where the frequency of the output signal output from is described as 226 [Hz], the present invention is not limited to this, and the point is that if the acoustic compliance of the middle ear can be effectively detected, the frequency of the output signal can be any number. good.

Further, in the above-described embodiment, the case where the equation (2) is calculated by the pressure detecting device 23 using a microprocessor has been described. However, the present invention is not limited to this, and as shown in FIG. A pressure detection device 40 constituted by a simple analog circuit may be used.

That is, in the pressure detecting device 40, the differential amplifier 41 detects the difference between the pressure values measured by the pressure sensor 21 and the pressure sensor 22, and the detected difference between the pressure values is sent to the variable attenuator 42. Next formula

(Equation 3) , And is supplied to the differential amplifier 43 as a pressure difference signal S31.

Further, the differential amplifier 43 includes the pressure sensor 22
And the pressure difference signal S31 described above is detected, and thus the pressure detecting device 40 can perform the operation of the equation (2). Further, in the above-described embodiment, the case where the length of the thin tube 20 is set to 10 [cm] and the diameter is set to 0.4 [mm] has been described. However, the present invention is not limited to this. The tubule can be of any length, diameter and shape as long as it performs the appropriate function.

Further, in the above-described embodiment, the air resistance is formed by connecting the middle of the air pipe 52 with the thin tube 20. However, the present invention is not limited to this, and a thin nickel rod or wire may be connected to the air pipe 52. In other words, any material may be used as long as it has an appropriate function as air resistance.

Further, in the above-described embodiment, the case where the air resistance is formed by connecting the middle of the air pipe 52 with the thin tube 20 has been described. However, the present invention is not limited to this, and a part of the inner wall of the air pipe 52 may be formed. Alternatively, a projection may be formed.

Further, in the above embodiment, the pressure in the ear canal 30 of the subject is increased from +200 dapa to -200 d.
The case where the pressure is continuously changed in the range of about apa has been described. However, the present invention is not limited to this, and the pressure in the ear canal 30 may be in any range as long as the acoustic compliance of the middle ear can be appropriately detected. Or discontinuous.

Further, in the above embodiment, the monitor 1
8 and the printer 19 are used to display a graph, but the present invention is not limited to this, and the point is that any presentation means can be used as long as the acoustic compliance of the middle ear, which is the measurement result, can be presented. May be.

[0041]

As described above, according to the present invention, air resistance is formed in the air passage when air is injected into the ear canal of the subject, and the first and second air resistances are formed on both sides of the air resistance. By connecting the pressure sensor and providing means for detecting the pressure in the ear canal of the subject based on the pressure data in the air passage supplied from the first and second pressure sensors, The pressure in the ear canal of the examiner can be accurately detected, and thus the usability of the examiner can be significantly improved, and at the same time, the performance of the impedance audiometer can be significantly improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of an impedance audiometer according to one embodiment of the present invention.

FIG. 2 is a schematic block diagram showing a configuration of an air system of an impedance audiometer according to one embodiment of the present invention.

FIG. 3 is a connection diagram showing the air system shown in FIG. 2 as an electric circuit by acoustoelectric conversion.

FIG. 4 is a block diagram showing a configuration of a pressure detecting device.

FIG. 5 is a block diagram showing a modification of the pressure detection device using an analog circuit.

FIG. 6 is a front view showing a graph example displayed by the impedance audiometer.

FIG. 7 is a schematic block diagram showing a configuration of an air system in a conventional impedance audiometer.

8 is a connection diagram showing the air system shown in FIG. 7 as an electric circuit by acoustoelectric conversion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Impedance audiometer, 4 ... Pressure variable device, 5 ... Ear plug, 8 ... External auditory canal pressure detection part, 16 ...
... Storage device, 17 ... Display unit, 20 ... Capillary tube, 21 ...
Pressure sensor A, S21 ... pressure signal, 22 ... pressure sensor B, S22 ... pressure signal, 23 ... pressure detection device, 2
7 ... microprocessor, 30 ... ear canal, 32 ...
eardrum.

Claims (1)

(57) [Claims] An air resistance formed in an air passage when air is injected into an ear canal of a subject, first and second pressure sensors coupled to both sides of the air resistance, and the first and second pressure sensors. Means for detecting the pressure in the ear canal based on pressure data in the air passage supplied from a second pressure sensor.