JP5563144B1 - Ear probe and impedance audiometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ear probe capable of improving the detection accuracy of a probe sound input to a microphone and an impedance audiometer provided with the ear probe.
An ear probe (1) used for an impedance audiometer used for an ossicular reflex examination, an acoustic filter (15) is formed in a propagation path (14) from an ear canal to a microphone (5), and a stimulus sound component that reaches the microphone (5) Reduce the sound pressure. The acoustic filter 15 is disposed by connecting the acoustic resistance tube 6 and the acoustic volume 7 to the propagation path 14. The cut-off frequency of the acoustic filter 15 is a value greater than 226 Hz and less than 500 Hz.
[Selection] Figure 1

Description

  The present invention relates to an ear probe used for ossicular reflex examination and an impedance audiometer including the ear probe.

An impedance audiometer is used for the ossicular reflex examination (reflex examination). The impedance audiometer main body is provided with an ear probe that emits sound in the ear canal of the subject and captures sound in the ear canal. The ossicular reflex examination (reflex examination) presents an intermittent sound (stimulation sound) using this ear probe while presenting a continuous sound (probe sound) of 226 Hz and 85 dBSPL to the sealed external auditory canal. Is done.

The stimulation sound is presented in 5 dB or 10 dB steps at a sound pressure level from 80 dBSPL to 110 dBBSPL for each frequency of 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz.

  The ossicular muscle shows a response that reflexly contracts with stimulating sound and increases the acoustic impedance of the eardrum. By measuring the change in the sound pressure of the probe sound in the external auditory canal with a microphone, the ossicular reflex examination is performed. Patent Document 1 or Patent Document 2 discloses an ossicular reflex measurement apparatus.

JP 2001-149345 A JP 2001-149346 A

In the ossicular reflex examination, 226 Hz probe sound and 500 Hz stimulation sound are output to the predetermined volume from the two earphones in the ear probe under the condition that the acoustic impedance does not change, and the microphone in the ear probe is within the predetermined volume. When detecting a sound, even if a 500 Hz stimulation sound is output, the detected probe sound component should not be affected. However, in some cases, it was confirmed that the sound pressure of the detected probe sound component may decrease when a 500 Hz stimulation sound is output.

  The present invention has been made in view of the problem that the stimulation sound has an influence on the probe sound detected by the microphone in the ear probe, which has not been seen in the prior art. An object of the present invention is to provide an ear probe capable of improving the detection accuracy of probe sound input to a microphone and an impedance audiometer equipped with the ear probe.

In order to solve the above-mentioned problem, the invention according to claim 1 is an ear probe used in an impedance audiometer used for ossicular reflex examination, and is an acoustic that lowers the sound pressure of a stimulation sound in a propagation path from the ear canal to a microphone. forming a filter by lowering the sound pressure of the stimuli to reach the microphone, lowering the sound pressure frequency component as a difference between the frequency of the probe tone of the stimuli, probes sound reaching the microphone This suppresses the change in sound pressure .

The acoustic filter can be disposed by connecting an acoustic resistance tube and an acoustic volume to the propagation path.

The cut-off frequency of the acoustic filter is preferably a value greater than 226 Hz and less than 500 Hz.

The invention according to claim 4 is an impedance audiometer comprising the ear probe according to any one of claims 1 to 3.

According to the first aspect of the present invention, the stimulation sound input to the microphone can be reduced by the acoustic filter. Further, if the acoustic resistance tube and the acoustic volume are connected in series, a small acoustic filter can be configured easily.

  If the cutoff frequency of the acoustic filter is set to a value larger than 226 Hz and smaller than 500 Hz, the influence on the probe sound (226 Hz) is almost eliminated, and the detection accuracy of the probe sound can be improved.

  According to the invention according to claim 4, by using the ear probe according to any one of claims 1 to 3, the detection accuracy of the probe sound is improved and an accurate ossicular reflex examination can be performed. it can.

Configuration diagram of ear probe according to the present invention It is an appearance explanatory drawing of an ear probe, (a) is a side view, (b) is a rear view Block diagram of impedance audiometer according to the present invention

In general, the shape of the portion of the ear probe 1 that is inserted into the ear canal is formed into a long and elongated shape so that it can be easily inserted into the ear canal. Therefore, the sound in the ear canal is detected by the microphone 5 in the ear probe via the tube 13 that passes through the elongated insertion portion. The stimulus sound output to the ear canal is sufficiently attenuated so as not to affect the detection of the probe sound while passing through the tube 13.

However, when the ear probe 1 is downsized, the probe sound detected by the microphone 5 may be smaller than the original size (85 dBSPL) depending on the stimulus sound. As a result, it was confirmed that it was a phenomenon that occurred in the case of a 500 Hz stimulation sound and that a 274 Hz sound was also generated at the same time.

In this phenomenon, since the tube 13 that transmits the sound in the ear canal to the microphone 5 is shortened, the 500 Hz stimulation sound having a relatively low frequency reaches the microphone 5 without being sufficiently attenuated and interacts with the probe sound of 226 Hz. It is presumed that 274 Hz sound is generated by the action, and the corresponding acoustic energy is consumed.

An embodiment of the present invention for eliminating this phenomenon will be described below with reference to the accompanying drawings. As shown in FIGS. 1 and 2, the ear probe 1 used in the impedance audiometer according to the present invention includes a case body 2, a probe sound earphone 3, a stimulus sound earphone 4, and a microphone 5 housed in the case body 2. And an acoustic resistance tube 6, an acoustic volume 7, and the like.

The outer dimensions of the ear probe 1 are, for example, large enough to be easily inspected by holding in a hand of L = about 80 mm, H = about 65 mm, and W = about 20 mm.

  Four openings 8a, 8b, 8c, and 8d are provided at the tip 1a of the ear probe 1 that is inserted into the ear canal. An earplug (not shown) is attached to the tip 1a of the probe 1 so that the ear canal is sealed when the ear canal is inserted.

The opening 8 a communicates with the probe sound earphone 3 through a tube 9. The opening 8 b communicates with the stimulation sound earphone 4 through the tube 10. The opening 8 c is connected to the pressure system pipe 11. The earphones 3 and 4 and the microphone 5 are electrically connected to the apparatus main body.

The opening 8 d is connected to the acoustic volume 7 by the tube 13, the acoustic volume 7 is connected to the acoustic resistance tube 6, and the acoustic resistance tube 6 is connected to the sound port 5 a of the microphone 5. The tube 13, the acoustic volume 7, and the acoustic resistance tube 6 constitute a propagation path 14 from the opening 8 d to the sound port 5 a of the microphone 5. The tube 13 is configured with an inner diameter of about 1 mmφ, for example.

  The acoustic resistance tube 6 is sufficiently thinner than the tube 13, and is formed of, for example, a tube having an inner diameter of about 0.2 mmφ and a length of about 13 mm. The acoustic volume 7 is formed of a cylinder that forms a space of, for example, 155 cubic mm or more.

The acoustic resistance tube 6 and the acoustic volume 7 constitute an acoustic filter 15 that is a low-pass filter. The cutoff frequency of the acoustic filter 15 is set to a value greater than 226 Hz and less than 500 Hz. The resistance values and shapes of the acoustic resistance tube 6 and the acoustic volume 7 are not limited to the numerical values in the embodiment of the present invention, and may be determined as appropriate according to specifications.

An impedance audiometer 20 according to the present invention includes an ear probe 1 and an apparatus main body 21 as shown in FIG. The ear probe 1 and the apparatus main body 21 are connected to each other by a cable 24 and an air tube 25 using connection portions 22 and 23 provided on the apparatus main body 21.

The cable 24 electrically connects the earphones 3 and 4 and the microphone 5 to the electric circuit of the apparatus main body 21 via the connection portion 22. The air tube 25 connects the pressure system pipe 11 of the ear probe 1 and the pressure part adjustment 26 of the apparatus main body 21 via the connection part 23.

  The apparatus main body 21 includes a pressure adjustment unit 26, an impedance measurement unit 27, a control unit 28, and an operation display unit 29. The pressure adjustment unit 26 includes an electromagnetic pump. In the ossicular reflex examination, the pressure inside the ear canal that is sealed so that the eardrum is the best compliance point where the eardrum is most easily measured, which is measured in advance by a chimpanometry examination. Adjust.

  The impedance measurement unit 27 includes an amplification unit 30 that amplifies the output signal of the microphone 5, a signal processing unit 31 that performs predetermined signal processing on the output signal of the amplification unit 30, and an input signal and stimulation sound of the probe sound earphone 3. The signal generation unit 32 generates an input signal of the earphone 4 for use. The signal processing unit 31 includes a 226 Hz band-pass filter, and detects and outputs the sound pressure of the 226 Hz component from the output signal of the microphone 5.

  The control unit 28 exchanges signals with the pressure adjustment unit 26, the impedance measurement unit 27, and the operation display unit 29, and controls setting storage and operation of the entire apparatus. The operation display unit 29 includes a liquid crystal display 33 for displaying inspection results and settings, an operation unit 34 for inputting settings and instructions by an inspector, and a built-in printer 35. The built-in printer 35 prints out the inspection result.

The ossicular reflex examination (reflex examination) by the impedance audiometer 20 according to the present invention configured as described above will be described. First, an earplug is attached to the tip 1a of the ear probe 1, and then the ear probe 1 with the earplug attached is inserted into the ear canal, and the ear canal is sealed. When the examination is started, the pressure adjustment unit 26 adjusts the atmospheric pressure in the ear canal.

Next, an input signal of the probe sound earphone 3 is output from the signal generator 32. This probe sound signal is input to the probe sound earphone 3, and is output from the probe sound earphone 3 as a probe sound (continuous sound of 226 Hz, 85 dBSPL) into the ear canal.

Next, a stimulus sound signal at an examination frequency preset by the operation unit 34 is output from the signal generation unit 32. The stimulus sound is presented in 5 dB or 10 dB steps at a sound pressure level from 80 dBSPL to 110 dBSPL for each frequency of 500 Hz, 1000 Hz, 2000 Hz, and 4000 Hz. The frequency of the stimulation sound can be switched automatically.

  Next, the sound pressure in the ear canal is detected by the microphone 5 via the acoustic filter 15. At this time, if the cutoff frequency of the acoustic filter 15 including the acoustic resistance tube 6 and the acoustic volume 7 is 300 Hz, for example, the stimulation sound detected by the microphone 5 including 500 Hz is sufficiently attenuated at each frequency.

Then, since the stimulation sound detected by the microphone 5 is reduced to a sound pressure that does not affect the probe sound, a change in the sound pressure of the probe sound of 226 Hz can be accurately detected, and the ossicular reflex examination (reflex examination) is performed. ) Can be performed accurately.

With the acoustic filter 15 of the present invention, the low-pass filter can be made small and inexpensive.

  According to the present invention, it is possible to reduce the stimulation sound (500 Hz) reaching the microphone by the acoustic filter, and thus the ear probe with improved detection accuracy of the probe sound (226 Hz) and the impedance audio including the ear probe A meter can be provided.

DESCRIPTION OF SYMBOLS 1 ... Ear probe, 1a ... Tip, 2 ... Case body, 3 ... Probe sound earphone, 4 ... Stimulus sound earphone, 5 ... Microphone, 5a ... Sound opening, 6 ... Acoustic resistance tube, 7 ... Acoustic volume, 8a 8b, 8c, 8d ... opening, 9, 10, 13 ... tube, 11 ... pressure system piping, 14 ... propagation path, 15 ... acoustic filter, 20 ... impedance audiometer, 21 ... device main body, 26 ... pressure adjustment part, 27: Impedance measurement unit, 28 ... Control unit, 29 ... Operation display unit.

Claims (4)

A ear probe used in the impedance audiometer used in ossicular reflex test, to form an acoustic filter for reducing the sound pressure stimulus sound propagation path from the ear canal to the microphone, the stimuli to reach the microphone An ear probe that reduces a sound pressure of a frequency component that is a difference between a frequency of the stimulation sound and a frequency of the probe sound by lowering a sound pressure and suppresses a change in the sound pressure of the probe sound reaching the microphone. . The ear probe according to claim 1, wherein the acoustic filter is disposed by connecting an acoustic resistance tube and an acoustic volume to the propagation path. 3. The ear probe according to claim 1, wherein a cutoff frequency of the acoustic filter is a value greater than 226 Hz and less than 500 Hz. An impedance audiometer comprising the ear probe according to any one of claims 1 to 3.

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