JP2009284097A - Canal type earphone, using method thereof, and resonant frequency calculation apparatus - Google Patents

Abstract

An object of the present invention is to suppress the influence of a direct wave from a speaker of an earphone when the canal-type earphone is inserted into the ear canal, and to accurately measure the acoustic characteristics of a reflected wave including a weak ear canal resonance.
A canal-type earphone includes an earphone housing, a speaker disposed in the earphone housing, a cylindrical nozzle attached to protrude outward from one end of the earphone housing, and a nozzle 3 is configured so as to form an annular space 20 that is attached to the outer ear canal 6 so as to surround the outer periphery of the nozzle 3 and is in close contact with the surface of the outer ear canal 6 over the entire periphery of the ear canal 6. And the microphone 5 disposed in the annular space 20. The ear tip 4 may have pores that lead to the ear canal 6 when inserted into the ear canal 6.
[Selection] Figure 1

Description

  The present invention relates to a canal type earphone that is used by being inserted into an ear hole (an ear canal) and closing the ear hole, a method for using the canal type earphone, and an apparatus that calculates a resonance frequency when using the canal type earphone.

As an earphone suitable for AV audio equipment such as a portable music player, a canal type earphone that is used by being inserted into an ear hole and sealing the ear hole is known (see Patent Document 1).
JP 2000-341784 A JP 2005-286500 A JP 2001-211491 A

  The music you listen to with earphones is not necessarily high-quality compared to listening to stereo. It is considered that one of the causes of sound quality degradation is that the earphone itself becomes a reflector when the earphone is worn, and the resonance frequency of the ear canal changes. Moreover, since there are individual differences in the ear canal, the resonance frequency is also different.

  Therefore, it is conceivable to use an earphone with a built-in microphone in order to acquire acoustic characteristics for each individual. Here, when an ultra-small microphone is attached to the tip of the earphone, the resonance peak can be detected. However, since the microphone protrudes, it is not practical for safety. Therefore, it is necessary to mount a microphone inside the earphone housing. In this case, since the earphone is attached to the ear, the size and weight can be reduced, and the microphone is disposed in the immediate vicinity of the speaker. However, under this arrangement, the resonance peak is buried in the direct sound from the speaker and is difficult to detect.

  The present invention has been made to solve the above-described problem, and includes a weak external ear canal resonance sound by suppressing the influence of a direct wave from a speaker of the earphone when the canal type earphone is inserted into the external ear canal. The object is to receive the reflected wave with a microphone and measure the acoustic characteristics with high accuracy.

  Patent Documents 2 and 3 disclose earphones with built-in microphones.

  Patent Document 2 discloses a technique for mounting a microphone near an earphone speaker. However, the purpose of use of the microphone in this document is a hearing aid for picking up external noise and adjusting the speaker volume according to the external sound level. For this reason, it is necessary to actively pick up external sound, the microphone is placed behind the speaker (the side away from the ear canal), and direct sound and vibration from the speaker are not returned to the microphone as much as possible to prevent howling. Such a device is devised. Therefore, it differs greatly from the configuration for picking up the speaker sound with the microphone as in the present invention.

  On the other hand, the earphone disclosed in Patent Document 3 is not a canal-type sealed earphone but a normal earphone. Therefore, there is no nozzle or ear tip, and the microphone is located near the ear hole and has a structure that is not arranged in the ear canal as in the canal type of the present invention.

  In order to solve the above-described problems, a canal type earphone according to the present invention includes an earphone case, a speaker disposed in the earphone case, and a cylindrical shape that is attached so as to protrude outward from one end of the earphone case. When the nozzle is attached so as to surround the outer periphery of the nozzle and inserted into the ear canal, the annular space is formed so as to be in close contact with the surface of the ear canal over the entire periphery of the ear canal and to surround the outer periphery of the nozzle. It has the comprised eartip and the microphone arrange | positioned in the said annular space, It is characterized by the above-mentioned.

  Further, another aspect of the canal-type earphone according to the present invention includes an earphone housing, a speaker disposed in the earphone housing, and a cylindrical nozzle attached to project outward from one end of the earphone housing. The outer circumference of the nozzle is attached so as to surround the outer periphery of the nozzle and is inserted into the ear canal so as to be in close contact with the surface of the ear canal over the entire circumference of the ear canal and to form an annular space surrounding the outer periphery of the nozzle. And a microphone embedded in the nozzle and having a sound receiving portion opened toward the annular space.

  Further, the resonance frequency calculation device according to the present invention includes an earphone housing, a speaker disposed in the earphone housing, a cylindrical nozzle attached to protrude outward from one end of the earphone housing, and the nozzle An ear tip that is attached so as to surround the outer periphery of the ear canal and that is in close contact with the surface of the ear canal over the entire circumference of the ear canal and that forms an annular space that surrounds the outer periphery of the nozzle; And a microphone for receiving a direct wave from the calibration sound and a reflected wave reflected by the eardrum through the ear canal when the calibration sound is emitted from the speaker. In a resonance frequency calculation apparatus for calculating a resonance frequency when using a type inner earphone, a calibration sound generator for causing the speaker to generate a calibration sound, and the microphone An impulse response calculation unit that calculates an impulse response of the calibration sound received by the voice, a direct wave detection unit that detects a direct wave from the impulse response calculated by the impulse response calculation unit, and a signal detected by the direct wave detection unit A direct wave amplitude suppression unit that suppresses the amplitude of the direct wave; a frequency conversion unit that converts the frequency of the output of the direct wave amplitude suppression unit; and a resonance frequency calculation unit that calculates a resonance frequency based on the output of the frequency conversion unit; It is characterized by having.

  Further, the method of using the canal type earphone according to the present invention includes an earphone housing, a speaker disposed in the earphone housing, a cylindrical nozzle attached to protrude outward from one end of the earphone housing, It is configured so as to form an annular space that is attached so as to surround the outer periphery of the nozzle and is in close contact with the surface of the ear canal over the entire circumference of the ear canal when inserted into the ear canal. A canal comprising: an eartip; and a microphone that receives a direct wave from the calibration sound when the calibration sound is emitted from the speaker and a reflected wave reflected by the eardrum through the ear canal through the ear canal The earphone is inserted into the ear canal, the calibration sound is generated by the speaker, the calibration sound is received by the microphone, and the microphone is used. Calculating the impulse response of the calibration sound received at the center, detecting the direct wave from the impulse response of the calibration sound, suppressing the amplitude of the detected direct wave, and reducing the amplitude of the direct wave The impulse response signal is frequency-converted, a resonance frequency is calculated based on the frequency-converted result, and the characteristics of the speaker are adjusted based on the calculated resonance frequency.

  ADVANTAGE OF THE INVENTION According to this invention, it is suppressed that a microphone receives the calibration sound emitted from the speaker directly, and it can implement | achieve the measurement of the acoustic characteristic containing the resonance sound of an ear canal by it.

  Embodiments of the present invention will be described below with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted.

[First Embodiment]
FIG. 1 is a schematic longitudinal sectional view showing a state in which the earphone according to the first embodiment of the present invention is attached to the ear canal.

  The earphone according to the present embodiment is a canal-type inner earphone that is used by being inserted into the ear canal (ear hole) 6. A cylindrical nozzle 3 attached so as to protrude outward at a position where the nozzle 3 protrudes, and an ear tip 4 attached to the outer periphery of the nozzle 3. The ear tip 4 is preferably made of, for example, a flexible rubber, and seals the ear canal 6 like an ear plug in close contact with the entire inner periphery of the ear canal 6 when inserted into the ear canal 6. An annular space 20 is formed in the ear tip 4 so as to surround the nozzle 3. The outer space 6 insertion side of the annular space 20 is closed, and the earphone housing 2 side is open.

  The microphone 5 is attached in the annular space 20, and the sound receiving portion 21 of the microphone 5 is directed to the back of the external auditory canal 6.

  The speaker 1 can output normal sound and can output a calibration sound for calculating the resonance frequency of the ear canal 6 when the earphone is attached to the ear canal 6. The calibration sound generated by the speaker 1 propagates through the ear canal 6, is reflected by the eardrum 7 at the back, and reaches the sound receiving unit 21 of the microphone 5 as the ear canal reflected sound 8. Since the microphone 5 is disposed in the annular space 20 outside the nozzle 3, a portion of the calibration sound generated by the speaker 1 that directly reaches the sound receiving unit 21 of the microphone 5 without passing through the ear canal 6. There are few.

  If the microphone 5 is installed in the earphone housing 2, the microphone 5 has the speaker 1 in the vicinity thereof, and therefore receives the direct sound from the speaker 1 having a higher sound pressure than the reflected sound from the ear canal as it is. End up. In that case, the weak external ear canal resonance sound is less likely to appear in the frequency characteristics.

  On the other hand, when the microphone 5 is disposed in the annular space 20 inside the ear chip 4 outside the speaker housing 2 as in the present embodiment, the direct wave from the speaker 1 is diffracted and reduced through the nozzle 3, Compared with the case in the earphone housing 2, the propagation energy is greatly reduced. When the microphone 5 is installed in the earphone housing 2, it is not overlooked that the housing resonance is increased. Therefore, according to the present embodiment, the reception sensitivity of the ear canal propagation energy reflected by the eardrum 7 via the nozzle 3 and the ear canal 6 is relatively improved.

  FIG. 2 is a graph showing a microphone measurement result obtained by actually mounting the earphone of the first embodiment on an ear canal model simulating a human ear canal. Here, the microphone 5 having a diameter of 4 mm was used. Further, FIG. 3 shows the result of actually measuring the frequency characteristics by generating a calibration sound using the speaker of the earphone of the first embodiment and placing another microphone (not shown) at the eardrum position of the simulated ear canal. It is a graph. Comparing the frequency characteristics of the ear canal in FIGS. 2 and 3 shows that resonance peaks A, B, and C can be measured.

[Second Embodiment]
FIG. 4 is a schematic longitudinal sectional view showing an earphone according to a second embodiment of the present invention, and FIG. 5 is a side view taken along line VV of FIG.

  In this embodiment, a pore 26 is formed at a position facing the back of the ear canal 6 of the ear tip 4. Thereby, the sound insulation performance of the eartip 4 is lowered, and the sound receiving sensitivity of the microphone 5 is improved.

  Usually, the eartip 4 is lighter in weight than the earphone housing 2 and has low sound insulation performance. For this reason, even if the microphone 5 is arranged inside the ear chip 4, reception is possible without sound insulation. However, in order to receive the resonance frequency in the high frequency range of 12 kHz or more with high sensitivity, it is necessary to lower the sound insulation. Therefore, the sound receiving sensitivity can be increased by providing the pores 26 in the eartip 4.

[Third Embodiment]
FIG. 6 is a schematic longitudinal sectional view showing an earphone according to a third embodiment of the present invention. In this embodiment, the microphone 5 is disposed in the annular space 20 in the ear tip 4, and the sound receiving portion 21 of the microphone 5 is in contact with the outer ear tip 4 wall of the annular space 20. When the earphone is inserted into the ear canal 6 and attached, the sound receiving portion 21 of the microphone 5 contacts the surface of the ear canal 6 through the wall of the ear tip 4. Therefore, the microphone 5 can measure the solid propagation sound in addition to the air propagation sound transmitted in the ear canal 6.

  In general, in order to measure the acoustic characteristics propagating through the ear canal 6, the measurement of the air propagation sound is accurate. However, if only the resonance frequency is specified, the resonance amplified energy is also present on the surface of the ear canal 6 during resonance. Therefore, the resonance frequency is also included in the solid propagation sound on the surface of the ear canal 6. Therefore, the resonance frequency can be identified by pressing the sound receiving portion 21 of the microphone against the surface of the ear canal 6 via the eartip 4.

[Fourth Embodiment]
FIG. 7 is a schematic longitudinal sectional view showing an earphone according to a fourth embodiment of the present invention. In this embodiment, the microphone 5 is built in the nozzle 3 outside the earphone housing 2, and the sound receiving portion 21 of the microphone 5 faces the annular space 20 in the eartip 4. When the earphone is inserted into the ear canal 6 and attached, the sound receiving unit 21 of the microphone 5 faces the inside of the ear canal 6. For this reason, the microphone 5 does not directly receive the calibration sound emitted from the speaker 1, but receives the ear canal propagation sound reflected by the eardrum 7 through the nozzle 3 and the ear canal 6. Thereby, the measurement of the acoustic characteristics including the resonance sound of the ear canal 6 can be realized.

  Since the sound receiving portion 21 of the microphone 5 is not inside the nozzle 3 but outside, that is, inside the ear tip 4, as in the first embodiment, the contribution of the direct sound becomes small and the reflected wave can be easily measured. Become.

[Fifth Embodiment]
FIG. 8 is a schematic longitudinal sectional view showing an earphone according to a fifth embodiment of the present invention and a resonance frequency calculation device 30 that cooperates with the earphone.

  In this embodiment, the microphone 5 is disposed inside the earphone housing 2, and the weak external auditory canal buried in the direct wave is obtained by suppressing or removing the direct sound 9 received by the microphone 5 from the speaker 1 calculated by the impulse response. Realization of acoustic characteristics of reflected waves including resonance.

  The purpose of detecting the weak external auditory canal reflection sound 8 that tends to be hidden behind the direct sound 9 from the speaker 1 with high accuracy is the same as in the first to fourth embodiments. In the fifth embodiment, signal processing is performed. Therefore, the resonance frequency calculating device 30 is configured to reproduce the weak external auditory canal characteristic buried in the direct wave.

  The resonance frequency calculation device 30 is calculated by a calibration sound generation unit 12 that causes the speaker 1 to generate a random calibration sound, an impulse response calculation unit 13 that calculates an impulse response of the calibration sound received by the microphone 5, and an impulse response calculation unit 13. A direct wave detection unit 14 that detects a direct wave (direct sound) from the impulse response that is generated, a direct wave amplitude suppression unit 15 that suppresses the amplitude of the direct wave detected by the direct wave detection unit 14, and a direct wave amplitude suppression unit A frequency conversion unit 16 that converts the frequency of the 15 outputs, and a resonance frequency calculation unit 17 that calculates a resonance frequency based on the output of the frequency conversion unit 16.

  According to this embodiment, the calibration sound generator 12 outputs a random calibration sound from the speaker 1, and the impulse response calculator 13 calculates the impulse response based on the received signal from the microphone 5.

  The direct wave detection unit 14 separates the direct wave (direct sound) and the reflected wave (reflection sound) of the impulse response, and the direct wave amplitude suppression unit 15 suppresses the direct wave component corresponding to the largest waveform from the origin. Or delete it. Then, with the contribution of the reflected wave being improved, the frequency conversion unit 16 performs FFT (Fourier frequency conversion) analysis, and the resonance frequency calculation unit 17 reproduces the resonance peak on the frequency characteristics.

  FIG. 9 is a graph showing an actual measurement result of an impulse response waveform detected by the microphone 5 in a state where the earphone according to the fifth embodiment is prototyped and attached to the ear canal 6. FIG. 10 is a graph showing the frequency characteristic measurement result of the microphone-equipped earphone based on the impulse response waveform of FIG. 9, and FIG. 11 is the frequency characteristic when a direct wave is removed from the measurement result of the impulse response waveform shown in FIG. It is a graph which shows a result.

  In FIG. 9, multiple reflections are noticeable. In the frequency characteristic at this time, as shown by the solid line in FIG. 10, the direct sound is dominant, and no resonance peak appears.

  On the other hand, when the frequency characteristic obtained by frequency conversion is obtained in a state in which the direct wave surrounded by the dotted rectangle in FIG. 9 is deleted, a resonance peak clearly appears as a result as shown in FIG.

[Other Embodiments]
Each embodiment described above is merely an example, and the present invention is not limited thereto. For example, in the fifth embodiment, the microphone 5 is arranged inside the earphone housing 2, but the arrangement position of the microphone 5 may be the same as in any of the first to fourth embodiments.

1 is a schematic longitudinal sectional view showing a state where an earphone according to a first embodiment of the present invention is attached to an external auditory canal. The graph which shows the microphone measurement result by the earphone of 1st Embodiment. The graph which shows the frequency characteristic measurement result in the eardrum position of a simulated ear canal with the earphone of 1st Embodiment. The schematic longitudinal cross-sectional view which shows the earphone which concerns on the 2nd Embodiment of this invention. The VV arrow side view of FIG. The schematic longitudinal cross-sectional view which shows the earphone which concerns on the 3rd Embodiment of this invention. The schematic longitudinal cross-sectional view which shows the earphone which concerns on the 4th Embodiment of this invention. The typical longitudinal cross-sectional view which shows the earphone which concerns on the 5th Embodiment of this invention, and the resonance frequency calculation apparatus which cooperates with this earphone. The graph which shows the measurement result of the impulse response waveform detected with the microphone of the earphone which concerns on 5th Embodiment. The graph which shows the frequency characteristic measurement result of the earphone with a built-in microphone based on the impulse response waveform of FIG. The graph which shows the frequency characteristic result at the time of removing a direct wave from the measurement result of the impulse response waveform shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Speaker 2 ... Earphone housing | casing 3 ... Nozzle 4 ... Ear tip 5 ... Microphone 6 ... External ear canal 7 ... Tympanic membrane 8 ... Ear canal reflected sound 9 ... Direct sound 12 ... Calibration sound generation part 13 ... Impulse response calculation part 14 ... Direct wave detection Unit 15 direct wave amplitude suppression unit 16 frequency conversion unit 17 resonance frequency calculation unit

Claims (6)

An earphone housing,
A speaker disposed in the earphone housing;
A cylindrical nozzle attached to protrude outward from one end of the earphone housing;
It is configured so as to form an annular space that is attached so as to surround the outer periphery of the nozzle and is in close contact with the surface of the ear canal over the entire circumference of the ear canal when inserted into the ear canal. Eartips,
A microphone disposed in the annular space;
Canal type earphone characterized by having.   The canal earphone according to claim 1, wherein the eartip has pores that lead to the ear canal when inserted into the ear canal.   The canal type earphone according to claim 1, wherein a sound receiving portion of the microphone is attached in contact with an inner side of a wall surface of the eartip that is in contact with the ear canal. An earphone housing,
A speaker disposed in the earphone housing;
A cylindrical nozzle attached to protrude outward from one end of the earphone housing;
It is configured so as to form an annular space that is attached so as to surround the outer periphery of the nozzle and is in close contact with the surface of the ear canal over the entire circumference of the ear canal when inserted into the ear canal. Eartips,
A microphone embedded in the nozzle and having a sound receiving portion opened toward the annular space;
Canal type earphone characterized by having. An earphone housing, a speaker disposed in the earphone housing, a cylindrical nozzle that protrudes outward from one end of the earphone housing, and is attached to surround the outer periphery of the nozzle and is inserted into the ear canal When the calibration sound is emitted from the ear tip configured to form an annular space in close contact with the surface of the ear canal over the entire circumference of the ear canal and surrounding the outer periphery of the nozzle. Resonance frequency when using a microphone-equipped canal-type inner earphone with a direct wave from the calibration sound and a microphone that receives the calibration sound reflected through the ear canal and reflected by the eardrum behind the ear canal In the resonance frequency calculation device,
A calibration sound generator for causing the speaker to generate a calibration sound;
An impulse response calculator for calculating an impulse response of the calibration sound received by the microphone;
A direct wave detector that detects a direct wave from the impulse response calculated by the impulse response calculator;
A direct wave amplitude suppression unit that suppresses the amplitude of the direct wave detected by the direct wave detection unit;
A frequency converter that converts the frequency of the output of the direct wave amplitude suppressor; and
A resonance frequency calculation unit that calculates a resonance frequency based on the output of the frequency conversion unit;
A resonance frequency calculation apparatus comprising: An earphone housing, a speaker disposed in the earphone housing, a cylindrical nozzle that protrudes outward from one end of the earphone housing, and is attached to surround the outer periphery of the nozzle and is inserted into the ear canal When the calibration sound is emitted from the ear tip configured to form an annular space in close contact with the surface of the ear canal over the entire circumference of the ear canal and surrounding the outer periphery of the nozzle. A microphone that receives a direct wave from the calibration sound and a reflected wave reflected by the eardrum at the back of the ear canal through the ear canal, and a method of using a canal type earphone,
Inserting the eartip into the ear canal,
Causing the speaker to generate a calibration sound;
The calibration sound is received by the microphone,
Calculate the impulse response of the calibration sound received by the microphone,
Detecting a direct wave from the impulse response of the calibration sound,
Suppress the amplitude of the detected direct wave;
Frequency conversion of the impulse response signal of the calibration sound in which the amplitude of the direct wave is suppressed,
Calculate the resonance frequency based on the frequency converted result,
Adjusting the characteristics of the speaker based on the calculated resonance frequency;
How to use a canal type earphone characterized by

Images