JP2010016792A - Earphone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an earphone suppressing deterioration in sound quality and having an audio output section included in an external auditory meatus. <P>SOLUTION: In the earphone 10, at least one portion of an insertion section 12 is inserted into the external auditory meatus of a user in use. A driver unit 30 outputs sound corresponding to a supplied electric signal. The entire driver unit 30 is included into the external auditory meatus when the insertion section 12 is inserted into an expected insertion position in the external auditory meatus. A back cavity 16c is in contact with a rear 30b of an audio output surface 30a in the external surface of the driver unit 30. The back cavity 16c is partially included in the external auditory meatus when the insertion section 12 is inserted into the expected insertion section of the external auditory meatus. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an earphone, and more particularly to an earphone having an insertion portion that is inserted into an ear canal.

For example, a canal-type earphone is known in which an earpiece or the like is inserted into the ear canal to listen to sound output from a sound output unit. In such a canal type earphone, a soundproof earphone in which an elongated earphone is wrapped with a soundproof elastic body has been proposed to suppress sound leakage to the outside (see, for example, Patent Document 1). In addition, in order to reduce the sound generation portion disposed outside the ear canal, for example, a piezoelectric earphone in which a piezoelectric acoustic body is disposed in an insertion tube fed into the ear canal has been proposed (see, for example, Patent Document 2). .
JP-A-8-237786 JP 09-252496 A

  In recent years, with the spread of portable music players, development of canal-type earphones capable of outputting sound with good sound quality has been increasingly demanded. However, for example, as described in the above-mentioned patent document, in order to arrange the audio output unit inside the ear canal, it is necessary to provide the audio output unit small. In general, the smaller the audio output unit, the more difficult it is to output sound with better sound quality.Therefore, when placing the audio output unit inside the ear canal, it is a problem to suppress the sound quality degradation of the output audio It becomes.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an earphone in which an audio output unit is included in the ear canal while suppressing deterioration in sound quality.

  In order to solve the above-described problems, an earphone according to an aspect of the present invention includes an insertion portion in which at least a part is inserted into the ear canal, and an ear canal when at least a portion of the insertion portion is inserted up to an assumed insertion position of the ear canal. And an audio output unit that outputs audio corresponding to the supplied electric signal, which is entirely included. The insertion part is provided so as to form a gap that is in contact with the back surface of the sound output surface from which sound is output out of the outer surface of the sound output part, and the gap part is at least part of the insertion part up to the assumed insertion position of the ear canal. When inserted, it is configured to be at least partially contained within the ear canal.

  ADVANTAGE OF THE INVENTION According to this invention, the earphone which included the audio | voice output part in the external auditory canal can be provided, suppressing a sound quality fall.

  Hereinafter, embodiments of the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings.

(First embodiment)
Fig.1 (a) is a front view of the earphone 10 which concerns on 1st Embodiment, FIG.1 (b) is a left view of the earphone 10 which concerns on 1st Embodiment, FIG.1 (c). These are top views of the earphone 10 according to the first embodiment. FIG. 2 is an exploded perspective view of the earphone 10 according to the first embodiment. Fig.1 (a)-FIG.1 (c) and FIG. 2 show the earphone 10 for left ears.

  Earphone 10 is included in an earphone unit (not shown) for stereo sound output. The earphone unit further includes a right-ear earphone, a connection plug, and a cable. An earphone for right ear (not shown) is formed symmetrically with the earphone 10. The cable is provided to be divided into two forks from the middle. A connection plug is coupled to an end portion that is not divided into two branches, and an earphone 10 for the left ear and an earphone for the right ear are coupled to each of the end portions divided into the two branches.

  The connection plug is inserted into a headphone terminal (not shown) of an audio output device such as a portable music player. When an electrical signal used for audio output is input to the connection plug at this time, the electrical signal used for left audio output is transmitted to the left earphone 10 via the cable and used for right audio output. The electrical signal is transmitted to the right earphone. An earphone unit may be provided for monaural sound output. Moreover, the earphone unit may not have two earphones but may have a single earphone for one ear.

  Hereinafter, the configuration of the earphone 10 will be described with reference to FIGS. 1 (a) to 1 (c) and FIG. 2. Note that the description of the earphone 10 for the left ear is omitted by describing the earphone 10 for the left ear.

  The earphone 10 includes a main body 16, an earpiece 18, a cushion 22, an ornament 24, a bushing 26, a driver unit 30, a unit holder 32, and a vibration damping gel 34. The main body 16 is made of resin and includes a cylindrical portion 16a and an inclined portion 16b that protrudes radially outward from the cylindrical portion 16a. The axial direction of the tube portion 16a is the insertion direction D1 of the earphone 10 into the ear canal. A unit holder 32 including the driver unit 30 is attached to the tip of the cylindrical portion 16a. A method for attaching the unit holder 32 to the cylindrical portion 16a will be described later. The earpiece 18 is attached so as to cover the unit holder 32 and the tip of the cylindrical portion 16a. Further, the cushion 22 is attached to the side surface of the inclined portion 16b where the cylindrical portion 16a extends. After the damping gel 34 is mounted inside the main body 16, the ornament 24 is attached to the front surface of the main body 16. Details of the driver unit 30, the unit holder 32, and the damping gel 34 will be described later. A bushing 26 is attached to the lower surface of the main body 16 so as to extend downward.

  Hereinafter, the components of the earphone 10 that extend in the insertion direction D1 of the earphone 10 into the ear canal, such as the tube portion 16a and the earpiece 18, are referred to as the insertion portion 12. The components of the earphone 10 that protrude radially outward from the insertion portion 12, such as the inclined portion 16 b and the cushion 22, are referred to as insertion restriction portions 14. The insertion portion 12 is partially inserted into the user's ear canal during use. When the insertion part 12 is inserted to the assumed insertion position, the insertion restriction part 14 abuts against a part of the auricle and regulates the insertion of the insertion part 12 into the heel from the assumed insertion position.

  FIG. 3A is a cross-sectional view of the earphone 10 according to the first embodiment as viewed from below, and FIG. 3B shows the earphone 10 when the ornament 24 is removed. It is the figure seen from the viewpoint P. Hereinafter, the structure of the earphone 10 will be described in detail with reference to both FIG. 3 (a) and FIG. 3 (b).

  The driver unit 30 is formed in a low columnar shape having the same outer diameter as the cylindrical portion 16a. The driver unit 30 outputs a vibration sound of a diaphragm (not shown) driven by an electric signal supplied to a voice coil (not shown) into the ear canal. Therefore, the driver unit 30 functions as an audio output unit. One end surface of the driver unit 30 serves as an audio output surface 30a from which sound emitted from the diaphragm is output.

  The unit holder 32 is formed so that the inner diameter is the same as the outer diameter of the driver unit 30. The bottom of the unit holder 32 is provided with a number of minute circular through-holes so that sound can pass through satisfactorily. In the vicinity of the opening of the unit holder 32, a locking protrusion 32a protruding inward in the diameter is provided by caulking work in the assembly process. On the other hand, a first locking groove 16h that is recessed radially inward is provided in the vicinity of the tip of the cylindrical portion 16a. The unit holder 32 accommodates the driver unit 30 therein so that the audio output surface 30a abuts against the bottom, and the first locking groove in a state where the opening end portion 16a1 of the cylindrical portion 16a is in contact with the back surface 30b of the driver unit 30. The locking protrusion 32a is formed on the unit holder 32 by caulking the outer peripheral surface of the unit holder 32 at a position corresponding to 16h inward. The locking projection 32a is fitted and locked in the first locking groove 16h, whereby the driver unit 30 is fixed to the main body 16.

  The unit holder 32 is formed in a thin cylindrical shape with a bottom by metal. Thus, by forming the unit holder 32 with a metal, the unit holder 32 can be formed thinly and the thickness of the insertion part 12 can be suppressed. In the first embodiment, the unit holder 32 is formed of an aluminum material. Of course, the material forming the unit holder 32 is not limited to an aluminum material, and other metal materials such as a copper alloy, an iron-based material, and a stainless material may be used. Further, the surface of the unit holder 32 may be subjected to a surface treatment such as chrome plating.

  Here, as will be described later, when the insertion unit 12 is inserted up to the assumed insertion position of the ear canal, the driver unit 30 is entirely included in the ear canal. Thus, in order to enable the driver unit 30 to be included in the ear canal, it is necessary to reduce the diameter of the driver unit 30. On the other hand, when the diameter of the driver unit 30 is reduced, it is necessary to reduce the size of the built-in voice coil, permanent magnet, and the like. Therefore, as the driver unit 30 is reduced in size, it becomes increasingly difficult to suppress the deterioration of the sound quality of the output sound.

  Therefore, a back cavity 16c, which is a gap having an opening at the tip, is provided in the cylindrical portion 16a of the main body 16. The back cavity 16 c is defined by the opening end portion 16 a 1 having an opening in the cylindrical portion 16 a contacting the back surface 30 b of the driver unit 30. By providing such a back cavity 16c, it is possible to suppress deterioration in sound quality due to downsizing of the driver unit 30. As a result of the inventor's research and development, the provision of the back cavity 16c has the effect of particularly complementing the lowering of the output in the low frequency range due to the downsizing of the driver unit 30.

  Further, the back cavity 16c is formed so that a part of the back cavity 16c is included in the ear canal when the insertion portion 12 is inserted to the assumed insertion position of the ear canal. Thereby, the size of the portion protruding to the outside of the auricle due to the provision of the back cavity 16c can be suppressed.

  The earpiece 18 is formed of an elastic material such as rubber. The earpiece 18 has a bottomed cylindrical portion, and the bottom portion is provided with an audio output hole 18a that is a circular through hole. In addition, the earpiece 18 is provided with an umbrella-shaped portion 18b that is integrally coupled to the bottom portion of the cylindrical portion. In the vicinity of the opening of the cylindrical portion of the earpiece 18, a locking protrusion 18c that protrudes inward in the diameter is provided. On the other hand, a second locking groove 16i that is recessed radially inward is provided on the surface of the cylindrical portion 16a that is slightly separated from the opening than the first locking groove 16h. When the locking projection 18c is locked in the second locking groove 16i, the earpiece 18 is attached to the main body 16 so as to wrap the entire unit holder 32 by the cylindrical portion. As described above, the sound from the sound output surface 30 a of the driver unit 30 is output to the outside through the numerous through holes of the unit holder 32 and the sound output holes 18 a of the earpiece 18.

  The main body 16 is provided with a gel insertion hole 16 f that extends coaxially across the back cavity 16 c and the bottom portion 16 l and opens at the front surface of the main body 16. A bottom portion 16l interposed between the back cavity 16c and the gel insertion hole 16f is provided with a wire insertion hole 16d that is a through hole and a plurality of ventilation holes 16e that are also through holes. A wire that is connected to the driver unit 30 and supplies an electrical signal is inserted through the wire insertion hole 16d. The vent hole 16e allows the back cavity 16c to communicate with the outside air so that the diaphragm built in the driver unit 30 can vibrate smoothly.

  A disc-shaped damping gel 34 having an outer diameter substantially the same as the inner diameter of the gel insertion hole 16f is disposed in the gel insertion hole 16f. The damping gel 34 suppresses transmission of sound generated by rubbing a cable and clothes to the eardrum, for example, and absorbs vibration generated by the driver unit 30 to suppress sound leakage to the outside. For this reason, the damping gel 34 is formed of a material having a high damping performance. The damping gel 34 is provided with a wire insertion hole 34a and a ventilation hole 34b formed in the same shape and the same position as the wire insertion hole 16d and the ventilation hole 16e, respectively. The damping gel 34 is inserted into the gel insertion hole 16f until it hits the bottom. A bushing insertion hole 16g for attaching the bushing 26 is provided on the side wall of the gel insertion hole 16f.

  On the front surface of the main body 16, an ornament attachment portion 16 k for attaching the ornament 24 is provided. The ornament attachment portion 16k is formed so as to be cut out from the front surface of the main body 16 at a certain depth. The ornament 24 is fitted and fixed to the ornament mounting portion 16k. The ornament 24 is made of an aluminum material. Of course, the ornament 24 may be formed of other materials.

  The inclined portion 16b of the main body 16 is provided with a cushion mounting hole 16j that penetrates the ornament mounting portion 16k and the back surface thereof. The cushion 22 includes an auricle contact portion 22a and an attachment projection 22b. The auricle contact portion 22a abuts on the auricle when the earphone 10 is attached to the user's ear. The attachment protrusion 22b is formed to protrude outward from the auricle contact portion 22a in order to attach the cushion 22 to the main body 16. The cushion 22 is fixed to the main body 16 by fitting the mounting protrusion 22b into the cushion mounting hole 16j.

  In the first embodiment, the insertion restricting portion 14 extends at an angle θ with respect to a plane perpendicular to the insertion direction D1 when the insertion portion 12 is inserted into the ear canal (hereinafter referred to as “vertical plane PL1”). Exists. Specifically, in consideration of the angle formed by the auricle and the extending direction of the external auditory canal in the vicinity of the opening, the insertion restricting portion 14 extends in a direction forming θ = 23.5 degrees with respect to the vertical plane PL1. . By setting such an angle, when the earphone 10 is attached to the user's ear, the ornament 24 can be arranged to extend in the front-rear direction, and the earphone 10 can be comfortably worn when worn. Both high design of the earphone 10 can be realized. The insertion restricting portion 14 may extend in a direction that forms an angle of, for example, 20 degrees to 30 degrees with respect to the vertical plane PL1. Even if the insertion restricting portion 14 extends in such an angle range, it is possible to maintain the feeling of wearing and design of the earphone 10 when worn.

  FIG. 4 is an external view showing a state when the right-ear earphone 10 is attached to the right ear of the user. Note that the earphone 10 shown in FIG. 4 is formed symmetrically with respect to the left-ear earphone 10 shown in FIGS. 1 and 3. The auricle 94 has a bowl-shaped portion 94a around the opening of the ear canal. The inclined portion 16b is formed in such a length that the tip portion 16m contacts the inner wall of the hook-shaped portion 94a when the earphone 10 is worn on the user's ear. As described above, the insertion restricting portion 14 extends at an angle θ with respect to the vertical plane PL1. Therefore, a reaction force is applied in the direction in which the insertion portion 12 is inserted into the ear canal by the inclined portion 16b coming into contact with the inner wall of the bowl-shaped portion 94a. For this reason, it is hard to take off and a good wearing feeling can be given to a user.

  Returning to FIG. The cushion 22 may extend to the position of the distal end portion 16m. Further, an elastic member different from the cushion 22 may be provided at the position of the distal end portion 16m. At this time, the other elastic member may be formed of a member softer than the cushion 22. Thereby, the wearing feeling of the earphone 10 can be further improved.

  Furthermore, the insertion restricting portion 14 has a width in a direction orthogonal to both the extending direction of the insertion restricting portion 14 and the insertion direction D1 when the insertion portion 12 is inserted into the ear canal, that is, the second width in the left-right direction in FIG. W2 is formed substantially the same as the first width W1 of the unit holder 32 in the direction of the insertion portion 12. In the first embodiment, the driver unit 30 is accommodated in the insertion portion 12. Therefore, since it is not necessary to accommodate the driver unit 30 in the insertion restricting portion 14, the width of the insertion restricting portion 14 can be easily made substantially the same as the width of the insertion portion 12.

  When the width of the insertion restricting portion 14 is increased, there is a possibility that a finger space for attaching and detaching the insertion restricting portion 14 is insufficient when the insertion restricting portion 14 is disposed on the hook-shaped portion 94a. Thus, by making the width of the insertion restricting portion 14 substantially the same as the width of the inserting portion 12, it is possible to secure a finger space around the insertion restricting portion 14 when the earphone 10 is attached to the user's ear. Thus, the earphone 10 can be easily attached to and detached from the ear.

  FIG. 5 is a diagram illustrating a state where the earphone 10 according to the first embodiment is attached to the user's ear. For ease of understanding, FIG. 5 shows a cross-sectional view around the ear canal. In FIG. 5, the ear canal and the eardrum are shown as the ear canal 100 and the eardrum 102, respectively. In FIG. 5, L1 indicates the length of the ear canal 100 along the center line from the ear canal opening 100a to the eardrum 102. L2 indicates an assumed insertion depth from the ear canal opening 100a to the tip of the earpiece 18 when the earphone 10 is inserted at the assumed insertion position. The ear canal opening 100a refers to the boundary between the ear canal 100 and the bowl-shaped portion 94a. Although the external auditory canal length L1 varies depending on the user, it is generally known that it is 25 mm or more and 30 mm or less. In the first embodiment, the assumed insertion depth L2 of the earphone 10 is 6 mm.

  6A is a diagram schematically illustrating a state in which the earphone 10 according to the first embodiment is attached to the user's ear, and FIG. 6B is an earphone used for comparison with the earphone 10. It is a figure which shows typically the state with which 120 was mounted | worn in a user's ear. Hereinafter, description will be made in relation to both FIG. 6 (a) and FIG. 6 (b).

  In general, the sound pressure applied to the eardrum by the earphone is inversely proportional to the square of the distance from the diaphragm as the sound source to the eardrum. For this reason, if the distance from the diaphragm to the eardrum is shortened, even when a driver unit with a small maximum output is used, the reduction of the sound pressure in the eardrum is suppressed by arranging the driver unit at a position close to the eardrum. be able to.

  On the other hand, in order for the driver unit 30 to be included in the ear canal 100 when the insertion portion 12 is inserted at the assumed insertion position, the driver unit 30 needs to be downsized. However, if the driver unit 30 is downsized in this way, the maximum sound pressure that can be output may be reduced. Therefore, the present inventor has come up with the idea that the diaphragm 40 is appropriately brought close to the eardrum 102 in order to compensate for the maximum sound pressure that is reduced by downsizing the driver unit 30 in this way. Specifically, the distance L3 between the diaphragm and the eardrum is a distance transmitted to the eardrum with a sound pressure equal to or higher than an appropriate sound pressure that can be appropriately perceived by the user.

  In FIG. 6A, the diaphragm included in the driver unit 30 is shown as a diaphragm 40. L3 indicates the distance along the center line of the ear canal 100 from the diaphragm 40 to the eardrum 102. In the earphone 10, the distance from the diaphragm 40 to the tip of the earpiece 18 is 1.9 mm. For this reason, the distance L3 between the diaphragm and the eardrum is 20.9 mm or more and 25.9 mm or less. The distance L4 from the ear canal opening 100a to the diaphragm 40 is 4.1 mm.

  The inventor conducted a comparative experiment with the earphone 120 as a comparative example in order to evaluate whether the sound output by the earphone 10 is perceived appropriately by the user. It has already been confirmed that the sound output from the earphone 120 is properly perceived by the user. The earphone 120 has a main body 122, an earpiece 124, and a driver unit 126. The main body 122 has a unit accommodating portion 122a and an earpiece attaching portion 122b that are integrally connected to each other. The unit accommodating portion 122a is formed in a cylindrical shape having a diameter larger than that of the ear canal 100. The earpiece mounting portion 122 b is formed in a cylindrical shape having a smaller diameter than the ear canal 100. A driver unit 126 having a diameter larger than that of the driver unit 30 is accommodated in the unit accommodating portion 122a. An earpiece 124 is attached to the earpiece mounting portion 122b. When the earphone 120 is inserted to the virtual insertion position, the driver unit 126 is disposed outside the ear canal 100. The assumed insertion depth L2 of the earphone 120 is also set to 6 mm.

  The driver unit 126 includes a diaphragm 128 that outputs sound when vibrated. In FIG. 6B, L5 indicates a distance along the center line of the ear canal 100 from the diaphragm 128 to the eardrum 102. In the earphone 120, the distance from the diaphragm 128 to the tip of the earpiece 124 is 11.2 mm. For this reason, the distance L5 between the diaphragm and the eardrum is 30.2 mm or more and 35.2 mm or less.

  From the above, L3 / L5 is 0.69 or more and 0.74 or less in the comparison of the same person. Therefore, if the driver unit 30 and the diaphragm 128 have the same maximum sound pressure, the sound pressure of the sound reaching the eardrum 102 is 2.6 dB or more and 3.2 dB or less in the earphone 10 than in the earphone 120. Get higher. Conversely, in order to make the sound pressure of the sound reaching the eardrum 102 the same as that of the earphone 120, the maximum sound pressure that can be output by the earphone 10 may be 2.6 dB or more and 3.2 dB or less lower than the earphone 120. become.

  As a result of confirmation by the inventor, although the diaphragm 40 is arranged in this manner, the driver unit 30 can be appropriately perceived by the user in the same manner as the earphone 120 even though the driver unit 30 is downsized to be included in the ear canal 100. It was confirmed that it was transmitted to the eardrum with a sound pressure higher than the appropriate sound pressure. If the distance L4 from the ear canal opening 100a to the diaphragm 40 is 3 mm or more, even if the driver unit 30 is downsized so as to be included in the ear canal 100, the sound output from the diaphragm 40 can be reproduced by the user. Has been confirmed to be transmitted to the eardrum at a sound pressure higher than the proper perceivable sound pressure.

(Second Embodiment)
FIG. 7 is a perspective view showing an appearance of the earpiece 50 according to the second embodiment. The configuration of the earphone according to the second embodiment is the same as that of the earphone 10 according to the first embodiment except that the earpiece 50 is employed instead of the earpiece 18.

  The back surface 30b of the driver unit 30 communicates with the outside air through the vent hole 16e and the vent hole 34b. However, since the driver unit 30 is included in the external auditory canal, it is difficult to communicate the audio output surface 30a of the driver unit 30 with the outside air as compared with the case where the driver unit 30 is disposed outside the external auditory canal.

  For this reason, the umbrella-shaped part 50b of the earpiece 50 is provided with a groove 50c extending from the front end to the rear end of the umbrella-shaped part 50b. Thereby, when the user inserts the earpiece 50 into the ear canal, the inside of the ear canal and the outside air can be communicated with each other through the groove 50c. For this reason, the audio output surface 30a can be communicated with the outside air through the audio output hole 50a provided at the tip of the earpiece 50, and the diaphragm 40 can be vibrated more smoothly.

(Third embodiment)
FIG. 8 is a perspective view showing an appearance of an earpiece 52 according to the third embodiment. The configuration of the earphone according to the third embodiment is the same as that of the earphone 10 according to the first embodiment except that an earpiece 52 is employed instead of the earpiece 18.

  The umbrella-shaped portion 52b of the earpiece 52 is provided with a texture that is uneven in the thickness direction over the entire outer surface. Thereby, when the user inserts the earpiece 52 into the ear canal, there are many minute paths through which the air flows between the wall surface of the ear canal and the outer surface of the umbrella-shaped portion 52b. It can be made to communicate via the outer surface of 52b. For this reason, the sound output surface 30a can be communicated with the outside air through the sound output hole 52a provided at the tip of the earpiece 52, and the diaphragm 40 can be vibrated more smoothly.

  The present invention is not limited to the above-described embodiments, and an appropriate combination of the elements of each embodiment is also effective as an embodiment of the present invention. Various modifications such as design changes can be added to each embodiment based on the knowledge of those skilled in the art, and embodiments to which such modifications are added can also be included in the scope of the present invention.

(A) is a front view of the earphone which concerns on 1st Embodiment, (b) is a left view of the earphone which concerns on 1st Embodiment, (c) is 1st Embodiment. It is a top view of the earphone. 1 is an exploded perspective view of an earphone according to a first embodiment. (A) is sectional drawing seen from the downward direction of the earphone which concerns on 1st Embodiment, (b) is the figure which looked at the earphone when the ornament was removed from the viewpoint P of (a). . It is an external view which shows a state when the earphone for right ears is mounted | worn with the user's right ear. It is a figure which shows the state with which the earphone which concerns on 1st Embodiment was mounted | worn with the user's ear. (A) is a figure which shows typically the state with which the earphone which concerns on 1st Embodiment was mounted | worn with a user's ear, (b) is the earphone used for the comparison with an earphone mounted | worn with a user's ear It is a figure which shows the made state typically. It is a perspective view which shows the external appearance of the earpiece which concerns on 2nd Embodiment. It is a perspective view which shows the external appearance of the earpiece which concerns on 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Earphone, 12 Insertion part, 14 Insertion restriction part, 16 Main body, 16a Tube part, 16b Inclination part, 16c Back cavity, 18 Earpiece, 30 Driver unit, 30a Audio | voice output surface, 30b Back surface, 32 Unit holder, 40 Diaphragm

Claims (8)

An insertion part into which at least a part is inserted into the ear canal;
An audio output unit that outputs the sound in accordance with the supplied electrical signal and is entirely contained in the external auditory canal when at least part of the insertion unit is inserted up to the assumed insertion position of the ear canal;
With
The earphone has an air gap that is in contact with a back surface of a sound output surface from which sound is output out of an outer surface of the sound output portion.   2. The earphone according to claim 1, wherein the gap is provided so that at least a part of the gap is included in the ear canal when the insertion part is inserted up to an assumed insertion position of the ear canal.   The audio output unit outputs vibration sound of a diaphragm driven by an electrical signal supplied to the voice coil into the ear canal when at least a part of the insertion unit is inserted up to an assumed insertion position of the ear canal. The sound pressure from the eardrum to the diaphragm along the external auditory canal is the maximum sound pressure that can be output and the sound pressure that is higher than the appropriate sound pressure that can be perceived appropriately by the user. The earphone according to claim 1, wherein the earphone is attached to the insertion portion so as to have a distance transmitted to the eardrum.   The audio output unit is attached to the insertion unit such that when at least a part of the insertion unit is inserted up to the assumed insertion position of the ear canal, the distance from the opening of the ear canal to the diaphragm is 3 mm or more. The earphone according to claim 3, wherein: An insertion restricting portion that abuts against a portion of the auricle and restricts insertion of the insertion portion into the heel from the assumed insertion position when at least a portion of the insertion portion is inserted to the assumed insertion position of the ear canal ,
5. The insertion restriction portion extends at an angle with respect to a plane perpendicular to an insertion direction when at least a part of the insertion portion is inserted into the ear canal. Earphones.   The insertion restricting portion has a width in a direction orthogonal to both the extending direction of the insertion restricting portion and the insertion direction when the inserting portion is inserted into the ear canal substantially the same as the width of the inserting portion in the direction. The earphone according to claim 5, wherein: A unit holder for accommodating the audio output unit and attaching to the insertion unit;
The earphone according to claim 1, wherein the unit holder is made of metal. The insertion portion includes a cylindrical portion formed in a cylindrical shape,
The earphone according to any one of claims 1 to 7, wherein the gap portion is defined by an end portion of the cylindrical portion having an opening portion coming into contact with the back surface of the audio output portion.

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