Open-type earphones

Abstract

An embodiment of the present specification includes a vocal part and an earpiece. The vocal part includes a transducer and a housing that accommodates the transducer. When worn, a portion of the earpiece is positioned between the user's earlobe and head, and another portion of the earpiece extends from the earlobe toward one side facing away from the head and is connected to the vocal part to fix the vocal part in a position near the ear canal but not blocking the ear canal. Herein, an output hole is opened on the side of the housing facing the earlobe and is used to extract sound generated by the transducer from the housing and transmit it to the ear canal, and the ratio of the area of ​​the output hole to the area of ​​the inner surface where the output hole is opened is between 0.015 and 0.25, thereby providing an open-type earphone.

Description

Technology Field [Cross-reference] The present invention claims priority to a Chinese application filed on October 28, 2022, with application number 202211336918.4, priority to a Chinese application filed on December 1, 2022, with application number 202223239628.6, and priority to an international application filed on December 30, 2022, with application number PCT / CN2022 / 144339, the entire contents of said prior applications are incorporated herein by reference. [Technology Field] The present invention relates to the field of acoustic technology, and specifically to open-type earphones. Background Technology With the advancement of audio output technology, audio devices (such as earphones) are already widely applied in people's daily lives and, when combined with electronic equipment like mobile phones and computers, can provide users with an auditory feast. Open-type earphones are portable audio output devices that enable sound conduction within a specific range. Compared to traditional in-ear and over-ear earphones, open-type earphones have the characteristic of not blocking or covering the ear canal; this allows users to acquire sound information from the external environment while listening to music, thereby enhancing safety and comfort. The output performance of open-type earphones has a significant impact on user comfort. Therefore, it is necessary to improve the output performance of open-type earphones by submitting a type of open-type earphone. An embodiment of the present invention provides an open-type earphone comprising a voice part and an earring, wherein the voice part comprises a transducer and a housing that accommodates the transducer, and when worn, a first part of the earring is positioned between the user's earlobe and head, and a second part of the earring extends from the earlobe to one side facing away from the head and is connected to the voice part to fix the voice part in a position near the ear canal but not blocking the ear canal, wherein an output hole is opened on the inner surface facing the earlobe from the housing, and is used to extract sound generated by the transducer from the housing and transmit it to the ear canal, and the ratio of the area of ​​the output hole to the area of ​​the inner surface where the output hole is opened is between 0.015 and 0.25. In some embodiments, when worn, at least a portion of the housing is inserted into the earwax, and the cross-sectional area of ​​the sound release hole is 2.87 mm 2 ~46.10mm 2 is, and the inner surface area is 160mm 2 ~240mm 2 am. In some embodiments, the ratio of the cross-sectional area of ​​the sound hole to the square of the depth of the sound hole is 0.31 to 512.2. In some embodiments, the range of the depth of the sound hole is 0.3mm to 3mm. In some embodiments, the range of distance from the center of the sound outlet to the lower side of the vocal part is 4.05 mm to 6.05 mm. In some embodiments, the range of distance from the center of the sound outlet to the rear side of the vocal part is 8.15 mm to 12.25 mm. In some embodiments, the transducer includes a magnetic circuit assembly, the magnetic circuit assembly is used to provide a magnetic field, and the range of distance from the center of the sound output hole to the bottom surface of the magnetic circuit assembly is 5.65 mm to 8.35 mm. In some embodiments, the range of distance from the center of the sound output hole to the center plane of the major axis of the magnetic circuit assembly is 1.45 mm to 2.15 mm. In some embodiments, when worn, the range of distance between the center of the sound hole and the upper top point of the earring is 22.5 mm to 34.5 mm. In some embodiments, when worn, the range of distance from the projection in the sagittal plane of the center of the sound hole to the projection in the sagittal plane of the upper apex of the earring is 18 mm to 30 mm. In some embodiments, when worn, the ratio of the distance from the center of the sound hole to the upper top point of the earring and the distance between the upper and lower edges of the inner surface is between 1.2 and 2.2. In some embodiments, when worn, the ratio of the distance from the center of the sound hole to the upper top point of the earring and the distance from the center of the sound hole to the upper side of the sounding part is between 1.94 and 2.93. In some embodiments, the range of distance from the projection point in the sagittal plane at the center of the sound hole to the projection point in the sagittal plane at the center of the ear hole is 2.2 mm to 3.8 mm. In some embodiments, the range of distance from the projection point in the sagittal plane at the center of the sound outlet to the projection point in the sagittal plane at the midpoint of the phase boundary of the inner surface is 10.0 mm to 15.2 mm. In some embodiments, the range of distance from the projection point in the sagittal plane of the midpoint of the upper boundary of the inner surface to the projection point in the sagittal plane of the center of this tool is 12 mm to 18 mm. In some embodiments, the range of distance from the projection point in the sagittal plane at the center of the sound outlet to the projection point in the sagittal plane at 1 / 3 of the lower boundary of the inner side is 3.5 mm to 5.6 mm. In some embodiments, the range of distance from the projection point in the sagittal plane at 1 / 3 of the lower boundary of the inner side to the projection point in the sagittal plane at the center of the tool is 1.7 mm to 2.7 mm. In some embodiments, when worn, at least a portion of the housing is located on the anti-helix portion, and the range of distance from the center of the sound hole to the lower side of the sound-producing part is 2.3 mm to 3.6 mm. In some embodiments, the range of distance from the center of the sound outlet to the rear side of the vocal part is 9.5 mm to 15.0 mm. In some embodiments, when worn, the range of distance between the center of the sound hole and the upper top point of the earring is 17.5 mm to 27.0 mm. In some embodiments, when worn, the ratio of the distance from the center of the sound hole to the upper top point of the earring and the distance between the upper and lower edges of the inner surface is between 0.95 and 1.55. In some embodiments, when worn, the ratio of the distance from the center of the sound hole to the upper top point of the earring and the distance from the center of the sound hole to the upper side of the sounding part is between 1.19 and 2.50. In some embodiments, the distance between the center of the sound hole and the plane where the earring is located is between 3mm and 6mm. In some embodiments, the ratio value range of the length of the major axis of the sound hole and the length of the minor axis of the sound hole is between 1 and 10. In some embodiments, the ratio value range of the length of the major axis of the sound hole and the length of the minor axis of the sound hole is between 2 and 4. The embodiments of the present specification also provide an open-type earphone comprising a voice part and an earring, wherein the voice part comprises a transducer and a housing that accommodates the transducer, and when worn, a first part of the earring is positioned between the user's earlobe and head, and a second part of the earring extends from the earlobe to one side facing away from the head and is connected to the voice part to fix the voice part in a position near the ear canal but not blocking the ear canal, wherein the transducer comprises a vibrating membrane, and an output hole is opened on the inner surface facing the earlobe from the housing to be used to extract sound generated by the vibration of the vibrating membrane from the housing and transmit it to the ear canal, wherein the ratio of the area of ​​the output hole to the area of ​​the projection of the vibrating membrane in its direction of vibration is between 0.016 and 0.261. In some embodiments, when worn, at least a portion of the housing is inserted into the earwax, and the cross-sectional area of ​​the sound release hole is 2.87 mm 2 ~46.10mm 2 and the projected area of ​​the vibrating membrane in the direction of vibration is 150mm 2 ~230mm 2 am. The embodiment of the present specification also includes a vocal part and an earpiece, wherein the vocal part includes a transducer and a housing that accommodates the transducer, and when worn, a first part of the earpiece is positioned between the user's earlobe and head, and a second part of the earpiece extends from the earlobe to one side facing away from the head and is connected to the vocal part to fix the vocal part in a position near the ear canal but not blocking the ear canal, wherein the transducer includes a vibrating membrane, and an output hole is opened on the inner surface facing the earlobe from the housing to be used to extract sound generated by the vibration of the vibrating membrane from the housing and transmit it to the ear canal, wherein the range of the distance between the center of the output hole and the upper top point of the earpiece is 22.5 mm to 34.5 mm, thereby providing an open-type earphone. Brief explanation of the drawing The present invention is further explained in the manner of exemplary embodiments, which are described in detail through the drawings. These embodiments are not limiting, and in these embodiments, like reference numerals denote like structures. FIG. 1 is a schematic diagram of an exemplary ear according to some embodiment of the present invention. FIG. 2 is an exemplary structural diagram of an open-type earphone according to some embodiments of the present specification. FIG. 3 is a schematic diagram of two point sound sources and listening positions according to some embodiments of the present invention. FIG. 4 is a comparison of leakage sound indices under different frequencies of a single-point sound source and a double-point sound source according to some embodiments of the present invention. FIG. 5 is an exemplary schematic diagram of a distribution in which a barrier plate is placed between two sound sources of a dipole sound source according to some embodiments of the present invention. FIG. 6 is a graph of the leakage sound index when a barrier plate is placed between two sound sources of a dipole sound source according to some embodiments of the present invention and when a barrier plate is not placed. FIG. 7 is an exemplary wearing schematic diagram of an open-type earphone according to some embodiments of the present invention. Figure 8 is a schematic diagram of the structure of one side facing the ear in the open earphone shown in Figure 7. FIG. 9 is an exemplary schematic diagram of a cavity structure arranged around one of the dipole sound sources according to some embodiments of the present invention. FIG. 10a is a schematic diagram of a sound principle in which a dipole sound source structure according to some embodiments of the present invention and a cavity structure are constructed around one of the dipole sound sources. FIG. 10b is a schematic diagram of a leakage sound principle in which a dipole sound source structure according to some embodiments of the present invention and a cavity structure are constructed around one of the dipole sound sources. FIG. 11a is a schematic diagram of a cavity structure having two horizontal openings according to some embodiments of the present invention. FIG. 11b is a schematic diagram of a cavity structure having two vertical openings according to some embodiments of the present invention. FIG. 12 is a comparative diagram of the acoustic index curves of a cavity structure having two openings and one opening according to some embodiments of the present invention. FIG. 13 is an exemplary wearing schematic diagram of an open earphone according to some other embodiments of the present invention. FIG. 14 is a schematic diagram of the structure of one side facing the ear in the open earphone shown in FIG. 13. FIG. 15 is a schematic diagram of a projection in the sagittal plane when an open earphone according to some embodiments of the present specification is worn. FIG. 16a is an exemplary internal structural diagram of a vocalization unit according to some embodiments of the present specification. FIG. 16b is an exemplary internal structure diagram of a transducer according to some embodiments of the present specification. FIG. 17a is a frequency response curve of an open earphone corresponding to sound output holes of different cross-sectional areas when the aspect ratio is constant, according to some embodiments of the present specification. FIG. 17b is a frequency response curve of a full cavity corresponding to a sound output hole of a different cross-sectional area according to some embodiments of the present specification. FIG. 18a is a frequency response curve of an open earphone corresponding to a sound output hole of a different aspect ratio according to some embodiments of the present specification. FIG. 18b is a frequency response curve of a full cavity corresponding to sound output holes of different depths according to some embodiments of the present specification. Specific details for implementing the invention To more clearly explain the technical solutions of the embodiments of the present invention, the drawings to be used in the description of the embodiments are briefly introduced below. Of course, the accompanying drawings in the description below are merely some examples or embodiments of the present invention, and those skilled in the art can apply the present invention to other similar situations based on these drawings without creative labor. Unless readily available in the preceding or following text or described separately, the same reference numerals in the drawings indicate the same structure or operation. It should be understood that as used herein, the terms “system,” “device,” “unit,” and / or “assembly” are merely one method of distinguishing different assemblies, parts, components, sections, or assemblies of different classes. However, where other words can achieve the same purpose, said words may be replaced by other expressions. As described in the invention and claims, unless otherwise clearly indicated by the context, words such as “one,” “one,” and / or “above” do not specifically refer only to the singular but may include the plural. Generally, the terms “include” and “comprehensively” mean merely including the specified procedures and elements, and such procedures and elements do not form an exclusive enumeration, and the method or apparatus may include other procedures or elements. In the description of this specification, it should be understood that terms such as "first," "second," "third," "fourth," etc. are for descriptive purposes only and should not be understood as indicating or implying relative importance or implying the quantity of the descriptive features indicated herein. Accordingly, the features defined by "first," "second," "third," and "fourth" specify or imply that they include at least one of the corresponding features. In the description of this specification, unless explicitly and specifically limited otherwise, the meaning of "plural" is to have at least two, for example, two, three, etc. In this specification, unless otherwise explicitly specified or limited, terms such as “connection,” “fixing,” etc., should be understood in a broad sense. Unless otherwise explicitly limited, the term “connection” may refer to a fixed connection, a detachable connection, or a monolithic molding; it may be a mechanical connection or an electrical connection; it may be a direct connection or an indirect connection through an intermediate medium; it may be communication within two elements or an interaction relationship between two elements. Those skilled in the art will understand the specific meaning of the above terms in this specification based on the specific circumstances. FIG. 1 is a schematic diagram of an exemplary ear according to some embodiment of the present invention. Referring to FIG. 1, the ear (100) (which may also be called an "earlobe") may include an external auditory canal (101), an auricular cavity (102), an auricular apex (103), a triangular fossa (104), a counter-helix (105), an tragus (106), an auricle (107), an earlobe (108), an auricle (109), and an auricular angle (1071). In some embodiments, stability of wearing an acoustic device may be achieved through support of one or more parts of the ear (100) for the acoustic device. In some embodiments, parts such as the external auditory canal (101), the auricular cavity (102), the auricular apex (103), and the triangular fossa (104) may have a certain depth and volume in 3D space and may be used to achieve the wearing requirement of the acoustic device. For example, an acoustic device (e.g., an in-ear earphone) may be worn within the external auditory canal (101). In some embodiments, the wearing of the acoustic device (e.g., an open earphone) may be achieved by using parts of the ear (100) other than the external auditory canal (101). For example, the wearing of the acoustic device may be achieved through parts such as the auricular fossa (103), the triangular fossa (104), the antihelix (105), the tragus (106), the auricle (107), or a combination thereof. In some embodiments, parts such as the user's earlobe (108) may be further utilized to improve the comfort and reliability of the wearing of the acoustic device. By using parts of the ear (100) other than the external auditory canal (101) to achieve the wearing of the acoustic device and the propagation of sound, the user's external auditory canal (101) can be "released." When a user wears an audio device (e.g., an open-type earphone), the audio device does not block the user's external auditory canal (101) (or ear canal or ear canal), and the user can receive not only sounds coming from the audio device but also sounds coming from the environment (e.g., a horn, a car bell, sounds of people around, traffic control sounds, etc.), thereby reducing the rate of traffic accidents.In some embodiments, based on the structure of the ear (100), the acoustic device may be designed to be suitable for the ear (100) so that the sounding part of the acoustic device can be worn at different positions of the ear. For example, when the acoustic device is an open earphone, the open earphone may include a suspension structure (e.g., an earring) and a sounding part, and the sounding part and the suspension structure are connected by a physical method, and the suspension structure is mutually matched with the shape of the earlobe so that the whole or part of the structure of the sounding part can be placed on the front side of the ear (109) (e.g., the area J enclosed by the dotted line in FIG. 1). For example, when a user wears an open-type earphone, the entire or partial structure of the vocal part may come into contact with the upper part of the external auditory canal (101) (for example, a location where one or more parts such as the auricle (103), triangular fossa (104), helix (105), tragus (106), helix (107), and helix angle (1071) are located). For example, when a user wears an open-type earphone, the entire or partial structure of the vocal part may be located within a cavity formed by one or more parts of the ear (100) (for example, the auricle cavity (102), auricle (103), triangular fossa (104), etc.) (for example, a region M1 including at least the auricle (103) and triangular fossa (104) and a region M2 including at least the auricle cavity (102) formed by the dotted line in FIG. 1). Since individual differences may exist among different users, there may be size differences, such as different shapes and sizes of the ears. For the convenience of explanation and understanding, unless otherwise specified, this specification further explains the method of wearing the acoustic device in said ear model in different embodiments by referring primarily to an ear model having a "standard" shape and size. For example, a mock device including a head and its (left and right) ears, such as GRAS 45BC KEMAR, may be manufactured in accordance with ANSI: S3.36, S3.25 and IEC: 60318-7 standards and used as a reference for wearing the acoustic device, thereby illustrating the scene of the majority of users wearing the acoustic device normally. By way of example, the ear used as a reference may have the following related features. The vertical axis dimension of the projection of the auricle in the sagittal plane may be within the range of 49.5 mm to 74.3 mm, and the sagittal axis dimension of the projection of the auricle in the sagittal plane may be within the range of 36.6 mm to 55 mm. Accordingly, in the present invention, descriptions such as "wearing by a user," "being in a state of being worn," and "in a state of being worn" may mean that the acoustic device mentioned in the present invention is worn on the ear of the aforementioned simulation device. Of course, considering the situation where individual differences exist among different users, the structure, shape, size, thickness, etc. of one or more parts of the ear (100) may be distinguished to a certain degree, and to satisfy the needs of different users, a differentiated design for the acoustic device may be carried out, and such a differentiated design may be adapted to different ears by having characteristic parameters of one or more parts of the acoustic device (e.g., the vocal part below, earring, etc.) have different ranges of values. It should be noted that in fields such as medicine and anatomy, the three basic planes of cross-section—the sagittal plane, the coronal plane, and the horizontal plane—and the three basic axes—the sagittal axis, the coronal axis, and the vertical axis—can be defined. Here, the sagittal plane is a plane of cross-section perpendicular to the ground in the anterior-posterior direction of the body, dividing the body into two parts: left and right. The coronal plane is a plane of cross-section perpendicular to the ground in the lateral direction of the body, dividing the body into two parts: anterior and posterior. The horizontal plane is a plane of cross-section perpendicular to the vertical direction of the body and parallel to the ground, dividing the body into upper and lower parts. Correspondingly, the sagittal axis is an axis perpendicular to the coronal plane in the anterior-posterior direction of the body, the coronal axis is an axis perpendicular to the sagittal plane in the left-right direction of the body, and the vertical axis is an axis perpendicular to the horizontal plane in the up-down direction of the body. In addition, the "anterior side of the ear" mentioned in the present invention is a concept relative to the "posterior side of the ear," where the former is the side facing away from the head from the ear, and the latter is the side facing towards the head from the ear. Here, by observing the ear of the simulation device along the direction in which the coronal axis of the human body is located, a schematic diagram of the anterior outline of the ear shown in FIG. 1 can be obtained. FIG. 2 is an exemplary structural diagram of an open-type earphone according to some embodiments of the present specification. In some embodiments, the open earphone (10) may include, but is not limited to, electroconductive earphones and bone electroconductive earphones. In some embodiments, the open earphone (10) may be combined with products such as glasses, head-worn earphones, head-worn display devices, and AR / VR headsets. As shown in FIG. 2, the open earphone (10) may include a vocal part (11) and an earring (12). The vocal unit (11) may be used to be worn on the user's body, and the vocal unit (11) may generate sound and input it into the user's ear canal. In some embodiments, the vocal unit (11) may include a transducer (e.g., the transducer (116) shown in FIG. 16a) and a housing (111) for receiving the transducer. The housing (111) may be connected to an earring (12). The transducer is used to generate sound by converting an electrical signal into a corresponding mechanical vibration. In some embodiments, an output hole (112) is opened on the side of the housing facing the earlobe, and the output hole (112) is used to extract the sound generated by the transducer from the housing (111) and transmit it to the ear canal so that the user can hear the sound. In some embodiments, a transducer (e.g., a vibrating membrane) divides the housing (111) to form a front cavity (e.g., a front cavity (114) shown in FIG. 16a) and a rear cavity of the earphone, and a sound output hole (112) communicates with the front cavity and can extract the sound generated by the front cavity from the housing (111) and transmit it to the ear canal. In some embodiments, a portion of the sound produced through the sound output hole (112) is propagated to the ear canal so that the user can hear the sound, and another portion is propagated to the outside of the ear and the open earphone (10) through the slot between the sound-producing part (11) and the ear (e.g., a portion of the ear canal not covered by the sound-producing part (11)) together with the sound reflected through the ear canal, thereby forming a first leakage sound in the far field, and at the same time, one or more pressure relief holes (113) may generally be opened on other sides of the housing (111) (e.g., a side away from or facing away from the user's ear canal).The pressure relief hole (113) is located further away from the ear canal compared to the sound output hole (112), and the sound propagating from the pressure relief hole (113) generally forms a second leakage sound in the far field, and the intensity of the first leakage sound and the intensity of the second leakage sound described above are substantial, and the phase of the first leakage sound and the phase of the second leakage sound described above are (almost) opposite to each other, so that the two are inversely canceled out in the far field, which is advantageous for reducing the leakage sound of the open earphone (10) in the far field. For more description of the sound-producing part (11), refer to other parts of this specification, for example, FIG. 7, FIG. 13, FIG. 16a, etc. and descriptions thereof. One end of the earring (12) may be connected to the vocalization part (11), and the other end may extend along the boundary between the user's ear and head. In some embodiments, the earring (12) may have an arc-shaped structure that matches the user's earlobe, so that the earring (12) may be suspended from the user's earlobe. For example, the earring (12) may have an arc-shaped structure that matches the boundary between the user's head and ear, so that the earring (12) may be suspended between the user's earlobe and head. In some embodiments, the earring (12) may have a clamping structure that matches the user's earlobe, so that the earring (12) may be clamped to the user's earlobe area. For example, the earring (12) may include a hook-shaped part (e.g., a first part (121) shown in FIG. 7) and a connecting part (e.g., a second part (122) shown in FIG. 7) connected in sequence. Here, the connecting part connects the hook-shaped part and the vocal part (11) so that the open earphone (10) exhibits a curved shape in 3D space when it is not worn (i.e., in a natural state). In other words, in 3D space, the hook-shaped part, the connecting part, and the vocal part (11) do not have a co-existent shape. When arranged in this way, when the open earphone (10) is worn, the hook-shaped part can be used to suspend mainly between the back of the user's ear and the head, and the vocal part (11) can be used to contact mainly the front of the user's ear, thus allowing the vocal part (11) and the hook-shaped part to be combined to clamp the ear. For example, the connecting part may extend from the head to the outside of the head and further combine with the hook-shaped part to provide a compressive force to the vocal part (11) against the front of the ear. Here, the vocal part (11) specifically comes into contact with the area where parts such as the ear canal (102), ear canal tip (103), triangular fossa (104), and helix (105) are located under the action of a compressive force, so that the external auditory canal (101) of the ear is not blocked when the open earphone (10) is worn. In some embodiments, to improve stability when the open earphone (10) is worn, the open earphone (10) may utilize any one or a combination of the following methods: 1) at least a portion of the earring (12) may be arranged in a simulated structure that is in close contact with at least one of the back of the ear (100) and the head, thereby increasing the contact area between the earring (12) and the ear (100) and / or head, thus increasing the resistance to the open earphone (10) falling off the ear (10). 2) at least a portion of the earring (12) may be arranged in an elastic structure to have a certain amount of deformation when worn, thereby increasing the positive pressure of the earring (12) on the ear and / or head, thus increasing the resistance to the open earphone (10) falling off the ear. 3) By positioning at least a portion of the earring (12) so as to be in contact with the head while worn, thereby forming a reaction force that presses down on the ear, the sounding part (11) is pressed down on the front side of the ear, and thus the resistance to the open earphone (10) falling out of the ear can be increased. 4) By positioning the sounding part (11) and the earring (12) to clamp the material area of ​​the antihelix, the material area of ​​the carapace, etc., from both the front and rear sides of the ear while worn, thus the resistance to the open earphone (10) falling out of the ear can be increased. 5) By positioning at least a portion of the sounding part (11) or the auxiliary structure connected thereto to be placed inside a cavity such as the carapace, carapace tip, triangular fossa, and tragus, the resistance to the open earphone (10) falling out of the ear can be increased. In some embodiments, the earring (12) may include, but is not limited to, an earring, an elastic band, etc., and allows the open earphone (10) to be more securely fixed to the user's body and prevents it from falling off when the user uses it. In some embodiments, the open earphone (10) may not include the earring (12), and the vocal part (11) may be fixed near the user's ear (100) using a suspension or clamping method. In some embodiments, the vocal part (11) may have a regular or irregular shape, such as a circular, elliptical, runway-shaped, polygonal, U-shaped, V-shaped, or semicircular shape, so that the vocal part (11) can be suspended directly from the user's ear (100). In some embodiments, the vocal part (11) may have a major axis direction X and a minor axis direction Y that are perpendicular to the thickness direction Z and are orthogonal to each other. Here, the major axis direction X may be defined as the direction having the maximum extension dimension in the shape of the 2D projection plane of the vocal part (11) (e.g., projection from the plane where the outer surface of the vocal part (11) is located, or projection from the sagittal plane) (e.g., when the projection shape is rectangular or approximate rectangular, the major axis direction, i.e., the length direction of the rectangular or approximate rectangular). The short axis direction Y can be defined as the direction perpendicular to the major axis direction X in the shape projected onto the sagittal plane by the vocal part (11) (for example, when the projected shape is rectangular or approximate rectangular, the short axis direction, i.e., the width direction of the rectangular or approximate rectangular). The thickness direction Z can be defined as the direction perpendicular to the 2D projection plane, for example, coincides with the direction of the coronal axis, and both can point to the left and right directions of the body. In some embodiments, when a user wears the open earphone (10), the vocal part (11) may be fixed in a position near the user's external auditory canal (101) but not in a position that blocks the canal. In some embodiments, when worn, the projection of the open earphone (10) in the sagittal plane may not cover the user's ear canal. For example, the projection of the vocal part (11) in the sagittal plane may be placed on both the left and right sides of the head at a position located anterior to the tragus on the sagittal axis of the human body (for example, a position indicated by solid line frame A in FIG. 2). At this time, the vocal part (11) is located anterior to the user's tragus, and the major axis of the vocal part (11) may be vertical or approximately vertical, the projection in the sagittal plane in the minor axis direction Y coincides with the direction of the sagittal axis, the projection in the sagittal plane in the major axis direction X coincides with the direction of the vertical axis, and the thickness direction Z is perpendicular to the sagittal plane. For example, the projection of the vocal part (11) in the sagittal plane may be placed on the anti-axillary helix (105) (for example, the position indicated by the dotted line frame C in FIG. 2). At this time, at least a portion of the vocal part (11) is located on the anti-axillary helix (105), the major axis of the vocal part (11) is horizontal or nearly horizontal, the projection in the sagittal plane along the major axis direction X of the vocal part (11) coincides with the direction of the sagittal axis, the projection in the sagittal plane along the minor axis direction Y coincides with the direction of the vertical axis, and the thickness direction Z is perpendicular to the sagittal plane. Accordingly, not only can the vocal part (11) prevent blocking the ear canal, but the user's ears can be freed, the contact area between the vocal part (11) and the ear (100) can be increased, and furthermore, the comfort of wearing the open-type earphone (10) can be improved. In some embodiments, when worn, the projection of the open earphone (10) in the sagittal plane may cover the user's ear canal or at least partially cover it. For example, the projection of the vocal part (11) in the sagittal plane may be placed within the auricular cavity (102) (e.g., the position indicated by the dotted frame B in FIG. 2) and may be in contact with the auricular angle (1071) and / or the auricular (107). At this time, at least a part of the vocal part (11) is located within the auricular cavity (102), the vocal part (11) is in an inclined state, and the projection of the vocal part (11) in the sagittal plane in the minor axis direction Y may have a certain angle with respect to the direction of the sagittal axis, that is, the minor axis direction Y is also positioned at an angle correspondingly inclined, and the projection in the sagittal plane in the major axis direction X may have a certain angle with respect to the direction of the sagittal axis, that is, the major axis direction X is also positioned at an angle, and the thickness direction Z is perpendicular to the sagittal plane. At this time, since the ear canal (102) has a certain volume and depth, a certain gap is provided between the inner surface (IS) of the open earphone (10) and the ear canal, and the ear canal is connected to the outside through a slot between the inner surface (IS) and the ear canal, thereby freeing both ears of the user. At the same time, the sound-producing part (11) can be combined with the ear canal to form an auxiliary cavity (e.g., a cavity structure described below) that is connected to the ear canal. In some embodiments, at least a part of the sound-producing hole (112) may be located within the auxiliary cavity described above, and the sound produced by the sound-producing hole (112) may be limited by the auxiliary cavity described above, that is, the auxiliary cavity described above concentrates the sound so that the sound propagates more within the ear canal, thereby improving the volume and quality of the sound heard by the user in the near field, and thus improving the acoustic effect of the open earphone (10). The above description of the open-type earphone (10) is for illustrative purposes only and is not intended to limit the scope of the invention. A person skilled in the art may make various changes and modifications based on the description of the invention. For example, the open-type earphone (10) may further include a battery assembly, a Bluetooth assembly, or a combination thereof. The battery assembly may be used to provide electricity to the open-type earphone (10). The Bluetooth assembly may be used to wirelessly connect the open-type earphone (10) to other devices (e.g., a mobile phone, a computer, etc.). Such changes and modifications are still within the scope of protection of the invention. In some embodiments, referring to FIG. 3, sound can be transmitted to the outside of the open earphone (10) through the sound output hole (112), the sound output hole (112) can be considered as a unipolar sound source (or point sound source) A1, and generates a first sound, and sound can be transmitted to the outside of the open earphone (10) through the pressure reduction hole (113), the pressure reduction hole (113) can be considered as a unipolar sound source (or point sound source) A2, and generates a second sound. The second sound and the first sound may have opposite or approximately opposite phases and may be inversely canceled out in the far field, that is, form an "acoustic dipole" to reduce leakage sound. In some embodiments, when worn, the connecting wire of the two unipolar sound sources may be directed toward the ear canal (described as the "listening position") so that the user can hear a sufficiently loud sound. Here, the sound pressure magnitude (indicated as Pear) at the listening position can indicate the intensity of the sound heard by the user (i.e., the sound pressure of the near-field listening). Additionally, by statistically analyzing the sound pressure magnitude (indicated as Pfar) on a sphere centered on the user's listening position (or on a sphere with radius r and the center of the dipole sound source (e.g., A1 and A2 shown in FIG. 3) as the centroid), the intensity of the leakage sound emitted by the open-type earphone (10) toward the far-field (i.e., the sound pressure of the far-field leakage sound) can be indicated. Here, Pfar can be obtained using various statistical methods, for example, by taking the average value of the sound pressure at each point on the sphere, or for example, by taking the sound pressure distribution at each point on the sphere and performing an area integral. It should be noted that the method for measuring leakage sound in this specification is described merely by way of example and is not limiting, and the method of measuring and calculating leakage sound may be reasonably adjusted based on actual conditions. For example, the center of a dipole sound source is set as the centrifugal point, and the sound pressure amplitudes of two or more points are uniformly taken and averaged based on a constant spatial angle in the far field. In some embodiments, the method of measuring the sound may select a location point near the point source as the listening location, and the sound pressure amplitude obtained by measuring at said listening location may be the value of the sound. In some embodiments, the listening location may be on the connecting line of two point sources, or it may not be on the connecting line of two point sources. The method of measuring and calculating the sound may be reasonably adjusted based on actual conditions, for example, the sound pressure amplitudes of other points in the near field or one or more points may be averaged. For example, a point source is set as the centrifugal point, and the sound pressure amplitudes of two or more points are taken and averaged based on a certain spatial angle in the near-field. In some embodiments, the distance between the near-field listening position and the point source is much smaller than the distance between the point source and the far-field leakage sound measurement surface. Of course, the sound pressure Pear that the open-type earphone (10) transmits to the user's ear must be sufficiently large to improve the listening effect, and the sound pressure Pfar of the far field must be sufficiently small to improve the leakage sound reduction effect. Therefore, the leakage sound index α can be used as an indicator to evaluate the leakage sound reduction ability of the open-type earphone (10). (1) From formula (1), it can be seen that the smaller the leakage sound index, the stronger the leakage sound reduction ability of the open-type earphones, and the smaller the far-field leakage sound when the listening volume is the same at the listening position. FIG. 4 is a comparison of leakage sound indices under different frequencies of a point source and a dipole source according to some embodiments of the present specification. The dipole source (also referred to as a "dipole source") in FIG. 4 may be a typical dipole source, that is, the spacing is fixed, the amplitude of the dipole source is the same, and the phase of the dipole source may be opposite. It should be understood that by selecting a typical dipole source and explaining only the principle and effect, the parameters of each point source can be adjusted according to actual needs to make it have a certain difference from the typical dipole source. As shown in FIG. 4, when the spacing is fixed, the leakage sound generated by the dipole source increases with increasing frequency, and the leakage sound reduction capability decreases with increasing frequency. When the frequency is greater than a single frequency value (e.g., 8000Hz as shown in Fig. 4), the leakage sound generated can be greater than that of the single-point sound source, and this frequency (e.g., 8000Hz) is the upper limit frequency at which the double-point sound source can reduce the leakage sound. In some embodiments, to improve the acoustic output effect of the open earphones, that is, to increase the sound intensity of the near-field listening position and at the same time reduce the volume of the far-field leakage sound, a barrier plate may be placed between the sound output hole (112) and the pressure reduction hole (113). FIG. 5 is an exemplary distribution schematic diagram showing a barrier plate placed between two sound sources of a dipole sound source according to some embodiments of the present specification. As shown in FIG. 5, when a barrier plate is placed between point source A1 and point source A2, in the near field, the sound waves of point source A2 must go around the barrier plate for interference to occur with the sound waves of point source A1 at the listening position, which is equivalent to increasing the acoustic path from point source A2 to the listening position. Therefore, assuming that point source A1 and point source A2 have the same amplitude, compared to the case where no barrier plate is placed, the difference in amplitude of the sound waves at the listening position of point source A1 and point source A2 increases, and thus the degree to which the two sounds cancel each other out at the listening position is reduced, and the volume at the listening position increases. In the far field, since the sound waves generated by point source A1 and point source A2 can interfere (similar to the situation without a barrier) within a relatively large spatial range without all of them going around the barrier, the leakage sound in the far field may not increase significantly compared to the case without a barrier. Therefore, if a barrier structure is placed around one of the sound sources, A1 and A2, the volume of the near-field listening position can be significantly improved in a situation where the volume of the leakage sound in the far field does not increase significantly. FIG. 6 is a graph of the leakage sound index when a barrier plate is placed between two dipole sound sources according to some embodiments of the present specification and when a barrier plate is not placed. After adding a barrier plate between the two point sound sources, it is equivalent to increasing the distance between the two point sound sources in the near field, and the volume at the near-field listening position is equivalent to that generated by a single point sound source with a relatively large distance, and the listening volume in the near field is relatively clearly increased compared to the case without a barrier plate. In the far field, the sound field of the two point sound sources is very little affected by the barrier plate, and the generated leakage sound is equivalent to that generated by a single point sound source with a relatively small distance. Therefore, as shown in FIG. 6, after adding a barrier plate, the leakage sound index is much smaller compared to when the barrier plate is not added; that is, under the same listening volume, the leakage sound in the far field is smaller than in the case without a barrier plate, and the leakage sound reduction capability is clearly enhanced. FIG. 7 is an exemplary wearing schematic diagram of an open earphone according to some embodiments of the present specification. FIG. 8 is a schematic diagram of the structure of one side facing the ear in the open earphone shown in FIG. 7. As shown in FIG. 7, the earring (12) has an arc-shaped structure that is in close contact with the boundary between the user's head and ear (100). The voice part (11) (or the housing (111) of the voice part (11)) may have a connecting end (CE) connected to the earring (12) and a free end (FE) not connected to the earring (12). When the open earphone (10) is worn, the first part (121) of the earring (12) (e.g., the hook-shaped part of the earring (12)) is suspended between the user's earlobe (e.g., the helix (107)) and the head, and the second part (122) of the earring (12) (e.g., the connecting part of the earring) extends from the earlobe to one side facing away from the head and is connected to the connecting end (CE) of the voice part (11), thereby fixing the voice part (11) in a position near the ear canal but not blocking the ear canal. Referring to the figures in FIGS. 7 and 8, the sounding part (11) may have an inner surface (IS) facing the ear in the thickness direction Z when worn (also called the "inner surface of the housing (111)"), an outer surface (OS) facing away from the ear (also called the "outer surface of the housing (111)"), and a connecting surface connecting the inner surface (IS) and the outer surface (OS). It should be noted that when observed along the material direction of the coronal axis (i.e., thickness direction Z) when worn, the sounding part (11) may be arranged in a shape such as a circle, an ellipse, a round square, or a round rectangle. Here, when the vocal part (11) is arranged in a circular or elliptical shape, the connecting surface may be an arc-shaped side of the vocal part (11), and when the vocal part (11) is arranged in a round square or round rectangle shape, the connecting surface may include the lower side (LS) (also called "lower side of the housing (111)"), upper side (US) (also called "upper side of the housing (111)"), and rear side (RS) (also called "rear side of the housing (111)" mentioned below. Here, the upper side (US) and the lower side (LS) may be the side facing away from the external auditory canal (101) in the short-axis direction Y and the side close to the external auditory canal (101), respectively, when worn, and the rear side (RS) is the side facing the back of the head in the longitudinal direction Y when worn. For convenience of explanation, this embodiment is described exemplarily with the case where the vocal part (11) is arranged in a rounded rectangle. Here, the length of the vocal part (11) in the major axis direction X may be greater than the width of the vocal part (11) in the minor axis direction Y. In some embodiments, to improve the aesthetics and comfort of wearing the earphone, the rear side (RS) of the earphone may be curved. A transducer may be placed within the sound-producing part (11) and can generate sound by converting an electrical signal into a corresponding mechanical vibration. The transducer (e.g., a vibrating membrane) may divide the housing (111) to form the front cavity and the rear cavity of the earphone. The phases of the sounds generated in the front cavity and the rear cavity are opposite. An output hole (112) communicating with the front cavity is opened on the inner surface (IS) so that the sound generated by the front cavity can be drawn out from the housing (111) and transmitted to the ear canal, allowing the user to hear the sound. One or more pressure relief holes (113) communicating with the rear cavity are opened on other sides of the housing (111) (e.g., outer side (OS), upper side (US), or lower side (LS), etc.) and are used to cancel out interference in the far field between the sound produced by the rear cavity and the sound produced by the sound output hole (112) after the sound produced by the rear cavity is extracted from the housing (111). In some embodiments, the pressure relief holes (113) are located further away from the ear canal compared to the sound output hole (112), thereby weakening the inverse cancellation at the listening position between the sound produced through the pressure relief holes (113) and the sound produced through the sound output hole (112). In some embodiments, as shown in FIG. 7, when the open earphone (10) is worn, the major axis direction X of the vocal part (11) may be positioned horizontally or approximately horizontally (similar to position C shown in FIG. 2), at least a portion of the vocal part (11) may be located in the area of ​​the anti-helix (105), and the free end (FE) of the vocal part (11) may be directed toward the back of the head. The vocal part (11) is in a horizontal or approximately horizontal state, and the projection of the major axis direction X of the vocal part (11) in the sagittal plane may coincide with the direction of the sagittal axis, the projection of the minor axis direction Y in the sagittal plane may coincide with the direction of the vertical axis, and the thickness direction Z is perpendicular to the sagittal plane. In some embodiments, to improve the seal between the open earphone (10) and the ear (100) and to improve the stability of wearing the open earphone (10), the inner surface (IS) of the housing (111) is pressed into contact with the surface of the ear (100) (e.g., the helix (105)), thereby increasing the resistance to the open earphone (10) falling out of the ear (100). In some embodiments, referring to FIGS. 7 and FIGS. 8, when the open earphone (10) is pressed against the ear (100), in order to prevent the sound output hole (112) on the inner surface (IS) from being blocked by the ear tissue, a portion or all of the projection of the sound output hole (112) in the sagittal plane may overlap with the projection of the concave structure of the ear (e.g., the auricle (103)) in the sagittal plane. In some embodiments, since the auricle (103) is in communication with the auricle cavity (102) and the ear canal is located within the auricle cavity (102), when at least a portion of the projection of the sound output hole (112) in the sagittal plane is located within the auricle (103), the sound output by the sound output hole (112) reaches the ear canal without obstruction, thereby allowing the volume of sound received by the ear canal to be relatively high. In some embodiments, the length of the major axis of the vocal part (11) must not be too long, and if it is too long, the projection of the free end (FE) in the sagittal plane exceeds the projection of the ear in the sagittal plane, which affects the sealing effect between the vocal part (11) and the ear. Accordingly, the length of the major axis of the vocal part (11) can be designed so that the projection of the free end (FE) in the sagittal plane does not exceed the projection of the helix (107) in the sagittal plane. In some embodiments, when the projection of the free end (FE) in the sagittal plane does not exceed the projection of the ring (107) in the sagittal plane, at least a portion of the projection of the sound-outlet hole (112) in the sagittal plane is located within the earpiece (103), that is, when actually worn, at least a portion of the sound-outlet hole (112) faces directly into the earpiece (103), and the distance from the center O of the sound-outlet hole (112) on the rear side (RS) in the X direction to the rear side (RS) of the vocal part (11) d 1The range is 9.5 mm to 15.0 mm. In some embodiments, the distance from the center O of the sound outlet (112) in the X direction to the rear side (RS) of the sound-producing part (11). d 1 The range is 10.5 mm to 14.0 mm. In some embodiments, the distance from the center O of the sound outlet (112) in the X direction to the rear side (RS) of the sound-producing part (11). d 1 The range is 11.0 mm to 13.5 mm. In some embodiments, the distance from the center O of the sound outlet (112) in the X direction to the rear side (RS) of the sound-producing part (11). d 1 The range is 11.5 mm to 13.0 mm. In some embodiments, the distance from the center O of the sound outlet (112) in the X direction to the rear side (RS) of the sound-producing part (11). d 1 The range is 12.0mm to 12.5mm. It should be noted that since the sound output hole (112) and the pressure relief hole (113) are positioned in the housing (111), and each side wall of the housing (111) has a constant thickness, therefore, the sound output hole (112) and the pressure relief hole (113) can both have holes of a constant depth. At this time, the sound output hole (112) and the pressure relief hole (113) can both have an inner opening and an outer opening. For convenience of explanation, in this specification, the center O of the sound output hole (112) in the upper and lower sections may refer to the center of the shape of the outer opening of the sound output hole (112). In some embodiments, to improve the aesthetics and wearing comfort of the earphone, the rear side surface (RS) of the earphone may be a curved surface. When the rear side (RS) is a curved surface, the distance from the center of the sound hole (112) to the rear side (RS) may be the distance from the center of the sound part to the tangent plane parallel to the short axis of the sound part, which is farthest from the center of the sound part. In this specification, the sound output hole (112) and the pressure reduction hole (113) connecting the front cavity and the rear cavity, respectively, can be considered as point sound source A1 and point sound source A2 shown in FIG. 5, respectively, and the ear canal can be considered as the listening position shown in FIG. 5. At least a portion of the housing and / or at least a portion of the auricle of the vocal part (11) can be considered as a membrane plate shown in FIG. 5, and accordingly, the acoustic path difference from the sound output hole (112) and the pressure reduction hole (113) to the ear canal is increased, thereby increasing the sound intensity in the ear canal, while simultaneously maintaining the effect of reducing leakage sound in the far field. When the open-type earphone (10) utilizes the structure shown in FIG. 7, that is, when at least a portion of the housing (111) is located in the area of ​​the helix (105), in terms of the sound effect, the sound waves from the sound output hole (112) can directly reach the ear canal, and at this time, the sound output hole (112) can be positioned close to the lower side (LS) from the inner side (IS), and the pressure relief hole (113) can be positioned far from the sound output hole (112), for example, the pressure relief hole (113) can be positioned far from the sound output hole (112) from the outer side (OS) or upper side (US). The sound waves of the pressure relief hole (113) must bypass the outer side of the vocalization part (11) to cause interference with the sound waves of the sound output hole (112) in the ear canal area, and also, a structure that is convex upward and concave downward in the auricle (e.g., the anti-auricle in the propagation path) can increase the acoustic path through which the sound of the pressure relief hole (113) is transmitted to the ear canal. Accordingly, the vocalization part (11) itself and / or the auricle correspond to a barrier plate between the sound output hole (112) and the pressure relief hole (113), and the barrier plate increases the acoustic path from the pressure relief hole (113) to the ear canal and reduces the intensity of the sound waves of the pressure relief hole (113) in the ear canal, thereby reducing the degree to which the two streams of sound emitted by the sound output hole (112) and the pressure relief hole (113) cancel each other out in the ear canal, and thus increasing the volume of sound in the ear canal.In terms of the leakage sound effect, since the sound waves generated by the sound output hole (112) and the pressure reduction hole (113) can interfere without all of them going around the vocal part (11) itself within a relatively large spatial range (similar to the case where there is no barrier plate), the leakage sound may not be clearly increased. Therefore, by arranging the sound output hole (112) and the pressure reduction hole (113) in appropriate positions, the volume of the ear canal can be significantly improved in a situation where the volume of the leakage sound is not clearly increased. In some embodiments, referring to FIG. 8, in order to improve the sound intensity of the sound outlet (112) at the ear canal (i.e., listening position), the sound outlet (112) may be positioned relatively close to the ear canal, that is, the sound outlet (112) may be closer to the lower side (LS) of the vocal part (11) in the Y direction. In some embodiments, the distance from the center O of the sound outlet (112) in the Y direction to the lower side (LS) of the vocal part (11). h 1 The range is 2.3mm to 3.6mm. In some embodiments, the distance from the center O of the sound output hole (112) in the Y direction to the lower side (LS) of the sound-producing part (11). h 1 The range is 2.5mm to 3.4mm. In some embodiments, the distance from the center O of the sound outlet (112) in the Y direction to the lower side (LS) of the sound-producing part (11). h 1 The range is 2.7mm to 3.2mm. In some embodiments, the distance from the center O of the sound output hole (112) in the Y direction to the lower side (LS) of the sound-producing part (11). h 1 The range is 2.8mm to 3.1mm. In some embodiments, the distance from the center O of the sound output hole (112) in the Y direction to the lower side (LS) of the sound-producing part (11). h 1 The range is 2.9mm to 3.0mm. In some embodiments, referring to FIG. 7, in order to ensure that a portion or all of the projection of the sound output hole (112) in the sagittal plane is located within the ear canal area when the user wears the open earphone (10), the range of the distance between the center O of the sound output hole (112) and the upper peak M of the earring (12) is 17.5 mm to 27.0 mm, where the upper peak of the earring (12) is the point closest to the head on the earring (12) in the vertical axis direction. In some embodiments, when the user wears the open earphone (10), the range of the distance between the center O of the sound output hole (112) and the upper peak M of the earring (12) is 20.0 mm to 25.5 mm. In some embodiments, when a user wears the open earphone (10), the range of distance between the center O of the sound output hole (112) and the upper top point M of the earring (12) is 21.0 mm to 24.5 mm. In some embodiments, when a user wears the open earphone (10), the range of distance between the center O of the sound output hole (112) and the upper top point M of the earring (12) is 22.0 mm to 23.5 mm. In some embodiments, when a user wears the open earphone (10), the range of distance between the center O of the sound output hole (112) and the upper top point M of the earring (12) is 22.5 mm to 23.0 mm. In some embodiments, the ratio value of the distance from the center O of the sound hole (112) to the upper top point M of the earring (12) and the distance between the upper and lower boundary of the inner surface (IS) (i.e., the distance between the upper surface (US) and the lower surface (LS) of the sounding part (11) or housing (111)) should not be excessive or insufficient. In some embodiments, when the upper surface (US) and / or the lower surface (LS) is curved, the distance between the upper surface (US) and the lower surface (LS) may be the distance between the tangent plane farthest from the center of the sounding part of the upper surface (US) and parallel to the major axis of the sounding part, and the tangent plane farthest from the center of the sounding part of the lower surface (LS) and parallel to the major axis of the sounding part. When the distance between the center O of the sound output hole (112) and the upper top point M of the earring (12) is constant, if the ratio value is too small, the width dimension of the inner surface (IS) may be too large, and in this case, the weight of the entire sound-producing part increases, the distance between the housing and the earring becomes too small, and the user may find it uncomfortable to wear. When the ratio value is too large, the width dimension of the inner surface (IS) becomes too small, the area where the transducer of the sound-producing part (11) can drive air becomes too small, and the sound-producing efficiency of the sound-producing part may become too low. Accordingly, in order to ensure that the vocalization efficiency of the vocal part is sufficiently high and to improve the user's wearing comfort, and so that at least a portion of the projection of the sound output hole (112) in the sagittal plane is located within the ear canal area, when the user wears the open earphone (10), the ratio value of the distance from the center O of the sound output hole (112) to the upper top point M of the earpiece (12) and the distance between the upper and lower edges of the inner surface (IS) is between 0.95 and 1.55. In some embodiments, the ratio value of the distance from the center O of the sound output hole (112) to the upper top point M of the earpiece (12) and the width dimension of the housing (111) is between 1.05 and 1.45. In some embodiments, the ratio value of the distance from the center O of the sound output hole (112) to the upper top point M of the earpiece (12) and the width dimension of the housing (111) is between 1.15 and 1.35.In some embodiments, the ratio of the distance from the center O of the sound hole (112) to the upper top point M of the earring (12) to the width dimension of the housing (111) is between 1.20 and 1.30. Under the wearing method of FIG. 7, since the sound outlet (112) is located relatively close to the ear canal on the inner side (IS), the ratio of the distance from the center O of the sound outlet (112) to the upper top point M of the earring (12) and the distance from the center O of the sound outlet (112) to the upper side (US) of the vocal part (11) should not be too large. In addition, in order to ensure a sufficient gap between the vocal part (11) and the upper top point M of the earring (12) (preventing the vocal part (11) and the earring (12) from forming excessive pressure on the ear), the ratio of the distance from the center O of the sound outlet (112) to the upper top point M of the earring (12) and the distance from the center O of the sound outlet (112) to the upper side (US) of the vocal part (11) should not be too small. In some embodiments, when a user wears the open earphone (10), the ratio of the distance from the center O of the sound outlet (112) to the upper top point M of the earpiece (12) and the distance from the center O of the sound outlet (112) to the upper side (US) of the voice part (11) is between 1.19 and 2.5. Preferably, the ratio of the distance from the center O of the sound outlet (112) to the upper top point M of the earpiece (12) and the distance from the center O of the sound outlet (112) to the upper side (US) of the voice part (11) is between 1.5 and 1.8. Under the wearing method of Fig. 7, since the sound outlet (112) is located relatively close to the ear canal on the inner side (IS), the ratio of the distance from the center O of the sound outlet (112) to the upper top point M of the earring (12) and the distance from the center O of the sound outlet (112) to the lower side (IS) of the vocal part (11) should not be too small. In addition, in order to ensure that the sound outlet has a sufficient area (preventing the area of ​​the sound outlet from being too small and causing excessive acoustic impedance), the width of the sound outlet (112) should not be too small, and the ratio of the distance from the center O of the sound outlet (112) to the upper top point M of the earring (12) and the distance from the center O of the sound outlet (112) to the lower side (IS) of the vocal part (11) should not be too large. In some embodiments, when a user wears the open earphone (10), the ratio value of the distance from the center O of the sound outlet (112) to the upper top point M of the earpiece (12) and the distance h3 from the center O of the sound outlet (112) to the lower side (IS) of the voice part (11) is between 6.03 and 9.05. Preferably, the ratio value of the distance from the center O of the sound outlet (112) to the upper top point M of the earpiece (12) and the distance from the center O of the sound outlet (112) to the lower side (IS) of the voice part (11) is between 7 and 8. In some embodiments, to improve the audible volume, particularly the audible volume of mid-low frequencies, and to simultaneously retain the effect of canceling far-field leakage sound, a cavity structure may be constructed around one of the dipole sound sources. FIG. 9 is an exemplary schematic diagram of a cavity structure arranged around one of the dipole sound sources according to some embodiments of the present specification. As shown in FIG. 9, when a cavity structure (41) is placed between dipole sound sources, one dipole sound source and the listening position are located inside the cavity structure (41), and the other dipole sound source is located outside the cavity structure (41). The sound produced by the dipole sound source inside the cavity structure (41) can be restricted by the cavity structure (41), that is, the cavity structure (41) concentrates the sound, thereby allowing the sound to propagate further into the listening position, thereby improving the volume and quality of the sound at the listening position. In this specification, "cavity structure" can be understood as a semi-closed structure formed by being jointly enclosed by the side wall of the vocal part (11) and the diaphragm structure, and the semi-closed structure is provided with a leakage structure (42) (e.g., opening, slot, conduit, etc.) that is acoustically connected to the external environment, so as not to be completely sealed and isolated from the internal and external environments. An exemplary leakage structure may include, but is not limited to, an opening, a slot, a conduit, etc., or any combination thereof. In some embodiments, the cavity structure (41) may include a listening position and at least one sound source. Here, "included" may indicate that at least one of the listening position and the sound source is inside the cavity, or that at least one of the listening position and the sound source is at an edge portion inside the cavity. In some embodiments, the listening position may be the entrance to the ear canal and may be an acoustic reference point of the ear. FIG. 10a is a schematic diagram of a sound principle in which a dipole sound source structure and a cavity structure are constructed around one of the dipole sound sources according to some embodiments of the present specification. FIG. 10b is a schematic diagram of a sound leakage principle in which a dipole sound source structure and a cavity structure are constructed around one of the dipole sound sources according to some embodiments of the present specification. In near-field listening, in a dipole where a cavity structure is constructed around one of the sound sources shown in FIG. 10a, since one of the sound sources A is surrounded by the cavity structure, most of the sound emitted from it can reach the listening position by direct or reflected light. In contrast, if there is no cavity structure, most of the sound emitted by the sound source cannot reach the listening position. Therefore, the arrangement of the cavity structure significantly improves the sound volume reaching the listening position. At the same time, only a relatively small portion of the inverse sound emitted by the inverse sound source B outside the cavity structure can enter the cavity structure through the leakage structure of the cavity structure. This corresponds to the generation of a secondary sound source B' in the leakage structure area, the intensity of which is significantly smaller than that of sound source B and significantly smaller than that of sound source A. The sound generated by the secondary sound source B' has a weak effect of causing inverse cancellation with respect to sound source A within the cavity, and significantly improves the listening volume at the listening position. Regarding leakage sound, as shown in FIG. 10b, the sound emitted externally by sound source A through the leakage structure of the cavity is equivalent to generating a secondary sound source A' in the leakage structure area, and since almost all of the sound emitted by sound source A is output from the leakage structure and the structural scale of the cavity is much smaller than the spatial scale for evaluating leakage sound (there is a difference of at least one quantitative class), the intensity of secondary sound source A' can be recognized as equivalent to sound source A. In the external space, the cancellation effect between the secondary sound source A' and the sound generated by sound source B is equivalent to the cancellation effect between sound source A and sound source B. That is, under the above cavity structure, a significant leakage sound reduction effect is still maintained. It should be understood that the above-mentioned leakage structure of a single opening is merely an example, and the leakage structure of a cavity structure may include one or more openings and may also achieve a relatively good audibility index, where the audibility index may be 1 / α, the reciprocal of the leakage sound index α. Taking the case of arranging two opening structures as an example, the cases of equal opening and equal porosity are analyzed below, respectively. Compared to a structure with only one opening, "equal opening" here means arranging two openings of the same size as the structure with only one opening, and "equal porosity" means that the sum of the areas of the two arranged openings is the same as the structure with only one opening. Equal openings are equivalent to expanding the relative opening size of a single opening (i.e., the ratio of the area S of the opening of the leakage structure in the cavity structure to the area S0 of the area directly affected by the sound source contained in the cavity structure) by one factor, and as described above, the overall sound index may be reduced. In the case of equal porosity, even if S / S0 is the same as a structure with only one opening, the distance from the two openings to the external sound source is different, and therefore, a different sound index may also result. FIG. 11a is a schematic diagram of a cavity structure having two horizontal openings according to some embodiments of the present specification. FIG. 11b is a schematic diagram of a cavity structure having two vertical openings according to some embodiments of the present specification. As shown in FIG. 11a, when the connecting lines of the two openings and the connecting lines of the two sound sources are parallel (i.e., two horizontal openings), the distance from the two openings to the external sound source is maximum and minimum, respectively, and as shown in FIG. 11b, when the two connecting lines are vertical (i.e., two vertical openings), the distance from the two openings to the external sound source is the same and obtains an intermediate value. FIG. 12 is a comparative curve of the acoustic index curves of a cavity structure having two openings and one opening according to some embodiments of the present specification. As shown in FIG. 12, the total acoustic index of a cavity structure with equal openings may be lower compared to a cavity structure with one opening. In a cavity structure with equal porosity, since the distance from the two openings to an external sound source is different, it may also result in different acoustic indices. Referring to FIG. 11a, FIG. 11b and FIG. 12, it can be seen that the acoustic index of a leakage structure with equal porosity, whether horizontal or vertical, is higher than that of a leakage structure with equal openings. This is because, relative to the leakage structure with equal openings, the relative opening size S / S0 of the leakage structure with equal porosity is reduced by a factor of 1 compared to the leakage structure with equal openings, resulting in a higher acoustic index. Referring to FIGS. 11a, 11b, and 12, it can be seen that the audibility index of the horizontal opening is higher regardless of whether it is an equal opening leakage structure or an equal porosity leakage structure. This is because in the horizontal opening leakage structure, the distance from one of the openings to an external sound source is smaller than the distance between two sound sources, and since the distance between the differential sound source formed in this way and the external sound source is relatively closer to the original two sound sources, the audibility index is higher and furthermore, the leakage sound reduction effect is improved. Therefore, to improve the leakage sound reduction effect, the distance from at least one opening to an external sound source can be made smaller than the distance between two sound sources. In addition, as shown in FIG. 12, a cavity structure using two openings can improve the resonance frequency of airborne sound within the cavity structure more effectively than a cavity structure with one opening, and the entire device can have a better audibility index in the high-frequency band (e.g., sound with a frequency approaching 10,000 Hz) compared to a cavity structure with only one opening. The high-frequency band is a frequency band that is more sensitive to the human ear, and therefore the demand for leakage sound reduction is higher. Accordingly, to improve the leakage sound reduction effect in the high-frequency band, a cavity structure with a number of openings greater than 1 can be selected. FIG. 13 is a schematic diagram of an exemplary wearing of an open earphone according to some other embodiment of the present specification. FIG. 14 is a schematic diagram of a structure on one side facing the ear in the open earphone shown in FIG. 13. The structure of the open earphone (10) shown in FIG. 13 and the open earphone (10) shown in FIG. 7 are similar, and the main difference is that the vocal part (11) is positioned at an angle, and at least a part of the housing (111) of the vocal part (11) is inserted into the ear cavity (102), for example, the free end (FE) of the vocal part (11) can enter into the ear cavity (102). The earring (12) and the vocal part (11) of this structure have a relatively good match with the user's ear (100), increase the resistance to the open earphone (10) falling out of the ear (100), and thus increase the wearing stability of the open earphone (10). In some embodiments, when worn, when observed along the thickness direction Z, the anterior end (CE) of the vocal part (11) is closer to the top of the head compared to the free end (FE), thereby allowing the free end (FE) to enter the ear canal. Accordingly, the angle between the major axis direction X and the material direction of the sagittal axis of the human body may be between 15° and 60°. Here, if the aforementioned angle is too small, the free end (FE) cannot enter the ear canal, and the distance between the sound outlet (112) of the vocal part (11) and the ear canal becomes too far; if the aforementioned angle is too large, the vocal part (11) likewise cannot enter the ear canal, and the ear canal is likely to be blocked by the vocal part (11). In other words, by arranging it in this way, the vocal part (11) is placed into the ear canal, and the sound outlet (112) in the vocal part (11) and the ear canal are placed at a suitable distance, thereby allowing the user to hear more of the sound produced by the vocal part (11) in a situation where the ear canal is not blocked. In some embodiments, the vocal part (11) and the earring (12) jointly grip the aforementioned ear region from both the front and rear sides of the ear region corresponding to the ear canal, thereby increasing the resistance to the open earphone (10) falling out of the ear and further improving the stability of the open earphone (10) in a worn state. For example, the free end (FE) of the vocal part (11) is pressed and held within the ear canal in the thickness direction Z. Also, for example, the free end (FE) comes into contact with the ear canal in the major axis direction X and the minor axis direction Y. In some embodiments, because the earring itself has elasticity, the distance between the vocal part and the earring may vary between the worn state and the unworn state (the distance in the unworn state is smaller than the distance in the worn state). Also, due to the physiological structure of the ear (100), in the worn state, the plane where the vocal part (11) is located must have a constant distance in the coronal axis direction from the plane where the earring (12) is located so that the vocal part (11) can form appropriate pressure on the ear (100). In some embodiments, to improve the comfort of wearing the open-type earphone (10) and to ensure that the vocal part (11) and the earring (12) are combined to keep the vocal part (11) pressed against the ear, in the unworn state, the distance between the center O of the sound output hole (112) and the plane where the earring (12) is located is between 3mm and 6mm. Because the earring (12) has an irregular shape, for example, the earring (12) may have an arc-shaped structure, and the plane on which the earring (12) is located (also referred to as the "earring plane") forms the earring plane by being in contact with at least three points on the earring when the earring is placed on a plane while not being worn. In some embodiments, when worn, the earring can be approximated as being in close contact with the head, and the relative deviation of the earring plane to the sagittal plane can be ignored. In some embodiments, when not worn, the distance between the center O of the sound hole (112) and the plane on which the earring (12) is located is between 3.5 mm and 5.5 mm. In some embodiments, when not worn, the distance between the center O of the sound hole (112) and the plane on which the earring (12) is located is between 4.0 mm and 5.0 mm. In some embodiments, when not worn, the distance between the center O of the sound hole (112) and the plane where the earring (12) is located is between 4.3mm and 4.7mm. As shown in FIG. 13, when a user wears an open-type earphone (10), the housing (111) of the vocal part (11) is positioned so that at least a portion of it is inserted into the ear canal (103), and the cavity formed by the inner surface (IS) of the vocal part (11) and the ear canal (103) being jointly surrounded can be considered as the cavity structure (41) shown in FIG. 9, and the slot formed between the inner surface (IS) and the ear canal (for example, a first leakage structure (UC) formed between the inner surface (IS) and the ear canal close to the top of the head, and a second leakage structure (LC) formed between the inner surface (IS) and the ear canal close to the ear canal) can be considered as the leakage structure (42) shown in FIG. 9. The sound output hole (112) placed on the inner side (IS) can be considered as a point sound source inside the cavity structure (41) shown in FIG. 9, and the pressure relief hole (113) placed on the other side of the sound-emitting part (11) (e.g., a side far away from or facing away from the user's ear canal) can be considered as a point sound source outside the cavity structure (41) shown in FIG. 9. Accordingly, according to the description in FIG. 9 to FIG. 12, when the open-type earphone (10) is worn in a manner in which at least a part of it is inserted into the ear cavity, that is, when it is worn in the manner shown in FIG. 13, regarding the listening effect, most of the sound emitted from the sound output hole (112) can reach the ear canal in a direct or reflected manner, and the volume of sound reaching the ear canal, especially the volume of mid-low frequency listening, can be significantly improved. At the same time, only a relatively small portion of the reverse sound emitted from the pressure relief hole (113) enters the ear canal through the slots (first leakage structure (UC) and second leakage structure (LC)), and the effect of creating cancellation with the sound output hole (112) is weak, significantly improving the sound volume of the ear canal. Regarding the sound leakage effect, the sound output hole (112) outputs sound to the outside through the slots and secures a sound leakage reduction effect by canceling out the sound generated by the pressure relief hole (113) in the far field. In some embodiments, referring to FIGS. 13 and 14, when wearing the open earphone (10), the projection of the sound outlet (112) in the sagittal plane may be located in part or in whole within the auricular cavity region, and at the same time, in order to improve the sound intensity of the sound outlet (112) in the ear canal (i.e., listening position), the sound outlet (112) may be positioned as close as possible to the ear canal. In some embodiments, the distance from the center O of the sound outlet (112) in the Y direction to the lower side (LS) of the vocal part (11) h 2 The range is 4.05mm to 6.05mm. In some embodiments, the distance from the center O of the sound output hole (112) in the Y direction to the lower side (LS) of the sound-producing part (11). h 2 The range is 4.50mm to 5.85mm. In some embodiments, the distance from the center O of the sound output hole (112) in the Y direction to the lower side (LS) of the sound-producing part (11). h 2 The range is 4.80mm to 5.50mm. In some embodiments, the distance from the center O of the sound output hole (112) in the Y direction to the lower side (LS) of the sound-producing part (11). h 2 The range is 5.20mm to 5.55mm. In some embodiments, in order to insert at least a portion of the vocalization part (11) into the carapace, the dimension of the long axis of the vocalization part (11) must not be too long. Under the premise of ensuring that at least a portion of the vocalization part (11) is inserted into the carapace, the distance from the center O of the sound-outlet hole (112) in the X direction to the rear side (RS) of the vocalization part (11) must not be short; otherwise, all or part of the area of ​​the sound-outlet hole may be blocked by the free end (FE) and the wall of the carapace, and the effective area of ​​the sound-outlet hole is reduced. Accordingly, in some embodiments, the distance from the center O of the sound-outlet hole (112) in the X direction to the rear side (RS) of the vocalization part (11) d 2The range is 8.15 mm to 12.25 mm. In some embodiments, the distance from the center O of the sound outlet (112) in the X direction to the rear side (RS) of the sound-producing part (11). d 2 The range is 8.50 mm to 12.00 mm. In some embodiments, the distance from the center O of the sound outlet (112) in the X direction to the rear side (RS) of the sound-producing part (11). d 2 The range is 8.85 mm to 11.65 mm. In some embodiments, the distance from the center O of the sound outlet (112) in the X direction to the rear side (RS) of the sound-producing part (11). d 2 The range is 9.25 mm to 11.15 mm. In some embodiments, the distance from the center O of the sound outlet (112) in the X direction to the rear side (RS) of the sound-producing part (11). d 2 The range is 9.60mm to 10.80mm. Referring to FIG. 13, in some embodiments, under the premise that at least a portion of the sound-producing part (11) is inserted into the ear canal, in order to position a portion or all of the projection of the sound-producing hole (112) in the sagittal plane within the ear canal area, when a user wears an open earphone (10), the range of distance between the center O of the sound-producing hole (112) and the upper peak M of the earring (12) is 22.5 mm to 34.5 mm. In some embodiments, when a user wears an open earphone (10), the range of distance between the center O of the sound-producing hole (112) and the upper peak M of the earring (12) is 25 mm to 32 mm. In some embodiments, when a user wears an open earphone (10), the range of distance between the center O of the sound-producing hole (112) and the upper peak M of the earring (12) is 27.5 mm to 29.5 mm. In some embodiments, when a user wears the open earphone (10), the range of distance between the center O of the sound output hole (112) and the upper top point M of the earpiece (12) is 28 mm to 29 mm. In some embodiments, when a user wears the open earphone (10), the range of distance between the projection of the center of the sound output hole (112) in the sagittal plane and the projection of the upper top point of the earpiece (12) in the sagittal plane is 18 mm to 30 mm. In some embodiments, the ratio value of the distance from the center O of the sound output hole (112) to the upper top point M of the earring (12) and the distance between the upper and lower boundary of the inner surface (IS) (i.e., the distance between the upper surface (US) and the lower surface (LS) of the vocal part (11) or housing (111)) must not be excessive or insufficient. When the distance between the center O of the sound output hole (112) and the upper top point M of the earring (12) is constant, if the ratio value is insufficient, the width dimension of the inner surface (IS) may be excessive, at which point the weight of the entire vocal part increases, the distance between the housing and the earring becomes insufficient, and the user's wearing becomes uncomfortable. When the ratio value is excessive, the width dimension of the inner surface (IS) becomes insufficient, the area where the transducer of the vocal part (11) can drive air becomes insufficient, and the vocal efficiency of the vocal part may become too low. Accordingly, to ensure that the vocalization efficiency of the vocal part is sufficiently high and to improve the user's wearing comfort, and so that at least a portion of the projection of the sound outlet (112) in the sagittal plane is located within the auricular cavity region and as close as possible to the ear canal, when the user wears the open-type earphone (10), the ratio value of the distance between the center O of the sound outlet (112) and the upper apex point M of the earpiece (12) and the width dimension of the housing (111) in the Y direction is between 1.2 and 2.2. In some embodiments, when the user wears the open-type earphone (10), the ratio value of the distance between the center O of the sound outlet (112) and the upper apex point M of the earpiece (12) and the width dimension of the housing (111) is between 1.4 and 2.0. In some embodiments, when a user wears the open earphone (10), the ratio value of the distance between the center O of the sound output hole (112) and the upper top point M of the earpiece (12) and the width dimension of the housing (111) is between 1.5 and 1.8. In some embodiments, when a user wears the open earphone (10), the ratio value of the distance between the center O of the sound output hole (112) and the upper top point M of the earpiece (12) and the width dimension of the housing (111) is between 1.6 and 1.7. In the wearing method of FIG. 13, since the sound-outlet hole (112) is located relatively close to the ear canal on the inner side (IS), the ratio of the distance from the center O of the sound-outlet hole (112) to the upper top point M of the earring (12) and the distance from the center O of the sound-outlet hole (112) to the upper side (US) of the vocal part (11) should not be too large. In addition, in order to ensure that there is a sufficient gap between the vocal part (11) and the upper top point M of the earring (12) so that it can enter the ear canal, the ratio of the distance from the center O of the sound-outlet hole (112) to the upper top point M of the earring (12) and the distance from the center O of the sound-outlet hole (112) to the upper side (US) of the vocal part (11) should not be too small. In some embodiments, when a user wears the open earphone (10), the ratio of the distance from the center O of the sound output hole (112) to the upper top point M of the earpiece (12) and the distance from the center O of the sound output hole (112) to the upper side (US) of the voice part (11) is between 1.94 and 2.93. Preferably, when a user wears the open earphone (10), the ratio of the distance from the center O of the sound output hole (112) to the upper top point M of the earpiece (12) and the distance from the center O of the sound output hole (112) to the upper side (US) of the voice part (11) is between 2.2 and 2.6. In the wearing method of FIG. 13, since the sound outlet (112) is located relatively close to the ear canal on the inner side (IS), the ratio of the distance from the center O of the sound outlet (112) to the upper top point M of the earring (12) and the distance from the center O of the sound outlet (112) to the lower side (IS) of the vocal part (11) should not be too small. In addition, in order to ensure that the sound outlet has a sufficient area (preventing the area of ​​the sound outlet from being too small and causing excessive acoustic impedance), the width of the sound outlet (112) should not be too small, and the ratio of the distance from the center O of the sound outlet (112) to the upper top point M of the earring (12) and the distance from the center O of the sound outlet (112) to the lower side (IS) of the vocal part (11) should not be too large. In some embodiments, when a user wears an open earphone (10), the ratio of the distance from the center O of the sound output hole (112) to the upper top point M of the earpiece (12) and the distance from the center O of the sound output hole (112) to the lower side (IS) of the sound-producing part (11) is between 4.50 and 6.76. FIG. 15 is a schematic diagram of a projection in the sagittal plane when an open earphone according to some embodiments of the present specification is worn. In some embodiments, with reference to FIG. 13 and FIG. 15, the voice part (11) is stably worn on the user's ear and forms a cavity structure as shown in FIG. 9, and in order for the cavity structure to have at least two leakage structures, the free end (FE) may be in contact with the carapace in the long axis direction X and short axis direction Y, and at this time, the inner surface (IS) of the voice part (11) is inclined relative to the sagittal plane, and at this time, between the inner surface (IS) of the voice part and the carapace, there is at least a first leakage structure (UC) near the top of the head (i.e., a slot between the upper boundary of the carapace and the inner surface (IS)) and a second leakage structure (LC) near the ear canal (i.e., a slot between the lower boundary of the carapace and the inner surface (IS)). Therefore, the sound volume, especially the sound volume of mid-low frequencies, can be improved, while at the same time still retaining the effect of canceling far-field leakage sound, and thus the acoustic output performance of the open earphone (10) can be improved. In some embodiments, when the open earphone (10) is worn in the manner shown in FIG. 13, the first leakage structure (UC) and the second leakage structure (LC) formed between the inner surface (IS) of the vocal part and the ear canal have a constant scale in both the major axis direction X and the thickness direction Z. In some embodiments, to facilitate understanding of the positions of the first leakage structure (UC) and the second leakage structure (LC), when the open earphone (10) is in a worn state, the midpoint of two points formed by the upper and lower edges of the inner surface (IS) intersecting with the ear (e.g., the side wall of the ear canal, the helix) may be used as the position reference point for the first leakage structure (UC) and the second leakage structure (LC), and the center of the ear canal opening may be used as the position reference point for the ear canal. In some embodiments, to facilitate understanding of the positions of the first leakage structure (UC) and the second leakage structure (LC), when the open earphone (10) is in a worn state, the midpoint of the upper boundary of the inner surface (IS) may be used as the position reference point for the first leakage structure (UC), and the third point near the free end (FE) on the lower boundary of the inner surface (IS) (abbreviated below as "1 / 3 point of the lower boundary of the inner surface (IS)") may be used as the position reference point for the second leakage structure (LC). In this specification, when the boundary position between the inner surface (IS) and the upper surface (US) and / or the lower surface (LS) is arc-shaped, the upper boundary of the inner surface (IS) may be the intersection line between the inner surface (IS) and the upper surface (US), and the lower boundary of the inner surface (IS) may be the intersection line between the inner surface (IS) and the lower surface (LS). In some embodiments, when one or more sides of the vocal part (11) (e.g., inner side (IS), upper side (US) and / or lower side (LS)) are curved, the intersection line of the two sides may be the intersection line between the two sides and a tangent plane that is furthest from the center of the vocal part and parallel to the major or minor axis of the vocal part. For example, in this specification, the midpoint of the upper boundary and the 1 / 3 point of the lower boundary of the inner surface (IS) are respectively designated as location reference points for the first leakage structure (UC) and the second leakage structure (LC). It should be noted that the selected midpoint of the upper boundary and the 1 / 3 point of the lower boundary of the inner surface (IS) are merely exemplary reference points to explain the locations of the first leakage structure (UC) and the second leakage structure (LC). In some embodiments, other reference points may be selected to explain the locations of the first leakage structure (UC) and the second leakage structure (LC). For example, due to differences in the user's ears, the first leakage structure (UC) / second leakage structure (LC) formed when the open earphone (10) is worn becomes a slot with a gradually changing width, and in this case, the reference position of the first leakage structure (UC) / second leakage structure (LC) may be a location close to the area where the width of the slot is maximum on the upper boundary / lower boundary of the inner surface (IS). For example, the first leakage structure (UC) can be positioned at the 1 / 3 point near the free end (FE) on the upper boundary of the inner side (IS), and the second leakage structure (LC) can be positioned at the midpoint of the lower boundary of the inner side (IS). In some embodiments, as shown in FIG. 15, the projection of the upper boundary of the inner side (IS) in the sagittal plane may overlap with the projection of the upper side (US) in the sagittal plane, and the projection of the lower boundary of the inner side (IS) in the sagittal plane may overlap with the projection of the lower side (LS) in the sagittal plane. The projection in the sagittal plane of the position reference point of the first leakage structure (UC) (i.e., the midpoint of the upper boundary of the inner surface (IS)) is point A, and the projection in the sagittal plane of the position reference point of the second leakage structure (LC) (i.e., the 1 / 3 point of the lower boundary of the inner surface (IS)) is point C, where "projection point A in the sagittal plane of the midpoint of the upper boundary of the inner surface (IS)" may be a projection point in the sagittal plane of the intersection point of the upper boundary of the inner surface (IS) and the minor axis center plane of the magnetic circuit assembly of the transducer (e.g., the magnetic circuit assembly (1144) described below). The minor axis center plane of the magnetic circuit assembly may be a plane that is parallel to the minor axis direction of the emitting part (11) and passes through the geometric center of the magnetic circuit assembly. "Projection point C in the sagittal plane of the 1 / 3 point of the lower boundary of the inner side (IS)" may be the projection point in the sagittal plane of the trisection point near the free end (FE) on the lower boundary of the inner side (IS). As shown in FIG. 15, in some embodiments, when worn, the projection in the sagittal plane of the sounding part (11) of the open earphone (10) covers at least a portion of the user's ear canal, but the ear canal communicates with the outside through the ear canal, thereby enabling the user's ears to be freed. In some embodiments, the sound of the pressure relief hole (113) is transmitted to the cavity structure through a leakage structure (e.g., a first leakage structure (UC) or a second leakage structure (LC)) and is canceled out by the sound of the sound output hole (112). Therefore, the pressure relief hole (113) should not be too close to the leakage structure, and under the premise that at least a part of the voice part (11) is inserted into the ear canal, the distance between the pressure relief hole (113) and the sound output hole (112) is limited by the size of the voice part (11). Therefore, in order to have a relatively high audibility index within the entire frequency band range of the open earphone (10), the pressure relief hole (113) should be located as far as possible from the sound output hole (112), for example, the pressure relief hole (113) should be placed on the upper side (US) of the voice part (11). At this time, the ratio of the distance from the projection point O' in the sagittal plane of the center O of the sound output hole (112) to the projection point A in the sagittal plane of the midpoint of the upper boundary of the inner side (IS) and the distance between the projection point O' in the sagittal plane of the center O of the sound output hole (112) and the projection point in the sagittal plane of the center of the pressure reduction hole (113) is between 0.7 and 1.3. When the relative positions of the sound output hole (112) and the pressure relief hole (113) do not change (i.e., the distance between the sound output hole (112) and the pressure relief hole (113) does not change), the larger the volume V of the cavity structure, the smaller the audibility index of the entire open earphone (10) (within the entire frequency band range). This is because, under the influence of air acoustic resonance within the cavity structure, air acoustic resonance occurs within the cavity structure at the resonance frequency of the cavity structure and emits a sound much louder than the pressure relief hole (113) to the outside, thereby greatly improving the leakage sound and causing the audibility index to become significantly smaller near the resonance frequency. The greater the distance from the projection point O' in the sagittal plane of the center O of the sound output hole (112) to the projection point A in the sagittal plane of the midpoint of the upper boundary of the inner surface (IS), the larger the volume V of the cavity structure. Therefore, in some embodiments, under the premise that at least a part of the vocalization part (11) is inserted into the ear canal, the sound output hole (112) is positioned close to the ear canal so that the cavity structure has a suitable volume V, thereby making the sound reception effect of the ear canal relatively good, the range of the distance from the projection point O' in the sagittal plane of the center O of the sound output hole (112) to the projection point A in the sagittal plane of the midpoint of the upper boundary of the inner surface (IS) is 10.0 mm to 15.2 mm. In some embodiments, the range of distance from the projection point O' in the sagittal plane of the center O of the sound output hole (112) to the projection point A in the sagittal plane of the midpoint of the phase boundary of the inner surface (IS) is 11.0 mm to 14.2 mm. In some embodiments, the range of distance from the projection point O' in the sagittal plane of the center O of the sound output hole (112) to the projection point A in the sagittal plane of the midpoint of the phase boundary of the inner surface (IS) is 12.0 mm to 14.7 mm. In some embodiments, the range of distance from the projection point O' in the sagittal plane of the center O of the sound output hole (112) to the projection point A in the sagittal plane of the midpoint of the phase boundary of the inner surface (IS) is 12.5 mm to 14.2 mm. In some embodiments, the range of distance from the projection point O' in the sagittal plane of the center O of the sound outlet (112) to the projection point A in the sagittal plane of the midpoint of the upper boundary of the inner surface (IS) is 13.0 mm to 13.7 mm. In some embodiments, since there is a migration near the eardrum, the sound outlet hole (112) is easily blocked by the migration. In order to ensure that the sound outlet hole (112) is located relatively close to the eardrum and not blocked, the range of distance from the projection point O' in the sagittal plane of the center O of the sound outlet hole (112) to the projection point B in the sagittal plane of the center of the eardrum is 2.2 mm to 3.8 mm. In some embodiments, the range of distance from the projection point O' in the sagittal plane of the center O of the sound outlet hole (112) to the projection point B in the sagittal plane of the center of the eardrum is 2.4 mm to 3.6 mm. In some embodiments, the range of distance from the projection point O' in the sagittal plane of the center O of the sound outlet hole (112) to the projection point B in the sagittal plane of the center of the eardrum is 2.6 mm to 3.4 mm. In some embodiments, the range of distance from the projection point O' in the sagittal plane of the center O of the sound hole (112) to the projection point B in the sagittal plane of the center of the tool is 2.8 mm to 3.2 mm. In some embodiments, in order to ensure that the vocal part (11) enters the ear canal and that a suitable slot (forming a “leakage structure of the cavity structure”) exists between the upper boundary of the inner surface (IS) and the ear canal, the range of distance from projection point A in the sagittal plane at the midpoint of the upper boundary of the inner surface (IS) to projection point B in the sagittal plane at the center of the ear tool is 12 mm to 18 mm. In some embodiments, the range of distance from projection point A in the sagittal plane at the midpoint of the upper boundary of the inner surface (IS) to projection point B in the sagittal plane at the center of the ear tool is 13 mm to 17 mm. In some embodiments, the range of distance from projection point A in the sagittal plane at the midpoint of the upper boundary of the inner surface (IS) to projection point B in the sagittal plane at the center of the ear tool is 14 mm to 16 mm. In some embodiments, the range of distance from projection point A in the sagittal plane of the midpoint of the phase boundary of the inner surface (IS) to projection point B in the sagittal plane of the center of the tool is 14.5 mm to 15.5 mm. In some embodiments, in order to ensure that the vocal part (11) enters the ear canal and that a suitable slot ("forming a cavity structure leakage structure") exists between the lower edge of the inner surface (IS) and the ear canal, the range of distance from projection point C in the sagittal plane at 1 / 3 of the lower edge of the inner surface (IS) to projection point B in the sagittal plane at the center of the ear tool is 1.7 mm to 2.7 mm. In some embodiments, the range of distance from projection point C in the sagittal plane at 1 / 3 of the lower edge of the inner surface (IS) to projection point B in the sagittal plane at the center of the ear tool is 1.8 mm to 2.6 mm. In some embodiments, the range of distance from projection point C in the sagittal plane at 1 / 3 of the lower boundary of the inner surface (IS) to projection point B in the sagittal plane at the center of the tool is 1.9 mm to 2.5 mm, and in some embodiments, the range of distance from projection point C in the sagittal plane at 1 / 3 of the lower boundary of the inner surface (IS) to projection point B in the sagittal plane at the center of the tool is 2.0 mm to 2.4 mm. In some embodiments, the range of distance from projection point C in the sagittal plane at 1 / 3 of the lower boundary of the inner surface (IS) to projection point B in the sagittal plane at the center of the tool is 2.1 mm to 2.3 mm. In some embodiments, the greater the distance from the projection point O' in the sagittal plane at the center O of the sound output hole (112) to the projection point C in the sagittal plane at the 1 / 3 point of the lower boundary of the inner side (IS), the larger the volume V of the cavity structure. Therefore, under the premise that at least a part of the vocalization part (11) is inserted into the ear canal, the sound output hole (112) is positioned close to the ear canal so that the cavity structure has a suitable volume V, thereby making the sound reception effect of the ear canal relatively good, in some embodiments, the range of the distance from the projection point O' in the sagittal plane at the center O of the sound output hole (112) to the projection point C in the sagittal plane at the 1 / 3 point of the lower boundary of the inner side (IS) is 3.5 mm to 5.6 mm. In some embodiments, the range of distance from the projection point O' in the sagittal plane of the center O of the sound output hole (112) to the projection point C in the sagittal plane at the 1 / 3 point of the lower boundary of the inner side (IS) is 3.9 mm to 5.2 mm. In some embodiments, the range of distance from the projection point O' in the sagittal plane of the center O of the sound output hole (112) to the projection point C in the sagittal plane at the 1 / 3 point of the lower boundary of the inner side (IS) is 4.3 mm to 4.8 mm. In some embodiments, the range of distance from the projection point O' in the sagittal plane of the center O of the sound output hole (112) to the projection point C in the sagittal plane at the 1 / 3 point of the lower boundary of the inner side (IS) is 4.5 mm to 4.6 mm. FIG. 16a is an exemplary internal structural diagram of a vocalization unit according to some embodiments of the present specification. As shown in FIG. 16a, the vocal unit (11) may include a main control circuit board (13) disposed within the housing (111) and a battery (not shown) disposed at one end of the earring (12) far from the vocal unit (11), and the battery and the transducer (116) are each electrically connected to the main control circuit board (13) so that the battery supplies electricity to the transducer (116) under the control of the main control circuit board (13). Of course, both the battery and the transducer (116) may be disposed within the vocal unit (11), the battery may be closer to the connection end (CE), and the transducer (116) may be closer to the free end (FE). In some embodiments, the open earphone (10) may include an adjustment unit connecting the vocal part (11) and the earring (12), and different users may adjust the relative position of the vocal part (11) in the ear through the adjustment unit while wearing it so that the vocal part (11) is positioned in one suitable position, thereby allowing the vocal part (11) and the ear canal to form a cavity structure. In addition, due to the presence of the adjustment unit, the user may also adjust the earphone (10) to wear it in a more stable and comfortable position. Since the ear canal has a certain volume and depth, after the free end (FE) enters the ear canal, a certain gap can be provided between the inner surface (IS) of the vocal part (11) and the ear canal. In other words, the vocal part (11) combines with the ear canal to form a cavity structure that communicates with the external auditory canal when worn, and at least a part of the sound output hole (112) can be located within the cavity structure described above. In this way, when worn, the sound waves propagating from the sound output hole (112) can be restricted by the cavity structure described above; that is, the cavity structure described above can concentrate the sound waves and allow the sound waves to propagate better into the external auditory canal, thereby improving the volume and sound quality of the sound heard by the user in the near field, which is advantageous for improving the acoustic effect of the earphone (10). In addition, the vocalization part (11) is positioned so as not to block the external auditory canal when worn, so the cavity structure described above can be positioned in a semi-open manner. Accordingly, a portion of the sound waves propagating from the sound output hole (112) can be propagated to the ear canal so that the user can hear the sound, and another portion propagates to the earphone (10) and the outside of the ear along with the sound reflected through the ear canal (e.g., a portion of the ear canal not covered by the sound output hole (11)), and can form a first leakage sound in the far field, and at the same time, the sound waves propagating through the pressure relief hole (113) opened in the sound output hole (11) can generally form a second leakage sound in the far field, and the intensity of the first leakage sound described above is equivalent to the intensity of the second leakage sound described above, and the phase of the first leakage sound described above and the phase of the second leakage sound described above are (almost) opposite to each other, so that the two can cancel each other out in the far field, which is advantageous for reducing the leakage sound in the far field of the open earphone (10). In some embodiments, the sound-producing unit (11) comprises a housing (111) connected mainly to an earring (12) and a transducer (116) disposed within the housing (111). Here, the housing (111) has an output hole (112) disposed on an inner surface (IS) facing the ear when worn, and sound waves generated by the transducer (116) propagate through the output hole (112) and enter the external auditory canal (101). It should be noted that the output hole (112) may be disposed on a lower surface (LS) of the housing (111) or may be disposed at a corner between the inner surface (IS) and the lower surface (LS) described above. In some embodiments, a full cavity (114) may be formed between the transducer (116) and the housing (111), and a sound output hole (112) is positioned in the area of ​​the full cavity (114) formed by surrounding the housing (111), and the full cavity (114) communicates with the outside through the sound output hole (112). In some embodiments, the entire cavity (114) is positioned between the diaphragm of the transducer (116) and the housing (111), and to ensure that the diaphragm has a sufficient vibration space, the entire cavity (114) may have a relatively large depth dimension (i.e., the distance dimension between the diaphragm of the transducer (116) and the housing (111) immediately facing it). In some embodiments, as shown in FIG. 16a, the sound output hole (112) is positioned on the inner surface (IS) in the thickness direction Z, where the depth of the entire cavity (114) may be the dimension in the Z direction of the entire cavity (114). However, if the depth of the entire cavity (114) becomes excessive, the size of the sound output part (11) also increases, which may affect the comfort of wearing the open earphone (10). In some embodiments, the depth of the entire cavity (114) may be 0.55 mm to 1.00 mm. In some embodiments, the depth of the entire cavity (114) may be 0.66 mm to 0.99 mm. In some embodiments, the depth of the entire cavity (114) may be 0.76 mm to 0.99 mm. In some embodiments, the depth of the entire cavity (114) may be 0.96 mm to 0.99 mm. In some embodiments, the depth of the entire cavity (114) may be 0.97 mm. In order to improve the vocalization effect of the open-type earphone (10), the resonance frequency of the pseudo-Helmholtz resonant cavity structure composed of the entire cavity (114) and the sound output hole (112) should be as high as possible, thereby causing the frequency response curve of the entire vocal part to have a relatively wide, flat region. In some embodiments, the resonance frequency of the entire cavity (114) f 1 It may be 3 kHz or higher. In some embodiments, the resonant frequency of the entire cavity (114) f 1 It may be 4 kHz or higher. In some embodiments, the resonant frequency of the entire cavity (114) f 1 It may be 6 kHz or higher. In some embodiments, the resonant frequency of the entire cavity (114) f 1It may be 7 kHz or higher. In some embodiments, the resonant frequency of the entire cavity (114) f 1 It can be 8kHz or higher. In some embodiments, the entire cavity (114) and the sound output hole (112) can be approximated as a single Helmholtz resonant cavity model, where the entire cavity (114) is the cavity of the Helmholtz resonant cavity model and the sound output hole (112) is the neck of the Helmholtz resonant cavity model. In this case, the resonant frequency of the Helmholtz resonant cavity model is the resonant frequency of the entire cavity (114). f 1 In the Helmholtz resonant cavity model, the size of the throat (e.g., the sound hole (112)) affects the resonant frequency f of the cavity, and the specific relationship can be expressed by formula (2). (2) Here, c indicates the speed of sound, S indicates the cross-sectional area of ​​the throat (e.g., sound outlet (112)), V indicates the volume of the cavity (e.g., full cavity (114)), and L indicates the depth of the throat (e.g., sound outlet (112)). From formula (2), when the cross-sectional area S of the sound output hole (112) is increased and the depth L of the sound output hole (112) is decreased, the resonance frequency of the entire cavity (114) f 1 It can be seen that this increases and shifts to a high frequency. In some embodiments, the total volume of air in the sound output hole (112) forms an acoustic mass, and the acoustic mass can resonate with the system (e.g., a Helmholtz resonant cavity) to generate a low-frequency output. Therefore, if the acoustic mass is relatively small, it can affect the low-frequency output of the Helmholtz resonant cavity model. The dimensions of the sound output hole (112) can also affect the acoustic mass Ma of the sound hole (112), and the specific relationship is as shown in Formula (3). (3) Here, ρ represents the air density, S represents the cross-sectional area of ​​the sound outlet (112), and L represents the depth of the sound outlet (112). From formula (3), it can be seen that if the cross-sectional area S of the sound outlet (112) increases and the depth L decreases, the acoustic mass Ma of the sound outlet (112) decreases. Referring to formulas (2) and (3), the larger the value of the ratio S / L of the cross-sectional area S and depth L of the sound output hole (112), the greater the resonance frequency of the entire cavity (114). f 1 It can be seen that the sound mass Ma of the sound outlet (112) is larger and smaller. Therefore, the ratio S / L of the cross-sectional area S and depth L of the sound outlet (112) must be within a suitable range of values, and specifically, for example, refer to FIG. 17a, FIG. 17b and FIG. 18b. FIG. 16b is an exemplary internal structure diagram of a transducer according to some embodiments of the present specification. As shown in FIG. 16b, the housing (111) accommodates a transducer (116), and the transducer (116) includes a vibrating membrane (1141), a voice coil (1142), a support (1143), and a magnetic circuit assembly (1144). Here, a support (1143) is arranged to surround the vibrating membrane (1141), the voice coil (1142), and the magnetic circuit assembly (1144) and is used to provide a mounting fixture, and a transducer (116) is connected to the housing (111) through the support (1143), and in the Z direction, the vibrating membrane (1141) covers the voice coil (1142) and the magnetic circuit assembly (1144), and the voice coil (1142) enters the magnetic circuit assembly (1144) and is connected to the vibrating membrane (1141), and the magnetic field generated after the voice coil (1142) is energized interacts with the magnetic field formed by the magnetic circuit assembly (1144) to drive the vibrating membrane (1141) to generate mechanical vibration, thereby propagating the generated sound through a medium such as air, and the sound is output through the sound output hole (112). In some embodiments, the magnetic circuit assembly (1144) comprises a magnetic conductive plate (11441), a magnetic body (11442), and a receiving member (11443), wherein the magnetic conductive plate (11441) is interconnected with the magnetic body (11442), and one side of the magnetic body (11442) that is far from the magnetic conductive plate (11441) is mounted on the bottom wall of the receiving member (11443), and there is a gap between the periphery side of the magnetic body (11442) and the periphery inner wall of the receiving member (11443). In some embodiments, the periphery outer wall of the receiving member (11443) is connected to and fixed by a support (1143). In some embodiments, both the receiving member (11443) and the magnetic conductive plate (11441) may be made of a magnetic conductive material (e.g., iron, etc.). In some embodiments, the circumferential side of the vibrating membrane (1141) may be connected to a support (1143) via a fixed ring (1145). In some embodiments, the material of the fixed ring (1145) may include stainless steel or other metal materials to suit the manufacturing process of the vibrating membrane (1141). Referring to FIG. 16a and FIG. 16b, in some embodiments, to improve the acoustic output (especially low-frequency output) effect of the vocal part (11) and to improve the ability of the vibrating membrane (1141) to drive air, the projected area of ​​the vibrating membrane (1141) in the Z direction is better the larger it is. However, if the area of ​​the vibrating membrane (1141) is excessive, the size of the transducer (116) becomes excessive, and consequently the housing (111) becomes excessive, making it easy for the housing (111) and the earlobe to collide and rub against each other, which affects the comfort of wearing the vocal part (11). Therefore, the size of the housing (111) must be designed. For example, the dimension in the Y direction of the armor (e.g., 17 mm) can determine the width dimension in the Y direction of the housing (111) and, based on the comfort of wearing, select an appropriate aspect ratio (i.e., the ratio of the dimension in the Y direction of the housing (111) to the dimension in the X direction), thereby determining the length dimension in the X direction of the housing (111) (e.g., 21.49 mm) so that it can be matched with the dimension in the Y direction of the armor. In some embodiments, a cavity structure with relatively good acoustic effects is formed so that at least a portion of the vocal part (11) can enter the ear canal when the majority of users wear the open earphone (10), for example, a first leakage structure (UC) and a second leakage structure (LC) are formed between the user's ear when the open earphone (10) is worn, thereby improving the acoustic performance of the earphone, and the size of the housing (111) may use a value in a preset range. In some embodiments, based on the range of the width dimension in the Y direction of the ear canal, the width dimension of the housing (111) in the Y direction may be within the range of 11 mm to 16 mm. In some embodiments, the width dimension of the housing (111) in the Y direction may be 11 mm to 15 mm. In some embodiments, the width dimension of the housing (111) in the Y direction may be 13 mm to 14 mm. In some embodiments, the ratio of the dimension in the X direction to the dimension in the Y direction of the housing (111) may be 1.2 to 5. In some embodiments, the ratio of the dimension in the X direction to the dimension in the Y direction of the housing (111) may be 1.4 to 4. In some embodiments, the ratio of the dimension in the X direction to the dimension in the Y direction of the housing (111) may be 1.5 to 2. In some embodiments, the length dimension in the X direction of the housing (111) may be within the range of 15 mm to 30 mm. In some embodiments, the length dimension in the X direction of the housing (111) may be 16 mm to 28 mm. In some embodiments, the length dimension in the X direction of the housing (111) may be 19 mm to 24 mm. In some embodiments, to prevent the volume of the housing (111) from being excessive and affecting the comfort of wearing the open earphone (10), the thickness dimension of the housing (111) in the Z direction may be within the range of 5 mm to 20 mm. In some embodiments, the thickness dimension of the housing (111) in the Z direction may be 5.1 mm to 18 mm. In some embodiments, the thickness dimension of the housing (111) in the Z direction may be 6 mm to 15 mm.In some embodiments, the thickness dimension of the housing (111) in the Z direction may be 7 mm to 10 mm. In some embodiments, the area of ​​the inner surface (IS) of the housing (111) (in the case where the inner surface (IS) is a rectangle, it is the product of the length dimension and the width dimension of the housing (111)) is 90 mm. 2 ~560mm 2 It may be. In some embodiments, the area of ​​the inner surface (IS) may be considered to be approximately the projected area of ​​the vibrating membrane (1141) in the Z direction. For example, there is a 10% difference between the area of ​​the inner surface (IS) and the projected area of ​​the vibrating membrane (1141) in the Z direction. In some embodiments, the area of ​​the inner surface (IS) is 150 mm 2 ~360mm 2 It may be. In some embodiments, the area of ​​the inner surface (IS) is 160 mm 2 ~240mm 2 It may be. In some embodiments, the area of ​​the inner surface (IS) is 180 mm 2 ~200mm 2 According to the principle of FIGS. 9 to 12, when worn in the manner shown in FIG. 13, the size of the open earphone (10) is superior to the acoustic performance of the current open earphone on the basis of satisfying the comfort of wearing, that is, under the premise of achieving equivalent superior acoustic performance, the size of the open earphone (10) can be smaller than the current open earphone. Referring to FIG. 16a and FIG. 16b, in some embodiments, the distance from the center O of the sound output hole (112) in the Z direction to the bottom surface of the magnetic circuit assembly (1144) may be related to the vibration range of the vibrating membrane (1141) and the thickness of the magnetic circuit assembly (1144). The vibration range of the vibrating membrane (1141) may affect the amount of air driven by the transducer of the vocal part (11). The larger the vibration range of the vibrating membrane (1141), the greater the amount of air driven by the transducer of the vocal part (11), and the higher the vocal efficiency of the vocal part. The larger the thickness of the magnetic circuit assembly (1144), the greater the total weight of the vocal part (11), which affects the comfort of the user wearing it. In addition, when the thickness of the sound-producing part in the Z direction is constant, the smaller the distance from the center O of the sound-producing hole (112) in the Z direction to the bottom surface of the magnetic circuit assembly (1144), the larger the volume of the rear cavity can be. At this time, from the formula (2) described above, it can be seen that the smaller the resonance frequency of the rear cavity, the lower the resonance peak of the rear cavity shifts to a lower frequency, and the range of the flat area of ​​the frequency response curve becomes smaller. In order to ensure that the vocalization efficiency of the vocal part is sufficiently high, the resonance frequency of the rear cavity is within a suitable frequency range (e.g., 1000Hz to 5000Hz), and that the user’s wearing is sufficiently comfortable, under circumstances where structural strength, the difficulty of implementing the process, and the total thickness of the housing (111) are comprehensively considered, the distance from the center O of the sound output hole (112) in the Z direction to the bottom surface of the magnetic circuit assembly (1144) (i.e., the side far from the sound output hole (112) in the receiving member (11443) in the Z direction) l 1 The range is 5.65 mm to 8.35 mm. In some embodiments, the distance from the center of the sound output hole (112) to the bottom surface of the magnetic circuit assembly (1144) in the Z direction. l 1 The range is 6.00mm to 8.00mm. In some embodiments, the distance from the center of the sound output hole (112) to the bottom surface of the magnetic circuit assembly (1144) in the Z direction. l1 The range is 6.35 mm to 7.65 mm. In some embodiments, the distance from the center of the sound output hole (112) to the bottom surface of the magnetic circuit assembly (1144) in the Z direction. l 1 The range is 6.70 mm to 7.30 mm. In some embodiments, the distance from the center of the sound output hole (112) to the bottom surface of the magnetic circuit assembly (1144) in the Z direction. l 1 The range is 6.95mm to 7.05mm. In some embodiments, the range of distance from the center O of the sound output hole (112) to the major axis center plane of the magnetic circuit assembly (1144) (e.g., the inwardly facing plane NN' which is perpendicular to the plane of paper shown in FIG. 13) is 1.45 mm to 2.15 mm. In this specification, the major axis center plane of the magnetic circuit assembly (1144) is a plane that is parallel to the lower side (LS) of the sound output part (11) and passes through the geometric center of the magnetic circuit assembly (1144). That is, the major axis center plane of the magnetic circuit assembly (1144) can divide the magnetic circuit assembly (1144) into equal two parts in the direction X. The distance between the center O of the sound output hole (112) and the major axis center plane of the magnetic circuit assembly (1144), that is, the distance from the minor axis direction of the center O of the sound output hole (112) to the major axis center plane in the Y direction. In some embodiments, the range of distance from the center O of the sound outlet (112) to the major axis center plane is 1.55 mm to 2.05 mm. In some embodiments, the range of distance from the center O of the sound outlet (112) to the major axis center plane is 1.65 mm to 1.95 mm. In some embodiments, the range of distance from the center O of the sound outlet (112) to the major axis center plane is 1.75 mm to 1.85 mm. FIG. 17a is a frequency response curve of an open-type earphone corresponding to a sound output hole of different cross-sectional areas when the aspect ratio is constant, according to some embodiments of the present specification. FIG. 17a is a frequency response curve corresponding to an open-type earphone (10) in which the cross-sectional area of ​​the sound output hole is within the range of 0.44 mm² to 100.43 mm² when other structures (e.g., pressure relief hole (113), rear cavity volume, etc.) are fixed and the aspect ratio of the sound output hole is constant. From FIG. 17a, under the above conditions, as the cross-sectional area S of the sound output hole (112) gradually increases, the resonance frequency corresponding to the front cavity in the frequency response curve of the open-type earphone (10) f 1 It can be seen that (i.e., the frequency corresponding to the resonance peak in the dotted line G) gradually shifts to a high frequency, and the resonance frequency corresponding to the rear cavity continuously maintains around 4.5 kHz. Specifically, as the cross-sectional area of ​​the sound output hole (112) increases, the resonance peak of the front cavity gradually shifts to a high frequency, and when it shifts to around 4.5 kHz, the resonance frequencies of the front cavity and the rear cavity can be basically the same, and in this process, the peak value of the resonance peak does not basically change. After the resonance peak of the current cavity shifts to 4.5 kHz, if the cross-sectional area S of the sound output hole (112) is continuously increased, the peak value of the resonance peak of the front cavity clearly shows a trend of gradually decreasing. Therefore, in some embodiments, in order to make the frequency response curve of the open earphone (10) have a relatively wide flat area, the cross-sectional area S of the sound output hole (112) is 2.87 mm 2 It can be made larger. Preferably, in order to make the frequency response curve of the open earphone (10) relatively flat in the range of 100Hz to 2.3kHz, the cross-sectional area S of the sound output hole (112) is 4.0mm 2 It can be made larger. Preferably, in order to make the frequency response curve of the open earphone (10) relatively flat in the range of 100Hz to 3.3kHz, the cross-sectional area S of the sound output hole (112) is 7.0mm 2It can be made larger.

[0012] Additionally, within a certain range of the cross-sectional area S of the sound output hole (112), as the cross-sectional area S of the sound output hole (112) increases, the resonance peak of the entire cavity shifts to a high frequency, while the peak value gradually decreases. Therefore, in some embodiments, in order to improve the sound quality of the open earphone (10) and at the same time make it convenient for EQ adjustment, if the frequency response of the open earphone (10) is sufficient in the high frequency range (e.g., 4.5 kHz to 9 kHz), the cross-sectional area S of the sound output hole (112) is 54 mm 2 It can be made smaller. Preferably, in order to sufficiently make the frequency response curve of the open earphone (10) within the range of 4.5kHz to 8kHz, the cross-sectional area S of the sound output hole (112) is 36.15mm 2 It can be made smaller. More preferably, in order to sufficiently make the frequency response curve of the open earphone (10) within the range of 4.5kHz to 6.5kHz, the cross-sectional area S of the sound output hole (112) is 21.87mm 2 It can be made smaller. In this specification, for convenience of explanation, the cross-sectional area S of the sound outlet (112) may be the area of ​​the outer opening of the sound outlet (112) (i.e., the area of ​​the opening on the inner side of the sound outlet (112)). It should be noted that in some other embodiments, the cross-sectional area S of the sound outlet (112) may be the area of ​​the inner opening of the sound outlet (112) or the average of the area of ​​the inner opening and the area of ​​the outer opening of the sound outlet (113). FIG. 17b is a frequency response curve of a full cavity corresponding to a sound output hole of a different cross-sectional area according to some embodiments of the present specification. As shown in FIG. 17b, the cross-sectional area of ​​the sound output hole (112) S Ga 2.875mm 2 46.10mm from 2 When the branch grows larger, the acoustic mass of the sound hole (112) M a 800kg / m² 4 From 50kg / m4 Reduced to and the resonance frequency of the entire cavity f 1 It can gradually increase from around 4 kHz to around 8 kHz. It should be noted that 200 kg / m² indicated in Fig. 17b 4 and 800kg / m 4 The parameters represent only the theoretical acoustic mass of the sound output hole (112), and there may be an error with the actual acoustic mass of the sound output hole (112). The acoustic output effect of the open earphone (10) is improved, and the resonance frequency of the entire cavity f 1 At the same time, improving the acoustic mass of the sound output hole (112) M a In order to ensure that it is sufficiently large, the cross-sectional area of ​​the sound outlet (112) S is It must have a suitable range of values. In addition, in the actual design, if the cross-sectional area of ​​the sound output hole (112) is excessive, it may have a certain effect on the appearance, structural strength, water resistance, dust resistance, and other aspects of the open-type earphone (10). In some embodiments, the range of the value of the cross-sectional area S of the sound output hole (112) is 2.87 mm 2 ~46.10mm 2 It may be. In some embodiments, the range of the value of the cross-sectional area S of the sound outlet (112) is 2.875 mm 2 ~46mm 2 It may be. In some embodiments, the range of the value of the cross-sectional area S of the sound outlet (112) is 10 mm 2 ~30mm 2 It may be. In some embodiments, the value of the cross-sectional area S of the sound outlet (112) is 25.29 mm 2 It may be. In some embodiments, the range of the value of the cross-sectional area S of the sound outlet (112) is 25 mm 2 ~26mm 2 It could be. In some embodiments, to increase the wearing stability of the open-type earphone (10), the area of ​​the inner surface (IS) of the vocal part (11) must be matched with the size of the ear canal of the human body. Additionally, when the vocal part (11) is worn in a manner where it is inserted into the ear canal, the inner surface (IS) and the side wall of the ear canal form a cavity structure. Therefore, compared to a normal wearing method (e.g., placing the vocal part (11) in front of the ear), the vocal efficiency of the vocal part (11) is high, and the overall size of the vocal part can be designed to be relatively small. Consequently, the ratio of the area of ​​the sound output hole (112) to the inner surface (IS) can be designed to be relatively large. At the same time, the area of ​​the sound output hole must not be excessive, otherwise it may affect the stability of the waterproof and dustproof structure and the support structure of the sound output hole area. The area of ​​the inner surface (IS) must not be insufficient, otherwise it may affect the area where the transducer drives air. In some embodiments, the ratio of the cross-sectional area S of the sound outlet (112) to the area of ​​the inner surface (IS) may be between 0.015 and 0.25. In some embodiments, the ratio of the cross-sectional area S of the sound outlet (112) to the area of ​​the inner surface (IS) may be between 0.02 and 0.2. In some embodiments, the ratio of the cross-sectional area S of the sound outlet (112) to the area of ​​the inner surface (IS) may be between 0.06 and 0.16. In some embodiments, the ratio of the cross-sectional area S of the sound outlet (112) to the area of ​​the inner surface (IS) may be between 0.1 and 0.12. In some embodiments, considering that the inner surface (IS) needs to come into contact with the ear (e.g., the ear canal) and to improve wearing comfort, the inner surface (IS) may be designed as a non-planar structure, for example, the edge area of ​​the inner surface (IS) may have a curvature that is uniformly curved relative to the center area, or a protrusion structure may be placed in the area near the free end (FE) of the inner surface (IS) to better make contact with the ear area, etc. In this case, to better reflect the influence of the cross-sectional area of ​​the sound output hole (112) on the wearing stability and vocalization efficiency of the open earphone (10), the ratio of the cross-sectional area S of the sound output hole (112) to the area of ​​the inner surface (IS) may be replaced with the ratio of the cross-sectional area S of the sound output hole (112) to the projected area in the vibration direction of the vibrating membrane of the inner surface (IS) (i.e., the Z direction in FIG. 16a). In some embodiments, the ratio of the cross-sectional area S of the sound output hole (112) to the projected area of ​​the vibrating membrane on the inner surface (IS) in the direction of vibration may be between 0.016 and 0.255. Preferably, the ratio of the cross-sectional area S of the sound output hole (112) to the projected area of ​​the vibrating membrane on the inner surface (IS) in the direction of vibration may be between 0.022 and 0.21. In some embodiments, the projected area of ​​the vibrating membrane of the transducer in the direction of vibration may be equal to or slightly smaller than the projected area of ​​the vibrating membrane of the inner surface (IS) in the direction of vibration. In this case, the ratio of the cross-sectional area S of the sound output hole (112) to the projected area of ​​the vibrating membrane in the direction of vibration may be between 0.016 and 0.261. Preferably, the ratio of the cross-sectional area S of the sound output hole (112) to the projected area of ​​the vibrating membrane of the inner surface (IS) in the direction of vibration may be between 0.023 and 0.23. In some embodiments, the shape of the sound outlet (112) may also affect the sound resistance of the sound outlet (112). The narrower and longer the sound outlet (112) is, the greater the sound resistance of the sound outlet (112), which is disadvantageous to the acoustic output of the entire cavity (114). Therefore, in order to ensure that the sound outlet (112) has appropriate sound resistance, the ratio of the length of the major axis and the length of the minor axis of the sound outlet (112) (also referred to as the "aspect ratio of the sound outlet (112)") must be within a range of pre-set appropriate values. In some embodiments, the shape of the sound outlet (112) may include, but is not limited to, a circular, elliptical, or runway shape. For convenience of explanation, the sound outlet (112) is described below as an example in which it is arranged in a runway shape. In some embodiments, as shown in FIG. 14, the sound outlet (112) may be in a runway shape, where the ends of the runway shape may be in a minor arc shape (an arc smaller than a semicircle) or a semicircle shape. In this case, the dimension of the major axis of the sound outlet (112) may be the maximum dimension in the X direction of the sound outlet (112) (e.g., the dimension of the major axis d shown in FIG. 14), and the dimension of the minor axis of the sound outlet (112) may be the maximum dimension in the Y direction of the sound outlet (112) (e.g., the dimension of the minor axis h shown in FIG. 14). FIG. 18a is a frequency response curve of an open earphone corresponding to an output hole of different aspect ratios according to some embodiments of the present specification. FIG. 18a is a frequency response curve of an open earphone corresponding to an output hole with aspect ratios of 1, 3, 5, 8, and 10, respectively, when other structures (e.g., pressure relief hole (113), rear cavity volume, etc.) are fixed and the area of ​​the output hole is constant. From FIG. 18a, when the cross-sectional area of ​​the sound output hole (112) is constant, as the aspect ratio of the sound output hole (112) increases, the resonance frequency of the resonance peak of the entire cavity (114) f 1It can be seen that the frequency gradually shifts to a higher frequency, and the intensity of the resonance peak gradually decreases. Therefore, when the cross-sectional area of ​​the sound output hole (112) is constant, in order to ensure that the intensity of the resonance peak of the entire cavity is sufficiently strong, the ratio value range between the length of the major axis of the sound output hole (112) and the length of the minor axis of the sound output hole (112) is between 1 and 10. In some embodiments, the ratio value range between the length of the major axis of the sound output hole (112) and the length of the minor axis of the sound output hole (112) may be between 2 and 8. The ratio value range between the length of the major axis of the sound output hole (112) and the length of the minor axis of the sound output hole (112) may be between 2 and 4. In some embodiments, the length of the major axis of the sound output hole (112) may be 7.67 mm, and the length of the minor axis of the sound output hole (112) may be 3.62 mm. FIG. 18b is a frequency response curve of a full cavity corresponding to sound output holes of different depths according to some embodiments of the present specification. As shown in FIG. 18b, when the depth L of the sound output hole (112) is increased from 0.3 mm to 3 mm, the acoustic mass Ma of the sound output hole (112) is 100 kg / m² 4 From 1000kg / m² 4 It increases up to, and the resonant frequency of the entire cavity f 1 The frequency drops from around 7kHz to around 3.7kHz. According to formula (2), in order to ensure that the entire cavity has a sufficiently large resonant frequency, the value of the depth L of the sound output hole (112) should be as small as possible. However, since the sound output hole (112) is placed in the housing (111), the depth of the sound output hole (112) is the thickness of the side wall of the housing (111). When the thickness of the housing (111) is too small, it affects the structural strength of the open-type earphone (10), and the difficulty of the corresponding processing process may be relatively high. In some embodiments, the range of the value of the depth L of the sound output hole (112) may be 0.3 mm to 3 mm. In some embodiments, the range of the value of the depth L of the sound output hole (112) may be 0.3 mm to 2 mm. In some embodiments, the value of the depth L of the sound output hole (112) may be 0.3 mm. In some embodiments, the value of the depth L of the sound outlet (112) may be 0.6 mm. In some embodiments, according to formula (2), when the volume of the entire cavity does not change easily, the ratio of the square of the cross-sectional area S and the depth L of the sound hole (112) S / L 2 The larger this is, the higher the resonance frequency of the entire cavity, and the better the effect within the mid-to-low frequency range of the sound emitted by the sound output hole. However, since it is preferable that the cross-sectional area S of the sound output hole (112) is not excessive, it is also preferable that the depth L (thickness of the housing (111)) is not insufficient. Accordingly, in some embodiments, the ratio of the square of the cross-sectional area S of the sound output hole (112) and the depth L is S / L 2 The range of the value of may be 0.31 to 512.2. In some embodiments, the ratio of the square of the cross-sectional area S and the depth L of the sound outlet hole (112) S / L 2 The range of the value of may be 1 to 400. In some embodiments, the ratio of the square of the cross-sectional area S and the depth L of the sound outlet (112) S / L 2 The range of the value of may be 3 to 300. In some embodiments, the ratio of the square of the cross-sectional area S and the depth L of the sound outlet hole (112) S / L 2The range of the value of may be 5 to 200. In some embodiments, the ratio of the square of the cross-sectional area S and the depth L of the sound outlet hole (112) S / L 2 The range of the value of can be 10 to 50. The basic concepts have been explained above. Of course, to those skilled in the art, the foregoing specification is merely an example and does not constitute a limitation to the present invention. Although not specified herein, those skilled in the art may make various changes, improvements, and modifications to the present invention. Such changes, improvements, and modifications are proposed in the present invention, and therefore, such changes, improvements, and modifications still fall within the essence and scope of the preferred embodiments of the present invention.

Claims

Claim 1 An open-type earphone comprises a vocal part and an earpiece, wherein the vocal part comprises a transducer and a housing that accommodates the transducer, wherein, when worn, a first part of the earpiece is positioned by being hooked between the user's earlobe and head, and a second part of the earpiece extends from the earlobe toward one side facing away from the head and is connected to the vocal part to fix the vocal part in a position near the ear canal but not obstructing the ear canal, wherein, an output hole is opened on the inner surface of the housing facing the earlobe and is used to extract sound generated by the transducer from the housing and transmit it to the ear canal, wherein the ratio of the area of ​​the output hole to the area of ​​the inner surface where the output hole is opened is between 0.015 and 0.25, and when worn, at least a portion of the housing is inserted into the ear cavity, and the area of ​​the inner surface is 160 mm 2 ~240mm 2 Open-type earphones within the range of. Claim 2 In claim 1, the cross-sectional area of ​​the sound output hole is 2.87 mm 2 ~46.10mm 2 In, open-type earphones. Claim 3 An open-type earphone according to paragraph 2, wherein the range of distance from the center of the sound output hole to the lower surface of the sound-producing part is 4.05mm to 6.05mm. Claim 4 An open-type earphone according to paragraph 2, wherein the range of distance from the center of the sound output hole to the rear side of the sound-producing part is 8.15mm to 12.25mm. Claim 5 An open-type earphone according to paragraph 2, wherein the range of distance from the projection point in the sagittal plane at the center of the sound output hole to the projection point in the sagittal plane at the center of the ear canal opening is 2.2mm to 3.8mm. Claim 6 An open-type earphone according to claim 5, wherein the range of distance from the projection point in the sagittal plane of the center of the sound output hole to the projection point in the sagittal plane of the midpoint of the phase boundary of the inner surface is 10.0 mm to 15.2 mm. Claim 7 An open-type earphone according to claim 6, wherein the range of distance from the projection point in the sagittal plane of the midpoint of the phase boundary of the inner surface to the projection point in the sagittal plane of the center of the ear tool is 12mm to 18mm. Claim 8 An open-type earphone according to claim 5, wherein the range of distance from the projection point in the sagittal plane at the center of the sound output hole to the projection point in the sagittal plane at 1 / 3 of the lower boundary of the inner surface is 3.5 mm to 5.6 mm. Claim 9 An open-type earphone according to claim 8, wherein the range of distance from the projection point in the sagittal plane at the 1 / 3 point of the lower boundary of the inner surface to the projection point in the sagittal plane at the center of the earpiece is 1.7mm to 2.7mm. Claim 10 delete Claim 11 delete Claim 12 delete Claim 13 delete Claim 14 delete Claim 15 delete Claim 16 delete Claim 17 delete Claim 18 delete Claim 19 delete Claim 20 delete Claim 21 delete Claim 22 delete Claim 23 delete Claim 24 delete Claim 25 delete Claim 26 delete Claim 27 delete Claim 28 delete

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