An open-back headphone

Abstract

This specification provides an open-back headphone, comprising: a sound-generating part including a transducer and a housing housing the transducer, wherein the transducer includes a diaphragm; an ear hook, wherein, in the wearing state, a first part of the ear hook is hung between the user's auricle and head, and a second part of the ear hook extends toward the side of the auricle away from the head and connects to the sound-generating part to fix the sound-generating part in a position near the ear canal without blocking the ear canal, wherein a sound outlet is formed on the inner side of the housing facing the auricle for discharging the sound generated on the front side of the diaphragm through the housing and transmitting it to the ear canal, and at least two pressure relief holes are formed on one or more of the outer side, upper side and lower side of the housing, the at least two pressure relief holes including a first pressure relief hole and a second pressure relief hole, the distance between the center of the first pressure relief hole and the center of the second pressure relief hole being 13.0mm-15.2mm.

Description

Cross-referencing

[0001] This application is a divisional application of Chinese application filed on March 2, 2023, with application number 202310237151.8, entitled "An Open-Type Headphone". It claims priority to Chinese application filed on October 28, 2022, with application number 202211336918.4; Chinese application filed on December 1, 2022, with application number 202223239628.6; and international application filed on December 30, 2022, with application number PCT / CN2022 / 144339, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of acoustics, and more particularly to an open-back headphone. Background Technology

[0003] With the development of acoustic output technology, acoustic devices (such as headphones) have been widely used in people's daily lives. They can be used with electronic devices such as mobile phones and computers to provide users with an auditory feast. Open-back headphones are portable audio output devices that achieve sound conduction within a specific range. Compared with traditional in-ear and over-ear headphones, open-back headphones are characterized by not blocking or covering the ear canal, allowing users to obtain sound information from the external environment while listening to music, improving safety and comfort. The output performance of open-back headphones has a significant impact on user comfort.

[0004] Therefore, it is necessary to propose an open-back headphone to improve its output performance. Summary of the Invention

[0005] One embodiment of this application provides an open-back headphone, comprising: a sound-generating part including a transducer and a housing accommodating the transducer, wherein the transducer includes a diaphragm; an ear hook, wherein, in the wearing state, a first part of the ear hook is hung between the user's auricle and head, and a second part of the ear hook extends toward the side of the auricle away from the head and connects to the sound-generating part to fix the sound-generating part in a position near the ear canal without blocking the ear canal, wherein a sound outlet is formed on the inner side of the housing facing the auricle to guide the sound generated on the front side of the diaphragm out of the housing and into the ear canal, and at least two pressure relief holes are formed on other sidewalls of the housing, including a first pressure relief hole and a second pressure relief hole, wherein the distance between the center of the first pressure relief hole and the center of the second pressure relief hole is 13.0mm-15.2mm, which allows the first pressure relief hole and the second pressure relief hole to be offset in the X direction so that the first pressure relief hole and the second pressure relief hole are not blocked by the tragus.

[0006] In some embodiments, the distance between the center of the sound outlet and the perpendicular bisector of the line connecting the center of the first pressure relief hole and the center of the second pressure relief hole is 0mm to 2mm, so that the first pressure relief hole and the second pressure relief hole are as far away from the sound outlet as possible, so as to avoid the sound output from the first pressure relief hole and the second pressure relief hole affecting the volume of the sound output from the sound outlet at the listening position.

[0007] In some embodiments, the first pressure relief hole is opened on the upper side of the housing and the second pressure relief hole is opened on the lower side of the housing. This can maximally disrupt the high-pressure region of the sound field in the rear cavity, shorten the wavelength of the standing wave in the rear cavity, and thus make the resonant frequency of the sound emanating from the first pressure relief hole / second pressure relief hole to the outside of the housing as high as possible.

[0008] In some embodiments, when worn, the housing is at least partially inserted into the concha cavity, and the distance from the center of the second pressure relief hole to the rear side of the housing is greater than the distance from the center of the first pressure relief hole to the rear side. Since the first pressure relief hole is located on the upper side and is farther from the sound outlet than the second pressure relief hole, the sound generated by the first pressure relief hole is more difficult to transmit to the ear canal than the second pressure relief hole. Therefore, to avoid the sound emitted by the second pressure relief hole canceling out the sound emitted by the sound outlet in the ear canal, resulting in a decrease in listening volume, the second pressure relief hole can be located further away from the rear side than the first pressure relief hole.

[0009] In some embodiments, the distance from the center of the first pressure relief hole to the inner surface of the housing facing the auricle ranges from 4.24 mm to 6.38 mm, which can prevent all or part of the area of ​​the first pressure relief hole and / or the second pressure relief hole from being blocked in the Z direction, thereby reducing the effective area of ​​the first pressure relief hole and / or the second pressure relief hole.

[0010] In some embodiments, the distance from the center of the first pressure relief hole to the rear side surface ranges from 10.44 mm to 15.68 mm. While ensuring that the sound-generating part is at least partially inserted into the concha cavity, by setting appropriate distances between the first and second pressure relief holes and the rear side surface RS of the sound-generating part, it is possible to avoid the entire or part of the area of ​​the first and / or second pressure relief holes being blocked in the X direction due to the contact between the free end FE and the concha cavity wall, thus ensuring that the effective area of ​​the first and / or second pressure relief holes is not reduced.

[0011] In some embodiments, the transducer includes a magnetic circuit assembly for providing a magnetic field, and the distance from the center of the first pressure relief hole to the bottom surface of the magnetic circuit assembly ranges from 1.31 mm to 1.98 mm. By rationally designing the distance from the center of the first pressure relief hole to the bottom surface of the magnetic circuit assembly, the volume of the rear cavity can have an appropriate range, thereby enabling the rear cavity to have a larger resonant frequency and a larger acoustic capacitance.

[0012] In some embodiments, the transducer includes a magnetic circuit assembly for providing a magnetic field. The distance between the center of the first pressure relief hole and the center plane of the long axis of the magnetic circuit assembly ranges from 5.45 mm to 8.19 mm, which can define the size of the sound-emitting part along the Y direction so that the size of the sound-emitting part can be adapted to the size of the concha cavity.

[0013] In some embodiments, the distance between the center of the second pressure relief hole and the inner side of the housing facing the auricle is in the range of 13.51 mm to 20.27 mm. In some embodiments, the distance between the center of the second pressure relief hole and the rear side is in the range of 13.51 mm to 20.27 mm. This allows the distance between the sound hole and the second pressure relief hole to be larger, so that the effect of the sound emitted by the second pressure relief hole canceling out the sound emitted by the sound outlet hole at the listening position (i.e., the ear canal) is weakened, thereby increasing the volume at the listening position.

[0014] In some embodiments, the transducer includes a magnetic circuit assembly for providing a magnetic field, and the distance from the center of the second pressure relief hole to the bottom surface of the magnetic circuit assembly ranges from 1.31 mm to 1.98 mm. By rationally designing the distance from the center of the second pressure relief hole to the bottom surface of the magnetic circuit assembly, the volume of the rear cavity can have an appropriate range, thereby enabling the rear cavity to have a larger resonant frequency and a larger acoustic capacitance.

[0015] In some embodiments, the transducer includes a magnetic circuit assembly for providing a magnetic field. The distance between the center of the second pressure relief hole and the center plane of the long axis of the magnetic circuit assembly ranges from 5.46 mm to 8.20 mm, which can define the size of the sound-emitting part along the Y direction so that the size of the sound-emitting part can be adapted to the size of the concha cavity.

[0016] In some embodiments, when worn, the shell is at least partially inserted into the concha cavity, and the area of ​​the second pressure relief hole is smaller than that of the first pressure relief hole, so as to reduce the sound intensity output from the second pressure relief hole and transmitted to the ear canal, so as to avoid the sound emitted from the second pressure relief hole from canceling the sound emitted from the sound outlet hole in the ear canal (i.e., the listening position) and thus reducing the listening volume.

[0017] In some embodiments, the area of ​​the first pressure relief orifice ranges from 3.78 mm. 2 ~22.07 mm 2 The area of ​​the second pressure relief hole is 2.78 mm. 2 ~16.07 mm 2By rationally designing the areas of the first and second pressure relief holes, the frequency response curve of open-back headphones can have a wider, flatter region, achieving better sound leakage reduction in the mid-to-high frequency range. Furthermore, while ensuring the high-pressure area of ​​the rear cavity's sound field is not disrupted, the sound generated in the rear cavity has sufficient intensity in the far field. Additionally, it avoids the impact of excessively large areas of the first and second pressure relief holes on the appearance, structural strength, waterproofing, dustproofing, and other aspects of the open-back headphones.

[0018] In some embodiments, the ratio of the area of ​​the first pressure relief hole to the area of ​​the upper side is between 0.036 and 0.093, and the ratio of the area of ​​the second pressure relief hole to the area of ​​the lower side is between 0.018 and 0.051. This can ensure that the resonant frequency of the rear cavity is high enough while maintaining the stability of the physical structure of the shell, thereby ensuring the service life of the open-back headphones.

[0019] In some embodiments, the transducer includes a magnetic circuit assembly for providing a magnetic field, wherein the overlapping area of ​​the projections of the first pressure relief orifice and the second pressure relief orifice onto the long axis center plane of the magnetic circuit assembly is no greater than 10.77 mm. 2 The first pressure relief hole and the second pressure relief hole can be staggered in the X direction so that the first pressure relief hole and the second pressure relief hole can destroy the standing wave of the rear cavity as much as possible, thereby increasing the resonant frequency of the rear cavity.

[0020] In some embodiments, the length of the line connecting the center of the first pressure relief hole and the center of the second pressure relief hole on the plane where the bottom surface of the magnetic circuit assembly is located ranges from 8.51 mm to 15.81 mm, which allows the first pressure relief hole and the second pressure relief hole to be staggered in the X direction.

[0021] In some embodiments, the angle between the connecting line and the minor axis of the housing ranges from 12.85° to 23.88°, which ensures that the first pressure relief hole and the second pressure relief hole are not too misaligned in the X direction.

[0022] In some embodiments, when worn, the housing at least partially covers the antihelix, and the difference between the center of the second pressure relief hole on the lower side and the rear side of the housing and the center of the first pressure relief hole on the upper side and the rear side is less than 10%, so that the first pressure relief hole and the second pressure relief hole can be approximately symmetrically distributed with respect to the long axis center plane of the sound-emitting part, which facilitates manufacturing.

[0023] In some embodiments, the distance from the center of the first pressure relief hole to the inner surface of the housing facing the auricle ranges from 4.43 mm to 7.96 mm, or the distance from the center of the second pressure relief hole to the inner surface ranges from 4.43 mm to 7.96 mm. This can increase the acoustic path from the first and / or second pressure relief holes to the ear canal, thereby further improving the sound production efficiency of the open-back headphones. Furthermore, the overall size of the sound-producing part cannot be too large (e.g., the size of the sound-producing part in the Z direction cannot be too large), otherwise it will increase the overall mass of the open-back headphones, affecting the user's wearing comfort.

[0024] In some embodiments, the distance between the center of the first pressure relief hole and the rear side surface ranges from 8.60 mm to 12.92 mm, or the distance between the center of the second pressure relief hole and the rear side surface ranges from 8.60 mm to 12.92 mm.

[0025] In some embodiments, the ratio of the major axis dimension to the minor axis dimension of the first pressure relief hole is between 1 and 8, or the ratio of the major axis dimension to the minor axis dimension of the second pressure relief hole is between 1 and 8, which can ensure the sound intensity output by the first pressure relief hole and the second pressure relief hole.

[0026] In some embodiments, there is a first distance between the center of the first pressure relief hole and the center of the sound outlet hole, and a second distance between the center of the second pressure relief hole and the sound outlet hole, wherein the difference between the first distance and the second distance is less than 10%, so that the center of the sound outlet hole is approximately on the perpendicular plane of the line connecting the center of the first pressure relief hole and the center of the second pressure relief hole.

[0027] In some embodiments, the first distance is 5.12 mm to 15.11 mm, which can prevent the sound waves emitted from the first pressure relief hole from canceling out the sound waves emitted from the sound outlet hole in the near field, thus affecting the user's listening quality.

[0028] In some embodiments, the distance between the projection point of the center of the first pressure relief hole in the sagittal plane and the projection point of the midpoint of the upper boundary of the inner side surface in the sagittal plane is no greater than 2 mm.

[0029] In some embodiments, the distance between the projection point of the midpoint of the upper boundary of the inner surface in the sagittal plane and the projection point of the center of the ear canal opening in the sagittal plane is in the range of 12 mm to 18 mm, which can ensure that the sound-producing part extends into the concha cavity and there is an appropriate gap between the upper boundary of the inner surface and the concha cavity (forming an opening for the cavity structure).

[0030] In some embodiments, the distance between the projection point of the center of the first pressure relief hole in the sagittal plane and the projection point of the center of the ear canal opening in the sagittal plane is in the range of 12 mm to 18 mm, which can ensure that the sound-producing part extends into the concha cavity and there is an appropriate gap between the upper boundary of the inner surface and the concha cavity (forming an opening for the cavity structure).

[0031] In some embodiments, the distance between the projection point of the center of the second pressure relief hole in the sagittal plane and the projection point of the center of the ear canal opening in the sagittal plane ranges from 6.88 mm to 10.32 mm, which can ensure that the sound-producing part extends into the concha cavity and that there is an appropriate gap (forming an opening in the cavity structure) between the upper boundary of the inner surface and the concha cavity.

[0032] In some embodiments, the distance between the projection point of the center of the second pressure relief hole in the sagittal plane and the projection point of the midpoint of the upper boundary of the inner surface in the sagittal plane ranges from 14.4 mm to 21.6 mm. This allows the cavity structure to have a suitable volume, provided that the sound-generating part is at least partially inserted into the concha cavity, so as to improve the sound reception effect of the ear canal.

[0033] In some embodiments, the distance between the projection point of the center of the first pressure relief hole in the sagittal plane and the projection point of the lower boundary of the inner side in the sagittal plane at 1 / 3 of the distance is in the range of 13.76 mm to 20.64 mm. This allows the cavity structure to have a suitable volume, provided that the sound-generating part is at least partially inserted into the concha cavity, so as to improve the sound reception effect of the ear canal.

[0034] In some embodiments, the distance between the projection point of the center of the second pressure relief hole in the sagittal plane and the projection point of the lower boundary of the inner side in the sagittal plane at 1 / 3 of the distance is in the range of 8.16 mm to 12.24 mm, so as to reduce the degree of sound cancellation between the second pressure relief hole and the sound outlet hole transmitted into the cavity structure through the second leakage structure.

[0035] In some embodiments, the distance between the projection point of the lower 1 / 3 point of the inner surface in the sagittal plane and the projection point of the ear canal opening in the sagittal plane ranges from 1.76 mm to 2.64 mm, which can ensure that the sound-producing part extends into the concha cavity and that there is an appropriate gap between the upper boundary of the inner surface and the concha cavity (forming an opening for the cavity structure).

[0036] In some embodiments, when worn, the distance between the first pressure relief hole and any point on the second part of the ear hook in the direction of the long axis of the sound-emitting part is in the range of 5.28 mm to 13.02 mm, so that the earphone can fit the user's ear when the user wears the open-back earphone.

[0037] This specification also provides an open-back headphone, comprising: a sound-generating part including a transducer and a housing accommodating the transducer, wherein the transducer includes a diaphragm; an ear hook, wherein, in the wearing state, a first part of the ear hook is hung between the user's auricle and head, and a second part of the ear hook extends toward the side of the auricle away from the head and connects to the sound-generating part to fix the sound-generating part in a position near the ear canal without blocking the ear canal, wherein a sound outlet is formed on the inner side of the housing facing the auricle for discharging the sound generated on the front side of the diaphragm through the housing and transmitting it to the ear canal, and at least two pressure relief holes are formed on other sidewalls of the housing, including a first pressure relief hole and a second pressure relief hole, wherein the distance between the center of the sound outlet and the perpendicular bisector of the line connecting the center of the first pressure relief hole and the center of the second pressure relief hole is 0mm to 2mm, so that the first pressure relief hole and the second pressure relief hole are as far away from the sound outlet as possible to avoid the sound output from the first pressure relief hole and the second pressure relief hole affecting the volume of the sound output from the sound outlet at the listening position.

[0038] This specification also provides an open-back headphone, comprising: a sound-emitting part including a transducer and a housing accommodating the transducer, wherein the transducer includes a diaphragm; an ear hook, wherein, in the wearing state, a first part of the ear hook is hung between the user's auricle and head, and a second part of the ear hook extends toward the side of the auricle away from the head and connects to the sound-emitting part to fix the sound-emitting part in a position near the ear canal without blocking the ear canal, wherein a sound outlet is formed on the inner side of the housing facing the auricle for discharging the sound generated on the front side of the diaphragm through the housing and transmitting it to the ear canal, and at least two pressure relief holes are formed on other sidewalls of the housing, including a first pressure relief hole and a second pressure relief hole, the housing is at least partially inserted into the concha cavity, and the area of ​​the second pressure relief hole is smaller than the area of ​​the first pressure relief hole to reduce the sound intensity discharged from the second pressure relief hole and transmitted to the ear canal, thereby reducing the degree of cancellation between the sound emitted from the second pressure relief hole and the sound emitted from the sound outlet in the ear canal (i.e., the listening position), thereby increasing the listening volume. Attached Figure Description

[0039] This application will be further described by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting; in these embodiments, the same reference numerals denote the same structures, wherein: Figure 1 This is a schematic diagram of an exemplary ear according to some embodiments of this application; Figure 2 These are exemplary structural diagrams of open-back headphones according to some embodiments of this application; Figure 3 This is a schematic diagram of two point sound sources and listening positions according to some embodiments of this application; Figure 4 This is a comparison chart of the sound leakage index of single-point sound sources and dual-point sound sources at different frequencies, based on some embodiments of this application. Figure 5 This is an exemplary distribution diagram of a baffle placed between two sound sources of a dipole sound source according to some embodiments of this application; Figure 6 This is a sound leakage index diagram of a dipole sound source with and without a baffle between two sound sources, according to some embodiments of this application. Figure 7 These are exemplary wearing diagrams of open-back headphones according to some embodiments of this application; Figure 8 yes Figure 7 A schematic diagram of the structure of an open-back headphone facing the ear; Figure 9 yes Figure 8 The diagram shows the structural schematic of the shell. Figure 10 This is an exemplary distribution diagram of a cavity structure surrounding one of the dipole sound sources shown in some embodiments of this application; Figure 11A This is a schematic diagram illustrating the listening principle of a dipole sound source structure and a cavity structure built around one of the dipole sound sources, as shown in some embodiments of this application. Figure 11B This is a schematic diagram illustrating the sound leakage principle of a dipole sound source structure and a cavity structure built around one of the dipole sound sources, according to some embodiments of this application. Figure 12A This is a schematic diagram of a cavity structure with two horizontal openings according to some embodiments of this application; Figure 12B This is a schematic diagram of a cavity structure with two vertical openings according to some embodiments of this application; Figure 13 This is a comparison diagram of the hearing index curves of a cavity structure with two openings and one opening, as shown in some embodiments of this application. Figure 14 These are exemplary wearing diagrams of open-back headphones according to other embodiments of this application; Figure 15 yes Figure 14 A schematic diagram of the structure of an open-back headphone facing the ear; Figure 16 This is a schematic diagram of the structure of the housing of an open-back headphone according to some embodiments of this application; Figure 17 These are frequency response curves of open-back headphones corresponding to first pressure relief holes of different areas, as shown in some embodiments of this application. Figure 18 These are frequency response curves of open-back headphones corresponding to second pressure relief holes of different areas, as shown in some embodiments of this application. Figure 19 This is a schematic diagram of the projection of an open-back headphone in the sagittal plane when it is in a wearing state, according to some embodiments of this application; Figure 20A This is an exemplary internal structure diagram of the sound-emitting part shown in some embodiments of this application; Figure 20B This is an exemplary structural diagram of a second acoustic cavity shown according to some embodiments of this specification; Figure 20C These are frequency response curves of the rear cavity corresponding to different included angles α as shown in some embodiments of this specification; Figure 21 This is an exemplary internal structure diagram of a transducer shown according to some embodiments of this application; Figure 22 This is a schematic diagram of the shell of an open-back headphone along the Z-direction on the plane containing the bottom surface of the magnetic circuit assembly. Detailed Implementation

[0040] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0041] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one way to distinguish different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0042] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0043] In the description of this application, it should be understood that the terms "first," "second," "third," "fourth," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first," "second," "third," or "fourth" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0044] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, the term "connection" can refer to a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0045] Figure 1 This is a schematic diagram of an exemplary ear according to some embodiments of this application. See also Figure 1The ear 100 (also referred to as the auricle) may include the external auditory canal 101, the concha 102, the cymba concha 103, the triangular fossa 104, the antihelix 105, the scaphoid fossa 106, the helix 107, the earlobe 108, the tragus 109, and the crus of the helix 1071. In some embodiments, the acoustic device can be stably worn by supporting it with one or more parts of the ear 100. In some embodiments, the external auditory canal 101, the concha 102, the cymba concha 103, the triangular fossa 104, etc., have a certain depth and volume in three-dimensional space, which can be used to meet the wearing requirements of the acoustic device. For example, the acoustic device (e.g., an in-ear headphone) can be worn in the external auditory canal 101. In some embodiments, the acoustic device (e.g., an open-back headphone) can be worn by using other parts of the ear 100 besides the external auditory canal 101. For example, the acoustic device can be worn using parts such as the cymba conchae 103, triangular fossa 104, antihelix 105, scaphoid fossa 106, and helix 107, or combinations thereof. In some embodiments, to improve the comfort and reliability of the acoustic device during wear, parts such as the user's earlobe 108 can also be used. 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 "liberated". When the user wears the acoustic device (e.g., open-back headphones), the acoustic device does not block the user's external auditory canal 101 (or ear canal or ear canal opening), and the user can receive both sound from the acoustic device and sound from the environment (e.g., horn sounds, car bell sounds, surrounding voices, traffic signals, etc.), thereby reducing the probability of traffic accidents. In some embodiments, the acoustic device can be designed to fit the ear 100 according to the structure of the ear 100, so that the sound-emitting part of the acoustic device can be worn at different positions on the ear. For example, when the acoustic device is an open-back headphone, the open-back headphone may include a suspension structure (e.g., an ear hook) and a sound-producing part, the sound-producing part being physically connected to the suspension structure, and the suspension structure being adapted to the shape of the auricle to place the entire or part of the sound-producing part in front of the tragus 109 (e.g., Figure 1 The area J enclosed by the dotted line. For example, when a user wears open-back headphones, the entire or partial structure of the sound-producing part can contact the upper part of the external auditory canal 101 (e.g., the location of one or more parts such as the cymba conchae 103, triangular fossa 104, antihelix 105, scaphoid 106, helix 107, and crus of helix 1071). For yet another example, when a user wears open-back headphones, the entire or partial structure of the sound-producing part can be located within the cavity formed by one or more parts of the ear 100 (e.g., the cavum conchae 102, cymba conchae 103, triangular fossa 104, etc.). Figure 1 The region M1, enclosed by the dashed line, includes at least the cymba conchae 103 and the triangular fossa 104, and the region M2, which includes at least the cavum conchae 102.

[0046] Individual differences may exist among users, resulting in variations in ear shape, size, and other dimensional differences. For ease of description and understanding, unless otherwise specified, this application will primarily use an ear model with a "standard" shape and size as a reference to further describe the wearing method of the acoustic device in different embodiments on this ear model. For example, a simulator containing a head and its (left and right) ears, such as the GRAS 45BC KEMAR, can be manufactured based on ANSI: S3.36, S3.25 and IEC: 60318-7 standards, as a reference for wearing the acoustic device, thus representing the scenario of most users normally wearing the acoustic device. As an example only, the reference ear may have the following related characteristics: the dimension of the auricle's projection in the sagittal plane along the vertical axis can be in the range of 49.5mm-74.3mm, and the dimension of the auricle's projection in the sagittal plane along the sagittal axis can be in the range of 36.6mm-55mm. Therefore, in this application, descriptions such as "user wearing," "in wearing state," and "under wearing state" can refer to the acoustic device described in this application being worn on the ear of the aforementioned simulator. Of course, considering the individual differences among different users, the structure, shape, size, thickness, etc. of one or more parts of the ear 100 may have certain differences. In order to meet the needs of different users, the acoustic device can be designed differently. These differentiated designs can be manifested in that the characteristic parameters of one or more parts of the acoustic device (e.g., the sound-emitting part, ear hook, etc. mentioned below) can have different ranges of values ​​to adapt to different ears.

[0047] It should be noted that in medicine, anatomy, and other fields, the human body can be defined by three basic planes: the sagittal plane, the coronal plane, and the horizontal plane; and three basic axes: the sagittal axis, the coronal axis, and the vertical axis. The sagittal plane is a section perpendicular to the ground along the anteroposterior direction of the body, dividing the body into left and right parts. The coronal plane is a section perpendicular to the ground along the left and right direction of the body, dividing the body into anterior and posterior parts. The horizontal plane is a section parallel to the ground along the vertical direction of the body, dividing the body into superior and inferior parts. Correspondingly, the sagittal axis is the axis along the anteroposterior direction of the body and perpendicular to the coronal plane; the coronal axis is the axis along the left and right direction of the body and perpendicular to the sagittal plane; and the vertical axis is the axis along the vertical direction of the body and perpendicular to the horizontal plane. Furthermore, the "front side of the ear" mentioned in this application is a concept relative to "back side of the ear," the former referring to the side of the ear away from the head, and the latter referring to the side of the ear facing the head. Specifically, by observing the ear of the simulator along the direction of the human coronal axis, one can obtain... Figure 1 A schematic diagram of the front outline of the ear is shown.

[0048] Figure 2 This is an exemplary structural diagram of an open-back headphone according to some embodiments of this application.

[0049] In some embodiments, the open-back headphones 10 may include, but are not limited to, air conduction headphones and bone conduction headphones. In some embodiments, the open-back headphones 10 may be combined with products such as glasses, headphones, head-mounted displays, and AR / VR headsets.

[0050] like Figure 2 As shown, the open-back headphones 10 may include a sound-emitting part 11 and an ear hook 12.

[0051] The sound-emitting part 11 can be worn on a user's body and can generate sound input into the user's ear canal. In some embodiments, the sound-emitting part 11 may include a transducer (e.g., Figure 20A The diagram shows a transducer 116 and a housing 111 for housing the transducer. The housing 111 can be connected to an ear hook 12. The transducer is used to convert electrical signals into corresponding mechanical vibrations to generate sound. In some embodiments, a sound outlet 112 is provided on the side of the housing facing the auricle. The sound outlet 112 is used to guide the sound generated by the transducer out of the housing 111 and into the ear canal so that the user can hear the sound. In some embodiments, the transducer (e.g., a diaphragm) can divide the housing 111 to form the front cavity of the earphone (e.g., a...). Figure 20AThe front cavity 114 and the rear cavity are shown. The sound outlet 112 can connect to the front cavity and transmit the sound generated in the front cavity to the ear canal after being discharged from the shell 111. In some embodiments, a portion of the sound emitted through the sound outlet 112 can propagate into the ear canal, allowing the user to hear the sound. Another portion, along with the sound reflected from the ear canal, can propagate through the gap between the sound-emitting part 11 and the ear (e.g., a portion of the concha not covered by the sound-emitting part 11) to the outside of the open-back headphones 10 and the ear, thus creating a first sound leakage in the far field. Simultaneously, one or more pressure relief holes 113 are typically provided on other sides of the housing 111 (e.g., sides away from or opposite to the user's ear canal). These pressure relief holes 113 are further away from the ear canal than the sound outlet 112, and the sound propagating from them typically creates a second sound leakage in the far field. The intensity of the first and second sound leakage is comparable, and their phases (close to each other) are opposite, allowing them to cancel each other out of phase in the far field, which helps reduce sound leakage in the far field of the open-back headphones 10. In some embodiments, at least two pressure relief holes 113 may be provided on other sides of the housing 111 besides the side facing the auricle. By providing at least two pressure relief holes 113, not only can the sound generated in the rear cavity be discharged from the housing 111, but the high-pressure region of the sound field in the rear cavity can also be disrupted, shortening the wavelength of the standing wave in the rear cavity. This results in the resonant frequency of the sound discharged from the pressure relief holes 113 to the outside of the housing 111 being as high as possible, for example, greater than 4kHz. At this time, the sound discharged from the sound outlet 112 and the sound discharged from the pressure relief holes 113 can maintain better consistency over a wider frequency range, and their far-field interference cancellation effect is better, thus achieving a better sound leakage reduction effect. For ease of description, this specification will use the example of two pressure relief holes on the sound-emitting part 11 for illustrative purposes. As an example only, the at least two pressure relief holes 113 may include a first pressure relief hole and a second pressure relief hole (e.g., as shown in the image). Figure 7 The first pressure relief hole 1131 and the second pressure relief hole 1132 are located on opposite sides of the housing 111, for example, opposite each other in the short axis direction Y, in order to minimize the high-pressure area of ​​the sound field in the rear cavity. In short, when a user wears the open-back headphones 10, the sound primarily heard is transmitted to the ear canal via the sound outlet 112. The pressure relief holes 113 are mainly used to balance the pressure in the rear cavity, allowing for sufficient vibration at low frequencies and large amplitudes. This results in a sound with deep bass and penetrating treble, while reducing sound leakage to the environment via the sound outlet 112. Further description of the sound-emitting part 11 can be found elsewhere in this application, such as... Figure 7 , Figure 14 , Figure 20A And their descriptions.

[0052] One end of the ear hook 12 can be connected to the sound-emitting part 11, and the other end extends along the junction of the user's ear and head. In some embodiments, the ear hook 12 can be an arc-shaped structure adapted to the user's auricle so that the ear hook 12 can be suspended at the user's auricle. For example, the ear hook 12 can have an arc-shaped structure adapted to the junction of the user's head and ear so that the ear hook 12 can be hung between the user's ear and head. In some embodiments, the ear hook 12 can also be a clamping structure adapted to the user's auricle so that the ear hook 12 can be clamped at the user's auricle. Exemplarily, the ear hook 12 may include hook-shaped portions (such as...) connected in sequence. Figure 7 The first part 121 shown) and the connecting part (such as Figure 7 The second part 122 shown. The connecting portion connects the hook-shaped portion and the sound-emitting portion 11, such that the open-back headphones 10 are curved in three-dimensional space when not worn (i.e., in their natural state). In other words, the hook-shaped portion, connecting portion, and sound-emitting portion 11 are not coplanar in three-dimensional space. This arrangement allows the hook-shaped portion to primarily hang between the back of the user's ear and head when the open-back headphones 10 are worn, and the sound-emitting portion 11 to primarily contact the front of the user's ear, thus allowing the sound-emitting portion 11 and the hook-shaped portion to cooperate in clamping the ear. As an example, the connecting portion can extend from the head outwards, thereby cooperating with the hook-shaped portion to provide pressure on the front of the ear for the sound-emitting portion 11. Specifically, the sound-emitting part 11 can press against the areas where the concha cavity 102, concha cymba 103, triangular fossa 104, and antihelix 105 are located under the action of the pressing force, so that the open-back headphones 10 do not block the external auditory canal 101 of the ear when they are worn.

[0053] In some embodiments, to improve the stability of the open-back headphones 10 during wear, the open-back headphones 10 may employ any one or a combination of the following methods: First, at least a portion of the ear hook 12 is configured as a conformal structure that conforms to at least one of the back of the ear 100 and the head, thereby increasing the contact area between the ear hook 12 and the ear 100 and / or the head, thus increasing the resistance to the open-back headphones 10 falling off the ear 100. Second, at least a portion of the ear hook 12 is configured as an elastic structure, allowing it to have a certain deformation during wear, thereby increasing the positive pressure of the ear hook 12 on the ear and / or the head, thus increasing the resistance to the open-back headphones 10 falling off the ear. Third, at least a portion of the ear hook 12 is configured to rest against the head during wear, creating a reaction force that presses against the ear, causing the sound-emitting part 11 to press against the front of the ear, thereby increasing the resistance to the open-back headphones 10 falling off the ear. Fourth, the sound-emitting part 11 and the ear hook 12 are configured to clamp the area where the antihelix and the concha are located from the front and back sides of the ear when worn, thereby increasing the resistance to the open-back headphones 10 falling off the ear. Fifth, the sound-emitting part 11 or the auxiliary structure connected to it is configured to at least partially extend into the concha, cymba conchae, triangular fossa, and scaphoid fossa, thereby increasing the resistance to the open-back headphones 10 falling off the ear.

[0054] In some embodiments, the ear hook 12 may include, but is not limited to, ear hooks, elastic bands, etc., so that the open-back headphones 10 can be better secured to the user and prevent the headphones from falling off during use. In some embodiments, the open-back headphones 10 may not include the ear hook 12, and the sound-producing part 11 may be fixed near the user's ear 100 by means of suspension or clamping.

[0055] In some embodiments, the sound-emitting part 11 can be, for example, a regular or irregular shape such as a ring, ellipse, racetrack shape, polygon, U-shape, V-shape, or semicircle, so that the sound-emitting part 11 can be directly attached to the user's ear 100. In some embodiments, the sound-emitting part 11 can have a major axis direction X and a minor axis direction Y that are perpendicular to the thickness direction Z and orthogonal to each other. The major axis direction X can be defined as the direction with the maximum extension dimension in the shape of the two-dimensional projection surface of the sound-emitting part 11 (e.g., the projection of the sound-emitting part 11 on the plane containing its outer surface, or the projection in the sagittal plane). (e.g., when the projection shape is rectangular or approximately rectangular, the major axis direction is the length direction of the rectangle or approximately rectangular.) The minor axis direction Y can be defined as the direction perpendicular to the major axis direction X in the shape of the projection of the sound-emitting part 11 in the sagittal plane (e.g., when the projection shape is rectangular or approximately rectangular, the minor axis direction is the width direction of the rectangle or approximately rectangular.) The thickness direction Z can be defined as a direction perpendicular to the two-dimensional projection surface, for example, consistent with the direction of the coronal axis, both pointing towards the left and right sides of the body.

[0056] In some embodiments, when a user wears the open-back headphones 10, the sound-emitting part 11 can be fixed near the user's external auditory canal 101 without blocking the ear canal. In some embodiments, when worn, the projection of the open-back headphones 10 onto the sagittal plane may not cover the user's ear canal. For example, the projection of the sound-emitting part 11 onto the sagittal plane may fall on the left and right sides of the head and be located in front of the tragus on the sagittal axis of the human body (e.g., Figure 2 (The position shown in the solid box A). At this time, the sound-emitting part 11 is located in front of the user's tragus. The major axis of the sound-emitting part 11 can be vertical or approximately vertical. The projection of the minor axis direction Y onto the sagittal plane is consistent with the direction of the sagittal axis. The projection of the major axis direction X onto the sagittal plane is consistent with the direction of the vertical axis. The thickness direction Z is perpendicular to the sagittal plane. For example, the projection of the sound-emitting part 11 onto the antihelix 105 can fall on the antihelix 105 (e.g., Figure 2 (The location is indicated by the dashed box C in the diagram). At this point, the sound-emitting part 11 is at least partially located at the antihelix 105. The major axis of the sound-emitting part 11 is horizontal or nearly horizontal. The projection of the major axis direction X of the sound-emitting part 11 onto the sagittal plane is consistent with the direction of the sagittal axis. The projection of the minor axis direction Y onto the sagittal plane is consistent with the direction of the vertical axis. The thickness direction Z is perpendicular to the sagittal plane. In this way, the sound-emitting part 11 can be prevented from covering the ear canal, thus freeing the user's ears. It can also increase the contact area between the sound-emitting part 11 and the ear 100, thereby improving the wearing comfort of the open-back headphones 10.

[0057] In some embodiments, when worn, the projection of the open-back headphone 10 onto the sagittal plane may cover or at least partially cover the user's ear canal. For example, the projection of the sound-emitting part 11 onto the sagittal plane may fall within the concha 102 (e.g., Figure 2(as shown in dashed box B), and in contact with the helix foot 1071 and / or the helix 107. At this time, the sound-emitting part 11 is at least partially located within the concha 102, and the sound-emitting part 11 is in an inclined state. The projection of the short axis direction Y of the sound-emitting part 11 onto the sagittal plane can have a certain angle with the direction of the sagittal axis, that is, the short axis direction Y is also set accordingly at an inclination. The projection of the long axis direction X onto the sagittal plane can also have a certain angle with the direction of the sagittal axis, that is, the long axis direction X is also set at an inclination. The thickness direction Z is perpendicular to the sagittal plane. At this time, since the concha 102 has a certain volume and depth, there is a certain gap between the inner surface IS of the open-back earphone 10 and the concha 10. The ear canal can communicate with the outside through the gap between the inner surface IS and the concha 10, thereby freeing the user's ears. At the same time, the sound-emitting part 11 and the concha 102 can cooperate to form an auxiliary cavity communicating with the ear canal (for example, the cavity structure mentioned later). In some embodiments, the sound outlet 112 may be located at least partially in the aforementioned auxiliary cavity. The sound emitted from the sound outlet 112 is limited by the aforementioned auxiliary cavity, that is, the aforementioned auxiliary cavity can concentrate the sound, so that the sound can propagate more into the ear canal, thereby improving the volume and quality of the sound heard by the user in the near field, thereby improving the acoustic effect of the open-back headphones 10.

[0058] The description of the open-back headphones 10 above is for illustrative purposes only and is not intended to limit the scope of this application. Those skilled in the art can make various changes and modifications based on the description in this application. For example, the open-back headphones 10 may also include a battery component, a Bluetooth component, or a combination thereof. The battery component can be used to power the open-back headphones 10. The Bluetooth component can be used to wirelessly connect the open-back headphones 10 to other devices (e.g., mobile phones, computers, etc.). These changes and modifications are still within the scope of protection of this application.

[0059] Figure 3 This is a schematic diagram illustrating two point sound sources and listening positions according to some embodiments of this application. In some embodiments, combined with Figure 3Sound can be transmitted to the outside of the open-back earphone 10 through the sound outlet 112, which can be regarded as a monopole sound source (or point sound source) A1, producing a first sound; sound can also be transmitted to the outside of the open-back earphone 10 through the pressure relief hole 113, which can be regarded as a monopole sound source (or point sound source) A2, producing a second sound. The second sound and the first sound can be out of phase or approximately out of phase, so that they can cancel each other out in the far field, that is, form an "acoustic dipole" to reduce sound leakage. In some embodiments, when worn, the line connecting the two monopole sound sources can point to the ear canal (denoted as the "hearing position") so that the user can hear a sufficiently loud sound. The sound pressure level at the hearing position (denoted as Pear) can be used to characterize the intensity of the sound heard by the user (i.e., near-field hearing sound pressure). Further, the sound pressure level can be statistically analyzed on a sphere centered on the user's hearing position (or on a sphere centered on the dipole sound source (e.g., Figure 3 The sound pressure level (denoted as Pfar) on a sphere with radius r centered at points A1 and A2 (as shown) can be used to characterize the intensity of sound leakage radiated from the open-back headphone 10 to the far field (i.e., the far-field sound leakage pressure). Pfar can be obtained using various statistical methods, such as taking the average sound pressure at each point on the sphere, or performing an area integral on the sound pressure distribution at each point on the sphere.

[0060] It should be understood that the method for measuring sound leakage in this application is only an illustrative example of the principle and effect, and is not intended to be limiting. The measurement and calculation methods for sound leakage can also be reasonably adjusted according to actual conditions. For example, with the center of the dipole sound source as the center, the sound pressure amplitude values ​​of two or more points are uniformly taken at a certain spatial angle in the far field and averaged. In some embodiments, the listening measurement method can be to select a location near the point sound source as the listening position, and use the sound pressure amplitude value measured at that listening position as the listening value. In some embodiments, the listening position can be on the line connecting the two point sound sources, or it can be not on the line connecting the two point sound sources. The measurement and calculation methods for listening can also be reasonably adjusted according to actual conditions. For example, the sound pressure amplitude values ​​of other points or one or more points in the near field can be averaged. As another example, with a certain point sound source as the center, the sound pressure amplitude values ​​of two or more points are uniformly taken at a certain spatial angle in the near field and averaged. In some embodiments, the distance between the near field listening position and the point sound source is much smaller than the distance between the point sound source and the far field sound leakage measurement sphere.

[0061] Clearly, the sound pressure level (Pear) delivered to the user's ear by the open-back headphones 10 should be high enough to enhance the listening experience; the sound pressure level (Pfar) in the far field should be low enough to increase sound leakage reduction. Therefore, the sound leakage index α can be used as an indicator to evaluate the sound leakage reduction capability of the open-back headphones 10. (1)

[0062] According to formula (1), the smaller the leakage index, the stronger the leakage reduction capability of open-back headphones. Under the condition that the near-field listening volume is the same at the listening position, the far-field leakage is smaller.

[0063] Figure 4 This is a comparison chart of the sound leakage index of single-point and dual-point sound sources at different frequencies, based on some embodiments of this application. Figure 4 The two-point sound source (also known as a dipole sound source) in the example can be a typical two-point sound source, meaning the spacing between the two points is fixed, the amplitudes of the two sound sources are the same, and the phases of the two sound sources are opposite. It should be understood that the selection of a typical two-point sound source is only for illustrating the principle and effect; the parameters of each sound source can be adjusted according to actual needs to make it differ from a typical two-point sound source. For example... Figure 4 As shown, with a fixed spacing, the sound leakage generated by a two-point sound source increases with increasing frequency, while the sound leakage reduction capability decreases with increasing frequency. When the frequency is greater than a certain value (e.g., as...), Figure 4 When the frequency is around 8000 Hz, the sound leakage generated will be greater than that of a single-point sound source. This frequency (e.g., 8000 Hz) is the upper limit frequency at which a dual-point sound source can reduce sound leakage.

[0064] In some embodiments, in order to improve the acoustic output effect of the open-back headphones 10, that is, to increase the sound intensity at the near-field listening position and reduce the volume of far-field sound leakage, a baffle can be provided between the sound outlet 112 and the pressure relief hole 113.

[0065] Figure 5 This is an exemplary distribution diagram showing a baffle placed between two sound sources of a dipole sound source according to some embodiments of this application. Figure 5 As shown, when a baffle is placed between point sound sources A1 and A2, in the near field, the sound wave from point sound source A2 needs to bypass the baffle to interfere with the sound wave from point sound source A1 at the listening position, which is equivalent to increasing the sound path from point sound source A2 to the listening position. Therefore, assuming that point sound sources A1 and A2 have the same amplitude, compared to the case without a baffle, the amplitude difference between the sound waves from point sound sources A1 and A2 at the listening position increases, thus reducing the degree of cancellation between the two sound paths at the listening position and increasing the volume at the listening position. In the far field, since the sound waves generated by point sound sources A1 and A2 do not need to bypass the baffle to interfere over a large spatial range (similar to the case without a baffle), the sound leakage in the far field does not increase significantly compared to the case without a baffle. Therefore, placing a baffle structure around one of the point sound sources A1 and A2 can significantly increase the volume at the near field listening position without significantly increasing the volume of sound leakage in the far field.

[0066] Figure 6This is a sound leakage index diagram of a dipole sound source with and without a baffle between two sound sources, according to some embodiments of this application. Adding a baffle between the two point sound sources effectively increases the distance between them in the near field. The volume at the near-field listening position is equivalent to being generated by a larger-distance two-point sound source, resulting in a significantly increased near-field listening volume compared to the case without a baffle. In the far field, the sound field of the two point sound sources is minimally affected by the baffle, and the resulting sound leakage is equivalent to being generated by a smaller-distance two-point sound source. Therefore, as... Figure 6 As shown, after adding the baffle, the sound leakage index is much smaller than that without the baffle. That is, at the same listening volume, the sound leakage in the far field is smaller than that without the baffle, and the sound leakage reduction capability is significantly enhanced.

[0067] Figure 7 This is an exemplary wearing diagram of an open-back headphone according to some embodiments of this application. Figure 8 yes Figure 7 The diagram shows the structure of an open-back headphone facing the ear. Figure 9 yes Figure 7 The diagram shows the structural structure of the shell of an open-back headphone.

[0068] like Figure 7 As shown, the ear hook 12 is an arc-shaped structure that fits against the junction of the user's head and ear 100. The sound-emitting part 11 (or the housing 111 of the sound-emitting part 11) may have a connecting end CE connected to the ear hook 12 and a free end FE not connected to the ear hook 12. When the open-back headphones 10 are in the wearing state, the first part 121 of the ear hook 12 (e.g., the hook-shaped part of the ear hook 12) is hung between the user's auricle (e.g., the helix 107) and the head, and the second part 122 of the ear hook 12 (e.g., the connecting part of the ear hook) extends toward the side of the auricle away from the head and connects to the connecting end CE of the sound-emitting part 11 to fix the sound-emitting part 11 in a position near the ear canal but without blocking the ear canal.

[0069] Combination Figure 7 and Figure 8As shown, the sound-emitting part 11 may have an inner surface IS (also called the inner surface of the housing 111) facing the ear along the thickness direction Z when worn, and an outer surface OS (also called the outer surface of the housing 111) facing away from the ear, as well as a connecting surface connecting the inner surface IS and the outer surface OS. It should be noted that when viewed along the direction of the coronal axis (i.e., the thickness direction Z) when worn, the sound-emitting part 11 may be shaped as a circle, an ellipse, a rounded square, a rounded rectangle, etc. When the sound-emitting part 11 is shaped as a circle, an ellipse, etc., the connecting surface may refer to the arc-shaped side of the sound-emitting part 11; while when the sound-emitting part 11 is shaped as a rounded square, a rounded rectangle, etc., the connecting surface may include the lower surface LS (also called the lower surface of the housing 111), the upper surface US (also called the upper surface of the housing 111), and the rear surface RS (also called the rear surface of the housing 111) mentioned later. In this specification, the upper side US and the lower side LS can refer to the side of the sound-emitting part 11 facing away from the external auditory canal 101 along the minor axis Y and the side closer to the external auditory canal 101, respectively, when worn; the rear side RS can refer to the side of the sound-emitting part 11 facing the back of the head along the length direction X when worn. For ease of description, this specification uses a rounded rectangle as an example for illustration. The length of the sound-emitting part 11 along the major axis X can be greater than the width of the sound-emitting part 11 along the minor axis Y. In some embodiments, to improve the aesthetics and wearing comfort of the headphones, the rear side RS of the headphones can be a curved surface.

[0070] A transducer may be provided within the sound-generating section 11, which converts electrical signals into corresponding mechanical vibrations to generate sound. The transducer (e.g., a diaphragm) divides the housing 111 into a front cavity and a rear cavity of the earphone. The sounds generated in the front and rear cavities are out of phase. A sound outlet 112 communicating with the front cavity is provided on the inner surface IS to guide the sound generated in the front cavity out of the housing 111 and into the ear canal so that the user can hear the sound. One or more pressure relief holes 113 communicating with the rear cavity may be provided on other sides of the housing 111 (e.g., the outer surface OS, the upper surface US, or the lower surface LS, etc.) to guide the sound generated in the rear cavity out of the housing 111 and cancel out the sound leaking through the sound outlet 112 in the far field. In some embodiments, the pressure relief hole 113 is further away from the ear canal than the sound outlet 112 to reduce the out-of-phase cancellation between the sound output through the pressure relief hole 113 and the sound output through the sound outlet 112 at the listening position (e.g., the ear canal), thereby increasing the sound volume at the listening position.

[0071] In some embodiments, besides the inner surface IS, at least two pressure relief holes 113 may be provided on other sides of the housing 111 (e.g., the outer surface OS, the upper surface US, or the lower surface LS). The arrangement of at least two pressure relief holes 113 can disrupt the standing waves in the rear cavity, making the resonant frequency of the sound vented from the pressure relief holes 113 to the outside of the housing 111 as high as possible. This results in a wider flat region in the frequency response of the rear cavity (e.g., the region before the resonant peak) and better sound leakage reduction in the mid-to-high frequency range (e.g., 2kHz-6kHz). By way of example only, the pressure relief holes 113 may include a first pressure relief hole 1131 and a second pressure relief hole 1132. The second pressure relief hole 1132 may be closer to the sound outlet 112 than the first pressure relief hole 1131. In some embodiments, the first pressure relief hole 1131 and the second pressure relief hole 1132 may be provided on the same side of the housing 111. For example, the first pressure relief hole 1131 and the second pressure relief hole 1132 may be provided simultaneously on the outer surface OS, the upper surface US, or the lower surface LS. In some embodiments, the first pressure relief hole 1131 and the second pressure relief hole 1132 may be respectively disposed on two different sides of the housing 111. For example, the first pressure relief hole 1131 may be disposed on the outer side OS and the second pressure relief hole 1132 may be disposed on the upper side US, or the first pressure relief hole 1131 may be disposed on the outer side OS and the second pressure relief hole 1132 may be disposed on the lower side LS. In some embodiments, in order to maximally destroy the standing wave in the rear cavity, the two pressure relief holes 113 may be located on opposite sides of the housing 111. For example, the first pressure relief hole 1131 may be disposed on the upper side US and the second pressure relief hole 1132 may be disposed on the lower side LS. For ease of description, this specification will use the example of the first pressure relief hole 1131 being disposed on the upper side US and the second pressure relief hole 1132 being disposed on the lower side LS for illustrative purposes.

[0072] In some embodiments, to prevent the sound output from the first pressure relief hole 1131 and the second pressure relief hole 1132 from affecting the volume of the sound output from the sound outlet 112 at the listening position, the first pressure relief hole 1131 and the second pressure relief hole 1132 should be as far away from the sound outlet 112 as possible. For example, the center of the sound outlet 112 can be located on or near the perpendicular bisector of the line connecting the center of the first pressure relief hole 1131 and the center of the second pressure relief hole 1132. In some embodiments, the center of the sound outlet 112 can be 0 mm to 2 mm away from the perpendicular bisector of the line connecting the center of the first pressure relief hole 1131 and the center of the second pressure relief hole 1132. In some embodiments, to further prevent the sound emitted from the second pressure relief hole 1132 from canceling out the sound emitted from the sound outlet 112 in the ear canal (i.e., the listening position), thus reducing the listening volume, the area of ​​the second pressure relief hole 1132 can be reduced to decrease the sound intensity transmitted from the second pressure relief hole 1132 to the ear canal. In this case, the area of ​​the second pressure relief hole 1132 can be smaller than the area of ​​the first pressure relief hole 1131 (e.g., ...). Figure 16 (As shown).

[0073] In some embodiments, such as Figure 7 As shown, when the open-back headphones 10 are in the wearing state, the long axis direction X of the sound-emitting part 11 can be set horizontally or approximately horizontally (with...). Figure 2 (Similar to position C shown), at this time, the sound-producing part 11 is at least partially located at the antihelix 105, and the free end FE of the sound-producing part 11 can face the back of the head. The sound-producing part 11 is in a horizontal or nearly horizontal state, and the projection of the long axis direction X of the sound-producing part 11 onto the sagittal plane can be consistent with the direction of the sagittal axis, the projection of the short axis direction Y onto the sagittal plane can be consistent with the vertical axis direction, and the thickness direction Z is perpendicular to the sagittal plane.

[0074] In some embodiments, in order to improve the fit between the open-back headphones 10 and the ear 100 and to improve the stability of wearing the open-back headphones 10, the inner side IS of the housing 111 can be pressed against the surface of the ear 100 (e.g., the antihelix 105) to increase the resistance to the open-back headphones 10 falling off the ear 100.

[0075] In some embodiments, combined with Figure 7 and Figure 8When the open-back earphone 10 is pressed against the ear 100, in order to prevent the sound outlet 112 on the inner surface IS from being blocked by ear tissue, the projection of the sound outlet 112 in the sagittal plane can partially or completely coincide with the projection of the concave structure of the ear (e.g., the cymba conchae 103) in the sagittal plane. In some embodiments, since the cymba conchae 103 communicates with the concha cavity 102 and the ear canal is located within the concha cavity 102, when at least a portion of the projection of the sound outlet 112 in the sagittal plane is located within the cymba conchae 103, the sound output from the sound outlet 112 can reach the ear canal without obstruction, thereby resulting in a higher volume received by the ear canal. In some embodiments, the long axis dimension of the sound-generating part 11 cannot be too long. If it is too long, the projection of the free end FE in the sagittal plane will exceed the projection of the ear in the sagittal plane, affecting the fit between the sound-generating part 11 and the ear. Therefore, the long axis dimension of the sound-generating part 11 can be designed such 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.

[0076] It should be understood that, since the sound outlet 112 and the pressure relief hole 113 (e.g., the first pressure relief hole 1131 and the second pressure relief hole 1132) are provided on the housing 111, and each side wall of the housing 111 has a certain thickness, both the sound outlet 112 and the pressure relief hole 113 are holes with a certain depth. In this case, both the sound outlet 112 and the pressure relief hole 113 can have an inner opening and an outer opening. For ease of description, in this application, the center O of the sound outlet 112 mentioned above and below can indicate the centroid of the outer opening of the sound outlet 112, and the center of the pressure relief hole 113 mentioned above and below can indicate the centroid of the outer opening of the pressure relief hole 113 (e.g., the center O1 of the first pressure relief hole 1131 can indicate the centroid of the outer opening of the first pressure relief hole 1131, and the center O2 of the second pressure relief hole 1132 can indicate the centroid of the outer opening of the second pressure relief hole 1132). In this specification, for ease of description, the area of ​​the sound outlet 112 and the pressure relief hole 113 (e.g., the first pressure relief hole 1131 and / or the second pressure relief hole 1132) can refer to the area of ​​the outer opening of the sound outlet 112 and the pressure relief hole 113 (e.g., the area of ​​the outer opening of the sound outlet 112 on the inner side IS, the area of ​​the outer opening of the first pressure relief hole 1131 on the upper side US, and the area of ​​the outer opening of the second pressure relief hole 1132 on the lower side LS). It should be understood that in some other embodiments, the area of ​​the sound outlet 112 and the pressure relief hole 113 can also refer to other cross-sectional areas of the sound outlet 112 and / or the pressure relief hole 113, such as the area of ​​the inner opening of the sound outlet 112 and / or the pressure relief hole 113, or the average of the inner opening area and the outer opening area of ​​the sound outlet 112 and / or the pressure relief hole 113.

[0077] In some embodiments, the sound outlet 112 communicating with the front cavity can be considered as Figure 5 The point sound source A1 shown, and the pressure relief port 113 (e.g., the first pressure relief port 1131 and / or the second pressure relief port 1132) connected to the rear cavity can be regarded as Figure 5 The ear canal can be considered as the point sound source A2 shown. Figure 5 The listening position is shown. At least a portion of the shell and / or at least a portion of the auricle of the sound-producing part 11 can be considered as... Figure 5 The baffle shown increases the sound path difference between the sound outlet 112 and the first pressure relief hole 1131 and / or the second pressure relief hole 1132 to the ear canal, thereby increasing the sound intensity in the ear canal while maintaining the far-field sound leakage reduction effect. When the open-back headphones 10 adopt Figure 7 When the structure shown is such that at least a portion of the housing 111 is located at the antihelix 105, the sound waves from the sound outlet 112 can directly reach the ear canal in terms of listening effect. In this case, the sound outlet 112 can be positioned on the inner surface IS near the lower surface LS, and at least one pressure relief hole can be positioned away from the sound outlet 112. For example, the first pressure relief hole 1131 can be positioned on the outer surface OS or the upper surface US away from the sound outlet 112. The sound waves from the first pressure relief hole 1131 need to bypass the outer side of the sound-emitting part 11 to interfere with the sound waves from the sound outlet 112 in the ear canal. Furthermore, the convex-concave structure of the auricle (e.g., the antihelix, tragus, etc. along its propagation path) also increases the sound path of the first pressure relief hole 1131 as it travels to the ear canal. Therefore, the sound-emitting part 11 itself and / or at least part of the auricle acts as a baffle between the sound outlet 112 and the first pressure relief hole 1131. The baffle increases the sound path from the first pressure relief hole 1131 to the ear canal and reduces the intensity of the sound wave from the first pressure relief hole 1131 in the ear canal. This reduces the degree to which the sounds emitted from the sound outlet 112 and the first pressure relief hole 1131 cancel each other out in the ear canal, thus increasing the volume of the ear canal. Regarding sound leakage, since the sound waves generated by the sound outlet 112 and the first pressure relief hole 1131 and / or the second pressure relief hole 1132 can interfere within a large spatial range without needing to bypass the sound-emitting part 11 itself (similar to the case without a baffle), sound leakage does not increase significantly. Therefore, by setting appropriate positions for the sound outlet 112, the first pressure relief hole 1131, and the second pressure relief hole 1132, the volume of the ear canal can be significantly increased without a significant increase in sound leakage.

[0078] In some embodiments, when the projection of the free end FE in the sagittal plane does not exceed the projection of the helix 107 in the sagittal plane, for ease of manufacturing, the first pressure relief hole 1131 and the second pressure relief hole 1132 are positioned relative to the long axis center plane of the sound-generating part 11 (e.g., as shown in the figure). Figure 8 The planes NN' (perpendicular to the paper and pointing inwards) shown can be approximately symmetrically distributed. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 on the lower side LS to the rear side RS is... a 2. The distance from the center O1 of the first pressure relief hole 1131 on the upper side US to the rear side RS aThe difference is less than 10%. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 on the lower side LS to the rear side RS is... a 2. The distance from the center O1 of the first pressure relief hole 1131 on the upper side US to the rear side RS a The difference is less than 5%. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 on the lower side LS to the rear side RS is... a 2. The distance from the center O1 of the first pressure relief hole 1131 on the upper side US to the rear side RS a The difference is less than 2%. It should be noted that in some embodiments, to improve the aesthetics and wearing comfort of the headphones, the rear side RS of the headphones can be curved. When the rear side RS is curved, the distance from a certain position (e.g., the center O1 of the first pressure relief hole 1131) to the rear side RS can refer to the distance from that position to the tangent plane parallel to the minor axis of the rear side RS.

[0079] In some embodiments, since the sound outlet 112 is positioned close to the ear canal, the second pressure relief hole 1132 on the lower side LS should be positioned as far away from the sound outlet 112 as possible. This reduces the canceling effect between the sound emitted from the second pressure relief hole 1132 and the sound emitted from the sound outlet 112 at the listening position (i.e., the ear canal), thereby increasing the volume at the listening position. Therefore, when the sound outlet 112 is positioned close to the lower side LS and the connecting end CE, the second pressure relief hole 1132 can be positioned close to the rear side RS, thereby maximizing the distance between the sound outlet 112 and the second pressure relief hole 1132. In some embodiments, when the projection of the free end FE in the sagittal plane does not exceed the projection of the helix 107 in the sagittal plane, the distance from the center O2 of the second pressure relief hole 1132 to the rear side RS is... a 2. The range can be 8.60 mm to 20.27 mm. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the rear side RS is... a 2. The range can be 8.60 mm to 12.92 mm. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the rear side RS is... a 2. The range can be 9.60 mm to 11.92 mm. In some embodiments, when the open-back headphones 10 are worn, the free end FE may come into contact with the ear (e.g., the helix 107), causing part of the upper side US and / or the lower side LS to be blocked by the ear. In this case, in order to prevent the second pressure relief hole 1132 on the lower side LS (or the first pressure relief hole 1131 on the upper side US) from being blocked by the ear 100, thereby affecting the acoustic performance of the open-back headphones 10, the distance from the center O2 of the second pressure relief hole 1132 to the rear side RS is... aThe range of 2 can be 10.10 mm to 11.42 mm. More preferably, the distance from the center O2 of the second pressure relief hole 1132 to the rear side RS is... a The range can be 10.30 mm to 11.12 mm. More preferably, the distance from the center O2 of the second pressure relief hole 1132 to the rear side RS is... a The range is 10.60 mm to 11.82 mm.

[0080] In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the rear side RS a 2. Distance from the center O1 of the first pressure relief hole 1131 to the rear side RS a When the difference between 1 and 2 is less than 10%, the distance from the center O1 of the first pressure relief hole 1131 to the rear side RS is... a The range can be 8.60 mm to 15.68 mm. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the rear side RS is... a The range can be 8.60 mm to 12.92 mm. In some embodiments, in order to make the projection of the first pressure relief hole 1131 in the sagittal plane largely coincide with the projection of the concave structure of the ear in the sagittal plane, the distance from the center O1 of the first pressure relief hole 1131 to the rear side surface RS is... a The range can be 9.60 mm to 11.92 mm. Preferably, the distance from the center O1 of the first pressure relief hole 1131 to the rear side RS is... a The range can be 10.10 mm to 11.42 mm. More preferably, the distance from the center O1 of the first pressure relief hole 1131 to the rear side RS is... a The range can be 10.30 mm to 11.12 mm. More preferably, the distance from the center O1 of the first pressure relief hole 1131 to the rear side RS is... a The range is 10.60 mm to 11.82 mm.

[0081] In some embodiments, the first pressure relief hole 1131 can be further away from the sound outlet hole 112 than the second pressure relief hole 1132, and because the gap between the ear portion 100 and the inner surface IS is smaller, the sound generated by the first pressure relief hole 1131 is more difficult to transmit to the ear canal than the second pressure relief hole 1132. Therefore, in some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the rear surface RS can be smaller than the distance from the center O2 of the second pressure relief hole 1132 to the rear surface RS. For example, the distance from the center O1 of the first pressure relief hole 1131 to the rear surface RS ranges from 10.44 mm to 15.68 mm, and the distance from the center O2 of the second pressure relief hole 1132 to the rear surface RS ranges from 13.51 mm to 20.27 mm.

[0082] In some embodiments, refer to Figure 9 To increase the acoustic path from the first pressure relief hole 1131 and / or the second pressure relief hole 1132 to the ear canal, the dimension of the open-back headphone 10 in the thickness direction Z can be increased, thereby improving the sound production efficiency (i.e., the listening volume at the listening position) of the open-back headphone 10. Furthermore, the first pressure relief hole 1131 and / or the second pressure relief hole 1132 can be positioned further away from the inner surface IS, thereby further increasing the acoustic path from the first pressure relief hole 1131 and / or the second pressure relief hole 1132 to the ear canal and improving the sound production efficiency of the open-back headphone 10. In addition, the overall size of the sound-emitting part 11 cannot be too large (e.g., the dimension of the sound-emitting part 11 in the Z direction cannot be too large), otherwise it will increase the overall mass of the open-back headphone 10 and affect the user's wearing comfort. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the inner surface IS is... d The range is 4.24 mm to 7.96 mm. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the inner surface IS is... d The range is 4.43 mm to 7.96 mm. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the inner surface IS is... d The range is 5.43 mm to 6.96 mm. In some embodiments, in the wearing state, in order to minimize or eliminate the overlap between the projection of the first pressure relief hole 1131 on the horizontal plane and the projection of the ear 100 on the horizontal plane, so that the sound output from the first pressure relief hole 1131 and / or the second pressure relief hole 1132 can radiate outward more, rather than being transmitted into the ear canal or transmitted into the ear canal after reflection and refraction by a part of the ear 100 (e.g., the auricle), the first pressure relief hole 1131 and / or the second pressure relief hole 1132 can be positioned away from the inner surface IS. This arrangement can further increase the sound path from the first pressure relief hole 1131 and / or the second pressure relief hole 1132 to the ear canal, improving the sound production efficiency of the open-back headphones 10. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the inner surface IS is... d The range is 5.63 mm to 7.96 mm. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the inner surface IS is... d 1. The range is 6.25 mm to 7.56 mm.

[0083] In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the inner surface IS is... d 2 can be the distance from the center O1 of the first pressure relief hole 1131 to the inner side IS. d 1. Same. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the inner surface IS is... d2. The range is 4.43 mm to 7.96 mm. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the inner surface IS is... d 2. The range is 5.43 mm to 6.96 mm. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the inner surface IS is... d 2. The range is 5.63 mm to 7.96 mm. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the inner surface IS is... d 2. The range is 6.25 mm to 7.56 mm.

[0084] In some embodiments, to bring the sound outlet 112 closer to the ear canal to increase the listening position, it is necessary to bring the sound outlet 112 closer to the lower side LS. In this case, the second pressure relief hole 1132 is closer to the inner side IS than the first pressure relief hole 1131. To reduce the canceling effect between the sound emitted by the second pressure relief hole 1132 and the sound emitted by the sound outlet 112 at the listening position (i.e., the ear canal), thereby increasing the volume at the listening position, in the Z direction, the second pressure relief hole 1132 can be further away from the inner side IS than the first pressure relief hole 1131, that is, the distance from the center O2 of the second pressure relief hole 1132 to the inner side IS is... d 2 can be the distance from the center O1 of the first pressure relief hole 1131 to the inner side IS. d 1. Different. For example, the distance from the center O1 of the first pressure relief hole 1131 to the inner surface IS. d 1. The range is 5.63 mm to 6.5 mm, and the distance from the center O2 of the second pressure relief hole 1132 to the inner side IS is... d 2. The range is 6.5 mm to 7.56 mm.

[0085] The description of the open-back headphone 10 above is for illustrative purposes only and is not intended to limit the scope of this application. Those skilled in the art can make various changes and modifications based on the description in this application. For example, when only one pressure relief hole is provided on the sound-emitting part 11, the pressure relief hole can be either the first pressure relief hole 1131 or the second pressure relief hole 1132 described above. For example, the pressure relief hole can be the first pressure relief hole 1131, that is, the pressure relief hole can be located on the upper side US. The distance from the center of the pressure relief hole to the inner side IS can range from 4.24 mm to 7.96 mm, and the distance from the center of the pressure relief hole to the rear side RS can range from 8.60 mm to 15.68 mm. These changes and modifications are still within the protection scope of this application.

[0086] In some embodiments, in order to increase the listening volume, especially the listening volume in the mid-low frequency range, while still retaining the effect of far-field sound leakage cancellation, a cavity structure can be constructed around one of the sound sources of the dual-point sound source. Figure 10 This is an exemplary distribution diagram of a cavity structure arranged around one of the dipole sound sources according to some embodiments of this application.

[0087] like Figure 10 As shown, when a cavity structure 41 is provided between the dipole sound sources, one dipole sound source and the listening position are located inside the cavity structure 41, while the other dipole sound source is located outside the cavity structure 41. The sound emitted by the dipole sound source inside the cavity structure 41 is limited by the cavity structure 41, that is, the cavity structure 41 can converge the sound, allowing more sound to propagate into the listening position, thereby improving the volume and quality of the sound at the listening position. In this application, "cavity structure" can be understood as a semi-enclosed structure formed by the sidewall of the sound-emitting part 11 and the concha cavity structure. This semi-enclosed structure ensures that the interior is not completely sealed and isolated from the external environment, but has a leakage structure 42 (e.g., an opening, a gap, a pipe, etc.) that acoustically communicates with the external environment. Exemplary leakage structures may include, but are not limited to, openings, gaps, pipes, etc., or any combination thereof.

[0088] In some embodiments, the cavity structure 41 may include a listening position and at least one sound source. Here, "including" can mean that at least one of the listening position and the sound source is inside the cavity, or it can mean that at least one of the listening position and the sound source is at the edge of the cavity. In some embodiments, the listening position may be the entrance to the ear canal or an acoustic reference point of the ear.

[0089] Figure 11A This is a schematic diagram illustrating the listening principle of a dipole sound source structure and a cavity structure built around one of the dipole sound sources, according to some embodiments of this application. Figure 11B This is a schematic diagram illustrating the sound leakage principle of a dipole sound source structure and a cavity structure built around one of the dipole sound sources, according to some embodiments of this application.

[0090] For near-field listening, such as Figure 11A The diagram shows a dipole with a cavity structure surrounding one of the sound sources. Because sound source A is enclosed by the cavity structure, most of the sound radiated from it reaches the listening position through direct or reflected rays. Conversely, without the cavity structure, most of the sound radiated from the source would not reach the listening position. Therefore, the cavity structure significantly increases the volume of the sound reaching the listening position. Simultaneously, only a small portion of the antiphase sound radiated from the antiphase sound source B outside the cavity structure enters the cavity structure through its leakage structure. This is equivalent to generating a secondary sound source B' at the leakage structure, whose intensity is significantly less than both sound source B and sound source A. The sound generated by the secondary sound source B' has a weak antiphase canceling effect on sound source A within the cavity, significantly increasing the listening volume at the listening position.

[0091] Regarding sound leakage, such as Figure 11B As shown, sound source A radiates sound to the outside through the leakage structure of the cavity, which is equivalent to generating a secondary sound source A' at the leakage structure. Since almost all the sound radiated 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 sound leakage (by at least one order of magnitude), the intensity of the secondary sound source A' can be considered comparable to that of sound source A. For the external space, the sound cancellation effect produced by the secondary sound source A' and sound source B is comparable to the sound cancellation effect produced by the sound source A and sound source B. That is, under this cavity structure, a considerable sound leakage reduction effect is still maintained.

[0092] It should be understood that the above-described leakage structure with one opening is merely an example. A cavity structure can contain one or more openings, achieving a superior listening index. The listening index can be defined as the reciprocal of the leakage index α, 1 / α. Taking a structure with two openings as an example, the cases of equal opening size and equal opening ratio are analyzed below. Comparing this to a structure with only one opening, "equal opening size" refers to having two openings of the same size as the structure with only one opening, and "equal opening ratio" refers to having the same sum of the opening areas of the two openings as the structure with only one opening. Equal opening size is equivalent to doubling the relative opening size of the structure with only one opening (i.e., the ratio of the opening area S of the leakage structure in the cavity structure to the area S0 directly affected by the contained sound source in the cavity structure). As mentioned earlier, the overall listening index will decrease. In the case of equal opening ratio, even if S / S0 is the same as the structure with only one opening, the distances from the two openings to the external sound source are different, thus resulting in different listening indices.

[0093] Figure 12A This is a schematic diagram of a cavity structure with two horizontal openings, according to some embodiments of this application. Figure 12B This is a schematic diagram of a cavity structure with two vertical openings, according to some embodiments of this application. For example... Figure 12A As shown, when the line connecting the two openings is parallel to the line connecting the two sound sources (i.e., two horizontal openings), the distances from the two openings to the external sound sources are at their maximum and minimum, respectively; as... Figure 12B As shown, when the two lines are perpendicular (i.e., two perpendicular openings), the distances from the two openings to the external sound source are equal and the intermediate value is obtained.

[0094] Figure 13 This is a comparison chart of hearing index curves for cavity structures with two openings and one opening, as shown in some embodiments of this application. For example... Figure 13 As shown, the overall listening comprehension index of a cavity structure with equal openings is lower than that of a cavity structure with only one opening. For cavity structures with equal opening ratios, the different distances from the two openings to the external sound source will also result in different listening comprehension indices. (Combined with...) Figure 12A , Figure 12B and Figure 13 It can be seen that, regardless of whether the opening is horizontal or vertical, the listening index of the leakage structure with equal opening ratio is higher than that of the leakage structure with equal opening ratio. This is because, compared to the leakage structure with equal opening ratio, the relative opening size S / S0 of the leakage structure with equal opening ratio is reduced by half, thus resulting in a higher listening index. Combined with... Figure 12A , Figure 12B and Figure 13 It can also be seen that, regardless of whether the leakage structure has equal orifice openings or equal orifice ratios, the listening index of the horizontal opening is higher. This is because in a horizontally opening leakage structure, the distance from one of the openings to the external sound source is less than the distance between the two sound sources. The resulting secondary sound source is closer to the external sound source than the original two sound sources, thus having a higher listening index and improving the sound leakage reduction effect. Therefore, to improve the sound leakage reduction effect, at least one opening should be made to be closer to the external sound source than the distance between the two sound sources.

[0095] In addition, such as Figure 13 As shown, a cavity structure with two openings improves the resonant frequency of airborne sound within the cavity structure compared to a cavity structure with one opening. This results in a better listening performance for the entire device in the high-frequency range (e.g., sounds near 10,000 Hz) compared to a cavity structure with only one opening. The high-frequency range is where the human ear is more sensitive, thus requiring greater noise reduction. Therefore, to improve noise reduction in the high-frequency range, a cavity structure with more than one opening can be selected.

[0096] Figure 14 This is an exemplary wearing diagram of an open-back headphone according to other embodiments of this application. Figure 15 yes Figure 14 The diagram shows the structure of an open-back headphone facing the ear.

[0097] Figure 14 The open-back headphones 10 shown are Figure 7 The structure of the open-back headphones 10 shown is similar. For example, the ear hook 12 is an arc-shaped structure that fits against the junction of the user's head and ear 100. The sound-emitting part 11 (or the housing 111 of the sound-emitting part 11) may have a connecting end CE connected to the ear hook 12 and a free end FE not connected to the ear hook 12. When the open-back headphones 10 are worn, the first part 121 of the ear hook 12 (e.g., the hook-shaped part of the ear hook 12) is hung between the user's auricle (e.g., the helix 107) and head, and the second part 122 of the ear hook 12 (e.g., the connecting part of the ear hook) extends toward the side of the auricle away from the head and connects to the connecting end CE of the sound-emitting part 11 to fix the sound-emitting part 11 in a position near the ear canal without blocking the ear canal. Figure 14The open-back headphones 10 shown are Figure 7 The structure of the open-back headphones 10 shown is similar, with the main difference being that the sound-emitting part 11 is angled, and the shell 111 of the sound-emitting part 11 is at least partially inserted into the concha 102. For example, the free end FE of the sound-emitting part 11 can extend into the concha 102. This structure of the ear hook 12 and the sound-emitting part 11 provides a better fit to the user's ear 100, increasing the resistance to the open-back headphones 10 falling off the ear 100, thereby increasing the wearing stability of the open-back headphones 10.

[0098] In some embodiments, when worn, viewed along the thickness direction Z, the connecting end CE of the sound-generating part 11 is closer to the top of the head than the free end FE, so that the free end FE can extend into the concha cavity. Based on this, the angle between the short axis direction Y and the direction of the human sagittal axis can be between 30° and 40°. If the aforementioned angle is too small, the free end FE may not be able to extend into the concha cavity, and the sound outlet 112 on the sound-generating part 11 may be too far from the ear canal; if the aforementioned angle is too large, the sound-generating part 11 may also not be able to extend into the concha cavity, and the ear canal may be blocked by the sound-generating part 11. In other words, this arrangement allows the sound-generating part 11 to extend into the concha cavity while maintaining a suitable distance between the sound outlet 112 on the sound-generating part 11 and the ear canal, so that the user can hear more of the sound generated by the sound-generating part 11 without the ear canal being blocked.

[0099] In some embodiments, the sound-generating part 11 and the ear hook 12 can jointly clamp the aforementioned ear region from both the front and rear sides of the ear region corresponding to the concha cavity, thereby increasing the resistance to the open-back headphones 10 falling off the ear and improving the stability of the open-back headphones 10 when worn. For example, the free end FE of the sound-generating part 11 is pressed into the concha cavity in the thickness direction Z. As another example, the free end FE abuts against the concha cavity in the major axis direction X and the minor axis direction Y.

[0100] In some embodiments, the two ends of the second portion 122 of the ear hook 12 can be connected to the first portion 121 of the ear hook 12 and the connecting end CE of the sound-emitting part 11, respectively (e.g., Figure 15(As shown). In some embodiments, the second portion 122 of the ear hook 12 may have a lowest point P and a highest point Q along the minor axis direction Y of the sound-generating portion 11. When the open-back headphones 10 are worn, in order to prevent the first pressure relief hole 1131 from being blocked by the ear structure (e.g., the helix or tragus), the distance h1 between the center of the first pressure relief hole 1131 and the lowest point P along the major axis direction X of the sound-generating portion 11 may be 5.28 mm to 7.92 mm. In some embodiments, in order to ensure that the headphones fit snugly against the user's ear when the user wears the open-back headphones 10, the distance h2 between the center of the first pressure relief hole 1131 and the highest point Q along the major axis direction X of the sound-generating portion 11 may be 8.68 mm to 13.02 mm. In some embodiments, when the user wears the open-back headphones, the distance between the center of the first pressure relief hole 1131 and any point on the second portion 122 of the ear hook 12 along the major axis direction X of the sound-generating portion 11 ranges from 5.28 mm to 14 mm. In some embodiments, the distance between the center of the first pressure relief hole 1131 and any point on the second portion 122 of the ear hook in the long axis X direction of the sound-emitting part 11 ranges from 5.28 mm to 13.02 mm. In some embodiments, the distance between the center of the first pressure relief hole 1131 and any point on the second portion 122 of the ear hook in the long axis X direction of the sound-emitting part 11 ranges from 6.58 mm to 12.02 mm. In some embodiments, the distance between the center of the first pressure relief hole 1131 and any point on the second portion 122 of the ear hook in the long axis X direction of the sound-emitting part 11 ranges from 7.58 mm to 10.02 mm. In some embodiments, the distance between the center of the first pressure relief hole 1131 and any point on the second portion 122 of the ear hook in the long axis X direction of the sound-emitting part 11 ranges from 8.58 mm to 9.02 mm.

[0101] like Figure 14 As shown, when a user wears the open-back headphones 10, by setting the housing 111 of the sound-emitting part 11 to be at least partially inserted into the concha 103, the cavity formed by the inner surface IS of the sound-emitting part 11 and the concha 103 can be considered as follows: Figure 10 The cavity structure 41 shown, the gap formed between the inner surface IS and the concha cavity (e.g., the first leakage structure UC near the top of the head formed between the inner surface IS and the concha cavity, and the second leakage structure LC near the ear canal formed between the inner surface IS and the ear) can be regarded as follows: Figure 10 The leakage structure 42 shown. The sound outlet 112 provided on the inner surface IS can be regarded as... Figure 10 The point sound source inside the cavity structure 41 shown, and the pressure relief holes 113 (e.g., the first pressure relief hole 1131 and the second pressure relief hole 1132) located on other sides (e.g., the upper side US and / or the lower side LS) of the sound-emitting part 11 can be regarded as as follows: Figure 10 The point sound source outside the cavity structure 41 shown. Therefore, based on... Figures 10-13 According to the relevant description, when the open-back headphones 10 are worn in a manner that at least partially inserts into the concha, that is, in the manner described... Figure 14 When worn as shown, in terms of sound quality, most of the sound radiated from the sound outlet 112 reaches the ear canal through direct or reflected light, significantly increasing the volume of sound reaching the ear canal, especially in the mid-to-low frequency range. Simultaneously, only a small portion of the out-of-phase sound radiated from the pressure relief holes 113 (e.g., the first pressure relief hole 1131 and the second pressure relief hole 1132) enters the concha cavity through the gaps (the first leakage structure UC and the second leakage structure LC), resulting in a weak canceling effect with the sound outlet 112, further significantly increasing the sound volume in the ear canal. Regarding sound leakage, the sound outlet 112 can output sound to the outside through the gaps and cancel out the sound generated by the pressure relief holes 113 (e.g., the first pressure relief hole 1131 and the second pressure relief hole 1132) in the far field, thus ensuring reduced sound leakage.

[0102] In some embodiments, the first pressure relief hole 1131 and the second pressure relief hole 1132 are offset in the X direction so that the first pressure relief hole 1131 and the second pressure relief hole 1132 are not obstructed by the tragus. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O2 of the second pressure relief hole 1132 can be 7mm-15.2mm. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O2 of the second pressure relief hole 1132 can be 8mm-13mm. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O2 of the second pressure relief hole 1132 can be 12.64mm. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O2 of the second pressure relief hole 1132 can be 7.5mm-14mm. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O2 of the second pressure relief hole 1132 can be 12mm-13mm. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O2 of the second pressure relief hole 1132 can be 13mm-15.2mm.

[0103] In some embodiments, in order to avoid the sound output from the first pressure relief hole 1131 and the second pressure relief hole 1132 affecting the volume of the sound output from the sound outlet 112 at the listening position, the first pressure relief hole 1131 and the second pressure relief hole 1132 should be as far away from the sound outlet 112 as possible. For example, the center of the sound outlet 112 can be located on or near the vertical plane of the line connecting the center of the first pressure relief hole 1131 and the center of the second pressure relief hole 1132.

[0104] In some embodiments, the relationship between the distance (also referred to as the first distance) between the center O1 of the first pressure relief hole 1131 and the center O of the sound outlet hole 112 and the distance (also referred to as the second distance) between the center O2 of the second pressure relief hole 1132 and the center O of the sound outlet hole 112 can be determined so that the center O of the sound outlet hole 112 is approximately on the perpendicular bisector of the line O1O2. In some embodiments, the difference between the first distance and the second distance is less than 10%. In some embodiments, the difference between the first distance and the second distance is less than 8%. In some embodiments, the difference between the first distance and the second distance is less than 5%. In some embodiments, the difference between the first distance and the second distance is less than 2%.

[0105] In some embodiments, to avoid near-field cancellation between the sound waves emitted from the pressure relief holes (e.g., the first pressure relief hole 1131 and the second pressure relief hole 1132) and the sound waves emitted from the sound outlet 112, thus affecting the user's listening quality, the distance between the first pressure relief hole 1131 and the second pressure relief hole 1132 and the sound outlet 112 should not be too close. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O of the sound outlet 112 can be 4mm-15.11mm. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O of the sound outlet 112 can be 4mm-15mm. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O of the sound outlet 112 can be 5.12mm-15.11mm. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O of the sound outlet 112 can be not less than 5mm-14mm. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O of the sound outlet hole 112 may be no less than 6mm-13mm. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O of the sound outlet hole 112 may be no less than 7mm-12mm. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O of the sound outlet hole 112 may be no less than 8mm-10mm. In some embodiments, the distance between the center O1 of the first pressure relief hole 1131 and the center O of the sound outlet hole 112 may be 9.55mm. In some embodiments, the distance between the center O2 of the second pressure relief hole 1132 and the center O of the sound outlet hole 112 may be 4mm-16.1mm. In some embodiments, the distance between the center O2 of the second pressure relief hole 1132 and the center O of the sound outlet hole 112 may be no less than 4mm-15mm. In some embodiments, the distance between the center O2 of the second pressure relief hole 1132 and the center O of the sound outlet hole 112 may be no less than 5mm-14mm. In some embodiments, the distance between the center O2 of the second pressure relief hole 1132 and the center O of the sound outlet hole 112 can be 5.12mm-16.1mm. In some embodiments, the distance between the center O2 of the second pressure relief hole 1132 and the center O of the sound outlet hole 112 can be not less than 6mm-13mm. In some embodiments, the distance between the center O2 of the second pressure relief hole 1132 and the center O of the sound outlet hole 112 can be not less than 7mm-12mm. In some embodiments, the distance between the center O2 of the second pressure relief hole 1132 and the center O of the sound outlet hole 112 can be not less than 8mm-10mm. In some embodiments, the distance between the center O2 of the second pressure relief hole 1132 and the center O of the sound outlet hole 112 can be 9.15mm.

[0106] In some embodiments, to maximize the distance between the first pressure relief hole 1131, the second pressure relief hole 1132, and the sound outlet hole 112, the angle between the line O1O connecting the center O1 of the first pressure relief hole 1131 and the center O of the sound outlet hole 112 and the line O2O connecting the center O2 of the second pressure relief hole 1132 and the center O of the sound outlet hole 112 can be reduced. In some embodiments, the angle between the lines O1O and O2O ranges from 46.40° to 114.04°. In some embodiments, the angle between the lines O1O and O2O ranges from 46.40° to 90.40°. In some embodiments, the angle between the lines O1O and O2O ranges from 46.40° to 70.04°. In some embodiments, the angle between the lines O1O and O2O ranges from 46.40° to 60.04°. In some embodiments, the angle between the line O1O2 connecting the center O1 of the first pressure relief hole 1131 and the center O2 of the second pressure relief hole 1132 and the line O2O is in the range of 19.72°-101.16°. In some embodiments, the angle between the line O1O2 and the line O2O is in the range of 19.71°-97.75°.

[0107] In some embodiments, the first pressure relief hole 1131 is further away from the connection end CE than the second pressure relief hole 1132. Since the center of the sound outlet 112 is located on or near the perpendicular plane of the line connecting the center of the first pressure relief hole 1131 and the center of the second pressure relief hole 1132, the sound outlet 112 is located in the Y direction on the side of the housing 111 closer to the second pressure relief hole 1132 rather than in the middle (e.g., Figure 16(As shown). Since the sound outlet 112 is located close to the ear canal, the second pressure relief hole 1132 is closer to the ear canal, while the first pressure relief hole 1131 is farther from the ear canal. Compared to the first pressure relief hole 1131, the sound waves emitted from the second pressure relief hole 1132 are more likely to cancel out the sound waves emitted from the sound outlet 112 in the near field. Therefore, compared to the first pressure relief hole 1131, the size of the second pressure relief hole 1132 can be smaller to reduce sound leakage; that is, the area of ​​the second pressure relief hole 1132 can be smaller than the area of ​​the first pressure relief hole 1131. In some embodiments, to ensure that the frequency response curves of the first pressure relief hole 1131 and the second pressure relief hole 1132 are as close as possible to achieve a better noise reduction effect, the difference in area between the first pressure relief hole 1131 and the second pressure relief hole 1132 should not be too large. In some embodiments, the ratio of the inner opening area of ​​the second pressure relief hole 1132 to that of the first pressure relief hole 1131 is not greater than 0.9. In some embodiments, the ratio of the inner opening area of ​​the second pressure relief hole 1132 to that of the first pressure relief hole 1131 is not greater than 0.8. In some embodiments, the ratio of the inner opening area of ​​the second pressure relief hole 1132 to that of the first pressure relief hole 1131 is not greater than 0.7. In some embodiments, the ratio of the inner opening area of ​​the second pressure relief hole 1132 to that of the first pressure relief hole 1131 is not greater than 0.6. In some embodiments, the ratio of the inner opening area of ​​the second pressure relief hole 1132 to that of the first pressure relief hole 1131 can be 0.55.

[0108] In some embodiments, for example Figure 14 In this configuration, to bring the sound outlet 112 closer to the user's ear canal, the sound outlet 112 can be positioned closer in the Y direction to the lower end of the sound-emitting part 11, i.e., the lower side LS where the second pressure relief hole 1132 is located (e.g., Figure 16(As shown). At this time, the distance between the sound outlet 112 and the first pressure relief hole 1131 in the Y direction is greater than the distance between the sound outlet 112 and the second pressure relief hole 1132 in the Y direction. This is to prevent the sound waves propagating through the sound outlet 112 and the first pressure relief hole 1131 from canceling each other in the near field, which helps to increase the volume of the sound propagating through the sound outlet 112 heard by the user. Correspondingly, the second pressure relief hole 1132 is closer to the connection end CE than the sound outlet 112 to increase the distance between them in the X direction, thereby preventing the sound waves propagating through the sound outlet 112 and the second pressure relief hole 1132 from canceling each other in the near field. This also helps to increase the volume of the sound propagating through the sound outlet 112 heard by the user. In some embodiments, the difference between the distance between the center O of the sound outlet 112 and the center O1 of the first pressure relief hole 1131 in the Y direction and the distance between the center O of the sound outlet 112 and the center O2 of the second pressure relief hole 1132 can be 2mm-10mm, and the difference between the distance between the center O2 of the second pressure relief hole 1132 and the connection end CE in the X direction and the distance between the center O of the sound outlet 112 and the connection end CE can be 2mm-15mm. In some embodiments, the difference between the distance between the center O of the sound outlet 112 and the center O1 of the first pressure relief hole 1131 in the Y direction and the distance between the center O of the sound outlet 112 and the center O2 of the second pressure relief hole 1132 can be 3mm-9mm, and the difference between the distance between the center O2 of the second pressure relief hole 1132 and the connection end CE in the X direction and the distance between the center O of the sound outlet 112 and the connection end CE can be 4mm-12mm. In some embodiments, the difference between the distance between the center O of the sound outlet 112 and the center O1 of the first pressure relief hole 1131 in the Y direction and the distance between the center O of the sound outlet 112 and the center O2 of the second pressure relief hole 1132 can be 5mm-7mm. The difference between the distance between the center O2 of the second pressure relief hole 1132 and the connecting end CE in the X direction and the distance between the center O of the sound outlet 112 and the connecting end CE can be 6mm-8mm. It should be noted that when the side of the housing 111 corresponding to the connecting end CE is an arc surface, the distance from a certain position (e.g., the center O1 of the first pressure relief hole 1131 or the center O2 of the second pressure relief hole 1132) to the connecting end CE (or that side surface) can refer to the distance from that position to the tangent plane parallel to the minor axis of the connecting end CE.

[0109] In some embodiments, combined with Figure 14 and Figure 15To ensure that the sound-generating part 11 is at least partially inserted into the concha cavity, the major axis dimension of the sound-generating part 11 cannot be too long. While ensuring that the sound-generating part 11 is at least partially inserted into the concha cavity, the distance between the first pressure relief hole 1131 and the second pressure relief hole 1132 and the rear surface RS of the sound-generating part 11 cannot be too short. Otherwise, all or part of the area of ​​the first pressure relief hole 1131 and / or the second pressure relief hole 1132 may be blocked in the X direction due to the contact between the free end FE and the wall of the concha cavity, thus reducing the effective area of ​​the first pressure relief hole 1131 and / or the second pressure relief hole 1132. Therefore, in some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the rear surface RS is... a The range of 3 is 8.60 mm to 15.68 mm. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the rear side RS is... a The range of 3 is 10.44 mm to 15.68 mm. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the rear side RS is... a The range of 3 is 11.00 mm to 14.55 mm. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the rear side RS is... a The range of 3 is 12.15 mm to 13.25 mm.

[0110] Furthermore, combined Figure 16 To avoid the effective area of ​​the first pressure relief hole 1131 and / or the second pressure relief hole 1132 being reduced due to the obstruction of all or part of its area in the Z direction, the distance from the center O1 of the first pressure relief hole 1131 to the inner surface IS of the sound-emitting part 11 in the Z direction cannot be too small. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the inner surface IS of the sound-emitting part 11 in the Z direction is... d The range of 3 is 4.24 mm to 6.38 mm. In some embodiments, the center O1 of the first pressure relief hole 1131 is a distance along the Z direction from the inner surface IS of the sound-generating part 11. d The range of 3 is 4.50 mm to 5.85 mm. In some embodiments, the center O1 of the first pressure relief hole 1131 is a distance along the Z direction from the inner surface IS of the sound-generating part 11. d The range of 3 is 4.80 mm to 5.50 mm. In some embodiments, the center O1 of the first pressure relief hole 1131 is a distance along the Z direction from the inner surface IS of the sound-generating part 11. d The range of 3 is 5.20 mm to 5.55 mm.

[0111] In some embodiments, to bring the sound outlet 112 closer to the ear canal to increase listening efficiency, it is necessary to bring the sound outlet 112 closer to the free end FE. In this case, to avoid the sound emitted by the second pressure relief hole 1132 canceling out the sound emitted by the sound outlet 112 at the ear canal (i.e., the listening position), resulting in a decrease in listening volume, the second pressure relief hole 1132 can be positioned further away from the rear side RS (or the free end FE). Further, regarding the first pressure relief hole 1131, since it is located on the upper side US and is farther from the sound outlet 112 than the second pressure relief hole 1132, and because the gap between the ear 100 and the inner side IS is smaller, the sound generated by the first pressure relief hole 1131 is more difficult to transmit to the ear canal compared to the second pressure relief hole 1132. Therefore, in some embodiments, the distance from the center of the first pressure relief hole 1131 to the rear side RS can be smaller than the distance from the center of the second pressure relief hole 1132 to the rear side RS. In some embodiments, the distance between the center of the first pressure relief hole 1131 and the rear side surface RS may be greater than or equal to the distance between the center of the second pressure relief hole 1132 and the rear side surface RS. In some embodiments, the distance between the center O2 of the second pressure relief hole 1132 and the rear side surface RS... a The range of 4 is 13.51 mm to 20.27 mm. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the rear side RS is... a The range of 4 is 15.00 mm to 19.55 mm. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the rear side RS is... a The range of 4 is 17.15 mm to 18.25 mm.

[0112] Furthermore, in some embodiments, the center O1 of the first pressure relief hole 1131 and the center O2 of the second pressure relief hole 1132 may be at the same distance from the inner surface IS of the sound-emitting part 11 along the Z direction. In some embodiments, the center O2 of the second pressure relief hole 1132 is at the same distance from the inner surface IS of the sound-emitting part 11 along the Z direction. d The range of 4 is 4.24 mm to 6.38 mm. In some embodiments, the center O2 of the second pressure relief hole 1132 is a distance along the Z direction from the inner surface IS of the sound-generating part 11. d The range of 4 is 4.50 mm to 5.85 mm. In some embodiments, the center O2 of the second pressure relief hole 1132 is a distance along the Z direction from the inner surface IS of the sound-generating part 11. d The range of 4 is 4.80 mm to 5.50 mm. In some embodiments, the center O2 of the second pressure relief hole 1132 is a distance along the Z direction from the inner surface IS of the sound-generating part 11. dThe range of 4 is 5.20 mm to 5.55 mm. In some embodiments, to bring the sound outlet 112 closer to the ear canal to increase listening efficiency, it is necessary to bring the sound outlet 112 closer to the lower side LS. In this case, to avoid the sound emitted by the second pressure relief hole 1132 canceling out the sound emitted by the sound outlet 112 at the ear canal (i.e., the listening position), resulting in a decrease in listening volume, in the Z direction, the second pressure relief hole 1132 can be further away from the inner side IS than the first pressure relief hole 1131. That is, the distance from the center O2 of the second pressure relief hole 1132 to the inner side IS can be different from the distance from the center O1 of the first pressure relief hole 1131 to the inner side IS. For example, the distance from the center O1 of the first pressure relief hole 1131 to the inner side IS is 2.24 mm to 5.57 mm, and the distance from the center O2 of the second pressure relief hole 1132 to the inner side IS is 5.57 mm to 6.36 mm.

[0113] In some embodiments, the shapes of the first pressure relief hole 1131 and the second pressure relief hole 1132 also affect their sound quality. Elongated shapes of the first pressure relief hole 1131 and the second pressure relief hole 1132 result in higher acoustic impedance, thereby reducing the sound intensity of the rear cavity. Therefore, to ensure the sound intensity output by the first pressure relief hole 1131 and the second pressure relief hole 1132, the ratio of their major axis to minor axis (also referred to as the aspect ratio of the pressure relief hole 113) cannot be too large. Simultaneously, due to the dimensional limitations of the sound-emitting part 11 in the thickness direction Z, the maximum dimensions of the first pressure relief hole 1131 and the second pressure relief hole 1132 in the thickness direction Z cannot be too large. Therefore, when the area of ​​the pressure relief hole 113 is constant, the ratio of its major axis to minor axis of the first pressure relief hole 1131 and the second pressure relief hole 1132 cannot be too small. In some embodiments, the shapes of the first pressure relief hole 1131 and the second pressure relief hole 1132 may include, but are not limited to, circular, elliptical, racetrack-shaped, etc. For ease of description, the following will exemplify the example of the first pressure relief hole 1131 and the second pressure relief hole 1132 being configured as a racetrack shape.

[0114] Figure 16 This is a schematic diagram of the housing structure of an open-back headphone according to some embodiments of this application. For example... Figure 16 As shown, the first pressure relief hole 1131 and the second pressure relief hole 1132 can be racetrack-shaped, wherein the two ends of the racetrack shape can be minor arcs or semicircles. In this case, the maximum dimension of the first pressure relief hole 1131 and the second pressure relief hole 1132 in the thickness direction Z is defined as their corresponding minor axis dimension. The minor axis dimension of the first pressure relief hole 1131 is... W 1. The minor axis dimension of the second pressure relief hole 1132 is... W 2; The maximum dimension of the first pressure relief hole 1131 and the second pressure relief hole 1132 in the major axis direction X is defined as their corresponding major axis dimension. The major axis dimension of the first pressure relief hole 1131 is:L 1. The major axis dimension of the second pressure relief hole 1132 is... L 2. Based on the above principle, the ratio of the major axis dimension to the minor axis dimension of the first pressure relief hole 1131 and the second pressure relief hole 1132 cannot be too large or too small. In some embodiments, the major axis dimension of the first pressure relief hole 1131 is... L 1. The minor axis dimension of the first pressure relief hole 1131 W The ratio of 1 can range from 1 to 8. In some embodiments, the major axis dimension of the first pressure relief hole 1131 is... L 1. The minor axis dimension of the first pressure relief hole 1131 W The ratio of 1 can range from 1.33 to 8. In some embodiments, the major axis dimension of the first pressure relief hole 1131 is... L 1. The minor axis dimension of the first pressure relief hole 1131 W The ratio of 1 can range from 3 to 7. In some embodiments, the major axis dimension of the first pressure relief hole 1131 is... L 1. The minor axis dimension of the first pressure relief hole 1131 W The ratio of 1 can range from 4 to 6. In some embodiments, the major axis dimension of the second pressure relief hole 1132 is... L 2. The minor axis dimension of the second pressure relief hole 1132 W The ratio of 2 can range from 1 to 8. In some embodiments, the major axis dimension of the second pressure relief hole 1132 is... L 2. The minor axis dimension of the second pressure relief hole 1132 W The ratio of 2 can range from 3 to 7. In some embodiments, the major axis dimension of the second pressure relief hole 1132 is... L 2. The minor axis dimension of the second pressure relief hole 1132 W The ratio of 2 can range from 4 to 6. In some embodiments, the major axis dimension of the second pressure relief hole 1132 is... L 2. The minor axis dimension of the second pressure relief hole 1132 W The ratio of 2 can also range from 1 to 6.

[0115] In some embodiments, when both the first pressure relief hole 1131 and the second pressure relief hole 1132 adopt a cylindrical structure, that is, their corresponding inner and outer opening dimensions are the same, then the major axis dimension of the first pressure relief hole 1131 is... L The value of 1 can range from 1.43mm to 16.38mm, which is the minor axis dimension. W The value of 1 can range from 1.43mm to 5.7mm. In some embodiments, the major axis dimension of the first pressure relief hole 1131 is... L The value of 1 can range from 4.10mm to 16.38mm, which is the minor axis dimension. WThe value of 1 can range from 1.43mm to 5.7mm. In some embodiments, the major axis dimension of the first pressure relief hole 1131 is... L The value of 1 can range from 6.14mm to 10.92mm, which is the minor axis dimension. W The value of 1 can range from 2.14 mm to 3.80 mm. In some embodiments, the major axis dimension of the second pressure relief hole 1132 is... L The value of 2 can range from 1.00mm to 10.38mm, which is the minor axis dimension. W The value of 2 can range from 1.00mm to 4.05mm. In some embodiments, the major axis dimension of the second pressure relief hole 1132 is... L The value of 2 can range from 2.59mm to 10.38mm, which is the minor axis dimension. W The value of 2 can range from 1.52mm to 4.05mm. In some embodiments, the major axis dimension of the second pressure relief hole 1132 is... L The value of 2 can range from 3.89mm to 6.92mm, which is the minor axis dimension. W The value of 2 can range from 2.28mm to 4.05mm.

[0116] In some embodiments, in order to facilitate processing and manufacturing and reduce process difficulty, both the first pressure relief hole 1131 and the second pressure relief hole 1132 can adopt a trumpet-shaped structure. For example, the area of ​​the inner opening is smaller than the area of ​​the corresponding outer opening, or the area of ​​the outer opening is smaller than the area of ​​the corresponding inner opening.

[0117] In some embodiments, when both the first pressure relief hole 1131 and the second pressure relief hole 1132 adopt a trumpet-shaped structure, the major axis dimension of the outer opening of the first pressure relief hole 1131 along the X direction can range from 4.10mm to 16.38mm, the minor axis dimension of the outer opening of the first pressure relief hole 1131 along the Z direction can range from 1.43mm to 5.7mm, and the area of ​​the outer opening of the first pressure relief hole 1131 ranges from 5.39 mm². 2 -86.21mm 2 The major axis dimension of the inner opening of the first pressure relief hole 1131 along the X direction can range from 3.92mm to 15.68mm, the minor axis dimension along the Z direction can range from 1.29mm to 5.14mm, and the area of ​​the inner opening of the first pressure relief hole 1131 can range from 4.58 mm². 2 -73.32mm 2The major axis dimension of the outer opening of the second pressure relief hole 1132 along the X direction can range from 2.59mm to 10.38mm, the minor axis dimension along the Z direction can range from 1.52mm to 4.05mm, and the area of ​​the outer opening of the second pressure relief hole 1132 ranges from 3.42mm². 2 -54.68mm 2 The major axis dimension of the inner opening of the second pressure relief hole 1132 along the X direction can range from 2.28mm to 9.1mm, the minor axis dimension along the Z direction can range from 1.26mm to 5.04mm, and the area of ​​the inner opening of the second pressure relief hole 1132 can range from 2.56mm². 2 -40.90mm 2 In some embodiments, when both the first pressure relief hole 1131 and the second pressure relief hole 1132 adopt a trumpet-shaped structure, the major axis dimension of the outer opening of the first pressure relief hole 1131 along the X direction can range from 6.14mm to 10.92mm, the minor axis dimension of the outer opening of the first pressure relief hole 1131 along the Z direction can range from 2.14mm to 3.80mm, and the area of ​​the outer opening of the first pressure relief hole 1131 ranges from 12.12mm². 2 -38.32mm 2 The major axis dimension of the inner opening of the first pressure relief hole 1131 along the X direction can range from 5.88mm to 10.45mm, the minor axis dimension along the Z direction can range from 1.93mm to 3.43mm, and the area of ​​the inner opening of the first pressure relief hole 1131 can range from 10.31mm². 2 -32.59mm 2 The major axis dimension of the outer opening of the second pressure relief hole 1132 along the X direction can range from 3.89mm to 6.92mm, the minor axis dimension along the Z direction can range from 2.28mm to 4.05mm, and the area of ​​the outer opening of the second pressure relief hole 1132 ranges from 7.69 mm². 2 -24.30mm 2 The major axis dimension of the inner opening of the second pressure relief hole 1132 along the X direction can range from 3.41mm to 6.61mm, the minor axis dimension along the Z direction can range from 1.89mm to 3.36mm, and the area of ​​the inner opening of the second pressure relief hole 1132 can range from 5.75mm². 2 -18.18mm 2In some embodiments, when both the first pressure relief hole 1131 and the second pressure relief hole 1132 adopt a trumpet-shaped structure, the major axis dimension of the outer opening of the first pressure relief hole 1131 along the X direction can be 8.19 mm, the minor axis dimension of the outer opening of the first pressure relief hole 1131 along the Z direction can be 2.85 mm, and the area of ​​the outer opening of the first pressure relief hole 1131 is 21.55 mm². 2 The major axis dimension of the inner opening of the first pressure relief hole 1131 along the X direction can be 7.84 mm, the minor axis dimension along the Z direction can be 2.57 mm, and the area of ​​the inner opening of the first pressure relief hole 1131 is 18.33 mm². 2 The major axis dimension of the outer opening of the second pressure relief hole 1132 along the X direction can be 5.19 mm, the minor axis dimension along the Z direction can be 3.04 mm, and the area of ​​the outer opening of the second pressure relief hole 1132 is 13.67 mm². 2 The major axis dimension of the inner opening of the second pressure relief hole 1132 along the X direction can be 4.55 mm, the minor axis dimension along the Z direction can be 2.52 mm, and the area of ​​the inner opening of the second pressure relief hole 1132 is 10.23 mm². 2 .

[0118] In some embodiments, the area ratio of the inner opening of the first pressure relief hole 1131 to the area of ​​the sound outlet hole 112 can be 0.1-15. In some embodiments, the area ratio of the inner opening of the second pressure relief hole 1132 to the area of ​​the sound outlet hole 112 can be 0.1-3. In some embodiments, the area ratio of the inner opening of the first pressure relief hole 1131 to the area of ​​the sound outlet hole 112 can be 0.2-10. In some embodiments, the area ratio of the inner opening of the second pressure relief hole 1132 to the area of ​​the sound outlet hole 112 can be 0.1-2. In some embodiments, the area ratio of the inner opening of the first pressure relief hole 1131 to the area of ​​the sound outlet hole 112 can be 0.3-5. In some embodiments, the area ratio of the inner opening of the second pressure relief hole 1132 to the area of ​​the sound outlet hole 112 can be 0.2-1.

[0119] In some embodiments, when the first pressure relief hole 1131 and the second pressure relief hole 1132 serve as acoustic holes and form a Helmholtz resonant cavity model with the rear cavity 116, it can be seen from the formula (2) described below that the larger the area of ​​the first pressure relief hole 1131 and the second pressure relief hole 1132, the larger the resonant frequency of the rear cavity 116, thereby causing the resonant frequency of its corresponding leakage sound to shift as far as possible to the higher frequency band (e.g., the frequency range greater than 4kHz), which is beneficial to improve the flat area in the frequency response curve and further helps to prevent its leakage sound from being heard.

[0120] Figure 17 This is a frequency response curve diagram of an open-back headphone corresponding to a first pressure relief hole of different areas, as shown in some embodiments of this application. Figure 18 This is a frequency response curve of an open-back headphone corresponding to a second pressure relief hole of different area, as shown in some embodiments of this application.

[0121] like Figure 17 As shown, curves 171, 172, 173, 174, and 175 represent areas of 0, 2.52 mm², and 175, respectively. 2 5.52mm 2 8.52mm 2 11.52mm 2 The frequency response curve corresponding to the first pressure relief hole 1131. For example... Figure 18 As shown, curves 181, 182, 183, 184, and 185 represent areas of 0, 4.02 mm², and 4.02 mm², respectively. 2 5.52mm 2 7.02mm 2 8.52mm 2 The frequency response curve corresponding to the second pressure relief hole 1132.

[0122] from Figure 17 It can be seen that when other structures (e.g., the sound outlet 112, the second pressure relief hole 1132, etc.) are fixed, as the area of ​​the first pressure relief hole 1131 gradually increases, the resonant frequency corresponding to the rear cavity in the frequency response curve of the open-back headphone 10 (i.e., the frequency corresponding to the resonant peak in the dashed coil G1) gradually shifts to higher frequencies, and the flat region of the frequency response curve widens. When the area of ​​the first pressure relief hole increases to 11.52 mm... 2 Subsequently, the resonant frequency corresponding to the rear cavity changes more slowly towards higher frequencies. It should be noted that... Figure 17 The frequency response curve in the simulation is the frequency response curve located 15mm directly in front of the center O of the sound outlet, obtained under the condition that the position and size of the second pressure relief hole 1132 remain unchanged. Similarly, from Figure 18 It can be seen that when other structures (e.g., the sound outlet 112, the first pressure relief hole 1131, etc.) are fixed, as the area of ​​the second pressure relief hole 1132 gradually increases, the resonant frequency corresponding to the rear cavity in the frequency response curve of the open-back headphone 10 (i.e., the frequency corresponding to the resonant peak in the dashed coil G2) gradually shifts to higher frequencies, and the flat region of the frequency response curve widens. It should be noted that... Figure 18 The frequency response curve in the simulation is the frequency response curve 15mm in front of the center O of the sound outlet, obtained under the condition that the position and size of the first pressure relief hole 1131 remain unchanged.

[0123] In some embodiments, to ensure that the frequency response curve of the open-back headphones has a wide, flat region (e.g., the region before the resonance peak) and achieves better sound leakage reduction in the mid-to-high frequency range (e.g., 2 kHz-6 kHz), and to ensure that the high-pressure region disrupting the sound field in the rear cavity is balanced while maintaining sufficient intensity of the sound generated in the far field, the area of ​​the first pressure relief hole 1131 and / or the area of ​​the second pressure relief hole 1132 cannot be too small. Furthermore, in practical applications, if the area of ​​the first pressure relief hole 1131 and / or the area of ​​the second pressure relief hole 1132 is too large, it will negatively impact the appearance, structural strength, waterproofing, dustproofing, and other aspects of the open-back headphones 10. Therefore, the area of ​​the first pressure relief hole 1131 and / or the area of ​​the second pressure relief hole 1132 cannot be too large either. In some embodiments, the area of ​​the first pressure relief hole 1131 is in the range of 3.78 mm. 2 -86.21mm 2 The area of ​​the second pressure relief hole 1132 is 2.78 mm². 2 -54.68mm 2 In some embodiments, the area of ​​the first pressure relief orifice 1131 ranges from 3.78 mm. 2 ~22.07 mm 2 The area of ​​the second pressure relief hole 1132 is 2.78 mm. 2 ~16.07 mm 2 In some embodiments, the area of ​​the first pressure relief orifice 1131 ranges from 6.78 mm. 2 ~20.07 mm 2 The area of ​​the second pressure relief hole 1132 is 4.78 mm². 2 ~13.07 mm 2 .

[0124] In some embodiments, since the pressure relief holes 113 (including the first pressure relief hole 1131 and the second pressure relief hole 1132) and the rear cavity provided on the housing 111 can be regarded as a Helmholtz resonant cavity model, the opening size of the first pressure relief hole 1131 and the second pressure relief hole 1132 will affect the resonant frequency of the rear cavity. To ensure that the resonant frequency of the rear cavity is at a relatively high frequency, for example, the resonant frequency of the rear cavity is in the frequency range of 2000Hz-6000Hz, this can be achieved by designing the ratio range of the opening size of the first pressure relief hole 1131 and the second pressure relief hole 1132 to the volume of the rear cavity. In some embodiments, in order to enable the sound-emitting part 11 to form a first leakage structure and / or a second leakage structure as described elsewhere in this application when it is at least partially inserted into the concha cavity, the dimension of the sound-emitting part 11 in the Y direction can be determined based on the size of the concha cavity. At this time, when the sound outlet 112 reaches the bottom surface of the transducer (e.g., Figure 20AWhen the distance between the transducer 116 and the bottom surface of the magnetic circuit assembly 1164 in the transducer 116 is constant, the volume of the rear cavity can be related to the area of ​​the upper side US and / or the lower side LS of the sound-emitting part 11. To ensure a sufficiently high resonant frequency in the rear cavity, the ratio of the area of ​​the pressure relief hole 113 to the volume of the rear cavity cannot be too small; in other words, the ratio of the area of ​​the pressure relief hole 113 to the area of ​​the upper side US and / or the lower side LS cannot be too small. Furthermore, to ensure the stability of the physical structure of the housing 111, thereby ensuring the service life of the open-back headphone 10, the ratio of the area of ​​the pressure relief hole 113 to the area of ​​the upper side US and / or the lower side LS cannot be too large. In some embodiments, the ratio of the area of ​​the first pressure relief hole 1131 to the area of ​​the upper side US is between 0.036 and 0.093, and the ratio of the area of ​​the second pressure relief hole 1132 to the area of ​​the lower side LS is between 0.018 and 0.051. In some embodiments, the ratio of the area of ​​the first pressure relief hole 1131 to the area of ​​the upper side US is between 0.046 and 0.083, and the ratio of the area of ​​the second pressure relief hole 1132 to the area of ​​the lower side LS is between 0.028 and 0.041. In some embodiments, the ratio of the area of ​​the first pressure relief hole 1131 to the area of ​​the upper side US is between 0.056 and 0.073, and the ratio of the area of ​​the second pressure relief hole 1132 to the area of ​​the lower side LS is between 0.031 and 0.038. In some embodiments, the ratio of the area of ​​the first pressure relief hole 1131 to the area of ​​the upper side US is between 0.061 and 0.068, and the ratio of the area of ​​the second pressure relief hole 1132 to the area of ​​the lower side LS is between 0.033 and 0.036.

[0125] Figure 19 This is a schematic diagram of the projection of an open-back headphone in the sagittal plane when it is in a wearing state, according to some embodiments of this application.

[0126] In some embodiments, combined with Figure 14 and Figure 19 In order to ensure that the sound-producing part 11 is stably worn in the user's ear and to facilitate its construction, as Figure 10 The cavity structure shown has at least two leakage structures. The free end FE can abut against the concha cavity in the long axis direction X and the short axis direction Y. At this time, the inner surface IS of the sound-emitting part 11 is inclined relative to the sagittal plane, and there is at least a first leakage structure UC near the top of the head (i.e., a gap formed between the concha cavity and the upper boundary of the inner surface IS) and a second leakage structure LC near the ear canal (i.e., a gap formed between the concha cavity and the lower boundary of the inner surface IS). As a result, the listening volume can be improved, especially the listening volume in the mid and low frequencies, while still retaining the effect of far-field leakage cancellation, thereby improving the acoustic output performance of the open-back headphones 10.

[0127] In some embodiments, when the open-back headphones 10 are Figure 14 When worn in the manner shown, the first leakage structure UC and the second leakage structure LC formed between the inner surface IS of the sound-emitting part and the concha cavity have certain dimensions in both the long 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, the midpoint of the two points formed by the intersection of the upper / lower boundaries of the inner surface IS with the ear (e.g., the side wall of the concha cavity, the crus of the helix) when the open-back earphone 10 is in the wearing state can 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 can 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-back earphone 10 is in the wearing state, the midpoint of the upper boundary of the inner surface IS can be used as the position reference point for the first leakage structure UC, and the third point of the lower boundary of the inner surface IS near the free end FE (hereinafter referred to as the 1 / 3 point of the lower boundary of the inner surface IS) can be used as the position reference point for the second leakage structure LC. In this specification, when the junction 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 refer to the intersection line between the inner surface IS and the upper surface US, and the lower boundary of the inner surface IS may refer to the intersection line between the inner surface IS and the lower surface LS. In some embodiments, when one or more sides of the sound-emitting part 11 (e.g., the inner surface IS, the upper surface US, and / or the lower surface LS) are arc surfaces, the intersection line of two sides may refer to the intersection line between the tangents of the two sides that are farthest from the center of the sound-emitting part and parallel to the long axis or short axis of the sound-emitting part.

[0128] For illustrative purposes only, this specification uses the midpoint of the upper boundary and the one-third point of the lower boundary of the inner surface IS as reference points for the positions of the first leakage structure UC and the second leakage structure LC, respectively. It should be understood that the selected midpoint of the upper boundary and one-third point of the lower boundary of the inner surface IS are merely exemplary reference points to describe the positions of the first leakage structure UC and the second leakage structure LC. In some embodiments, other reference points may be selected to describe the positions of the first leakage structure UC and the second leakage structure LC. For example, due to differences in the ears of different users, the first leakage structure UC / second leakage structure LC formed when the open-back headphones 10 are worn may be a gradually widening gap. In this case, the reference position of the first leakage structure UC / second leakage structure LC can be the position on the upper / lower boundary of the inner surface IS near the area with the largest gap width. For example, the position of the first leakage structure UC can be the one-third point of the upper boundary of the inner surface IS near the free end FE, and the position of the second leakage structure LC can be the midpoint of the lower boundary of the inner surface IS.

[0129] In some embodiments, such as Figure 19 As shown, the projection of the upper boundary of the inner surface IS onto the sagittal plane can coincide with the projection of the upper surface US onto the sagittal plane, and the projection of the lower boundary of the inner surface IS onto the sagittal plane can coincide with the projection of the lower surface LS onto the sagittal plane. The position reference point of the first leakage structure UC is located at (i.e., the midpoint of the upper boundary of the inner surface IS), and its projection onto the sagittal plane is point A. The position reference point of the second leakage structure LC is located at (i.e., the 1 / 3 point of the lower boundary of the inner surface IS), and its projection onto the sagittal plane is point C. Here, "the projection point A of the midpoint of the upper boundary of the inner surface IS onto the sagittal plane" can be the intersection point of the upper boundary of the inner surface IS and the minor axis center plane of the transducer's magnetic circuit assembly (e.g., magnetic circuit assembly 1144 described below), and the projection point onto the sagittal plane. The minor axis center plane of the magnetic circuit assembly refers to a plane parallel to the minor axis direction of the sound-emitting part 11 and passing through the geometric center of the magnetic circuit assembly. "The projection point C of the lower third point of the medial surface IS onto the sagittal plane" can be the projection point of the trisection of the lower boundary of the medial surface IS near the free end FE onto the sagittal plane.

[0130] like Figure 19 As shown, in some embodiments, when worn, the projection of the sound-emitting part 11 of the open-back earphone 10 onto the sagittal plane can at least partially cover the user's ear canal, but the ear canal can communicate with the outside through the concha cavity, thereby freeing the user's ears. In some embodiments, since the sound from the pressure relief hole 113 can enter the cavity structure through the leakage structure (e.g., the first leakage structure UC or the second leakage structure LC) and cancel out the sound from the sound outlet 112, the first pressure relief hole 1131 and the second pressure relief hole 1132 cannot be too close to the upper and lower leakage structures.

[0131] In some embodiments, the projection point O1' of the center O1 of the first pressure relief hole 1131 in the sagittal plane and the projection point A of the midpoint of the upper boundary of the inner surface IS in the sagittal plane can substantially coincide. In some embodiments, the distance from the projection point O1' of the center O1 of the first pressure relief hole 1131 in the sagittal plane to the projection point A of the midpoint of the upper boundary of the inner surface IS in the sagittal plane is no greater than 2 mm. In some embodiments, the distance from the projection point O1' of the center O1 of the first pressure relief hole 1131 in the sagittal plane to the projection point A of the midpoint of the upper boundary of the inner surface IS in the sagittal plane is no greater than 1 mm. In some embodiments, the distance from the projection point O1' of the center O1 of the first pressure relief hole 1131 in the sagittal plane to the projection point A of the midpoint of the upper boundary of the inner surface IS in the sagittal plane is no greater than 0.5 mm.

[0132] When the relative positions of the sound outlet 112 and the first pressure relief hole 1131 remain unchanged (i.e., the distance between the center O of the sound outlet 112 and the center O1 of the first pressure relief hole 1131 remains unchanged), the larger the volume V of the cavity structure, the smaller the overall listening index (across the entire frequency range) of the open-back headphone 10. This is because, due to the influence of air-acoustic resonance within the cavity structure, at the resonant frequency of the cavity structure, air-acoustic resonance is generated within the cavity structure and radiates outwards a sound much greater than that of the pressure relief hole 113, resulting in a significant increase in sound leakage, which in turn causes the listening index to decrease significantly near that resonant frequency.

[0133] In some embodiments, the greater the distance between the projection point O2' of the center O2 of the second pressure relief hole 1132 in the sagittal plane and the projection point A of the midpoint of the upper boundary of the inner surface IS in the sagittal plane, the larger the volume V of the cavity structure. Therefore, in some embodiments, provided that the sound-emitting part 11 is at least partially inserted into the concha cavity, in order to make the cavity structure have a suitable volume V so as to improve the sound reception effect of the ear canal, the distance between point O2' and point A ranges from 14.4 mm to 21.6 mm. In some embodiments, the distance between point O2' and point A ranges from 16.4 mm to 19.6 mm. In some embodiments, the distance between point O2' and point A ranges from 17.4 mm to 18.6 mm. In some embodiments, the distance between point O2' and point A ranges from 17.8 mm to 18.2 mm.

[0134] In some embodiments, to ensure that the sound-generating part 11 extends into the concha cavity and that there is an appropriate gap (forming an opening in the cavity structure) between the upper boundary of the inner surface IS and the concha cavity, the distance from the projection point A of the midpoint of the upper boundary of the inner surface IS in the sagittal plane to the projection point O3' of the center O3 of the ear canal opening in the sagittal plane ranges from 12 mm to 18 mm, and the distance from the projection point O2' of the center O2 of the second pressure relief hole in the sagittal plane to the projection point O3' of the center O3 of the ear canal opening in the sagittal plane ranges from 6.88 mm to 10.32 mm. In some embodiments, the distance from the projection point A of the midpoint of the upper boundary of the inner surface IS in the sagittal plane to the projection point O3' of the center O3 of the ear canal opening in the sagittal plane ranges from 14 mm to 16 mm, and the distance from the projection point O2' of the center O2 of the second pressure relief hole in the sagittal plane to the projection point O3' of the center O3 of the ear canal opening in the sagittal plane ranges from 7.88 mm to 9.32 mm. In some embodiments, the distance between the midpoint of the upper boundary of the inner surface IS and the projection point A in the sagittal plane from the center O3 of the ear canal opening and the projection point O3' in the sagittal plane is in the range of 14.5 mm to 15.5 mm, and the distance between the center O2 of the second pressure relief hole and the projection point O2' in the sagittal plane from the center O3 of the ear canal opening and the projection point O3' in the sagittal plane is in the range of 7.88 mm to 8.32 mm.

[0135] In some embodiments, to ensure that the sound-generating part 11 extends into the concha cavity and that there is an appropriate gap (forming an opening in the cavity structure) between the upper boundary of the inner surface IS and the concha cavity, the distance between the projection point O1' of the center O1 of the first pressure relief hole 1131 in the sagittal plane and the projection point O3' of the center O3 of the ear canal opening in the sagittal plane ranges from 12 mm to 18 mm. In some embodiments, the distance between the projection point O1' of the center O1 of the first pressure relief hole 1131 in the sagittal plane and the projection point O3' of the center O3 of the ear canal opening in the sagittal plane ranges from 14 mm to 16 mm. In some embodiments, the distance between the projection point O1' of the center O1 of the first pressure relief hole 1131 in the sagittal plane and the projection point O3' of the center O3 of the ear canal opening in the sagittal plane ranges from 14.5 mm to 15.5 mm.

[0136] In some embodiments, the greater the distance between the projection point O1' of the center O1 of the first pressure relief hole 1131 in the sagittal plane and the projection point B of the lower third point of the inner surface IS in the sagittal plane, the larger the volume V of the cavity structure. Therefore, in some embodiments, provided that the sound-emitting part 11 is at least partially inserted into the concha cavity, in order to make the cavity structure have a suitable volume V and to improve the sound reception effect of the ear canal, the distance between the projection point O1' of the center O1 of the first pressure relief hole 1131 in the sagittal plane and the projection point B of the lower third point of the inner surface IS in the sagittal plane ranges from 13.76 mm to 20.64 mm. In some embodiments, the distance between the projection point O1' of the center O1 of the first pressure relief hole 1131 in the sagittal plane and the projection point B of the lower third point of the inner surface IS in the sagittal plane ranges from 15.76 mm to 18.64 mm. In some embodiments, the distance between the projection point O1' of the center O1 of the first pressure relief hole 1131 in the sagittal plane and the projection point B of the lower boundary of the inner side surface IS in the sagittal plane ranges from 16.16 mm to 18.24 mm.

[0137] In some embodiments, to reduce the noise from the second pressure relief hole 1132 entering the cavity structure through the second leakage structure LC and canceling out the noise from the sound outlet hole 112, the distance from the projection point O2' of the center O2 of the second pressure relief hole 1132 in the sagittal plane to the projection point B of the lower boundary of the inner surface IS in the sagittal plane ranges from 8.16 mm to 12.24 mm. In some embodiments, the distance from the projection point O2' of the center O2 of the second pressure relief hole 1132 in the sagittal plane to the projection point B of the lower boundary of the inner surface IS in the sagittal plane ranges from 9.16 mm to 11.24 mm. In some embodiments, the distance from the projection point O2' of the center O2 of the second pressure relief hole 1132 in the sagittal plane to the projection point B of the lower boundary of the inner surface IS in the sagittal plane ranges from 9.66 mm to 10.74 mm.

[0138] In some embodiments, to ensure that the sound-generating part 11 extends into the concha cavity and that there is an appropriate gap (forming an opening in the cavity structure) between the upper boundary of the inner surface IS and the concha cavity, the distance from the projection B of the lower third point of the inner surface in the sagittal plane to the projection point O3' of the center O3 of the ear canal opening in the sagittal plane ranges from 1.76 mm to 2.64 mm. In some embodiments, the distance from the projection B of the lower third point of the inner surface in the sagittal plane to the projection point O3' of the center O3 of the ear canal opening in the sagittal plane ranges from 1.96 mm to 2.44 mm. In some embodiments, the distance from the projection B of the lower third point of the inner surface in the sagittal plane to the projection point O3' of the center O3 of the ear canal opening in the sagittal plane ranges from 2.16 mm to 2.24 mm.

[0139] Figure 20A This is an exemplary internal structure diagram of the sound-generating part according to some embodiments of this application.

[0140] like Figure 20A As shown, the sound-generating part 11 may include a housing 111 connected to the ear hook 12 and a transducer 116 disposed within the housing 111. In some embodiments, the sound-generating part 11 may further include a main control circuit board 13 disposed within the housing 111 and a battery (not shown) disposed at the end of the ear hook 12 away from the sound-generating part 11. The battery and the transducer 116 are electrically connected to the main control circuit board 13, allowing the battery to supply power to the transducer 116 under the control of the main control circuit board 13. Of course, the battery and the transducer 116 may both be disposed within the sound-generating part 11, with the battery closer to the connection end CE and the transducer 116 closer to the free end FE.

[0141] In some embodiments, the open-back headphones 10 may include an adjustment mechanism connecting the sound-emitting part 11 and the ear hook 12. Different users can adjust the relative position of the sound-emitting part 11 on their ears through the adjustment mechanism to ensure that the sound-emitting part 11 is in a suitable position, thereby forming a cavity structure between the sound-emitting part 11 and the concha. In addition, due to the presence of the adjustment mechanism, users can also adjust the headphones 10 to a more stable and comfortable position.

[0142] Because the concha has a certain volume and depth, after the free end FE extends into the concha, there can be a certain distance between the inner surface IS of the sound-generating part 11 and the concha. In other words, when worn, the sound-generating part 11 and the concha can cooperate to form a cavity structure communicating with the external auditory canal. The sound-generating part 11 (e.g., the inner surface IS) is provided with a sound outlet 112, and the sound outlet 112 can be at least partially located within the aforementioned cavity structure. Thus, when worn, the sound waves propagating from the sound outlet 112 are restricted by the aforementioned cavity structure, that is, the aforementioned cavity structure can concentrate the sound waves, allowing 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 beneficial to improving the acoustic effect of the headphones 10. Furthermore, since the sound-generating part 11 can be configured not to block the external auditory canal when worn, the aforementioned cavity structure can be semi-open. Thus, a portion of the sound waves propagating from the sound outlet 112 can propagate to the ear canal so that the user can hear the sound, while another portion, together with the sound reflected through the ear canal, can propagate through the gap between the sound-emitting part 11 and the ear (e.g., a part of the concha not covered by the sound-emitting part 11) to the outside of the earphone 10 and the ear, thereby forming a first sound leakage in the far field. At the same time, the sound waves propagating through the pressure relief holes 113 (e.g., the first pressure relief hole 1131 and the second pressure relief hole 1132) opened on the sound-emitting part 11 will generally form a second sound leakage in the far field. The intensity of the first sound leakage is comparable to that of the second sound leakage, and the phases of the first sound leakage and the second sound leakage are (close to) opposite to each other, so that the two can cancel each other in the far field. This is beneficial to reduce the sound leakage of the open-back earphone 10 in the far field.

[0143] In some embodiments, a front cavity 114 may be formed between the transducer 116 and the housing 111, and a sound outlet 112 is disposed on the housing 111 surrounding the area forming the front cavity 114, and the front cavity 114 communicates with the outside through the sound outlet 112.

[0144] In some embodiments, the front cavity 114 is disposed between the diaphragm of the transducer 116 and the housing 111. To ensure that the diaphragm has sufficient vibration space, the front cavity 114 may have a large depth dimension (i.e., the distance between the diaphragm of the transducer 116 and the housing 111 directly opposite it). In some embodiments, such as Figure 20AAs shown, the sound outlet 112 is disposed on the inner surface IS in the thickness direction Z. In this case, the depth of the front cavity 114 can refer to the dimension of the front cavity 114 in the Z direction. However, if the depth of the front cavity 114 is too large, it will lead to an increase in the size of the sound-emitting part 11, affecting the wearing comfort of the open-back headphones 10. In some embodiments, the depth of the front cavity 114 can be 0.55 mm-1.00 mm. In some embodiments, the depth of the front cavity 114 can be 0.66 mm-0.99 mm. In some embodiments, the depth of the front cavity 114 can be 0.76 mm-0.99 mm. In some embodiments, the depth of the front cavity 114 can be 0.96 mm-0.99 mm. In some embodiments, the depth of the front cavity 114 can be 0.97 mm.

[0145] To improve the sound output of the open-back headphone 10, the resonant frequency of the Helmholtz-like resonant cavity structure formed by the front cavity 114 and the sound outlet 112 should be as high as possible, so that the overall frequency response curve of the sound-emitting part has a wide and flat region. In some embodiments, the resonant frequency of the front cavity 114 is... f 1 can be no lower than 3kHz. In some embodiments, the resonant frequency of the front cavity 114 is... f The resonant frequency of the front cavity 114 may be no less than 4 kHz. In some embodiments, the resonant frequency of the front cavity 114 may be no less than 6 kHz. In some embodiments, the resonant frequency of the front cavity 114 may be no less than 7 kHz. In some embodiments, the resonant frequency of the front cavity 114 may be no less than 8 kHz.

[0146] Please refer to Figure 20AIn some embodiments, an acoustic barrier 118 may be provided at the positions corresponding to the first pressure relief hole 1131 and / or the second pressure relief hole 1132. The acoustic barrier 118 can adjust the amplitude at the resonant frequency of the rear cavity, and also serves as a dustproof and waterproof function. When other parameters of the acoustic barrier 118 are fixed, its acoustic resistance is related to its thickness, and acoustic barrier 118 of different thicknesses will have a certain impact on the acoustic output performance of the corresponding acoustic holes. Therefore, the thickness of the acoustic barrier 118 is limited to a certain range. In some embodiments, the thickness range of the acoustic barrier 118 provided at the first pressure relief hole 1131 and the second pressure relief hole 1132 can be 35μm-300μm. In some embodiments, the thickness range of the acoustic barrier 118 provided at the first pressure relief hole 1131 and the second pressure relief hole 1132 can be 40μm-150μm. In some embodiments, the thickness range of the acoustic barrier 118 provided at the first pressure relief hole 1131 and the second pressure relief hole 1132 can be 50μm-65μm. In some embodiments, the thickness of the acoustic barrier 118 disposed at the first pressure relief hole 1131 and the second pressure relief hole 1132 can range from 55μm to 62μm. On the other hand, the greater the distance between the end of the acoustic barrier 118 facing the outside of the housing 111 (i.e., the upper surface of the acoustic barrier 118) and the outer surface of the housing 111, the closer the acoustic barrier 118 is to the rear cavity, and the smaller the volume of the rear cavity. In some embodiments, the distance between the upper surface of the acoustic barrier 118 disposed at the first pressure relief hole 1131 and the outer surface of the housing 111 can be 0.8mm-0.9mm, and the distance between the upper surface of the acoustic barrier 118 disposed at the second pressure relief hole 1132 and the outer surface of the housing 111 can be 0.7mm-0.8mm. In some embodiments, the distance between the upper surface of the acoustic barrier 118 disposed at the first pressure relief hole 1131 and the outer surface of the housing 111 can be 0.82mm-0.88mm, and the distance between the upper surface of the acoustic barrier 118 disposed at the second pressure relief hole 1132 and the outer surface of the housing 111 can be 0.72mm-0.76mm. In some embodiments, the distance between the upper surface of the acoustic barrier 118 disposed at the first pressure relief hole 1131 and the outer surface of the housing 111 can be 0.86mm, and the distance between the upper surface of the acoustic barrier 118 disposed at the second pressure relief hole 1132 and the outer surface of the housing 111 can be 0.73mm.

[0147] Figure 20B This is an exemplary structural diagram of a second acoustic cavity according to some embodiments of this specification.

[0148] Reference Figure 20A and Figure 20BIn some embodiments, a support 117 may be provided inside the housing 111, and a cavity 115 may be formed between the support 117 and the transducer 116, so that the cavity 115 is separated from other structures (such as the main control circuit board 13) inside the housing 111, which is beneficial to improving the acoustic performance of the sound-generating part 11. It should be noted that the rear cavity described elsewhere in this specification may include not only the cavity 115, but also other areas located behind the diaphragm and communicating with the cavity 115 (e.g., the space between the diaphragm and the magnetic circuit assembly). The housing 111 is provided with a pressure relief hole 113 (e.g., a first pressure relief hole 1131 and / or a second pressure relief hole 1132), and the support 117 is provided with an acoustic channel communicating with the pressure relief hole 113 and the cavity 115, so that the cavity 115 can communicate with the external environment, that is, air can freely enter and exit the rear cavity, which is beneficial to reducing the resistance of the diaphragm of the transducer 116 during vibration.

[0149] In some embodiments, for the acoustic output performance of the open-back headphone 10, the frequency response curve of the rear cavity needs to have a wide flat region, therefore the resonant frequency of the rear cavity can be set relatively high. Further, in order to better cancel out the first leakage sound formed by the aforementioned pressure relief hole 113, in some embodiments, the resonant frequency of the rear cavity can be equal to the resonant frequency of the front cavity 114. In some embodiments, the difference between the resonant frequency of the rear cavity and the resonant frequency of the front cavity 114 can be no greater than 1 kHz. In some embodiments, the difference between the resonant frequency of the rear cavity and the resonant frequency of the front cavity 114 can be no greater than 500 Hz. In some embodiments, the difference between the resonant frequency of the rear cavity and the resonant frequency of the front cavity 114 can be no greater than 200 Hz. In some embodiments, the resonant frequency of the rear cavity can be no less than 4.5 kHz. In some embodiments, the resonant frequency of the rear cavity can be no less than 6 kHz. In some embodiments, the resonant frequency of the rear cavity can be 8 kHz.

[0150] In some embodiments, the combination of the rear cavity and the pressure relief hole 113 provided on the housing 111 can be regarded as a Helmholtz resonant cavity model. The rear cavity can serve as the body of the Helmholtz resonant cavity model, and the pressure relief hole can serve as 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 rear cavity. In the Helmholtz resonant cavity model, the size of the neck (e.g., the first pressure relief hole 1131 or the second pressure relief hole 1132) can affect the resonant frequency f of the body (e.g., the rear cavity), as shown in formula (2): (2) Where c represents the speed of sound, S represents the area of ​​the neck (e.g., the first pressure relief hole 1131 or the second pressure relief hole 1132), V represents the volume of the cavity (e.g., the rear cavity), and L represents the depth of the neck (e.g., the first pressure relief hole 1131 or the second pressure relief hole 1132).

[0151] As can be seen from formula (2), when the volume V of the rear cavity decreases, the resonant frequency f2 of the rear cavity increases. Therefore, in order for the rear cavity to have a sufficiently large resonant frequency, the volume of the rear cavity needs to be small enough.

[0152] However, the volume of the rear cavity also affects its acoustic capacitance Ca. Changes in the acoustic capacitance Ca of the rear cavity will lead to changes in the capacitive reactance characteristics of the rear cavity, thereby affecting its vibration characteristics. The specific relationship between the volume of the rear cavity and its acoustic capacitance Ca is shown in formula (3): (3) Where ρ represents air density and c represents the speed of sound. V This represents the volume of the posterior cavity.

[0153] Combining formulas (2) and (3), it can be seen that when the volume of the rear cavity... V Increasing the volume of the rear cavity increases the acoustic volume (Ca), but correspondingly decreases the resonant frequency of the rear cavity. To achieve a high resonant frequency while maintaining a large acoustic volume (Ca), the volume of the rear cavity... V It needs to have an appropriate range of values.

[0154] like Figure 20BAs shown, in some embodiments, the cross-section of the cavity 115 can be composed of two vertical sides and a curved side. Connecting the two endpoints of the curved side, the cross-section (e.g., cross-section C1C2C3) can be approximated as a triangle. The hypotenuse C1C3 is formed by the line connecting the two endpoints of the curved surface formed on the support 115 and the two straight sides. The two straight sides C1C2 and C2C3 are formed by the transducer 116's frame, with an included angle α between the hypotenuse C1C3 and the straight side C2C3. In some embodiments, since the frame of the sound-generating part 11 needs to have an acoustic hole (e.g., a sound-transmitting hole) in the area where the straight side C2C3 is located, the sound generated by the vibration of the diaphragm 1161 can radiate to the cavity 115, providing a good channel for radiated sound between the rear side of the diaphragm 1161 and the cavity 115. To ensure acoustic performance, the length of the straight side C1C2 can be adjusted to regulate the included angle α, thereby changing the area of ​​triangle C1C2C3 and thus the volume of cavity 115, and consequently the volume of the rear cavity. In some embodiments, due to the limitation of the sound transmission aperture, the length of the straight side C2C3 is not less than 0.67 mm. In some embodiments, the length of the straight side C2C3 can be 0.7 mm. In some embodiments, since the value of the included angle α is limited, the value of the volume V of cavity 115 is also limited.

[0155] Figure 20C These are frequency response curves of the rear cavity corresponding to different included angles α, as shown in some embodiments of this specification. Figure 20C As shown, when the length of the straight side BC is reduced to decrease the included angle α from 67.6° to 45°, the volume V of the rear cavity decreases, and the corresponding acoustic volume Ca of the rear cavity decreases from 7×10⁻¹² m³ / Pa to 2.88×10⁻¹² m³ / Pa. However, the resonant frequency of the rear cavity increases from approximately 4.5 kHz to approximately 6 kHz. When the length of the straight side BC is increased to increase the included angle α from 67.6° to 79.11°, the volume V of the rear cavity increases, and the corresponding acoustic volume Ca of the rear cavity increases from 7×10⁻¹² m³ / Pa to 15×10⁻¹² m³ / Pa. However, the resonant frequency of the rear cavity decreases from approximately 4.5 kHz to approximately 3 kHz. It should be noted that... Figure 20C The parameters shown, such as 7×10-12 m3 / Pa and 15×10-12 m3 / Pa, only represent the acoustic volume corresponding to the theoretical volume of the rear cavity, and there may be errors with the actual data.

[0156] In some embodiments, the included angle α in the cavity 115 can range from 45° to 79.11°. In some embodiments, the included angle α in the cavity 115 can range from 60° to 70°. In some embodiments, the included angle α in the cavity 115 can be 67.6°. In some embodiments, the included angle α in the cavity 115 can range from 67° to 68°.

[0157] Figure 21 This is an exemplary internal structure diagram of a transducer shown according to some embodiments of this application.

[0158] like Figure 21 As shown, the housing 111 houses a transducer 116, which includes a diaphragm 1161, a voice coil 1162, a frame 1163, and a magnetic circuit assembly 1164. The frame 1163 surrounds the diaphragm 1161, voice coil 1162, and magnetic circuit assembly 1164, providing a mounting platform. The transducer 116 can be connected to the housing 111 via the frame 1163. The diaphragm 1161 covers the voice coil 1162 and magnetic circuit assembly 1164 in the Z direction. The voice coil 1162 extends into the magnetic circuit assembly 1164 and is connected to the diaphragm 1161. When the voice coil 1162 is energized, the magnetic field it generates interacts with the magnetic field formed by the magnetic circuit assembly 1164, thereby driving the diaphragm 1161 to produce mechanical vibration. This vibration then propagates through a medium such as air to generate sound, which is output through the sound outlet 112.

[0159] In some embodiments, the magnetic circuit assembly 1164 includes a magnetic guide plate 11641, a magnet 11642, and a receiving member 11643. The magnetic guide plate 11641 and the magnet 11642 are interconnected. The side of the magnet 11642 away from the magnetic guide plate 11641 is mounted on the bottom wall of the receiving member 11643, and there is a gap between the periphery of the magnet 11642 and the inner periphery of the receiving member 11643. In some embodiments, the outer periphery of the receiving member 11643 is fixedly connected to the tray frame 1163. In some embodiments, both the receiving member 11643 and the magnetic guide plate 11641 can be made of a magnetically conductive material (e.g., iron).

[0160] In some embodiments, the periphery of the diaphragm 1161 can be connected to the frame 1163 via a retaining ring 1155. In some embodiments, the retaining ring 1165 may be made of stainless steel or other metal materials to suit the manufacturing process of the diaphragm 1161.

[0161] Reference Figure 20A and Figure 21In some embodiments, to improve the acoustic output (especially low-frequency output) of the sound-generating part 11 and enhance the air-moving ability of the diaphragm 1161, the larger the projected area of ​​the diaphragm 1161 along the Z direction, the better. However, an excessively large area of ​​the diaphragm 1161 will result in an excessively large transducer 116, which in turn will lead to an excessively large housing 111. This can easily cause the housing 111 to collide and rub against the auricle, affecting the wearing comfort of the sound-generating part 11. Therefore, the dimensions of the housing 111 need to be designed. For example, the minor axis dimension (also called the width dimension) of the housing 111 in the Y direction can be determined based on the dimension of the concha cavity along the Y direction (e.g., 17 mm). Then, a suitable length-to-short ratio (i.e., the ratio of the size of the housing 111 in the X direction to the size in the Y direction) can be selected based on wearing comfort to determine the major axis dimension (also called the length dimension) of the housing 111 in the X direction (e.g., 21.49 mm) to match the size of the concha cavity along the X direction.

[0162] In some embodiments, to facilitate wearing by most users (e.g., so that the sound-emitting part 11 can be inserted into the concha or rest against the antihelix region when most users wear the open-back headphones 10), and to form a cavity structure with better acoustic performance, for example, such that the open-back headphones 10 form a first leakage structure UC and a second leakage structure LC between themselves and the user's ear when worn, thereby improving the acoustic performance of the headphones, the size of the housing 111 can be within a preset range. In some embodiments, the width of the housing 111 in the Y direction can be in the range of 11mm-16mm, depending on the width range of the concha. In some embodiments, the width of the housing 111 in the Y direction can be 11mm-15mm. In some embodiments, the width of the housing 111 in the Y direction can be 14mm-15mm. In some embodiments, the ratio of the size of the housing 111 in the X direction to its size in the Y direction can be 1.2-5. In some embodiments, the ratio of the size of the housing 111 in the X direction to its size in the Y direction can be 1.4-4. In some embodiments, the ratio of the size of the housing 111 in the X direction to its size in the Y direction can be 1.5-2. In some embodiments, the length of the housing 111 in the X direction can be in the range of 15mm-30mm. In some embodiments, the length of the housing 111 in the X direction can be 16mm-28mm. In some embodiments, the length of the housing 111 in the X direction can be 19mm-24mm. In some embodiments, to avoid the housing 111 being too large and affecting the wearing comfort of the open-back headphones 10, the thickness of the housing 111 in the Z direction can be in the range of 5mm-20mm. In some embodiments, the thickness of the housing 111 in the Z direction can be 5.1mm-18mm. In some embodiments, the thickness of the housing 111 in the Z direction can be 6mm-15mm. In some embodiments, the thickness of the housing 111 in the Z direction can be 7mm-10mm. In some embodiments, the area of ​​the inner surface IS of the housing 111 (which, when the inner surface IS is rectangular, is equal to the product of the length and width of the housing 111) can be 90mm². 2 -560mm 2 In some embodiments, the area of ​​the inner surface IS can be considered as approximately the projected area of ​​the diaphragm 1161 along the Z direction. For example, the area of ​​the inner surface IS differs from the projected area of ​​the diaphragm 1161 along the Z direction by 10%. In some embodiments, the area of ​​the inner surface IS can be 150 mm². 2 -360mm 2 In some embodiments, the area of ​​the inner surface IS can be 160 mm². 2 -240mm 2 In some embodiments, the area of ​​the inner surface IS can be 180 mm².2 -200mm 2 .based on Figures 10-13 The principle described is as follows: Figure 14 The open-back headphones 10 are designed to be comfortable to wear, and their acoustic performance is superior to that of existing open-back headphones. In other words, the size of the open-back headphones 10 can be smaller than that of existing open-back headphones while achieving the same excellent acoustic performance.

[0163] In some embodiments, in order to achieve a large resonant frequency in the rear cavity while also having a large acoustic capacitance Ca, the volume of the rear cavity is... V An appropriate range of values ​​is required. In some embodiments, to ensure that the volume of the rear cavity has an appropriate range of values, the distance between the center O1 of the first pressure relief hole 1131 and the bottom surface of the magnetic circuit assembly 1164 can be reasonably designed. (Refer to...) Figure 20A and 21 When the thickness of the sound-generating part 11 in the Z direction is constant, the smaller the distance from the center O1 of the first pressure relief hole 1131 to the bottom surface of the magnetic circuit assembly 1164 along the Z direction, the larger the volume of the rear cavity may be. At this time, according to the aforementioned formula (3), the acoustic capacity Ca of the rear cavity increases, but the resonant frequency of the corresponding rear cavity decreases. In order to ensure that the sound-generating efficiency of the sound-generating part 11 is high enough, the resonant frequency of the rear cavity is within a suitable frequency range (e.g., 2000Hz-6000Hz), and the user is comfortable enough, taking into account the structural strength, the difficulty of process implementation, and the overall thickness of the shell 111, the distance from the center O1 of the first pressure relief hole 1131 to the bottom surface of the magnetic circuit assembly 1164 (i.e., the side of the accommodating part 11643 away from the sound outlet hole 112 along the Z direction) is... d The range of 5 is 1.31 mm to 1.98 mm. In some embodiments, the center O1 of the first pressure relief hole 1131 is a distance along the Z direction from the bottom surface of the magnetic circuit assembly 1164. d The range of 5 is 1.31 mm to 1.98 mm. In some embodiments, the center O1 of the first pressure relief hole 1131 is a distance along the Z direction from the bottom surface of the magnetic circuit assembly 1164. d The range of 5 is 1.41 mm to 1.88 mm. In some embodiments, the center O1 of the first pressure relief hole 1131 is a distance along the Z direction from the bottom surface of the magnetic circuit assembly 1164. d The range of 5 is 1.51 mm to 1.78 mm. In some embodiments, the center O1 of the first pressure relief hole 1131 is a distance along the Z direction from the bottom surface of the magnetic circuit assembly 1164. d The range of 5 is 1.56 mm to 1.72 mm. Similarly, in some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the bottom surface of the magnetic circuit assembly 1164 along the Z direction is... dThe range of 6 is 1.31 mm to 1.98 mm. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the bottom surface of the magnetic circuit assembly 1164 along the Z direction is... d The range of 6 is 1.41 mm to 1.88 mm. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the bottom surface of the magnetic circuit assembly 1164 along the Z direction is... d The range of 6 is 1.51 mm to 1.78 mm. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the bottom surface of the magnetic circuit assembly 1164 along the Z direction is... d The range of 6 is 1.56 mm to 1.72 mm.

[0164] In some embodiments, to adapt the size of the sound-emitting part 11 to the size of the concha cavity, the size of the sound-emitting part 11 along the Y direction can be defined. In some embodiments, the size of the sound-emitting part 11 along the Y direction can be defined by the distance from the center O1 of the first pressure relief hole 1131 to the center plane of the long axis of the magnetic circuit assembly 1164 (e.g., as shown in the figure). Figure 21 The distance from the plane NN' perpendicular to the paper and pointing inwards, as shown, is determined. In some embodiments, for ease of design, the distance from the center O1 of the first pressure relief hole 1131 to the center plane of the major axis of the magnetic circuit assembly 1164 (e.g., as shown) can be determined. Figure 21The distance is defined by the plane NN' perpendicular to the paper and pointing inwards. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the center plane of the major axis of the magnetic circuit assembly 1164 ranges from 5.45 mm to 8.19 mm. In this application, the center plane of the major axis of the magnetic circuit assembly 1164 refers to a plane parallel to the lower side LS of the sound-generating part 11 and passing through the center of mass of the magnetic circuit assembly 1164. That is, the center plane of the major axis of the magnetic circuit assembly 1164 can divide the magnetic circuit assembly 1164 into two identical parts along the direction X. The distance between the center O1 of the first pressure relief hole 1131 and the center plane of the major axis of the magnetic circuit assembly 1164 is also the distance from the center O1 of the first pressure relief hole 1131 to the center plane of the major axis along the minor axis direction Y. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the center plane of the major axis of the magnetic circuit assembly 1164 ranges from 5.95 mm to 8.69 mm. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the center plane of the major axis of the magnetic circuit assembly 1164 ranges from 6.45 mm to 7.19 mm. In some embodiments, the distance from the center O1 of the first pressure relief hole 1131 to the center plane of the major axis of the magnetic circuit assembly 1164 ranges from 6.65 mm to 6.99 mm. Similarly, in some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the center plane of the major axis of the magnetic circuit assembly 1164 ranges from 5.46 mm to 8.20 mm. In some embodiments, the distance from the center O2 of the second pressure relief hole 1132 to the center plane of the major axis of the magnetic circuit assembly 1164 ranges from 5.96 mm to 8.70 mm. In some embodiments, the distance from the center O1 of the second pressure relief hole 1132 to the center plane of the major axis of the magnetic circuit assembly 1164 ranges from 6.46 mm to 7.20 mm. In some embodiments, the distance between the center O1 of the second pressure relief hole 1132 and the center plane of the long axis of the magnetic circuit assembly 1164 ranges from 6.66 mm to 7.00 mm.

[0165] In some embodiments, due to the presence of pressure relief holes 113 (e.g., first pressure relief hole 1131 and second pressure relief hole 1132), the air pressure near the pressure relief hole 113 in the rear cavity 115 is similar to the external air pressure, while the air pressure further away from the pressure relief hole 113 is higher than the external air pressure. Since the frame 1163 is provided with a sound-permeable hole (not shown) connecting the rear side of the diaphragm 1161 to the cavity 115, the sound-permeable hole on the frame can be asymmetrically arranged to better balance the airflow in order to balance the air pressure between the rear side of the diaphragm 1161 and the cavity 115. Specifically, at positions farther from the first pressure relief hole 1131 and / or the second pressure relief hole 1132, the air pressure is higher, so the size of the sound-permeable hole can be larger; at positions closer to the first pressure relief hole 1131 and / or the second pressure relief hole 1132, the air pressure is lower, so the size of the sound-permeable hole can be smaller. In some embodiments, adjusting the sizes (e.g., cross-sectional areas) of the first pressure relief hole 1131, the second pressure relief hole 1132, and / or the sound transmission hole can make the low-frequency vibration of the open-back headphone 10 smoother. In some embodiments, to make the air pressure in the rear cavity more stable, thereby making the diaphragm vibration smoother, the first pressure relief hole 1131 and the second pressure relief hole 1132 can be offset in the X direction. In this case, the projection portions of the first pressure relief hole 1131 and the second pressure relief hole 1132 on the long axis center plane may or may not overlap. In some embodiments, the overlapping area of ​​the projections of the first pressure relief hole 1131 and the second pressure relief hole 1132 on the long axis center plane is no greater than 10.77 mm. 2 In some embodiments, the overlapping area of ​​the projections of the first pressure relief hole 1131 and the second pressure relief hole 1132 on the long axis center plane is no greater than 6.77 mm. 2 In some embodiments, the overlapping area of ​​the projections of the first pressure relief hole 1131 and the second pressure relief hole 1132 on the long axis center plane is no greater than 4.77 mm. 2 In some embodiments, the overlapping area of ​​the projections of the first pressure relief hole 1131 and the second pressure relief hole 1132 on the long axis center plane is no greater than 2.77 mm. 2 .

[0166] Figure 22 This is a schematic diagram of the shell of an open-back headphone along the Z-direction on the plane containing the bottom surface of the magnetic circuit assembly.

[0167] In some embodiments, the projection point of the center O1 of the first pressure relief hole 1131 along the Z direction onto the plane containing the bottom surface of the magnetic circuit assembly 1164 is O1'', and the projection point of the center O2 of the second pressure relief hole 1132 along the Z direction onto the plane containing the bottom surface of the magnetic circuit assembly 1164 is O2''. To offset the first pressure relief hole 1131 and the second pressure relief hole 1132 in the X direction, the length of the connecting line O1''O2'' can be greater than the minor axis dimension of the sound-generating part 11. In some embodiments, the length of the connecting line O1''O2'' ranges from 11 mm to 16 mm. In some embodiments, the length of the connecting line O1''O2'' ranges from 8.51 mm to 15.81 mm. In some embodiments, the length of the connecting line O1''O2'' ranges from 10.51 mm to 15.81 mm. In some embodiments, the length of the connecting line O1''O2'' ranges from 11.51 mm to 14.81 mm. In some embodiments, the length of the connecting lines O1''O2'' ranges from 12.51 mm to 13.81 mm. In some embodiments, the ratio of the length of the connecting lines O1''O2'' to the width of the sound-emitting part 11 can be between 1 and 1.88.

[0168] In some embodiments, the offset between the first pressure relief hole 1131 and the second pressure relief hole 1132 in the X direction should not be too large. If the offset is too large, the first pressure relief hole 1131 and the second pressure relief hole 1132 may be close to the free end FE or the connecting end CE in the X direction, resulting in the first pressure relief hole 1131 and / or the second pressure relief hole 1132 being blocked by ear structures (e.g., the concha lateral wall, tragus, etc.) when the open-back earphone 10 is worn. In some embodiments, the offset between the first pressure relief hole 1131 and the second pressure relief hole 1132 in the X direction may be related to the angle β between the connecting line O1''O2'' and the minor axis direction Y. In some embodiments, the angle β may range from 12.85° to 23.88°. In some embodiments, the angle β may range from 14.85° to 21.88°. In some embodiments, the angle β may range from 16.85° to 19.88°. In some embodiments, the included angle β can range from 18.85° to 29.88°.

[0169] The description of the open-back headphone 10 above is for illustrative purposes only and is not intended to limit the scope of this application. Those skilled in the art can make various changes and modifications based on the description in this application. For example, when only one pressure relief hole is provided on the sound-emitting part 11, the pressure relief hole can be either the first pressure relief hole 1131 or the second pressure relief hole 1132 described above. For example, the pressure relief hole can be the first pressure relief hole 1131, that is, the pressure relief hole can be located on the upper side US. The distance between the center of the pressure relief hole and the inner side IS can range from 4.24 mm to 6.38 mm, and the distance between the center of the pressure relief hole and the rear side RS can range from 10.44 mm to 15.68 mm. These changes and modifications are still within the protection scope of this application.

[0170] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

Claims

1. An open-back headphone, comprising: The sound-emitting part includes a transducer and a housing that accommodates the transducer; In the wearing state, the first part of the ear hook is hung between the user's auricle and head, and the second part of the ear hook is connected to the sound-producing part to fix the sound-producing part in a position near the ear canal but without blocking the ear canal, and the sound-producing part is at least partially located in the concha cavity; The housing has a sound outlet on its inner side facing the auricle. At least two pressure relief holes are provided on one or more of the outer side, upper side, and lower side of the housing. The at least two pressure relief holes include a first pressure relief hole and a second pressure relief hole. The first pressure relief hole and the second pressure relief hole are offset in the long axis direction of the sound-emitting part, and the distance between the center of the first pressure relief hole and the center of the second pressure relief hole is 7mm-15.2mm. The long axis direction is the direction with the maximum extension dimension in the projection shape of the two-dimensional projection surface of the sound-emitting part. The two-dimensional projection surface is the plane where the outer side is located, or the two-dimensional projection surface is the human sagittal plane.

2. The open-back headphone according to claim 1, wherein, The sound-producing part has a connecting end that is connected to the ear hook and a free end that is not connected to the ear hook. When worn, the free end extends into the concha cavity and is pressed into the concha cavity in the thickness direction. or, The free end abuts against the concha cavity in the major axis direction and the minor axis direction, the thickness direction is perpendicular to the two-dimensional projection plane, and the major axis direction and the minor axis direction are orthogonal to each other and perpendicular to the thickness direction.

3. The open-back headphone according to claim 1, wherein, There is a certain distance between the inner surface and the concha cavity, and the ear canal communicates with the outside through the gap between the inner surface and the concha cavity.

4. The open-back headphone according to claim 3, wherein, The first pressure relief hole is farther away from the sound outlet hole than the second pressure relief hole, and the distance from the center of the first pressure relief hole to the rear side of the sound-emitting part is less than the distance from the center of the second pressure relief hole to the rear side.

5. The open-back headphone according to claim 4, wherein, The distance between the center of the first pressure relief hole and the rear side is in the range of 10.44mm-15.68mm, and the distance between the center of the second pressure relief hole and the rear side is in the range of 13.51mm-20.27mm.

6. The open-back headphone according to claim 3, wherein, The distance from the center of the first pressure relief hole to the inner side surface ranges from 4.24 mm to 6.38 mm.

7. The open-back headphone according to claim 3, wherein, The distance between the center of the second pressure relief hole and the inner side surface ranges from 4.50 mm to 5.85 mm.

8. The open-back headphone according to claim 3, wherein, The distance from the center of the first pressure relief hole to the inner side surface is 2.24 mm to 5.57 mm, and the distance from the center of the second pressure relief hole to the inner side surface is 5.57 mm to 6.36 mm.

9. The open-back headphone according to claim 1, wherein, The distance from the center of the sound outlet to the perpendicular bisector of the line connecting the center of the first pressure relief hole and the center of the second pressure relief hole is 0mm-2mm.

10. The open-back headphone according to claim 9, wherein, The second pressure relief hole is closer to the ear canal than the first pressure relief hole, and the area of ​​the second pressure relief hole is smaller than the area of ​​the first pressure relief hole.

11. The open-back headphone according to claim 10, wherein, The ratio of the inner opening area of ​​the second pressure relief hole to that of the first pressure relief hole is not greater than 0.

9.

12. The open-back headphone according to claim 9, wherein, The difference between the first distance between the center of the first pressure relief hole and the center of the sound outlet hole and the second distance between the center of the second pressure relief hole and the center of the sound outlet hole is less than 10% of the second distance.

13. The open-back headphone according to claim 9, wherein, The first distance between the center of the first pressure relief hole and the center of the sound outlet hole is 4mm-15.11mm, and the second distance between the center of the second pressure relief hole and the center of the sound outlet hole is 4mm-16.1mm.

14. The open-back headphone according to any one of claims 1-13, wherein, The transducer divides the housing to form the front and rear chambers of the open-back earphone. The first and second pressure relief holes communicate with the rear chamber, and the area of ​​the first pressure relief hole is 3.78 mm². 2 ~22.07 mm 2 The area of ​​the second pressure relief hole is 2.78 mm. 2 ~16.07 mm 2 .

15. The open-back headphone according to any one of claims 1-13, wherein, The transducer includes a magnetic circuit assembly for providing a magnetic field. The length of the line connecting the center of the first pressure relief hole and the center of the second pressure relief hole on the plane where the bottom surface of the magnetic circuit assembly is located ranges from 8.51 mm to 15.81 mm. The ratio of the length of the line to the width of the sound-emitting part in its minor axis direction is between 1 and 1.

88. The minor axis direction is the direction perpendicular to the major axis direction in the projected shape of the sound-emitting part on the two-dimensional projection plane.

16. The open-back headphone according to claim 15, wherein, The angle between the connecting line and the minor axis of the housing ranges from 12.85° to 23.88°, and the thickness direction is perpendicular to the two-dimensional projection plane.

17. The open-back headphone according to any one of claims 1-13, wherein, The first pressure relief hole is located on the upper side of the housing, and the second pressure relief hole is located on the lower side of the housing.

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