Acoustic device

Abstract

An embodiment of the present specification provides an acoustic device comprising: a diaphragm; the shell is used for containing the vibrating diaphragm and forming a first acoustic cavity and a second acoustic cavity which correspond to the front side and the rear side of the vibrating diaphragm respectively, and the vibrating diaphragm radiates sound to the first acoustic cavity and the second acoustic cavity respectively; sound is led out through a first acoustic hole coupled with the first acoustic cavity and a second acoustic hole coupled with the second acoustic cavity; the sound absorption structure is coupled with the second acoustic cavity and is used for absorbing sound transmitted to the second acoustic hole through the second acoustic cavity in a target frequency range, the sound absorption structure comprises a micro-perforated plate and a cavity, the micro-perforated plate comprises a through hole, the cavity is used for accommodating the through hole, and the through hole is communicated with the cavity. The second acoustic cavity is communicated with the cavity through the through hole; and the hanging structure is used for wearing the shell at a position near the ear canal of a user but not blocking the ear canal.

Description

An acoustic device

[0001] Cross-references

[0002] This specification claims priority to the international application with application number PCT / CN2023 / 100403 filed on June 15, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This specification relates to the field of acoustics, and in particular to an acoustic device. Background Art

[0004] In order to solve the sound leakage problem of the sound-emitting part, two or more sound sources are usually used to emit two sound signals with opposite phases. Under far-field conditions, the difference in the sound path between the two sound sources with opposite phases reaching a certain point in the far field is basically negligible, so the two sound signals can cancel each other out to reduce far-field sound leakage. Although this method can achieve the effect of reducing sound leakage to a certain extent, it still has certain limitations. For example, since the wavelength of high-frequency leakage sound is shorter, the distance between the two sound sources under far-field conditions cannot be ignored compared to the wavelength, resulting in the sound signals emitted by the two sound sources being unable to cancel each other out. For another example, when the acoustic transmission structure of the sound-emitting part resonates, there is a certain phase difference between the phase of the sound signal actually radiated by the sound outlet of the sound-emitting part and the original phase of the position where the sound wave is generated, and additional resonance peaks will be added to the transmitted sound wave, resulting in a chaotic sound field distribution and it is difficult to ensure the sound leakage reduction effect in the far field at high frequencies, and may even increase sound leakage.

[0005] Therefore, it is desirable to provide an acoustic device with a better directional sound field.

[0006] Summary of the Invention

[0007] One of the embodiments of the present specification provides an acoustic device, comprising: a diaphragm; a shell, used to accommodate the diaphragm and form a first acoustic cavity and a second acoustic cavity corresponding to the front and rear sides of the diaphragm, respectively, wherein the diaphragm radiates sound to the first acoustic cavity and the second acoustic cavity, respectively, and respectively extracts the sound through a first acoustic hole coupled to the first acoustic cavity and a second acoustic hole coupled to the second acoustic cavity; a sound-absorbing structure, which is coupled to the second acoustic cavity and is used to absorb sound within a target frequency range that is transmitted to the second acoustic hole through the second acoustic cavity, wherein the sound-absorbing structure includes a micro-perforated plate and a cavity, the micro-perforated plate includes a through hole, and the second acoustic cavity is connected to the cavity through the through hole; and a suspension structure, used to wear the shell near the user's ear canal but not blocking the ear canal opening.

[0008] In some embodiments, a ratio of an opening area of ​​the first acoustic hole to an opening area of ​​the second acoustic hole ranges from 0.5 to 2.

[0009] In some embodiments, a difference in acoustic load between the first acoustic hole and the second acoustic hole is less than 0.15.

[0010] In some embodiments, an angle between a normal line of a side surface of the micro-perforated plate facing the second acoustic cavity and a vibration direction of the diaphragm is in a range of 0°-90°.

[0011] In some embodiments, the sound absorbing structure is arranged in the vibration direction of the diaphragm, and the angle between the normal of the side of the micro-perforated plate facing the second acoustic cavity and the vibration direction of the diaphragm is in the range of 0°-10°.

[0012] In some embodiments, the acoustic device further includes a magnetic circuit assembly and a coil, wherein the coil is connected to the diaphragm and is at least partially located in the magnetic gap formed by the magnetic circuit assembly. When the coil is energized, it drives the diaphragm to vibrate to generate sound, wherein the micro-perforated plate includes an annular structure arranged around the magnetic circuit assembly.

[0013] In some embodiments, the aperture of the through hole is in the range of 0.2mm-0.4mm, the perforation rate of the micro-perforated plate is in the range of 1%-5%, the thickness of the micro-perforated plate is in the range of 0.2mm-0.7mm, and the height of the cavity is in the range of 4mm-9mm.

[0014] In some embodiments, the target frequency range includes 4 kHz.

[0015] In some embodiments, the aperture of the through hole is in the range of 0.1mm-0.3mm, the perforation rate of the micro-perforated plate is in the range of 0.5%-5%, the thickness of the micro-perforated plate is in the range of 0.2mm-0.6mm, and the height of the cavity is in the range of 4mm-10mm.

[0016] In some embodiments, the target frequency range includes 2kHz-3kHz.

[0017] In some embodiments, the acoustic device further includes a magnetic circuit assembly and a coil, wherein the coil is connected to the diaphragm and is at least partially located in the magnetic gap formed by the magnetic circuit assembly. When the coil is energized, it drives the diaphragm to vibrate to generate sound, wherein the micro-perforated plate and the magnetic circuit assembly are spaced apart in the vibration direction of the diaphragm.

[0018] In some embodiments, the aperture of the through hole is in the range of 0.1mm-0.2mm, the perforation rate of the micro-perforated plate is in the range of 2%-5%, the thickness of the micro-perforated plate is in the range of 0.2mm-0.7mm, and the height of the cavity is in the range of 7mm-10mm.

[0019] In some embodiments, the target frequency range includes 4 kHz.

[0020] In some embodiments, the aperture of the through hole is in the range of 0.1mm-0.3mm, the perforation rate of the micro-perforated plate is in the range of 0.5%-5%, the thickness of the micro-perforated plate is in the range of 0.2mm-0.6mm, and the height of the cavity is in the range of 4mm-10mm.

[0021] In some embodiments, the target frequency range includes 2kHz-3kHz.

[0022] In some embodiments, the shell has a long axis direction and a short axis direction that are perpendicular to the vibration direction of the diaphragm and orthogonal to each other, the sound absorbing structure is arranged in the long axis direction, and the angle between the side of the micro-perforated plate facing the second acoustic cavity and the long axis direction is in the range of 0°-90°.

[0023] In some embodiments, a side of the micro-perforated plate facing the second acoustic cavity is perpendicular to the long axis direction.

[0024] In some embodiments, the shell has a long axis direction and a short axis direction that are perpendicular to the vibration direction of the diaphragm and orthogonal to each other, the sound absorption structure is arranged in the short axis direction, and the angle between the side of the micro-perforated plate facing the second acoustic cavity and the short axis direction is in the range of 0°-90°.

[0025] In some embodiments, a side of the micro-perforated plate facing the second acoustic cavity is perpendicular to the short axis direction.

[0026] In some embodiments, the sound absorbing structure includes a plurality of independently arranged sub-sound absorbing structures, each of which includes a sub-microperforated plate and a sub-cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present application will be further described in the form of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting, and in these embodiments, like numbers represent like structures, wherein:

[0028] FIG1 is a schematic diagram of an exemplary ear according to some embodiments of the present specification;

[0029] FIG2 is an exemplary structural diagram of an acoustic device according to some embodiments of this specification;

[0030] FIG3A is a schematic diagram illustrating an exemplary wearing method of an acoustic device according to some embodiments of the present specification;

[0031] FIG3B is a schematic structural diagram of an acoustic device in a non-wearing state according to some embodiments of this specification;

[0032] FIG4 is a schematic diagram of an acoustic cavity formed by the acoustic device shown in FIG3A ;

[0033] FIG5 is a schematic diagram of an exemplary wearing method of an acoustic device according to other embodiments of the present specification;

[0034] FIG6 is a schematic diagram of an acoustic cavity formed by the acoustic device shown in FIG5 ;

[0035] FIG7 is a schematic diagram of an acoustic device according to some embodiments of the present specification;

[0036] FIG8A is a schematic diagram of the sound pressure level sound field distribution of the acoustic device shown in FIG7 at medium and low frequencies;

[0037] FIG8B is a schematic diagram of the sound pressure level sound field distribution of the acoustic device shown in FIG7 at high frequencies;

[0038] FIG9 is a schematic structural diagram of an acoustic device provided with a sound absorbing structure according to some embodiments of this specification;

[0039] FIG10 is a diagram showing the sound absorption effects of acoustic devices using metal micro-perforated plates and non-metal micro-perforated plates according to some embodiments of this specification;

[0040] FIG11 is a frequency response graph of acoustic devices using metal micro-perforated plates and non-metal micro-perforated plates according to some embodiments of this specification;

[0041] FIG12 is a frequency response curve of the second acoustic hole measured when a 025HY type gauze is provided on the side of the micro-perforated plate facing the diaphragm and when no gauze is provided according to some embodiments of this specification;

[0042] FIG13 is a graph showing sound absorption coefficients of a micro-perforated plate sound absorption structure with different cavity heights according to some embodiments of this specification;

[0043] FIG14 is a comparison diagram of the maximum sound absorption coefficient and the 0.5 sound absorption octave at different cavity heights according to some embodiments of this specification;

[0044] FIG15 is a diagram showing the sound absorption effect of a micro-perforated plate having through-hole diameters of 0.15 mm and 0.3 mm, respectively, according to some embodiments of this specification;

[0045] FIG16 is a frequency response graph of a micro-perforated plate 351 with 0.15 mm and 0.3 mm apertures according to some embodiments of this specification;

[0046] FIG17 is a schematic structural diagram of an acoustic device provided with a sound absorbing structure according to some embodiments of this specification;

[0047] FIG18 is a frequency response graph of the second acoustic cavity of the acoustic device corresponding to different filling material filling rates according to some embodiments of this specification;

[0048] FIG19 is a schematic structural diagram of an acoustic device provided with a sound absorbing structure according to some embodiments of this specification;

[0049] FIG20 is a schematic structural diagram of another acoustic device provided with a sound absorbing structure according to some embodiments of this specification;

[0050] FIG21 is a diagram showing the internal structure of an acoustic device according to some embodiments of this specification;

[0051] FIG22 is a diagram showing the internal structure of an acoustic device according to some embodiments of this specification;

[0052] FIG23A is a frequency response curve diagram of a second acoustic hole of an acoustic device;

[0053] FIG23B is a frequency response curve diagram of another second acoustic hole of the acoustic device;

[0054] FIG24 is a diagram showing the internal structure of an acoustic device according to some embodiments of this specification;

[0055] FIG25A is a diagram illustrating the internal structure of an acoustic device according to some embodiments of the present specification;

[0056] FIG25B is a diagram illustrating the internal structure of another acoustic device according to some embodiments of the present specification;

[0057] FIG26 is a frequency response curve diagram of the second acoustic hole of the acoustic device shown in FIG25A and FIG25B;

[0058] FIG27 is a schematic diagram of the structure of an acoustic device shown in some embodiments of this specification;

[0059] 28A-28C are schematic structural diagrams of acoustic devices according to some embodiments of this specification;

[0060] 29A-29C are schematic structural diagrams of acoustic devices according to some embodiments of this specification;

[0061] FIG30 is a schematic structural diagram of an acoustic device shown in some other embodiments of this specification. DETAILED DESCRIPTION

[0062] To more clearly illustrate the technical solutions of the embodiments of this application, the following is a brief introduction to the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without inventive effort. Unless otherwise apparent from the context or otherwise noted, the same reference numerals in the figures represent the same structure or operation.

[0063] It should be understood that the terms "system," "device," "unit," and / or "module" used herein are a method for distinguishing different components, elements, parts, portions, or assemblies at different levels. However, if other terms can achieve the same purpose, the terms may be replaced by other expressions.

[0064] As used in this application and the claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not intended to refer to the singular but may include the plural. Generally speaking, the terms "comprises" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0065] Flowcharts are used in this application to illustrate the operations performed by the systems according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0066] FIG1 is a schematic diagram of an exemplary ear according to some embodiments of the present application. Referring to FIG1 , the ear 100 (also referred to as the auricle) may include an external auditory canal 101, a cavity concha 102, a cymba concha 103, a triangular fossa 104, an antihelix 105, a scaphoid 106, an auricle 107, an earlobe 108, a tragus 109, and an auricle crus 1071. In some embodiments, the acoustic device may be supported by one or more parts of the ear 100 to achieve stability in wearing the acoustic device. In some embodiments, the external auditory canal 101, the cavity concha 102, the cymba concha 103, the triangular fossa 104, and other parts 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, an acoustic device (e.g., an in-ear headphone) may be worn in the external auditory canal 101. In some embodiments, the wearing of the acoustic device may be achieved by means of other parts of the ear 100 other than the external auditory canal 101. For example, the acoustic device can be worn by means of the cymba concha 103, the triangular fossa 104, the antihelix 105, the scaphoid 106, the helix 107, or a combination thereof. In some embodiments, to improve the comfort and reliability of the acoustic device in wearing, it can also be further utilized by means of the user's earlobe 108 or other parts. By utilizing other parts of the ear 100 other than the external auditory canal 101 to achieve wearing of the acoustic device and sound transmission, the user's external auditory canal 101 can be "liberated". When the user wears the acoustic device, the acoustic device will not block the user's external auditory canal 101 (or ear canal or ear canal opening). The user can receive both the sound from the acoustic device and the sound from the environment (for example, horns, car bells, surrounding human voices, traffic signals, etc.), thereby reducing the probability of traffic accidents. In this specification, an acoustic device that does not block the user's external auditory canal 101 (or ear canal or ear canal opening) when worn by the user can be referred to as an open-earphone. In some embodiments, the acoustic device can be designed to be compatible with 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 earphone, the earphone can include a suspension structure (e.g., an ear hook) and a sound-emitting part. The sound-emitting part is physically connected to the suspension structure, and the suspension structure can be adapted to the shape of the auricle to place the entire or partial structure of the sound-emitting part on the front side of the tragus 109 (e.g., the area M3 surrounded by dotted lines in FIG1 ). For another example, when the user wears the earphone, the entire or partial structure of the sound-emitting part can be in contact with the upper part of the external auditory canal 101 (e.g., the location of one or more parts such as the cymba concha 103, the triangular fossa 104, the antihelix 105, the scaphoid 106, the helix 107, and the crus helix 1071).For another example, when a user wears headphones, the entire or partial structure of the sound-producing part may be located in a cavity formed by one or more parts of the ear 100 (for example, the cavum concha 102, the bacula concha 103, the fossa triangularis 104, etc.) (for example, the area M1 surrounded by dotted lines in FIG1 , which includes at least the bacula concha 103 and the fossa triangularis 104, and the area M2 which includes at least the cavum concha 102).

[0067] Different users may have individual differences, resulting in different shapes, sizes and other dimensional differences in the ears. For the sake of ease of description and understanding, unless otherwise specified, this specification will mainly use an ear model with a "standard" shape and size as a reference to further describe how the acoustic device in different embodiments is worn on the ear model. For example, a simulator containing a head and its (left and right) ears, such as GRAS 45BC KEMAR, can be made based on ANSI: S3.36, S3.25 and IEC: 60318-7 standards as a reference for wearing an acoustic device, thereby presenting a scenario in which most users normally wear the acoustic device. Just as an example, the ear used as a reference may have the following relevant characteristics: the size of the projection of the auricle on the sagittal plane in the vertical axis direction may be in the range of 49.5mm-74.3mm, and the size of the projection of the auricle on the sagittal plane in the sagittal axis direction may be in the range of 36.6mm-55mm. Therefore, in this application, descriptions such as "worn by a user," "in a worn state," and "in a worn state" may refer to the acoustic device described in this application being worn on the ear of the aforementioned simulator. Of course, considering individual differences among different users, the structure, shape, size, thickness, etc. of one or more parts of the ear 100 may vary to a certain extent. In order to meet the needs of different users, the acoustic device may be designed differently. These differentiated designs may be manifested in that the characteristic parameters of one or more parts of the acoustic device (for example, the sound-emitting part, ear hook, etc. described below) may have different ranges of values ​​to adapt to different ears.

[0068] It should be noted that in fields such as medicine and anatomy, the human body can be defined as three basic planes: the sagittal plane, the coronal plane, and the horizontal plane, as well as three basic axes: the sagittal axis, the coronal axis, and the vertical axis. The sagittal plane refers to a plane perpendicular to the ground, drawn along the front-to-back direction of the body, dividing the body into left and right parts; the coronal plane refers to a plane perpendicular to the ground, drawn along the left-to-right direction of the body, dividing the body into front and back parts; and the horizontal plane refers to a plane perpendicular to the ground, drawn along the top-to-bottom direction of the body, dividing the body into top and bottom parts. Accordingly, the sagittal axis refers to the axis along the front-to-back direction of the body and perpendicular to the coronal plane; the coronal axis refers to the axis along the left-to-right direction of the body and perpendicular to the sagittal plane; and the vertical axis refers to the axis along the top-to-bottom direction of the body and perpendicular to the horizontal plane. Furthermore, the "front side of the ear" as used herein is a concept relative to the "back side of the ear." The front side refers to the side of the ear facing away from the head, while the back side refers to the side of the ear facing toward the head. Observing the ear of the simulator along the coronal axis of the human body yields the frontal outline diagram shown in Figure 1.

[0069] FIG. 2 is a diagram illustrating an exemplary structure of an acoustic device according to some embodiments of the present specification.

[0070] As shown in FIG. 2 , the acoustic device 10 may include a sound-emitting portion 11 and a suspension structure 12 .

[0071] In some embodiments, the acoustic device 10 may include, but is not limited to, an air conduction acoustic device and a bone air conduction acoustic device. In some embodiments, the acoustic device 10 may be combined with products such as glasses, head-mounted acoustic devices, head-mounted display devices, AR / VR helmets, etc. In some embodiments, the acoustic device 10 may include a low-frequency (e.g., 30Hz to 150Hz) speaker, a mid-low-frequency (e.g., 150Hz to 500Hz) speaker, a mid-high-frequency (e.g., 500Hz to 5kHz) speaker, a high-frequency (e.g., 5kHz to 16kHz) speaker, or a full-range (e.g., 30Hz to 16kHz) speaker, or any combination thereof. The low frequency, high frequency, etc. mentioned here only represent the approximate range of frequencies, and different division methods may be used in different application scenarios. For example, a crossover point can be determined, where the low frequency represents the frequency range below the crossover point, and the high frequency represents the frequency range above the crossover point. The crossover point can be any value within the audible range of the human ear, for example, 500Hz, 600Hz, 700Hz, 800Hz, 1000Hz, etc.

[0072] As shown in FIG. 2 , the acoustic device 10 may include a sound-emitting portion 11 and a suspension structure 12 .

[0073] In some embodiments, the acoustic device 10 can be mounted on the user's body (e.g., the head, neck, or upper torso) by means of a suspension structure 12. ... Furthermore, the acoustic device 10 can be mounted on the user's body by means of a suspension structure 12 to secure the sound emitting portion 11 near the ear canal without obstructing the ear canal opening.

[0074] In some embodiments, one end of the suspension structure 12 may be connected to the sound-emitting portion 11, and the other end thereof may extend along the junction of the user's ear 100 and head. In some embodiments, the suspension structure 12 may be an arc-shaped structure that adapts to the user's auricle 100, so that the suspension structure 12 can be suspended from the user's auricle 100. For example, the suspension structure 12 may have an arc-shaped structure that adapts to the junction of the user's head and auricle 100, so that the suspension structure 12 can be hung between the user's auricle 100 and the head. In some embodiments, the suspension structure 12 may also be a clamping structure that adapts to the user's auricle 100, so that the suspension structure 12 can be clamped to the user's auricle 100. In some embodiments, the suspension structure 12 may include, but is not limited to, a suspension structure, an elastic band, etc., so that the acoustic device 10 can be better fixed to the user and prevent the user from dropping it during use. In some embodiments, the acoustic device 10 may not include a suspension structure 12, and the sound-emitting portion 11 may be fixed near the user's auricle 100 by hanging or clamping.

[0075] For example, when the acoustic device 10 is in a worn state, the suspension structure 12 can be suspended between the back of the user's auricle 100 and the head, and the sound-emitting portion 11 contacts the front of the user's auricle 100 (e.g., area M3 in FIG. 1 ) or the auricle 100 (e.g., areas M1 and M2 in FIG. 1 ). The suspension structure 12 or the suspension structure 12 and the sound-emitting portion 11 cooperate to provide the sound-emitting portion 11 with a pressing force on the front of the auricle 100 or the auricle 100. Under the action of the pressing force, the sound-emitting portion 11 can be pressed against the front of the auricle 100 or the areas where the cavum concha 102, cymba concha 103, triangular fossa 104, and antihelix 105 are located, so that the acoustic device 10 does not block the ear canal opening 101 of the auricle 100 when the acoustic device 10 is in a worn state.

[0076] The sound-emitting portion 11 can generate sound to input into the user's ear canal. In some embodiments, the sound-emitting portion 11 can be, for example, a regular or irregular shape such as a ring, an ellipse, a runway, a polygon, a U-shape, a V-shape, a semicircle, etc., so that the sound-emitting portion 11 can be directly hung on the user's auricle 100. In some embodiments, the sound-emitting portion 11 can have a long axis direction Y, a short axis direction Z and a thickness direction X that are orthogonal to each other. Among them, the long axis direction Y can be defined as the direction with a larger extension dimension in the shape of the two-dimensional projection surface of the sound-emitting portion 11 (for example, the projection of the sound-emitting portion 11 on the plane where its inner side is located, or the projection on the sagittal plane) (for example, when the projection shape is a rectangle or an approximate rectangle, the long axis direction is the length direction of the rectangle or the approximate rectangle). For ease of explanation, this specification will be described based on the projection of the sound-emitting portion on the sagittal plane. The short axis Z can be defined as the direction perpendicular to the long axis Y in the shape of the projection of the vocal part 11 on the sagittal plane (for example, when the projection shape is a rectangle or a near rectangle, the short axis is the width direction of the rectangle or near rectangle). The thickness direction X can be defined as the direction perpendicular to the sagittal plane, for example, the same as the direction of the coronal axis, both pointing in the left and right directions of the body.

[0077] In some embodiments, the sound-emitting part 11 may include a diaphragm (not shown in the figure) and a shell 111 for accommodating the diaphragm. The shell 111 (or the sound-emitting part 11) may be connected to the suspension structure 12. In some embodiments, the diaphragm is an element that can receive an excitation signal and convert it into a sound wave output. The diaphragm generates corresponding mechanical vibrations in response to the excitation signal (such as an electrical signal) to produce sound. In some embodiments, the sound-emitting part 11 may also include a voice coil and a magnetic circuit assembly. One end of the voice coil is fixedly connected to the diaphragm, and the other end extends into the magnetic gap formed by the magnetic circuit assembly. By providing current to the voice coil, the voice coil can be vibrated in the magnetic gap, thereby driving the diaphragm to vibrate to generate sound waves.

[0078] In some embodiments, the diaphragm can separate the housing 111 to form a first acoustic cavity and a second acoustic cavity of the acoustic device. The first acoustic hole 112 opened on the housing 111 is acoustically coupled with the first acoustic cavity and outputs the sound generated by the first acoustic cavity out of the housing 111. The second acoustic hole 113 opened on the housing 111 is acoustically coupled with the second acoustic cavity and outputs the sound generated by the second acoustic cavity out of the housing 111. In some embodiments, the first acoustic hole 112 can be provided on the inner side of the housing 111 close to or facing the auricle 100, so that the first acoustic hole is facing or close to the ear canal opening, and then the first acoustic hole 112 outputs the sound generated by the diaphragm out of the housing 111 and transmits it to the ear canal so that the user can hear the sound. The sound output through the first acoustic hole 112 can also be transmitted to the outside of the acoustic device 10 and the auricle 100, thereby forming a first sound leakage in the far field. In some embodiments, a second acoustic hole 113 is provided on the other side of the housing 111 (for example, the side away from or facing away from the user's ear canal). The second acoustic hole 113 is further away from the ear canal opening than the first acoustic hole 112. The sound transmitted from the second acoustic hole 113 will form a second sound leakage in the far field. The intensity of the first sound leakage is comparable to the intensity of the second sound leakage, and the phase of the first sound leakage and the phase of the second sound leakage are (close to) opposite to each other, so that the two can cancel each other out in the far field, which helps to reduce the sound leakage of the acoustic device 10 in the far field. For more information about the sound-emitting portion 11, please refer to the content elsewhere in this manual, such as Figures 3A and 3B and the corresponding content of the manual.

[0079] In some embodiments, when the user wears the acoustic device 10, the sound-emitting portion 11 can be worn near the user's ear canal but not blocking the ear canal opening 101. In some embodiments, when in the worn state, the projection of the acoustic device 10 on the sagittal plane may not cover the user's ear canal opening 101. For example, the projection of the sound-emitting portion 11 on the sagittal plane may fall on the left and right sides of the head and in front of the tragus on the human body's sagittal axis (e.g., the position shown in the solid-line box A in FIG2 ). In this case, the sound-emitting portion 11 is located in front of the user's tragus, the long axis of the sound-emitting portion 11 can be in a vertical or approximately vertical state, the projection of the short axis direction Z on the sagittal plane is consistent with the direction of the sagittal axis, the projection of the long axis direction Y on the sagittal plane is consistent with the vertical axis direction, and the thickness direction X is perpendicular to the sagittal plane. For another example, the projection of the sound-emitting portion 11 on the sagittal plane may fall on the antihelix 105 (e.g., the position shown in the dotted-line box C in FIG2 ). At this point, the sound-producing portion 11 is at least partially located at the antihelix 105, with the long axis of the sound-producing portion 11 horizontal or approximately horizontal. The projection of the long axis Y of the sound-producing portion 11 on the sagittal plane is aligned with the sagittal axis, the projection of the short axis Z on the sagittal plane is aligned with the vertical axis, and the thickness direction X is perpendicular to the sagittal plane. This prevents the sound-producing portion 11 from obstructing the ear canal, thereby freeing up the user's ears. It also increases the contact area between the sound-producing portion 11 and the ear 100, thereby improving the wearing comfort of the acoustic device 10. In some embodiments, when worn, the projection of the acoustic device 10 on the sagittal plane may also cover or at least partially cover the user's ear canal opening 101. For example, the projection of the sound-producing portion 11 on the sagittal plane may fall within the cavum conchae 102 (e.g., as shown by the dashed box B in FIG. 2 ) and contact the crus helix 1071 and / or the helix 107. At this time, the sound-producing part 11 is at least partially located in the concha cavity 102, and the sound-producing part 11 is in a tilted state. The projection of the short axis direction Z of the sound-producing part 11 on the sagittal plane can have a certain angle with the direction of the sagittal axis, that is, the short axis direction Z is also tilted accordingly, and the projection of the long axis direction Y on the sagittal plane can have a certain angle with the direction of the sagittal axis, that is, the long axis direction Y is also tilted, and the thickness direction X is perpendicular to the sagittal plane.

[0080] For example, referring to FIG3A , when worn, the distal end FE of the sound-emitting portion 11 can extend into the cavum concha. Optionally, the sound-emitting portion 11 and the suspension structure 12 can be configured to jointly clamp the auricle 100 from both the front and rear sides of the region of the auricle 100 corresponding to the cavum concha 102, thereby increasing resistance to the acoustic device 10 falling off the ear and thereby improving the stability of the acoustic device 10 when worn. For example, the distal end FE of the sound-emitting portion is pressed against the cavum concha in the thickness direction X. For another example, the distal end FE abuts the cavum concha in the major axis direction Y and / or the minor axis direction Z (e.g., abuts against the inner wall of the cavum concha opposite the distal end FE). It should be noted that the distal end FE of the sound-emitting portion 11 refers to the end of the sound-emitting portion 11 located opposite the fixed end connected to the suspension structure 12, also referred to as the free end. The sound-emitting portion 11 can have a regular or irregular structure. An exemplary illustration is provided here to further illustrate the distal end FE of the sound-emitting portion 11. For example, when the sound-emitting portion 11 is a rectangular parallelepiped structure, the end wall surface of the sound-emitting portion 11 is a plane. In this case, the end FE of the sound-emitting portion 11 is the end side wall of the sound-emitting portion 11 opposite the fixed end connected to the suspension structure 12. For another example, when the sound-emitting portion 11 is a sphere, an ellipsoid, or an irregular structure, the end FE of the sound-emitting portion 11 may refer to a specific region away from the fixed end obtained by cutting the sound-emitting portion 11 along the X-Z plane (the plane formed by the minor axis direction Z and the thickness direction X). The ratio of the dimension of the specific region along the major axis direction Y to the dimension of the sound-emitting portion along the major axis direction Y may be 0.05 to 0.2.

[0081] 3A and 3B , an ear hook is used as an example of the suspension structure 12. In some embodiments, the ear hook 12 may include a first portion 121 and a second portion 122 connected in sequence, wherein the first portion 121 may be hung between the posterior medial side of the user's auricle 100 and the head, and the second portion 122 may extend toward the anterior lateral side of the ear (the side of the ear facing away from the human head along the coronal axis) and connect to the sound-emitting portion, thereby fixing the sound-emitting portion 11 near the user's ear canal but not blocking the ear canal opening. In some embodiments, a first acoustic hole may be provided on the side wall of the sound-emitting portion 11 facing the auricle 100, thereby directing the sound generated by the diaphragm out of the sound-emitting portion 11 and then transmitting it to the user's ear canal opening 101.

[0082] As shown in Figure 3B, in some embodiments, a first acoustic hole 112 connected to the first acoustic cavity is provided on the inner side IS of the shell to guide the sound generated by the first acoustic cavity out of the shell and then transmit it to the ear canal so that the user can hear the sound. One or more second acoustic holes 113 connected to the second acoustic cavity may be provided on other sides of the shell (for example, the upper side US or the lower side LS, etc.) to guide the sound generated by the second acoustic cavity out of the shell and then interfere with the sound output by the first acoustic hole 112 in the far field. In some embodiments, the second acoustic hole 113 is farther away from the ear canal than the first acoustic hole 112 to reduce the anti-phase cancellation between the sound output through the second acoustic hole 113 and the sound output through the first acoustic hole 112 at the listening position.

[0083] By extending the sound-emitting portion 11 at least partially into the concha cavity, the listening volume at the listening position (e.g., at the opening of the ear canal), especially the listening volume of mid- and low-frequency sounds, can be increased, while still maintaining a good far-field sound leakage cancellation effect. For illustrative purposes only, when the entire or partial structure of the sound-emitting portion 11 extends into the concha cavity 102, the sound-emitting portion 11 and the concha cavity 102 form a cavity-like structure (hereinafter referred to as a quasi-cavity). In the embodiments of the specification, the quasi-cavity structure can be understood as a semi-enclosed structure surrounded by the side walls of the sound-emitting portion 11 and the concha cavity 102 structure. This semi-enclosed structure makes the listening position (e.g., at the opening of the ear canal) not completely sealed and isolated from the external environment, but has a leakage structure (e.g., an opening, a gap, a pipe, etc.) that is acoustically connected to the external environment. When a user wears the acoustic device 10, one or more first acoustic holes 112 may be provided on the side of the housing of the sound-emitting portion 11 close to or facing the user's ear canal, and one or more second acoustic holes 113 may be provided on the other sidewall of the housing of the sound-emitting portion 11 (e.g., the sidewall facing away from or away from the user's ear canal). The first acoustic holes 112 are acoustically coupled to the first acoustic cavity of the acoustic device 10, and the second acoustic holes 113 are acoustically coupled to the second acoustic cavity of the acoustic device 10. Taking the example of a sound-emitting portion 11 including a first acoustic hole 112 and a second acoustic hole 113, the sound output by the first acoustic hole 112 and the sound output by the second acoustic hole 113 can be approximately regarded as two sound sources, the sounds of the two sound sources having opposite phases. The corresponding inner walls of the sound-emitting portion 11 and the cavum conchae 102 form a cavity-like structure, wherein the sound source corresponding to the first acoustic hole 112 is located within the cavity-like structure, and the sound source corresponding to the second acoustic hole 113 is located outside the cavity-like structure, forming the acoustic model shown in FIG.

[0084] As shown in Figure 4, the cavity-like structure 402 may include a listening position and at least one sound source 401A. The "include" here may mean that at least one of the listening position and the sound source 401A is inside the cavity-like structure 402, or it may mean that at least one of the listening position and the sound source 401A is at the inner edge of the cavity-like structure 402. The listening position may be equivalent to the entrance of the ear canal or inside the ear canal, or it may be an acoustic reference point of the ear, such as the ear reference point (ERP), the ear-drum reference point (DRP), etc., or it may be an entrance structure leading to the listener, etc. The sound source 401B is located outside the cavity-like structure 402, and the sound sources 401A and 401B with opposite phases radiate sound to the surrounding space respectively and cause interference and destructive sound waves to achieve a sound leakage cancellation effect. Specifically, since the sound source 401A is wrapped by the cavity-like structure 402, most of the sound radiated by it will reach the listening position by direct radiation or reflection. In contrast, in the absence of the cavity-like structure 402, most of the sound radiated by the sound source 401A would not reach the listening position. Therefore, the provision of the cavity structure significantly increases the volume of the sound reaching the listening position. At the same time, only a small portion of the anti-phase sound radiated by the anti-phase sound source 401B outside the cavity-like structure 402 will enter the cavity-like structure 402 through the leakage structure 403 of the cavity-like structure 402. This is equivalent to generating a secondary sound source 401B' at the leakage structure 403, whose intensity is significantly smaller than that of the sound source 401B and also significantly smaller than that of the sound source 401A. The sound generated by the secondary sound source 401B' has a weak anti-phase cancellation effect on the sound source 401A in the cavity, which significantly increases the listening volume at the listening position. As for sound leakage, the sound source 401A radiating sound to the outside through the leakage structure 403 of the cavity is equivalent to generating a secondary sound source 401A' at the leakage structure 403. Since almost all the sound radiated by the sound source 401A is output from the leakage structure 403, and the scale of the cavity-like structure 402 is much smaller than the spatial scale of the evaluated sound leakage (at least one order of magnitude different), it can be considered that the intensity of the secondary sound source 401A' is equivalent to that of the sound source 401A, and still maintains a considerable sound leakage reduction effect.

[0085] In some embodiments of the present specification, a cavity-like structure that is connected to the outside world is formed between the sound-emitting part 11 and the outline of the concha by extending part or the entire structure of the sound-emitting part 11 into the concha cavity. Furthermore, by arranging the first acoustic hole 112 in a position where the shell of the sound-emitting part faces the opening of the user's ear canal and is close to the edge of the concha cavity, the acoustic model shown in Figure 4 can be constructed, so that the user can hear a louder listening volume when wearing the acoustic device. In other words, by specially designing the structure of the sound-emitting part and the wearing method, the sound-emitting part 11 can have a better sound output efficiency. The better sound output efficiency mentioned here can be understood as that even if a smaller input signal is provided to the sound-emitting part 11 (for example, a smaller input voltage or input power is provided to the diaphragm of the sound-emitting part 11), the sound-emitting part can still provide a sufficiently loud volume to the user, that is, a sound pressure exceeding a specific threshold can be generated in the user's ear canal.

[0086] In some embodiments, the sound-emitting portion may be worn in a different manner than the one shown in FIG3A, which is inserted into the concha cavity, and may also achieve better sound output efficiency.

[0087] FIG5 is a schematic diagram of an exemplary wearing method of an acoustic device according to other embodiments of the present specification.

[0088] In some embodiments, when the acoustic device 10 is worn, at least a portion of the sound-emitting portion 11 can cover the user's anti-helix area. In this case, the sound-emitting portion 11 is located above the cavum conchae 102 and the opening of the ear canal, and the opening of the user's ear canal is open. In some embodiments, the housing of the sound-emitting portion 11 may include at least one first acoustic hole 112 and a second acoustic hole 113. The first acoustic hole 112 is acoustically coupled to the first acoustic cavity of the acoustic device 10, and the second acoustic hole 113 is acoustically coupled to the second acoustic cavity of the acoustic device 10. The sound output by the first acoustic hole 112 and the sound output by the second acoustic hole 113 can be approximately considered two sound sources, with the sounds of the two sound sources having opposite phases. When the user wears the acoustic device, the first acoustic hole 112 is located on the side wall of the sound-emitting portion 11 facing or close to the opening of the user's ear canal, and the second acoustic hole 113 is located on the side wall of the sound-emitting portion 11 facing away from or away from the opening of the user's ear canal. In this case, the sound-emitting portion 11 and the user's auricle 100 can be considered a baffle structure. Among them, the sound source corresponding to the first acoustic hole 112 is located on one side of the baffle, and the sound source corresponding to the second acoustic hole 113 is located on the other side of the baffle after bypassing the sound-emitting part 11 and the user's auricle 100, forming the acoustic model shown in Figure 6.

[0089] As shown in Figure 6, when a baffle is placed between sound sources A1 and A2, in the near field, the sound field of sound source A2 needs to bypass the baffle to interfere with the sound waves of sound source A1 at the listening position, which is equivalent to increasing the sound path from sound source A2 to the listening position. Therefore, assuming that sound sources A1 and A2 have the same amplitude, the amplitude difference between the sound waves of sound sources A1 and A2 at the listening position increases compared to the case without a baffle, thereby reducing the degree of cancellation of the two sounds at the listening position, resulting in an increase in the volume at the listening position. In the far field, since the sound waves generated by sound sources A1 and A2 do not need to bypass the baffle to interfere in a larger spatial range (similar to the case without a baffle), the far-field sound leakage does not increase significantly compared to the case without a baffle. Therefore, placing a baffle structure around one of the sound sources A1 and A2 can significantly increase the volume at the near-field listening position without significantly increasing the far-field sound leakage volume.

[0090] In some embodiments of this specification, by at least partially covering the anti-helix area of ​​the user with the sound-emitting portion 11, the user can hear a louder listening volume when wearing the acoustic device. This approach can also provide the sound-emitting portion 11 with better sound output efficiency.

[0091] Figure 7 is a schematic diagram of an acoustic device according to some embodiments of this specification. As shown in Figure 7, the acoustic device 200 may include a housing 210 and a diaphragm 220. The diaphragm 220 may be disposed within the cavity formed by the housing 210. A first acoustic cavity 230 and a second acoustic cavity 240 are provided on the front and rear sides of the diaphragm 220, respectively, for radiating sound. The housing 210 is provided with a first acoustic hole 211 and a second acoustic hole 212. The first acoustic cavity 230 may be acoustically coupled to the first acoustic hole 211, and the second acoustic cavity 240 may be acoustically coupled to the second acoustic hole 212. When a user wears the acoustic device 200, the acoustic device 200 may be positioned near the user's auricle, with the first acoustic hole 211 facing the user's ear canal opening. The second acoustic hole 212 may be positioned further away from the ear canal opening relative to the first acoustic hole 211, and the distance between the first acoustic hole 211 and the ear canal opening may be smaller than the distance between the second acoustic hole 212 and the ear canal opening.

[0092] In some embodiments, the front and rear sides of the diaphragm 220 can respectively serve as a sound wave generating structure to generate a set of sound waves (or sounds) with equal amplitude and (approximately) opposite phases. In some embodiments, a set of sound waves with equal amplitude and opposite phases can be radiated outward through the first acoustic hole 211 and the second acoustic hole 212 respectively. When the diaphragm 220 outputs sound waves, the sound waves on the front side of the diaphragm 220 (or called the first sound waves) can be emitted from the first acoustic hole 211 through the first acoustic cavity 230, and the sound waves on the rear side of the diaphragm 220 (or called the second sound waves) can be emitted from the second acoustic hole 212 through the second acoustic cavity 240, thereby forming a dual sound source including the first acoustic hole 211 and the second acoustic hole 212. The dual sound sources can interfere and destructively decompose at a spatial point (for example, the far field), thereby effectively improving the sound leakage problem in the far field of the acoustic device 200.

[0093] Figure 8A is a schematic diagram of the sound pressure level sound field distribution of the acoustic device shown in Figure 7 at medium and low frequencies. As shown in Figure 8A, in the medium and low frequency range (for example, 50Hz-1kHz), the sound field distribution of the acoustic device 200 in the auricle 100 area shows good directivity. Among them, the sound field area with higher sound pressure is distributed close to the ear canal opening 101, and the sound field area with lower sound pressure is distributed away from the ear canal opening 101, so that the sound leakage reduction effect is significant. That is to say, in the medium and low frequency range, the dual sound sources composed of the first acoustic hole 211 and the second acoustic hole 212 of the acoustic device 200 output sound waves with opposite or nearly opposite phases. According to the principle of anti-phase cancellation of sound waves, the two sound waves cancel each other out in the far field, thereby achieving the effect of reducing far-field sound leakage.

[0094] FIG8B is a schematic diagram of the sound pressure level sound field distribution of the acoustic device shown in FIG7 at high frequencies. As shown in FIG8B , in a higher frequency range, the sound field distribution of the acoustic device 200 is relatively chaotic. In some embodiments, in a higher frequency range (for example, 1500 Hz-20 kHz), the wavelengths of the first sound wave and the second sound wave are shorter than those in the medium and low frequency ranges. At this time, the distance between the dual sound sources formed by the first acoustic hole 211 and the second acoustic hole 212 is not negligible compared to the wavelength, resulting in the sound waves emitted by the two sound sources being unable to cancel each other out, making it difficult to ensure the sound leakage reduction effect of the sound-emitting part in the far field in a higher frequency range, and may even increase the sound leakage, and make the sound field distribution of the sound-emitting part relatively chaotic. For illustrative purposes only, the distance between the first acoustic hole 211 and the second acoustic hole 212 can make the acoustic paths of the first sound wave and the second sound wave from a certain spatial point (for example, the far field) different, so that the phase difference between the first sound wave and the second sound wave at the spatial point is small (for example, the phase is the same or close), resulting in the first sound wave and the second sound wave being unable to interfere with each other at the spatial point, and may also be superimposed at the spatial point, increasing the amplitude of the sound wave at the spatial point, resulting in increased sound leakage.

[0095] In some embodiments, the sound waves emitted from the front and rear sides of the diaphragm 220 may first pass through the acoustic transmission structure and then radiate outward from the first acoustic hole 211 and / or the second acoustic hole 212. The acoustic transmission structure may refer to the acoustic path through which the sound waves radiate from the diaphragm 220 to the external environment. In some embodiments, the acoustic transmission structure may include a shell 210 between the diaphragm 220 and the first acoustic hole 211 and / or the second acoustic hole 212. In some embodiments, the acoustic transmission structure may include an acoustic cavity (including a first acoustic cavity 230 and a second acoustic cavity 240). In some embodiments, the acoustic transmission structure may be acoustically connected to the first acoustic hole 211 and / or the second acoustic hole 212, and the first acoustic hole 211 and / or the second acoustic hole 212 may also serve as part of the acoustic transmission structure. In some embodiments, when the radiation direction of the sound waves generated by the diaphragm 220 is not in the expected direction or away from the ear canal opening, the sound waves can be guided to the expected direction through the sound guide tube, and then radiated to the external environment through the first acoustic hole 211 and / or the second acoustic hole 212. Therefore, the acoustic transmission structure can also include a sound guide tube.

[0096] In some embodiments, the acoustic transmission structure may have a resonant frequency, and when the frequency of the sound wave generated by the diaphragm 220 is near the resonant frequency, the acoustic transmission structure may resonate. Under the action of the acoustic transmission structure, the sound wave located in the acoustic transmission structure also resonates, and the resonance may change the frequency component of the transmitted sound wave (for example, adding an additional resonant peak in the transmitted sound wave) or change the phase of the sound wave transmitted in the acoustic transmission structure. Compared with when no resonance occurs, the phase and / or amplitude of the sound wave radiated from the first acoustic hole 211 and / or the second acoustic hole 212 changes, and the change in the phase and / or amplitude may cause the sound field of the dual sound source structure near the resonant frequency to be chaotic, affecting the effect of the sound waves radiated from the first acoustic hole 211 and the second acoustic hole 212 interfering and destructing at a spatial point. For example, when resonance occurs, the phase difference of the sound waves radiated by the first acoustic hole 211 and the second acoustic hole 212 changes. For example, when the phase difference of the sound waves radiated by the first acoustic hole 211 and the second acoustic hole 212 is small (for example, less than 120°, less than 90°, or 0), the effect of the sound waves interfering and destructing at the spatial point is weakened, making it difficult to achieve the effect of reducing sound leakage; or, the sound waves with a small phase difference may also superimpose on each other at the spatial point, increasing the amplitude of the sound waves at the spatial point (for example, the far field) near the resonant frequency, thereby increasing the far-field sound leakage of the acoustic device 200. For another example, the resonance may increase the amplitude of the transmitted sound waves near the resonant frequency of the acoustic transmission structure (for example, manifested as a resonance peak near the resonant frequency), resulting in a chaotic sound field of the dual-source structure near the resonant frequency. At this time, the amplitude of the sound waves radiated from the first acoustic hole 211 and the second acoustic hole 212 differ greatly, and the effect of the sound waves interfering and destructing at the spatial point is weakened, making it difficult to achieve the effect of reducing sound leakage. In some embodiments, differences in parameters such as the volume of the first acoustic cavity 230 and the second acoustic cavity 240 of the sound-emitting portion, and the size and height of the first acoustic hole 211 and the second acoustic hole 212, can lead to inconsistent resonant frequencies of the first acoustic cavity 230 and the second acoustic cavity 240 (also referred to as simply the acoustic cavity), resulting in different resonant frequencies of the acoustic transmission structures on the front and back sides of the acoustic device 200. In some embodiments, the obstruction and / or reflection of high-frequency sound waves by structures such as the auricle 100 can also lead to a chaotic sound field distribution of the acoustic device 200.

[0097] Based on the description of Figures 7-8B, the dual sound sources have a chaotic sound field in the high-frequency range, and the sound leakage reduction effect is poor, and in some cases may even increase the sound leakage. In order to improve the sound leakage reduction effect of the acoustic device in the high-frequency range, a sound-absorbing structure can be set in the second acoustic cavity of the acoustic device. The sound-absorbing structure can absorb the sound waves within the target frequency range of the second acoustic cavity to reduce or avoid the superposition of the first sound wave and the second sound wave at a certain spatial point outside the acoustic device (for example, the far field), reduce the amplitude of the sound wave within the target frequency range at the spatial point, adjust the directivity of the acoustic device, and achieve the effect of reducing far-field sound leakage.

[0098] A sound-absorbing structure is a structure that absorbs sound waves within a specific frequency band (e.g., a target frequency range). The sound-absorbing structure can be coupled to the second acoustic cavity to absorb sound within the target frequency range that radiates from the second acoustic cavity toward the second acoustic hole. Accordingly, within the target frequency range, the sound pressure level at the second acoustic hole can be greater when the sound-absorbing structure is not present than when the sound-absorbing structure is present.

[0099] In some embodiments, the target frequency range may include a frequency range near the resonant frequency of the second acoustic cavity. The sound-absorbing structure can absorb sound waves near the resonant frequency of the second acoustic cavity to prevent changes in the phase and / or amplitude of the second sound waves caused by resonance of the second acoustic cavity near the resonant frequency, thereby reducing the amplitude of the sound waves near the resonant frequency, thereby ensuring the sound leakage reduction effect of the acoustic device 200. In some embodiments, the resonant frequency may occur in the mid-to-high frequency band, for example, 2kHz-8kHz. Accordingly, the target frequency range may include frequencies in this mid-to-high frequency band. For example, the target frequency range may be in the range of 1kHz-10kHz. In some embodiments, in the higher frequency range, because the distance between the dual sound sources formed by the first and second acoustic holes is not negligible compared to the wavelength, the first and second sound waves cannot interfere with each other at a spatial point and may even superimpose at the spatial point, increasing the amplitude of the sound waves at that spatial point. In some embodiments, to reduce the increase in the amplitude of the sound waves caused by superimposition of the first and second sound waves in the higher frequency range, the target frequency range may also include frequencies greater than the resonant frequency. Thus, the sound-absorbing structure can absorb sound waves in a higher frequency range to reduce or avoid the superposition of the first sound wave and the second sound wave at a spatial point, and reduce the amplitude of the sound waves in the target frequency range of the spatial point. For example, the target frequency range can be in the range of 1kHz-20kHz. It should be noted that the resonant frequency of the second acoustic cavity can be obtained through a variety of testing methods. Here is an example. When testing the frequency response curve of the second acoustic cavity without setting or removing the sound-absorbing structure, the first acoustic hole is kept open, and the frequency response curve of the second acoustic hole position is tested using a microphone device (for example, the microphone device is placed 2-5mm in front of the second acoustic hole) to obtain the resonant frequency corresponding to the resonant peak on the frequency response curve.

[0100] In some embodiments, a sound-absorbing structure (e.g., the location and absorption frequency of the sound-absorbing structure) can be provided to enable the acoustic device to produce different acoustic effects at specific points in space. In some embodiments, the resonance of the first acoustic cavity can also affect the sound wave radiation of the second acoustic cavity, generating redundant resonance peaks on the frequency response curve measured at the location of the second acoustic hole. Therefore, to avoid adding additional resonance peaks to the sound waves transmitted by the second acoustic cavity due to the resonance of the first acoustic cavity, the target frequency range can also include the resonance frequency of the first acoustic cavity. In some embodiments, another sound-absorbing structure can be provided in the first acoustic cavity to absorb sound waves near the resonance frequency of the first acoustic cavity, thereby preventing interference enhancement between the sound waves near the resonance frequency of the first acoustic cavity and the sound waves in the same frequency range output by the second acoustic hole at a specific point in space (e.g., a specific point in space), thereby reducing the amplitude of the sound waves near the resonance frequency of the first acoustic cavity received at that specific point in space. In some embodiments, the sound-absorbing structure can also be provided in both the first acoustic cavity and the second acoustic cavity, thereby absorbing the sound waves near the resonance frequency of the first and second acoustic waves, thereby further reducing the amplitude of the sound waves at any specific point in space. In some embodiments, the sound-absorbing structure can also absorb low-frequency sounds within a specific frequency range. For example, the sound-absorbing structure can be disposed within the second acoustic cavity to reduce low-frequency sounds within a specific frequency range output from the second acoustic aperture, preventing interference and cancellation between the low-frequency sounds within this specific frequency range and the low-frequency sounds within the same frequency range output from the first acoustic aperture at a spatial point (e.g., in the near field), thereby increasing the volume of the acoustic device within this specific frequency range in the near field (i.e., transmitted to the user's ear). In some embodiments, the sound-absorbing structure can further include sub-sound-absorbing structures that absorb sounds in different frequency ranges, such as mid-high frequency bands and low frequency bands, to absorb sounds in different frequency ranges.

[0101] In some embodiments, because the wavelength of high-frequency sound waves is shorter in the high-frequency range greater than the resonant frequency of the second acoustic cavity, the distance between the two acoustic holes (for example, the distance between the geometric centers of the two acoustic holes) may affect the phase difference of the sound waves radiated by the two acoustic holes at a point in space, thereby weakening the sound leakage reduction effect of the dual sound sources formed by the two acoustic holes in the high-frequency range. Therefore, in order to reduce the high-frequency output of the second acoustic cavity, the target frequency range can include a high-frequency range greater than the resonant frequency of the second acoustic cavity, so that the sound-absorbing structure can absorb high-frequency sound waves, thereby improving the problem of unsatisfactory sound leakage reduction effect of the dual sound sources in the high-frequency range.

[0102] Since the human ear is relatively sensitive to sounds of 3kHz-6kHz near the resonant frequency and in the relatively high frequency range, in some embodiments, the target frequency range may include a frequency range of 3kHz-6kHz to achieve more targeted and effective leakage sound reduction. In some embodiments, the target frequency range may include 4kHz-6kHz. In some embodiments, the target frequency range may include sounds below the resonant frequency. For example, the human ear is most sensitive to sounds near 1kHz-3kHz, so the target frequency range may include a frequency range of 1kHz-3kHz. It should be noted that the resonant frequency here mainly refers to the resonant frequency of the second acoustic cavity. In some embodiments, it may also refer to the resonant frequency of the second acoustic cavity or the resonant frequency of the first acoustic cavity, hereinafter referred to as the resonant frequency.

[0103] According to the above embodiment, the sound absorbing structure can absorb the sound waves in the target frequency range of the first sound wave and / or the second sound wave, thereby reducing the amplitude of the sound waves in the target frequency range at the spatial point. For the first sound wave and the second sound wave outside the target frequency range (for example, a sound wave less than the resonant frequency), the first sound wave and the second sound wave can be transmitted to the spatial point through the acoustic transmission structure and interfere at the spatial point, and the interference can reduce the amplitude of the sound waves outside the target frequency range at the spatial point. That is, the first sound wave and the second sound wave outside the target frequency range (or referred to as the first frequency range) can interfere with each other at the spatial point to achieve the effect of dual sound source leakage reduction; the first sound wave and / or the second sound wave within the target frequency range (or referred to as the second frequency range) can be absorbed by the sound absorbing structure, thereby reducing or avoiding the interference enhancement of the first sound wave and / or the second sound wave at the spatial point, or weakening or absorbing the additional resonance peak generated by the first sound wave or the second sound wave under the action of the acoustic transmission structure, thereby reducing the amplitude of the sound waves in the target frequency range at the spatial point. Therefore, the embodiments of this specification can enable the acoustic device to output the first sound wave and the second sound wave in the first frequency range by setting a sound-absorbing structure, and can reduce the sound wave output of the acoustic device (for example, the second acoustic hole) near or above the resonant frequency of the acoustic transmission structure. While ensuring that the acoustic device interferes and cancels in the first frequency range, the increase in the sound wave amplitude in the second frequency range at a spatial point (for example, the far field) is reduced or avoided, thereby adjusting the directivity of the acoustic device to ensure the leakage reduction effect in the entire frequency band.

[0104] The sound absorption effect of a sound-absorbing structure refers to the amount of sound absorbed by the structure within a target frequency range and can be expressed as the sound pressure level. For example, the sound absorption effect of a sound-absorbing structure can be expressed by the difference in sound pressure levels measured at the same frequency and location within the second acoustic cavity, with and without the sound-absorbing structure. By way of example only, the difference in sound pressure levels within the second acoustic cavity, with and without the sound-absorbing structure, can be expressed by the difference in sound pressure levels at the second acoustic hole, with and without the sound-absorbing structure. By way of example only, the sound pressure level at the second acoustic hole, with and without the sound-absorbing structure, can be measured as follows: a test microphone is positioned directly at the second acoustic hole, at a distance of approximately 2 mm to 5 mm, and the sound pressure level at the second acoustic hole is measured with and without the sound-absorbing structure. The test frequency is near the resonant frequency of the second acoustic cavity or around 1 kHz. In some embodiments, the difference in sound pressure levels at the same location within the second acoustic cavity, with and without the sound-absorbing structure, at the same frequency can be no less than 3 dB. For example, the difference in sound pressure levels at the second acoustic hole measured at the same frequency when the sound-absorbing structure is present and absent is no less than 3 dB. In some embodiments, the target frequency range can be referred to as the sound absorption bandwidth of the sound-absorbing structure. When the sound absorption bandwidth is in the range of 3 kHz to 6 kHz, the sound-absorbing structure can effectively absorb sound waves within this range with a sound absorption efficiency of no less than 3 dB, thereby improving sound leakage in the acoustic device within this range. In some embodiments, to further reduce sound leakage in the acoustic device, the sound absorption efficiency of the sound-absorbing structure can be no less than 5 dB within the target frequency range. In some embodiments, to further reduce sound leakage in the acoustic device, the sound absorption efficiency of the sound-absorbing structure can be no less than 6 dB within the target frequency range. In some embodiments, to further reduce sound leakage in the acoustic device, the sound absorption efficiency of the sound-absorbing structure can be no less than 8 dB within the target frequency range. In some embodiments, to further reduce sound leakage in the acoustic device, the sound absorption efficiency of the sound-absorbing structure can be no less than 10 dB within the target frequency range. In some embodiments, the sound absorption efficiency of the sound-absorbing structure can vary across different frequency ranges. For example, within the 3kHz-6kHz range, the sound absorption effect of the sound absorption structure is no less than 3dB. For another example, within the 4kHz-6kHz range, the sound absorption effect of the sound absorption structure is no less than 6dB. For another example, within the 5kHz-6kHz range, the sound absorption effect of the sound absorption structure is no less than 8dB, thereby more effectively reducing sound leakage in higher frequency ranges.

[0105] Because the frequency response curve of the second acoustic cavity exhibits a resonant peak at a specific frequency (e.g., the resonant frequency), and the vibration amplitude at the resonant frequency is relatively large, to achieve a better sound leakage reduction effect at the resonant frequency of the second acoustic cavity, the sound-absorbing structure needs to absorb more sound at the resonant frequency. Therefore, in some embodiments, the sound-absorbing structure has a sound absorption effect of not less than 14 dB for sound at the resonant frequency or sound with a vibration frequency close to the resonant frequency. In this way, sound waves at or near the resonant frequency of the second acoustic cavity can be effectively absorbed by the sound-absorbing structure, reducing or preventing resonance of sound waves near the resonant frequency under the action of the acoustic cavity. This reduces or prevents changes in amplitude and phase differences between the first and second sound waves near the resonant frequency, which can lead to a deterioration in the sound leakage reduction effect at a spatial point, or even a situation where the two groups of sounds not only do not cancel each other but actually interfere with each other, thereby reducing sound leakage from the acoustic device at a far-field spatial point. In some embodiments, to further reduce sound leakage from the acoustic device, the sound-absorbing structure has a sound absorption effect of not less than 16 dB for sound at the resonant frequency or sound with a vibration frequency close to the resonant frequency. In some embodiments, to further reduce sound leakage from the acoustic device, the sound absorbing structure has a sound absorption effect of no less than 18 dB on sounds at the resonant frequency or sounds at vibration frequencies close to the resonant frequency. In some embodiments, to further reduce sound leakage from the acoustic device, the sound absorbing structure has a sound absorption effect of no less than 20 dB on sounds at the resonant frequency or sounds at vibration frequencies close to the resonant frequency. In some embodiments, to further reduce sound leakage from the acoustic device, the sound absorbing structure has a sound absorption effect of no less than 22 dB on sounds at the resonant frequency or sounds at vibration frequencies close to the resonant frequency. In some embodiments, to further reduce sound leakage from the acoustic device, the sound absorbing structure has a sound absorption effect of no less than 25 dB on sounds at the resonant frequency or sounds at vibration frequencies close to the resonant frequency.

[0106] In some embodiments, the sound absorbing structure may include at least one of a resistive sound absorbing structure and a reactive sound absorbing structure. For example, the function of the sound absorbing structure may be achieved by a resistive sound absorbing structure. For another example, the function of the sound absorbing structure may be achieved by a reactive sound absorbing structure. For another example, the function of the sound absorbing structure may be achieved by a hybrid of resistive and reactive sound absorbing structures.

[0107] A resistive sound-absorbing structure may refer to a structure that provides acoustic resistance to the passage of sound waves. In some embodiments, the resistive sound-absorbing structure may include at least one of a porous sound-absorbing material or an acoustic gauze. In some embodiments, the resistive sound-absorbing structure may be positioned at any location along the transmission path of the first and / or second sound waves. For example, the porous sound-absorbing material or acoustic gauze may be attached to the inner wall of the acoustic transmission structure. In another example, the porous sound-absorbing material or acoustic gauze may constitute at least a portion of the inner wall of the acoustic transmission structure. In another example, the porous sound-absorbing material or acoustic gauze may fill at least a portion of the interior of the acoustic transmission structure. A reactive sound-absorbing structure may refer to a structure that absorbs sound through resonance. In some embodiments, reactive sound-absorbing structures may include, but are not limited to, Helmholtz sound-absorbing cavities, perforated plate sound-absorbing structures, micro-perforated plate sound-absorbing structures, thin plates, thin films, quarter-wave resonance tubes, or any combination thereof. In some embodiments, both a resistive sound-absorbing structure and a reactive sound-absorbing structure may be provided simultaneously as an impedance hybrid sound-absorbing structure to achieve the function of a sound-absorbing structure. For example, the impedance hybrid sound absorbing structure may include a micro-perforated plate sound absorbing structure and a porous sound absorbing material or an acoustic gauze, wherein the porous sound absorbing material or the acoustic gauze may be arranged in the cavity of the micro-perforated plate sound absorbing structure, or may be arranged inside the acoustic transmission structure. For another example, the impedance hybrid sound absorbing structure may include a 1 / 4 wavelength resonance tube structure and a porous sound absorbing material or an acoustic gauze, wherein the 1 / 4 wavelength resonance tube structure may be arranged inside or outside the acoustic transmission structure, and the porous sound absorbing material or the acoustic gauze may be arranged inside the acoustic transmission structure. For another example, the impedance hybrid sound absorbing structure may include a micro-perforated plate sound absorbing structure, a 1 / 4 wavelength resonance tube structure, and a porous sound absorbing material or an acoustic gauze.

[0108] The sound-absorbing structure can be coupled to the second acoustic cavity. In some embodiments, the sound-absorbing structure can include a microperforated plate sound-absorbing structure. The microperforated plate sound-absorbing structure includes a microperforated plate and a cavity, wherein the microperforated plate includes through-holes. The acoustic cavity coupled to the microperforated plate structure communicates with the cavity via the through-holes in the microperforated plate. For more information on the microperforated plate sound-absorbing structure, please refer to other sections of this specification, such as Figure 9 and the corresponding specification.

[0109] In some embodiments of this specification, by coupling a sound-absorbing structure with a second acoustic cavity, sound waves within a target frequency range are absorbed by the sound-absorbing structure, which can reduce or avoid resonance of sound waves near a specific frequency (e.g., a resonant frequency) under the action of the acoustic cavity. This can reduce or avoid changes in amplitude and phase differences between the first and second sound waves near the specific frequency of the cavity, which can lead to a deterioration in the sound leakage reduction effect at a spatial point, or even a situation where the two groups of sounds not only do not cancel each other but instead interfere with each other, thereby reducing sound leakage within the target frequency range. The first and second sound waves outside the target frequency range can cancel each other, reducing sound leakage at the spatial point.

[0110] In some embodiments, in order to reduce the sound leakage of the acoustic device 10 in the far field, in addition to being opposite or nearly opposite in phase, the intensity of the first sound leakage and the intensity of the second sound leakage should be close. Therefore, the acoustic load (or acoustic resistance) of the first acoustic hole 112 and the second acoustic hole 113 should be close. In some embodiments, in order to make the acoustic loads of the first acoustic hole 112 and the second acoustic hole 113 close, the opening areas of the first acoustic hole 112 and the second acoustic hole 113 should be close. In some embodiments, the ratio of the opening areas of the first acoustic hole 112 and the second acoustic hole 113 is between 0.5 and 2. In some embodiments, in order to make the acoustic loads of the first acoustic hole 112 and the second acoustic hole 113 close to each other and to make the opening area of ​​the first acoustic hole 112 large enough to ensure the user's listening effect, the ratio of the opening areas of the first acoustic hole 112 and the second acoustic hole 113 is between 1.0 and 1.8. In some embodiments, in order to make the acoustic loads of the first acoustic hole 112 and the second acoustic hole 113 equivalent, and to make the area of ​​the second sound outlet hole 113 large enough to ensure the far-field sound leakage reduction effect, the ratio of the opening area of ​​the first acoustic hole 112 and the second acoustic hole 113 is 0.5-0.9. When there are two or more second acoustic holes 113, the opening area of ​​the second acoustic hole 113 refers to the sum of the opening areas of the multiple second acoustic holes 113. In some embodiments, other parameters of the first acoustic hole 112 and the second acoustic hole 113 can also be set to make the acoustic loads of the first acoustic hole 112 and the second acoustic hole 113 close. For example, the first acoustic hole 112 and the second acoustic hole 113 can be respectively provided with an acoustic resistance net, and the acoustic resistance of the acoustic resistance net is the same or close.

[0111] In some embodiments, to make the intensity of the first sound leakage close to the intensity of the second sound leakage, the difference in acoustic load between the first acoustic hole 112 and the second acoustic hole 113 is less than 0.15. In some embodiments, to make the intensity of the first sound leakage close to the intensity of the second sound leakage, the difference in acoustic load between the first acoustic hole 112 and the second acoustic hole 113 is less than 0.1. In some embodiments, to further make the intensity of the first sound leakage close to the intensity of the second sound leakage, the difference in acoustic load between the first acoustic hole 112 and the second acoustic hole 113 is less than 0.05. In some embodiments, there can be one or more second acoustic holes 113. When there are two or more second acoustic holes 113, the acoustic load of the second acoustic hole 113 refers to the sum of the acoustic loads of the multiple second acoustic holes 113.

[0112] In some embodiments, the acoustic loads of the first acoustic hole 112 and the second acoustic hole 113 are close, and the sound generated by the second acoustic cavity and radiated outward (for example, in the far field) through the second acoustic hole 212 cannot be ignored. In some embodiments, when the sound waves radiated outward from the second acoustic cavity pass through the acoustic transmission structure between the diaphragm and the second acoustic hole 113, the resonance of the acoustic transmission structure causes the sound waves located therein to also resonate. Compared with when no resonance occurs, the phase and / or amplitude of the sound waves radiated from the second acoustic hole 113 changes. The change in phase and / or amplitude may cause confusion in the sound field of the sound-emitting part 11 near the resonant frequency, affecting the effect of interference and cancellation of the sound waves radiated from the first acoustic hole 112 and the second acoustic hole 113 in the far field. Therefore, it is necessary to adjust the sound waves in the second acoustic cavity so that the output of the second acoustic cavity in the target frequency range (for example, including the resonant frequency of the acoustic transmission structure) is reduced without affecting the low-frequency output of the second acoustic cavity, thereby achieving the effect of reducing far-field sound leakage. For example, a sound-absorbing structure can be provided to absorb sound waves in the second acoustic cavity within the target frequency range, thereby adjusting the sound waves in the second acoustic cavity and effectively reducing far-field sound leakage. Furthermore, in frequency bands outside the target frequency range (e.g., low-frequency bands), by aligning the intensity of the first and second sound leakage, far-field sound leakage can be effectively reduced.

[0113] FIG9 is a schematic structural diagram of an acoustic device provided with a sound absorbing structure according to some embodiments of this specification.

[0114] As shown in FIG9 , in some embodiments, an acoustic device 300 may include a housing 310 and a diaphragm 320. The diaphragm 320 is disposed within a housing formed by the housing 310, with a first acoustic cavity 330 and a second acoustic cavity 340 disposed on the front and rear sides of the diaphragm 320, respectively. The housing 310 is provided with a first acoustic hole 311 and a second acoustic hole 312. The first acoustic cavity 330 can be acoustically coupled to the first acoustic hole 311, and the second acoustic cavity 340 can be acoustically coupled to the second acoustic hole 312.

[0115] In some embodiments, as shown in FIG9 , the acoustic device 300 may further include a micro-perforated plate sound-absorbing structure 350, which may be coupled to the second acoustic cavity 340. In some embodiments, the micro-perforated plate sound-absorbing structure 350 may include a micro-perforated plate 351 and a cavity 352. The micro-perforated plate 351 includes through-holes, wherein the second acoustic cavity 340 coupled to the micro-perforated plate structure communicates with the cavity 352 via the through-holes in the micro-perforated plate. It should be noted that the acoustic device 300 shown in FIG9 is merely illustrative, and the specific configuration of the micro-perforated plate sound-absorbing structure 350 may be subject to various variations or modifications.

[0116] Sound waves from the second acoustic cavity 340 can enter the cavity 352 of the micro-perforated plate sound-absorbing structure 350 through one or more through-holes, causing resonance in the micro-perforated plate sound-absorbing structure 350 under certain conditions. For example, when the vibration frequency of the sound waves entering the cavity 352 approaches the resonant frequency of the micro-perforated plate sound-absorbing structure 350, the sound waves entering the cavity 352 cause the micro-perforated plate sound-absorbing structure 350 to resonate. The air within the cavity 352 resonates with the micro-perforated plate sound-absorbing structure 350, dissipating energy and achieving a sound absorption effect. The frequency of the sound waves absorbed by the micro-perforated plate sound-absorbing structure 350 is the same as or close to its resonant frequency.

[0117] In some embodiments, the material of the micro-perforated plate 351 can be metal (e.g., aluminum) or non-metal (e.g., acrylic, polycarbonate (PC), etc.). When the micro-perforated plate 351 is a non-metal plate, the thermal conductivity of the non-metal plate is relatively small, and the process of the sound wave passing through the through hole can be regarded as an adiabatic process. When the micro-perforated plate 351 is a metal plate, the thermal conductivity of the metal plate is relatively large, and when the aperture of the through hole is relatively small, the process of the sound wave passing through the through hole can be regarded as an isothermal process. The conduction of heat represents an enhancement of energy dissipation, so the equivalent damping of the metal plate is greater than that of the non-metal plate.

[0118] Figure 10 illustrates the sound absorption effects of acoustic devices using metal and non-metallic microperforated panels, respectively, according to some embodiments of this specification. The horizontal axis in Figure 10 represents the sound absorption frequency, and the vertical axis represents the sound absorption coefficient. Curve L1 represents the sound absorption effect of the non-metallic microperforated panel, while curve L2 represents the sound absorption effect of the metal microperforated panel. As shown in Figure 10, the maximum sound absorption coefficient of the metal microperforated panel is slightly lower than that of the non-metallic microperforated panel. However, the sound absorption bandwidth of the metal microperforated panel is wider than that of the non-metallic microperforated panel. This is because the metal microperforated panel has better thermal conductivity and greater equivalent damping for sound waves.

[0119] Figure 11 shows frequency response curves for acoustic devices using metal microperforated plates and non-metal microperforated plates, respectively, according to some embodiments of this specification. In Figure 11, the horizontal axis represents frequency, and the vertical axis represents sound pressure level. Curve L3 represents the frequency response for the metal microperforated plate, while curve L4 represents the frequency response for the non-metal microperforated plate. The frequency response here refers to the frequency response at the second acoustic hole (e.g., 10 mm directly in front of the second acoustic hole). As shown in Figure 11, the metal microperforated plate exhibits better sound absorption than the non-metal microperforated plate in the mid- and low-frequency range (e.g., below 4 kHz), reducing sound leakage in the acoustic device by approximately 2-3 dB. In this case, the metal microperforated plate is aluminum. Although the non-metal microperforated plate has slightly inferior sound absorption, its use can reduce the weight of the acoustic device, improving its portability and reducing its cost. In some embodiments, since metal plates and non-metal plates each have their own advantages, metal micro-perforated plates or non-metal micro-perforated plates can be flexibly selected based on multiple aspects such as weight, cost, and corrosion resistance.

[0120] If the natural frequency of the microperforated plate 351 installed in an acoustic device (or in a fixed state) falls within the target frequency range, the microperforated plate 351 may resonate within the target frequency range, affecting the sound absorption effect. Therefore, the natural frequency of the microperforated plate 351 in the fixed state should be much greater than the target frequency. In some embodiments, the natural frequency of the microperforated plate 351 in the fixed state is difficult to measure. The natural frequency of the microperforated plate 351 in the free state can be used to characterize its natural frequency in the fixed state. The free state can refer to the state when the microperforated plate 351 is not installed in the acoustic device. The natural frequency of the microperforated plate 351 in the fixed state is much greater than the natural frequency in the free state. The natural frequency in the free state can be measured by maintaining the microperforated plate 351 in the free state, applying an excitation force with a constant amplitude and varying frequency from low to high to the microperforated plate 351 via an exciter, and measuring the velocity amplitude of the microperforated plate 351 using a laser vibrometer. The frequency at which the velocity amplitude of the microperforated plate 351 reaches a maximum value is recorded, which is the natural frequency of the microperforated plate 351 in the free state. In some embodiments, the sound absorption bandwidth ranges from 3 kHz to 6 kHz. To prevent the natural frequency of the microperforated plate in the fixed state from falling within the sound absorption bandwidth, the theoretical value of the natural frequency of the microperforated plate 351 in the free state can be greater than 500 Hz (e.g., 500 Hz to 3.6 kHz). This ensures that the natural frequency of the microperforated plate in the fixed state is significantly greater than the upper limit of sound absorption (i.e., the maximum frequency in the sound absorption bandwidth, e.g., 6 kHz). The natural frequency is related to the stiffness and mass of the microperforated plate 351. Therefore, the natural frequency of the microperforated plate 351 can be determined by adjusting its stiffness and / or mass, thereby enabling it to absorb sound waves within a target frequency range. In some embodiments, microperforated plates 351 of different shapes, materials, etc. have different stiffness and / or mass, resulting in different natural frequencies. In some embodiments, the microperforated plate 351 can be regular or irregular shapes, such as circular, sector-shaped, rectangular, or diamond-shaped. In some embodiments, the material of the microperforated plate 351 can be non-metallic or metallic.

[0121] In some embodiments, the microperforated plate 351 may be a racetrack-type microperforated plate. In some embodiments, when the microperforated plate 351 is a racetrack-type microperforated plate, the Young's modulus of the material thereof may be in the range of 5 GPa to 200 GPa in order to ensure that the natural frequency of the microperforated plate 351 in the free state is within the range of 500 Hz to 3.6 kHz. For example, the Young's modulus of the material may be in the range of 10 GPa to 180 GPa. For another example, the Young's modulus of the material may be in the range of 20 GPa to 150 GPa. For another example, the Young's modulus of the material may be in the range of 50 GPa to 100 GPa. In some embodiments, the thickness of the microperforated plate 351 may affect its natural frequency. When the microperforated plate 351 is a racetrack-type microperforated plate, the thickness of the racetrack-type microperforated plate may be in the range of 0.1 mm to 0.8 mm in order to ensure that the natural frequency of the microperforated plate 351 in the free state is within the range of 500 Hz to 3.6 kHz. For example, the thickness of the racetrack-shaped micro-perforated plate may be in the range of 0.2 mm to 0.7 mm. For another example, the thickness of the racetrack-shaped micro-perforated plate may be in the range of 0.3 mm to 0.6 mm.

[0122] In some embodiments, the microperforated plate 351 can be a circular microperforated plate. With the same parameters (e.g., pore size, plate thickness, perforation rate, and cavity (e.g., cavity 652) height), the natural frequency of the circular microperforated plate 351 is lower than that of the racetrack-type microperforated plate 351. Therefore, the circular microperforated plate needs to be made of a material with greater rigidity and / or a thicker plate thickness than the racetrack-type microperforated plate to ensure that its natural frequency is far greater than the upper limit frequency of sound absorption. In some embodiments, when the microperforated plate 351 is a circular microperforated plate, in order to ensure that the natural frequency of the microperforated plate 351 in the free state is within the range of 500 Hz-3.6 kHz, the Young's modulus of the material of the microperforated plate 351 is within the range of 50 GPa-200 GPa. For example, the Young's modulus of the material of the circular microperforated plate is within the range of 60 GPa-180 GPa. For another example, the Young's modulus of the material of the circular microperforated plate is within the range of 80 GPa-150 GPa. For another example, the Young's modulus of the circular microperforated plate material ranges from 100 GPa to 150 GPa. In some embodiments, when the microperforated plate 351 is a circular perforated plate, in order to make the natural frequency of the microperforated plate 351 in the free state range from 500 Hz to 3.6 kHz, the thickness of the circular microperforated plate needs to be within the range of 0.3 mm to 1 mm. For example, the thickness of the circular microperforated plate needs to be within the range of 0.4 mm to 0.9 mm. For another example, the thickness of the circular microperforated plate needs to be within the range of 0.5 mm to 0.8 mm. For another example, the thickness of the circular microperforated plate needs to be within the range of 0.6 mm to 0.7 mm.

[0123] By setting the Young's modulus and / or thickness of the micro-perforated plate 351 and adjusting its natural frequency, it is possible to prevent the natural frequency of the micro-perforated plate 351 in a fixed state from falling within the sound absorption bandwidth and affecting its sound absorption effect.

[0124] In some embodiments, a waterproof and breathable structure may be provided on the side of the micro-perforated plate 351 facing the diaphragm 320, and the waterproof and breathable structure may be used to prevent water and dust. Specifically, since the aperture of the through-holes of the micro-perforated plate 351 is relatively small, capillary phenomena may easily occur, and water may be difficult to drain out after entering, which may affect the sound leakage reduction effect of the sound-absorbing structure. Therefore, a waterproof and breathable structure needs to be provided on the interface between the micro-perforated plate 351 and the second acoustic cavity 340. In some embodiments, the waterproof and breathable structure may cover the entire side of the micro-perforated plate 351 in contact with the second acoustic cavity 340. In some embodiments, the waterproof and breathable structure may cover all through-holes on the micro-perforated plate 351, so that the through-holes are connected to the second acoustic cavity 340 through the waterproof and breathable structure.

[0125] In some embodiments, the waterproof and breathable structure can be a gauze. Figure 12 is a frequency response curve diagram of the second acoustic hole measured when a 025HY type gauze is set on the side of the micro-perforated plate facing the diaphragm and when no gauze is set according to some embodiments of this specification. In Figure 12, the horizontal axis represents frequency, the vertical axis represents sound pressure level, curve L5 represents the frequency response curve measured at the second acoustic hole 312 (for example, 10 mm directly in front of the second acoustic hole 312) when the 025HY type gauze is set, and curve L6 represents the frequency response curve measured at the second acoustic hole 312 (for example, 10 mm directly in front of the second acoustic hole 312) when the gauze is not set. As shown in Figure 12, curve L5 is slightly higher than curve L6, and the difference in sound pressure level between the two is not much. It can be seen that the sound absorption effect of the micro-perforated plate 351 with 025HY type gauze is slightly lower than that of the micro-perforated plate 351 without gauze, and the effect is not significant, but it can play a role in waterproofing and dustproofing to a certain extent (for example, the acoustic device using 025HY type gauze can pass the IPX7 waterproof test). Therefore, in some embodiments, a 025HY type gauze can be provided on the side of the micro-perforated plate 351 facing the diaphragm to achieve the purpose of waterproofing and dustproofing the sound absorption structure of the micro-perforated plate. In some embodiments, the acoustic resistance of the 025HY type gauze is lower than 50 MKS Rayls. Therefore, a gauze can be provided on the side of the micro-perforated plate 351 facing the diaphragm, and the acoustic resistance of the gauze can be lower than 50 MKS Rayls, so that it is waterproof and dustproof while having almost no effect on the output effect of the acoustic device (for example, the second acoustic hole).

[0126] Cavity 352 is located on the side of the microperforated plate 351 facing away from the second acoustic cavity 340 and communicates with the outside world only through the through-holes in the microperforated plate 351. In some embodiments, the shape of cavity 352 includes, but is not limited to, the rectangular parallelepiped shown in FIG9 , and may also include regular shapes such as a sphere or cylinder, or irregular shapes such as a runway. In some embodiments, cavity 352 has a certain height D (see FIG9 ). The larger the cavity height D, the wider its sound absorption bandwidth. Therefore, in some embodiments, a larger cavity height D can be used to enhance the sound absorption effect of the microperforated plate sound absorption structure. It should be understood that when the shape of cavity 352 is regular, its height dimension is equal to cavity height D. However, when the shape of cavity 352 is irregular, its height dimension is difficult to determine. The equivalent cavity height D can be expressed as the ratio between the volume of cavity 352 and the area of ​​the microperforated plate 351 (i.e., the area of ​​the side of the microperforated plate facing cavity 352). The volume of the irregular cavity 352 can be measured by the glue injection method. Special glue is injected into the cavity 352 through the acoustic hole on the acoustic output device. After shaping, the shell is peeled off and the volume of the shaped special glue is measured using the drainage method to obtain the volume of the irregular cavity 352.

[0127] Figure 13 shows a graph of sound absorption coefficients for micro-perforated plate sound absorption structures with different cavity heights, according to some embodiments of this specification. As shown in Figure 13, as cavity height D increases, the peak value of the corresponding curve shifts leftward, the peak value decreases, and the coverage width of the corresponding curve increases. Therefore, a larger cavity height D corresponds to a lower sound absorption frequency, a smaller maximum sound absorption coefficient, and a wider sound absorption bandwidth.

[0128] Figure 14 compares the maximum sound absorption coefficient and the 0.5 octave band for different cavity heights according to some embodiments of this specification. The 0.5 octave band refers to the octave range spanned by the sound absorption curve when the sound absorption coefficient is 0.5. A larger octave band indicates a wider sound absorption bandwidth. As shown in Figure 14, as the cavity height D increases, the corresponding maximum sound absorption coefficient gradually decreases, but the 0.5 octave band gradually increases, meaning the sound absorption bandwidth gradually widens.

[0129] In summary, the greater the height D of cavity 352, the wider the sound absorption bandwidth achieved near the desired resonant sound absorption frequency. However, as the cavity height increases, the maximum sound absorption coefficient corresponding to the resonant sound absorption frequency also decreases. Therefore, in some embodiments, to balance the sound absorption bandwidth and maximum sound absorption coefficient of the microperforated plate sound absorption structure, the cavity height D may be in the range of 0.5 mm to 10 mm. For example, the cavity height D may be in the range of 2 mm to 9 mm. For another example, the cavity height D may be in the range of 4 mm to 9 mm. For another example, the cavity height D may be in the range of 7 mm to 10 mm.

[0130] In some embodiments, the micro-perforated plate 351 may be provided with a plurality of through holes, with the plurality of through holes spaced apart. In some embodiments, the plurality of through holes may be distributed in any manner. For example, the plurality of through holes may be distributed in an array. In another example, the plurality of through holes may be distributed in a ring around a central point. In some embodiments, the spacing between the through holes (referred to as the hole spacing) may be the same or different. The spacing between the through holes described in the specification refers to the minimum distance between the edge of a through hole and the edge of an adjacent through hole.

[0131] In some embodiments, the inter-hole spacing between the through holes can be much larger than the aperture of the through hole (the aperture here refers to the diameter of the through hole), and the ratio between the inter-hole spacing and the aperture of the through hole can be greater than 3. In some embodiments, the inter-hole spacing can be much larger than the aperture of the through hole, and the ratio between the inter-hole spacing and the aperture of the through hole can be greater than 5. In some embodiments, the inter-hole spacing can be much larger than the aperture of the through hole, and the ratio between the inter-hole spacing and the aperture of the through hole can be greater than 7. In some embodiments, the inter-hole spacing can be much larger than the aperture of the through hole, and the ratio between the inter-hole spacing and the aperture of the through hole can be greater than 10. When the inter-hole spacing is greater than the aperture, the characteristics of sound waves transmitted between the holes can be independent of each other.

[0132] In some embodiments, the hole spacing between the through holes on the microperforated plate can be much smaller than the wavelength of the sound within the target frequency range. In some embodiments, the ratio of the wavelength of the sound within the target frequency range to the hole spacing can be greater than 5. In some embodiments, the ratio of the wavelength of the sound within the target frequency range to the hole spacing can be greater than 7. In some embodiments, the ratio of the wavelength of the sound within the target frequency range to the hole spacing can be greater than 10. By way of example only, the target frequency range can be 3kHz-6kHz, and the wavelength of the sound within the target frequency range can be in the range of 53mm-110mm. The ratio of the wavelength of the sound within the target frequency range to the hole spacing can be greater than 5, for example, the hole spacing can be in the range of 10mm-22mm. When the hole spacing is much smaller than the wavelength, the reflection of the sound wave by the plate between the holes (the area of ​​the microperforated plate 351 between the edge of the through hole and the edge of the adjacent through hole) can be ignored, thereby avoiding the influence of the reflection of the plate between the holes on the sound wave propagation process.

[0133] In some embodiments, within the effective aperture range, smaller through-hole diameters increase the acoustic resistance of sound waves passing through them, dissipating more energy and broadening the sound absorption bandwidth. Therefore, the sound absorption performance of a microperforated plate sound-absorbing structure can be enhanced by setting smaller through-hole diameters. The effective aperture range refers to the range within which the sound absorption bandwidth of a microperforated plate sound-absorbing structure with aperture sizes meets the requirements for sound leakage reduction. Within the effective aperture range, smaller apertures provide improved sound absorption. When the aperture is smaller than the effective aperture range, the sound absorption bandwidth decreases significantly. In some embodiments, the effective aperture range can be 0.1 mm to 1 mm. Considering processing requirements, in some embodiments, the effective aperture range can be 0.2 mm to 0.4 mm; for example, the effective aperture range can be 0.2 mm to 0.3 mm. In some embodiments, the effective aperture range can be 0.1 mm to 0.4 mm; for example, the effective aperture range can be 0.1 mm to 0.2 mm.

[0134] Figure 15 shows the sound absorption performance of microperforated plates with through-hole diameters of 0.15 mm and 0.3 mm, respectively, according to some embodiments of this specification. The horizontal axis in Figure 15 represents the sound absorption frequency, and the vertical axis represents the sound absorption coefficient. Curve 151 shows the sound absorption performance of the microperforated plate 351 with a pore diameter of 0.15 mm, and curve 152 shows the sound absorption performance of the microperforated plate 351 with a pore diameter of 0.3 mm. As shown in Figure 15 , the width of curve 151 is greater than that of curve 152, but the heights of the two are similar. This shows that the sound absorption bandwidth and sound absorption performance of the microperforated plate 351 with a pore diameter of 0.15 mm are significantly superior to those of the microperforated plate 351 with a pore diameter of 0.3 mm.

[0135] Figure 16 shows frequency response curves for microperforated plates 351 with 0.15mm and 0.3mm apertures, according to some embodiments of this specification. In Figure 16, the horizontal axis represents frequency, and the vertical axis represents sound pressure level. Curve 161 shows the frequency response of the microperforated plate 351 with a 0.15mm aperture, while curve 162 shows the frequency response of the microperforated plate 351 with a 0.3mm aperture. The frequency response here refers to the frequency response of the sound emitted by the second acoustic hole. As shown in Figure 16, the sound leakage of curve 161 in the 2kHz-4kHz frequency range is approximately 6dB lower than that of curve 162. This indicates that the microperforated plate 351 with a 0.15mm aperture significantly outperforms the microperforated plate 351 with a 0.3mm aperture in the mid- and high-frequency range. Therefore, in some embodiments, a microperforated plate 351 with an aperture of 0.15mm or close to 0.15mm may be used for better sound absorption. For example, a micro-perforated plate 351 with a pore size of 0.1 mm to 0.2 mm is used. In some embodiments, considering the need for dust prevention and drainage, a micro-perforated plate 351 with a pore size of 0.3 mm or close to 0.3 mm (eg, 0.28 mm to 0.35 mm) can be used.

[0136] In some embodiments, to avoid excessive number of through-holes resulting in too small a spacing between holes, which would affect the acoustic wave transmission characteristics between the through-holes, the perforation ratio of the micro-perforated plate 351 can be less than 5%. The perforation ratio refers to the ratio of the total area of ​​the through-holes to the area of ​​the side of the micro-perforated plate 351 adjacent to the second acoustic cavity 340.

[0137] In some embodiments, too small a micropore size may increase the difficulty of the process, and a deeper cavity depth D may increase the size of the acoustic device. Therefore, the sound absorption effect of the micro-perforated plate sound absorption structure can be improved by a resistive sound absorption structure. Figure 17 is a structural schematic diagram of an acoustic device provided with a sound absorption structure according to some embodiments of this specification. As shown in Figure 17, the resistive sound absorption structure can be arranged in the cavity 352 of the micro-perforated plate sound absorption structure. In some embodiments, the resistive sound absorption structure may further include a filling material 354 (for example, N'Bass particles or porous sound absorption material). The filling material 354 can be used to increase the equivalent height of the cavity 352 of the micro-perforated plate sound absorption structure, thereby reducing the design size of the acoustic device 1300 while improving the sound absorption effect of the micro-perforated plate sound absorption structure. Specifically, the filling material 354 has a "sponge" effect. When sound waves propagate, air molecules will be adsorbed and desorbed between the pores of the filling material 354, which can be regarded as a decrease in the speed of sound in the filling material 354, which is equivalent to increasing the volume of the cavity 352, thereby achieving the purpose of broadening the sound absorption bandwidth of the micro-perforated plate 351 and increasing the sound absorption coefficient (without affecting the center frequency of the sound absorption), thereby improving the sound absorption effect of the micro-perforated plate sound absorption structure while reducing the design size of the acoustic device.

[0138] In some embodiments, cavity 352 may be filled with N'Bass (aluminosilicate) sound-absorbing particles. In some embodiments, the N'Bass sound-absorbing particles may be placed in cavity 352 in a variety of ways. By way of example only, the N'Bass sound-absorbing particles may be placed directly in cavity 352, or in a powder bag placed in cavity 352, or in a mesh of a specific shape placed in cavity 352, or in a powder bag placed in cavity 352, or in a combination of at least two of the above methods.

[0139] In some embodiments, the smaller the N'Bass sound-absorbing particles, the closer the spacing between them, meaning they have a stronger adsorption effect on air molecules. Consequently, smaller particles require more N'Bass sound-absorbing particles, increasing costs. Therefore, the diameter of the N'Bass sound-absorbing particles can be within the range of 0.15mm-0.7mm to ensure both sound absorption and cost. For example, the diameter of the N'Bass sound-absorbing particles can be within the range of 0.15-0.6mm. For another example, the diameter of the N'Bass sound-absorbing particles can be within the range of 0.2-0.6mm. For another example, the diameter of the N'Bass sound-absorbing particles can be within the range of 0.3-0.5mm.

[0140] In some embodiments, as the filling rate of N'Bass sound-absorbing particles in cavity 352 gradually increases, the more N'Bass sound-absorbing particles there are in cavity 352, the stronger the sound absorption effect. The filling rate refers to the ratio of the volume of the filled N'Bass sound-absorbing particles to the volume of cavity 352. However, when cavity 352 is completely filled with N'Bass sound-absorbing particles, the pressure from the micro-perforated plate surface on the N'Bass sound-absorbing particles may cause the particles to break, thereby blocking the gaps between the particles and reducing the sound absorption effect.

[0141] Figure 18 is a graph showing the frequency response of the second acoustic cavity of an acoustic device according to various filling material filling ratios, as described in some embodiments of this specification. As shown in Figure 18 , when the filling ratio of the filling material (e.g., N'Bass sound-absorbing particles) is 0%, meaning that no filling material is present within the cavity of the microperforated plate sound-absorbing structure, the frequency response curve of the second acoustic cavity of the acoustic device forms a peak near 2kHz (as indicated by the dashed circle in Figure 18 ), indicating that the second acoustic cavity has a high sound output at 2kHz. When the filling material filling ratio is 25%, meaning that 25% of the cavity of the microperforated plate sound-absorbing structure is filled with filling material, the peak near 2kHz is significantly absorbed, but a small peak still exists. When the filling material filling ratio is 50%, meaning that 50% of the cavity of the microperforated plate sound-absorbing structure is filled with filling material, the peak near 2kHz is further absorbed, and the corresponding frequency response curve approaches a flattened state. When the filling material fill rate reaches 75%, meaning that 75% of the cavity within the microperforated plate sound-absorbing structure is filled with filling material, the peak near 2 kHz is further absorbed, but a new peak forms near 3 kHz, causing a slight increase in the sound output of the second acoustic cavity near 3 kHz. When the filling material fill rate reaches 100%, meaning that the cavity within the microperforated plate sound-absorbing structure is completely filled with filling material, the peak near 2 kHz is further absorbed, but the peak near 3 kHz grows further, becoming more pronounced, further increasing the sound output of the second acoustic cavity near 3 kHz. To ensure a smoother frequency response curve for the second acoustic cavity and minimize peaks within a predetermined range (e.g., 2 kHz to 3 kHz), in some embodiments, the filling material fill rate can range from 30% to 100%. In some embodiments, the filling rate can range from 70% to 95%. For example, the filling rate can range from 75% to 90%. For another example, the filling rate can range from 80% to 90%. In some embodiments, taking into account the cost of filling N'Bass sound-absorbing particles, the filling rate may be in the range of 75%-85%. For example, the filling rate may be 80%.

[0142] Setting the filling rate of N'Bass sound-absorbing particles within the range of 70%-95% can ensure the sound absorption effect while avoiding the pressure of the micro-perforated plate sound absorption structure on the N'Bass sound-absorbing particles causing clogging of the gaps, thereby reducing the sound absorption effect.

[0143] In some embodiments, because the diameter of the N'Bass sound-absorbing particles is close to or smaller than the aperture of the through-holes, to prevent the N'Bass sound-absorbing particles from clogging the through-holes, a gauze 353 may be provided between the N'Bass sound-absorbing particles and the micro-perforated plate 351, as shown in FIG17 . In some embodiments, the side of the micro-perforated plate 351 facing away from the second acoustic cavity 340 (or diaphragm 320) may be covered with gauze 353, which covers all through-holes on the micro-perforated plate 351. In some embodiments, the gauze 353 may be provided in the cavity 352 between the N'Bass sound-absorbing particles and the micro-perforated plate 351. Specifically, the gauze 353 may be connected to the inner wall of the cavity 352 between the N'Bass sound-absorbing particles and the micro-perforated plate 351.

[0144] In some embodiments, the micro-perforated plate sound-absorbing structure can be arranged toward the second acoustic cavity. For example, the angle between the normal of the micro-perforated plate facing the side of the second acoustic cavity and the vibration direction of the diaphragm (for example, the angle α shown in FIG20 ) is in the range of 0°-90°, thereby effectively absorbing the sound waves of the target frequency in the second acoustic cavity. It should be noted that the angle here refers to the absolute value of the angle between the normal and the vibration direction of the diaphragm. For example, for the micro-perforated plate sound-absorbing structures 350 and 350′ shown in FIG28C , the angle between the normal of the micro-perforated plate facing the side of the second acoustic cavity 340 and the vibration direction of the diaphragm is 90°.

[0145] In some embodiments, the microperforated plate can be arranged parallel or nearly parallel to the diaphragm. For example, the angle between the normal of the side of the microperforated plate facing the second acoustic cavity and the vibration direction of the diaphragm can be within a range of 0°-10°. This improves the tolerance for assembly of the sound-absorbing structure and the housing, while also avoiding the need to increase the thickness of the sound-emitting portion along the vibration direction due to excessive inclination of the microperforated plate sound-absorbing structure, thereby reducing the volume and / or weight of the sound-emitting portion.

[0146] In some embodiments, the micro-perforated plate can be tilted relative to the diaphragm. For example, the angle between the normal of the micro-perforated plate facing the side of the second acoustic cavity and the vibration direction of the diaphragm can be in the range of 10°-90° to meet the needs of different structures or functions. In some embodiments, the angle between the normal of the micro-perforated plate facing the side of the second acoustic cavity and the vibration direction of the diaphragm can be in the range of 10°-45°. At this time, the micro-perforated plate has a certain tilt relative to the diaphragm, which can realize a specific structure or meet specific sound absorption requirements. For example, the micro-perforated plate can be tilted relative to the diaphragm to adjust the distance between it and the two second acoustic holes, thereby adjusting the sound absorption effect. In some embodiments, the angle between the normal of the microperforated plate facing the side of the second acoustic cavity and the vibration direction of the diaphragm can be in the range of 45°-90°. For example, the angle between the normal of the microperforated plate facing the side of the second acoustic cavity and the vibration direction of the diaphragm can be 90°, meaning that the microperforated plate can be positioned perpendicular to the diaphragm. In this case, the microperforated plate sound-absorbing structure can be positioned at a corner of the second acoustic cavity to avoid increasing the thickness of the sound-emitting portion due to a large inclination angle of the microperforated plate sound-absorbing structure. By way of example only, referring to Figure 28B , the microperforated plate can be positioned along the long axis of the sound-emitting portion and tilted relative to the vibration direction of the diaphragm and the long axis direction Y of the sound-emitting portion. For another example, referring to Figure 29B , the microperforated plate can be positioned along the short axis of the sound-emitting portion and tilted relative to the vibration direction of the diaphragm and the short axis direction Z of the sound-emitting portion. The following describes exemplary embodiments of the microperforated plate being positioned parallel to or tilted relative to the diaphragm, with reference to Figures 19-29C .

[0147] In some embodiments, the micro-perforated plate sound absorbing structure 350 may be arranged within the housing of the acoustic device, extending along the vibration direction of the diaphragm 320. For example, the micro-perforated plate sound absorbing structure 350 may be arranged in the vibration direction of the diaphragm 320, wherein the angle between the normal of the side of the micro-perforated plate in the micro-perforated plate sound absorbing structure 350 facing the second acoustic cavity (or the plane on which the micro-perforated plate is located) and the vibration direction may be within a range of 0°-10°.

[0148] Figure 19 is a schematic diagram of an acoustic device with a sound-absorbing structure, according to some embodiments of this specification. As shown in Figure 19 , the microperforated plate 351 included in the acoustic device 500 can be positioned in the vibration direction of the diaphragm, with the normal of the side of the microperforated plate 351 facing the second acoustic cavity 340 being substantially parallel to the vibration direction of the diaphragm 320. In this case, the second acoustic hole 312 is located on the side of the second acoustic cavity 340 adjacent to the microperforated plate 351.

[0149] Figure 20 is a schematic diagram of another acoustic device with a sound-absorbing structure, according to some embodiments of this specification. As shown in Figure 20 , the microperforated plate 351 included in the acoustic device 500 can be positioned in the vibration direction of the diaphragm, with the normal of the microperforated plate 351 facing the side of the second acoustic cavity 340 forming a certain angle α with the vibration direction of the diaphragm 320, wherein the angle α is greater than 0° and less than 10°. In this case, the second acoustic hole 312 is located on the side of the second acoustic cavity 340 adjacent to the microperforated plate 351.

[0150] Some embodiments of this specification utilize the rear cavity space by positioning the microperforated plate sound absorption structure in the vibration direction of the diaphragm. This allows the second acoustic hole located on the side of the sound-emitting portion (e.g., the upper side wall US or the lower side wall LS) to be positioned adjacent to the microperforated plate sound absorption structure. For example, when the second acoustic hole is positioned on the upper side wall US or the lower side wall LS of the sound-emitting portion, as shown in FIG3B , the microperforated plate sound absorption structure is positioned in the vibration direction of the diaphragm and connected to the upper side wall US and the lower side wall LS. This positions the microperforated plate sound absorption structure close to the second acoustic hole, thereby enhancing the microperforated plate sound absorption structure's absorption effect on the sound at the second acoustic hole. When multiple second acoustic holes are positioned on the upper side wall US or the lower side wall LS of the sound-emitting portion, positioning the microperforated plate sound absorption structure in the vibration direction of the diaphragm can shorten the distance between each second acoustic hole and the microperforated plate sound absorption structure, thereby ensuring the comprehensive sound absorption effect of the microperforated plate sound absorption structure on all second acoustic holes. In addition, the angle between the normal of the side of the micro-perforated plate facing the second acoustic cavity and the vibration direction of the diaphragm can be set in the range of 0°-10°, thereby avoiding the need to increase the thickness of the sound-emitting part along the vibration direction due to the excessive inclination angle of the micro-perforated plate sound-absorbing structure, which is beneficial to reducing the volume and / or weight of the sound-emitting part.

[0151] In some embodiments, for an acoustic device wearing the configuration shown in FIG3A (i.e., the sound-producing portion can partially extend into the cavum concha), when the microperforated plate sound-absorbing structure is positioned in the vibration direction of the diaphragm, the microperforated plate sound-absorbing structure can be positioned at an end away from the end FE along the long axis of the sound-producing portion. This configuration avoids increasing the thickness of the end FE of the sound-producing portion along the vibration direction, thereby preventing the end FE of the sound-producing portion from being unable to penetrate into the cavum concha due to excessive thickness. In some embodiments, for an acoustic device wearing the configuration shown in FIG5 (i.e., the sound-producing portion can partially cover the antihelix region), when the microperforated plate sound-absorbing structure is positioned in the vibration direction of the diaphragm, the microperforated plate sound-absorbing structure can be positioned at any position along the length or width of the sound-producing portion without affecting the wearing experience of the acoustic device.

[0152] In some embodiments, the angle between the normal of the side of the microperforated plate facing the second acoustic cavity and the vibration direction can be in the range of 0°-10°, and the microperforated plate sound-absorbing structure can be arranged outside the vibration direction of the diaphragm. For example, as shown in FIG28A , the angle between the normal of the side of the microperforated plate facing the second acoustic cavity and the vibration direction can be approximately 0°, and the microperforated plate sound-absorbing structure can be arranged along the long axis Y of the sound-emitting portion. For another example, as shown in FIG29A , the angle between the normal of the side of the microperforated plate facing the second acoustic cavity and the vibration direction can be approximately 0°, and the microperforated plate sound-absorbing structure can be arranged along the short axis Z of the sound-emitting portion. For details on how the microperforated plate sound-absorbing structure can be arranged along the long axis and / or short axis, please refer to FIG28A-29C and the related descriptions.

[0153] Figure 21 is a diagram illustrating the internal structure of an acoustic device according to some embodiments of the present specification. Figure 22 is a diagram illustrating the internal structure of an acoustic device according to some embodiments of the present specification.

[0154] As shown in Figures 21 and 22, the diaphragm 720 of the acoustic device 700 divides the housing 710 into a first acoustic cavity 730 and a second acoustic cavity 740. The acoustic device also includes a coil 722, a frame 723, and a magnetic circuit assembly 721. The frame 723 surrounds the diaphragm 720, coil 722, and magnetic circuit assembly 721, providing a mounting platform. The diaphragm 720 can be connected to the housing 710 via the frame 723. The diaphragm 720 covers the coil 722 and magnetic circuit assembly 721 in the vibration direction. At least a portion of the coil 722 extends into the magnetic gap formed by the magnetic circuit assembly 721 and is connected to the diaphragm 720. When energized, the magnetic field generated by the coil 722 interacts with the magnetic field formed by the magnetic circuit assembly 721, driving the diaphragm 720 to produce mechanical vibrations. This in turn generates sound through a medium such as air, which is output through the holes in the housing 710. A micro-perforated plate sound-absorbing structure can be disposed within the second acoustic cavity 740. For example, a micro-perforated plate sound-absorbing structure can be disposed around the magnetic circuit assembly 721. The micro-perforated plate sound-absorbing structure includes a micro-perforated plate 751 and a filling layer 753. The side of the micro-perforated plate 751 away from the diaphragm 720 along the vibration direction is connected to the filling layer 753. The micro-perforated plate 751 is an annular structure disposed around the magnetic circuit assembly 721. The filling layer 753 is filled with N'Bass sound-absorbing particles or porous sound-absorbing material. In some embodiments, the housing 710 (e.g., the back plate 752) can be combined with the magnetic circuit assembly 721 to form a sealed cavity, i.e., the cavity of the micro-perforated plate sound-absorbing structure, and the filling layer 753 can be filled in the cavity.

[0155] In some embodiments, the magnetic circuit assembly 721 includes a magnetic plate 7211, a magnet 7212, and a magnetic cover 7213. The magnetic plate 7211 and the magnet 7212 are interconnected. The side of the magnet 7212 facing away from the magnetic plate 7211 is mounted on the bottom wall of the magnetic cover 7213, and a magnetic gap is formed between the circumference of the magnet 7212 and the inner circumferential wall of the magnetic cover 7213. In some embodiments, the outer circumferential wall of the magnetic cover 7213 is fixedly connected to the frame 723. In some embodiments, both the magnetic cover 7213 and the magnetic plate 7211 can be made of a magnetically conductive material (e.g., iron).

[0156] In some embodiments, a plurality of through holes may be provided on the micro-perforated plate 751, and the plurality of through holes are provided around the magnet assembly, which is conducive to ensuring appropriate hole spacing and perforation rate. In some embodiments, since a closed cavity of a certain height needs to be provided on the side of the micro-perforated plate 751 away from the diaphragm, if the micro-perforated plate 751 is completely provided on the side of the magnetic circuit assembly away from the diaphragm, the micro-perforated plate 751 and the filling layer 753 may occupy too much space in the shell 710, making it difficult to meet the design requirements of the small size of the acoustic device. However, the acoustic device 700 of this embodiment sets the micro-perforated plate 751 as an annular structure surrounding the magnetic circuit assembly, which can effectively utilize the circumferential space of the magnetic circuit assembly without increasing the thickness of the acoustic device (i.e., the size along the vibration direction), which is conducive to the miniaturization design of the acoustic device.

[0157] From the above content, it can be seen that the cavity height D, the thickness of the micro-perforated plate 751, the through-hole diameter, and the perforation rate all affect the sound absorption bandwidth and sound absorption coefficient of the micro-perforated plate 751. The comprehensive values ​​of these parameters can be referred to the following description.

[0158] Generally, the acoustic impedance of a single through hole on the micro-perforated plate 751 is:

[0159] (1) In the formula, ρ is the air density, μ is the air kinematic viscosity, t is the plate thickness, and d is the aperture. When the plate thickness of the through hole is equivalent to the aperture, it is necessary to consider the end correction of the through hole, that is, the effective plate thickness is increased by 0.85d. The micro-perforated plate 751 is provided with multiple through holes, and its acoustic impedance can be equivalent to the parallel connection of the acoustic impedances of multiple through holes. That is, the acoustic impedance ratio of the micro-perforated plate 751 can be obtained by dividing the acoustic impedance ratio of a single through hole by the perforation ratio:

[0160] (2) where σ is the perforation rate, k is the wave number, and the expression is Where ω is the angular frequency and c is the speed of sound. The cavity 652 of the micro-perforated plate sound-absorbing structure is equivalent to the acoustic capacitance, and its acoustic impedance is:

[0161] (3) Where D is the cavity height. The acoustic impedance of the micro-perforated plate sound absorption structure can be expressed as:total =Z MPP +Z D (4)

[0162] After normalization:

[0163] (5) In the formula, r is the relative acoustic resistivity and m is the relative acoustic mass, specifically:

[0164] When the sound wave is incident vertically, the sound absorption coefficient α of the micro-perforated plate sound absorption structure can be solved as:

[0165] The resonant frequency of the sound absorbing structure 350 is:

[0166] According to equations (1) to (9), the sound absorption bandwidth and the sound absorption coefficient of the sound absorption structure 350 can be controlled by adjusting the aperture, perforation rate, plate thickness, and cavity height of the micro-perforated plate 751.

[0167] In addition, the values ​​of parameters such as aperture, perforation ratio, plate thickness, and cavity height can be combined with considerations such as the sound absorption coefficient, sound absorption frequency range, and structural dimensions to comprehensively determine the parameter combination. For example, the sound absorption bandwidth and maximum sound absorption coefficient of a sound-absorbing structure are mutually constrained and can be balanced according to actual needs. For example, the smaller the aperture of a microperforated plate, the wider the sound absorption bandwidth. A wider sound absorption bandwidth corresponds to an effective aperture range. When the aperture is within the effective aperture range, the smaller the aperture, the better the sound absorption effect. When the aperture is smaller than the effective aperture range, the sound absorption bandwidth will be significantly reduced. For another example, a small aperture, a large perforation ratio, a small plate thickness, and a small cavity height are suitable for high-frequency sound absorption, while the opposite is true for low-frequency sound absorption.

[0168] In some embodiments, the parameter combination of the micro-perforated plate 751 can be determined based on the resonant frequency of the second acoustic cavity 740, so that the sound-absorbing structure can absorb sound waves near the resonant frequency of the second acoustic cavity 740, so as to avoid changes in the phase and / or amplitude of the second sound wave caused by the resonance of the second acoustic cavity 740 near the resonant frequency, thereby reducing the amplitude of the sound wave near the resonant frequency, thereby ensuring the effect of reducing sound leakage. In some embodiments, the parameter combination of the micro-perforated plate 751 can be set so that the target frequency range of sound absorption includes the resonant frequency, so that it can absorb sound near the resonant frequency. In some embodiments, the second acoustic cavity 740 may resonate near 4kHz, and the human ear is more sensitive to sound near this frequency. Therefore, the parameter range can be set so that the target frequency range of the sound-absorbing structure includes 4kHz, so as to achieve more targeted and effective sound leakage reduction.

[0169] In some embodiments, the pore size of the micro-perforated plate 751 can be in the range of 0.2 mm to 0.4 mm, the perforation rate can be in the range of 1% to 5%, the plate thickness can be in the range of 0.2 mm to 0.7 mm, and the cavity height can be in the range of 4 mm to 9 mm. In some embodiments, the pore size of the micro-perforated plate 751 can be in the range of 0.25 mm to 0.35 mm, the perforation rate can be in the range of 1.2% to 4.5%, the plate thickness can be in the range of 0.3 mm to 0.6 mm, and the cavity height can be in the range of 5 mm to 8 mm. By way of example only, the pore size of the micro-perforated plate 751 can be 0.25 mm, the perforation rate can be 2.8%, the plate thickness can be 0.4 mm, and the cavity height can be 6 mm. For another example, the pore size of the micro-perforated plate 751 can be 0.3 mm, the perforation rate can be 3.2%, the plate thickness can be 0.5 mm, and the cavity height can be 6.5 mm. For another example, the micro-perforated plate 751 may have a pore diameter of 0.35 mm, a perforation rate of 3.6%, a plate thickness of 0.55 mm, and a cavity height of 7 mm.

[0170] Figure 23A is a frequency response graph at the second acoustic hole of an acoustic device. Figure 23B is a frequency response graph at another second acoustic hole of an acoustic device. In Figures 23A and 23B, the horizontal axis represents frequency, and the vertical axis represents sound pressure level. Curve a1 represents the frequency response of acoustic device 200 (without a microperforated sound-absorbing structure) at the second acoustic hole, curve a2 represents the frequency response of acoustic device 200 at the other second acoustic hole, curve b1 represents the frequency response of acoustic device 300 (with a microperforated sound-absorbing structure) at the second acoustic hole, curve b2 represents the frequency response of acoustic device 300 at the other second acoustic hole, curve c1 represents the frequency response of acoustic device 400 (with a microperforated sound-absorbing structure and N'Bass sound-absorbing particles) at the second acoustic hole, and curve c2 represents the frequency response of acoustic device 400 at the other second acoustic hole. The second acoustic hole and the other second acoustic hole are acoustic holes located at different locations on the shell corresponding to the second acoustic cavity. Among them, curves b1, b2, c1 and c2 are all measured under the conditions of the above-mentioned parameter combination of the micro-perforated plate. The above-mentioned parameter combination means that the aperture of the micro-perforated plate is in the range of 0.2mm-0.4mm, the perforation rate is in the range of 1%-5%, the plate thickness is in the range of 0.2mm-0.7mm, and the cavity height is in the range of 4mm-9mm. Specifically, the aperture of the micro-perforated plate is 0.3mm, the perforation rate is 2.8%, the plate thickness is 0.6, and the cavity height is 6mm.

[0171] As shown in Figures 23A and 23B, curves a1 and a2 exhibit high resonance peaks near 4kHz, with 3.8kHz corresponding to the resonant frequency of the second acoustic cavity. The microperforated plate sound absorption structure (curves b1 and b2) effectively reduces the sound pressure level within the 3kHz-6kHz frequency range by 4dB-20dB, reaching a low point near 4kHz. This indicates that the microperforated plate sound absorption structure can effectively absorb sound waves in the 3kHz-6kHz range, and the microperforated plate sound absorption structure absorbs approximately 20dB of sound waves near 4kHz. This can reduce or prevent the resonance of sound waves near the resonant frequency caused by the second acoustic cavity, thereby reducing sound leakage at the resonant frequency. Filling the cavity of the microperforated plate sound absorption structure with N'Bass sound-absorbing particles (curves c1 and c2) increases the sound absorption bandwidth. Both combined sound absorption schemes exhibit good sound absorption effects. Therefore, by setting the pore size of the micro-perforated plate within the range of 0.2mm-0.4mm, the perforation rate within the range of 1%-5%, the plate thickness within the range of 0.2mm-0.7mm, and the cavity height within the range of 4mm-9mm, sound waves around 4kHz can be effectively absorbed, thereby reducing sound leakage of the acoustic device around 4kHz.

[0172] FIG. 24 is a diagram illustrating the internal structure of an acoustic device according to some embodiments of the present specification.

[0173] As shown in FIG24 , the acoustic device 800 includes a diaphragm 820, a magnetic circuit assembly 821, a coil (not shown), and a basket (not shown). The diaphragm 820 divides the housing 810 into a first acoustic cavity 830 and a second acoustic cavity 840. The coordination between the diaphragm 820, the magnetic circuit assembly 821, the coil, and the basket is similar to that of the acoustic device 700. A micro-perforated plate sound-absorbing structure is coupled to the second acoustic cavity 840. A micro-perforated plate 851 is disposed on the side of the magnetic circuit assembly 821 facing away from the diaphragm 820, and the micro-perforated plate 851 and the magnetic circuit assembly 821 are spaced apart in the vibration direction. In some embodiments, the micro-perforated plate can be a panel (e.g., oval, circular, etc.) that matches the shape of the second acoustic cavity 840 or the housing 810. In some embodiments, parameters such as the aperture, perforation ratio, and hole spacing of the microperforated plate 851 can be consistent with those of the aforementioned microperforated plates (e.g., the microperforated plate with an annular structure disposed around the magnetic circuit assembly). This allows the panel-shaped microperforated plate to have a larger area, a relatively greater number of through-holes, and improved sound absorption, while also simplifying its structure and facilitating assembly. In some embodiments, the parameters of the microperforated plate 851 can be different from those of the aforementioned annular microperforated plate. For example, while maintaining a similar sound absorption frequency band, the perforation ratio of the microperforated plate 851 spaced from the magnetic circuit assembly can be smaller than that of the annular microperforated plate. In this case, due to the relatively larger area of ​​the microperforated plate 851, a good sound absorption effect can still be achieved. For another example, while maintaining a similar sound absorption frequency band, the aperture of the microperforated plate 851 spaced from the magnetic circuit assembly can be larger than that of the annular microperforated plate. In this case, due to the relatively larger area of ​​the microperforated plate 851, a good sound absorption effect can still be achieved.

[0174] Some embodiments of this specification enhance the sound absorption of a microperforated plate sound absorption structure by spacing the microperforated plate and magnetic circuit assembly in the direction of diaphragm vibration. This provides a simple structure and facilitates assembly. Furthermore, spacing the microperforated plate and magnetic circuit assembly in the direction of diaphragm vibration allows for more flexible design of parameters such as aperture and perforation ratio, simplifying the manufacturing process while ensuring effective sound absorption.

[0175] In some embodiments, for an acoustic device that adopts the wearing method as shown in Figure 5 (i.e., the sound-emitting part can partially cover the antihelix area), the perforated plate and the magnetic circuit assembly can be spaced apart in the vibration direction of the diaphragm, thereby improving the sound absorption effect of the micro-perforated plate sound absorption structure and allowing for more flexible design of parameters such as aperture and perforation rate without affecting the wearing of the acoustic device.

[0176] In some embodiments, the parameter combination of the microperforated plate 851 can be determined based on the resonant frequency of the second acoustic cavity 840, so that the sound-absorbing structure can absorb sound waves near the resonant frequency of the second acoustic cavity 840, thereby avoiding changes in the phase and / or amplitude of the second sound wave caused by the resonance of the second acoustic cavity 840 near the resonant frequency, thereby reducing the amplitude of the sound wave near the resonant frequency, thereby reducing sound leakage. In some embodiments, the parameter combination of the microperforated plate 851 can be set so that the target frequency range for sound absorption includes the resonant frequency, thereby absorbing sound near the resonant frequency. In some embodiments, the second acoustic cavity 840 may resonate near 4 kHz, and the human ear is more sensitive to sound near this frequency. Therefore, the parameter range can be set so that the target frequency range of the sound-absorbing structure includes 4 kHz, thereby achieving more targeted and effective sound leakage reduction.

[0177] In some embodiments, the micro-perforated plate 851 may have a pore size in the range of 0.1 mm to 0.2 mm, a perforation rate in the range of 2% to 5%, a plate thickness in the range of 0.2 mm to 0.7 mm, and a cavity height in the range of 7 mm to 10 mm. For example only, the micro-perforated plate 851 may have a pore size in the range of 0.1 mm to 0.2 mm, a perforation rate in the range of 2.18% to 4.91%, a plate thickness in the range of 0.3 mm to 0.6 mm, and a cavity height in the range of 7.5 mm to 9.5 mm. For example, the aperture of the micro-perforated plate 851 can be 0.15 mm, the perforation rate can be 2.18%, the plate thickness can be 0.3 mm, and the cavity height can be 8 mm; for another example, the aperture of the micro-perforated plate 851 can be 0.15 mm, the perforation rate can be 2.76%, the plate thickness can be 0.4 mm, and the cavity height can be 8.5 mm; for another example, the aperture of the micro-perforated plate 851 can be 0.15 mm, the perforation rate can be 3.61%, the plate thickness can be 0.5 mm, and the cavity height can be 9 mm.

[0178] In some embodiments of the present specification, by setting the parameter combination of the micro-perforated plate to a pore diameter in the range of 0.1mm-0.2mm, a perforation rate in the range of 2%-5%, a plate thickness in the range of 0.2mm-0.7mm, and a cavity height in the range of 7mm-10mm, the target frequency range of the sound-absorbing structure including the micro-perforated plate includes 4kHz, and the optimal sound absorption effect is achieved near 4kHz, thereby reducing or avoiding the resonance of sound waves near the resonant frequency under the action of the second acoustic cavity, thereby reducing sound leakage at the resonant frequency.

[0179] In some embodiments, the second acoustic cavity (for example, the second acoustic cavity 740 shown in FIG. 21 , the second acoustic cavity 840 shown in FIG. 24 , etc.) may resonate near 2kHz-3kHz, and the human ear is more sensitive to sounds near this frequency. Therefore, the parameter range can be set so that the target frequency range of the sound-absorbing structure includes 2kHz-3kHz to achieve more targeted and effective sound leakage reduction.

[0180] In some embodiments, the micro-perforated plate (e.g., micro-perforated plate 751, micro-perforated plate 851, etc.) may have a pore size in the range of 0.1 mm to 0.3 mm, a perforation rate in the range of 0.5% to 5%, a plate thickness in the range of 0.2 mm to 0.6 mm, and a cavity height in the range of 4 mm to 10 mm. For example only, the pore size of the micro-perforated plate may be in the range of 0.3 mm to 0.3 mm, a perforation rate in the range of 0.7% to 2.3%, a plate thickness in the range of 0.25 mm to 0.55 mm, and a cavity height in the range of 4 mm to 7.5 mm. For example, in order to make the sound absorption center frequency of the micro-perforated plate sound absorption structure near 3 kHz, the pore diameter of the micro-perforated plate can be 0.2 mm, the perforation rate can be 0.87%, the plate thickness can be 0.3 mm, and the cavity height can be 4.5 mm; for another example, in order to make the sound absorption center frequency of the micro-perforated plate sound absorption structure near 3 kHz, the pore diameter of the micro-perforated plate can be 0.25 mm, the perforation rate can be 1%, the plate thickness can be 0.4 mm, and the cavity height can be 4.5 mm; for another example, in order to make the sound absorption center frequency of the micro-perforated plate sound absorption structure near 3 kHz, the pore diameter of the micro-perforated plate can be 0.3 mm, the perforation rate can be 0.97%, the plate thickness can be 0.4 mm, and the cavity height can be 4.5 mm.

[0181] In some embodiments of the present specification, by setting the parameter combination of the micro-perforated plate to a pore diameter in the range of 0.1mm-0.3mm, a perforation rate in the range of 0.5%-5%, a plate thickness in the range of 0.2mm-0.6mm, and a cavity height in the range of 4mm-10mm, the target frequency range of the sound-absorbing structure including the micro-perforated plate includes 2kHz-3kHz, and the optimal sound absorption effect is achieved near 2kHz-3kHz, thereby achieving more targeted and effective sound leakage reduction.

[0182] In some embodiments, the cavity of the micro-perforated plate sound-absorbing structure can have regular or irregular shapes, including spheres, cylinders, and racetracks. For example, the cavity can be annular, surrounding the magnetic circuit assembly, as shown in FIG25A . Another example is a flat plate, as shown in FIG25B . In some embodiments, the cavity height and cross-sectional area perpendicular to the cavity height differ, but the cavity volume is the same, as shown in FIG25A and FIG25B . Based on this, and in conjunction with FIG26 , the effect of cavity volume and cavity height on the sound absorption effect of the sound-absorbing structure can be determined.

[0183] Figure 26 is a graph of the frequency response at the second acoustic hole of the acoustic device shown in Figures 25A and 25B. In Figure 26, the horizontal axis represents frequency, and the vertical axis represents sound pressure level. Curve 261 represents the frequency response at the second acoustic hole of the acoustic device shown in Figure 25A, and curve 262 represents the frequency response at the same second acoustic hole of the acoustic device shown in Figure 25B. Curve 261 is measured using a microperforated plate with a pore diameter of 0.3 mm, a perforation ratio of 2.1%, a plate thickness of 0.6 mm, and a cavity height of 4 mm. Curve 262 is measured using a microperforated plate with a pore diameter of 0.3 mm, a perforation ratio of 2.1%, a plate thickness of 0.6 mm, and a cavity height of 2 mm. The cavities of the acoustic devices shown in Figures 25A and 25B are both filled with the same volume of N'Bass sound-absorbing particles, and the two curves correspond to the same cavity volume. As shown in Figure 26, curves 261 and 262 essentially overlap. As can be seen, adjusting the cavity height and shape of the sound-absorbing structure while maintaining the same cavity volume will have a negligible effect on the sound absorption effect of the structure. Therefore, in some embodiments, the cavity height and shape of the sound-absorbing structure can be adjusted while maintaining the same cavity volume to suit the functional and structural requirements of the acoustic device. For example, the cavity height can be reduced while maintaining the same cavity volume, thereby reducing the size of the acoustic device and achieving a miniaturized design.

[0184] FIG27 is a schematic diagram of the structure of an acoustic device shown in some embodiments of this specification.

[0185] As shown in FIG27 , in some embodiments, the arrangement direction A of the microperforated plate 351 can be arranged obliquely to the vibration direction, that is, the normal of the microperforated plate 351 facing the side of the second acoustic cavity forms a certain angle α. For example, 10° < α < 90°. In some embodiments, in conjunction with FIG27 , the acoustic device 900 has two second acoustic holes (i.e., second acoustic holes 3121 and 3122). The two second acoustic holes can be located on opposite sides of the shell 310, for example, arranged opposite to each other in a direction perpendicular to the vibration direction, in order to maximize the destruction of the high-pressure area of ​​the sound field in the second acoustic cavity. Taking the acoustic device 10 shown in FIG3A above, in which the sound-emitting portion can partially extend into the concha cavity when worn, as an example, and in conjunction with FIG27 , the first acoustic hole 311 is on the inner side IS facing the ear canal, the second acoustic hole 3121 is on the upper side wall US, and the second acoustic hole 3122 is on the lower side wall LS. In some embodiments, in the vibration direction (i.e., the thickness direction X shown in FIG3A ), the distances from the second acoustic holes 3121 and the second acoustic holes 3122 to the inner side surface IS may be different. In this case, the microperforated plate 351 may be tilted so that the distances from the microperforated plate 351 (e.g., the connection between the microperforated plate 351 and the housing 310) to the two second acoustic holes are the same or close, thereby making the sound absorption effect of the microperforated plate 351 on the two second acoustic holes substantially consistent. Specifically, the direction B connecting the centers of the two second acoustic holes is substantially parallel to the arrangement direction A of the microperforated plate, or the difference between the shortest distance from the centroid of the second acoustic hole 3121 to the microperforated plate 351 and the shortest distance from the centroid of the second acoustic hole 3122 to the microperforated plate 351 is within a preset range, for example, not exceeding 1 / 10 of the size of the sound-emitting portion in the vibration direction.

[0186] In some embodiments, the second acoustic hole 3121 and the second acoustic hole 3122 may be at the same distance from the medial side IS. When the acoustic device is worn, when the sound-emitting portion partially extends into the cavum conchae or covers the antihelix region (e.g., as shown in FIG3A or FIG5 ), the second acoustic hole 3122 on the lower side LS may be closer to the ear canal opening. To prevent the sound emitted by the second acoustic hole 3122 from canceling out the sound emitted by the first acoustic hole 311 in the near field, the sound-absorbing structure 350 may be adjusted to absorb more of the sound emitted by the second acoustic hole 3122. In this case, the microperforated plate 351 is tilted further toward the second acoustic hole 3122, such that the distance from the microperforated plate 351 to the second acoustic hole 3122 is less than the distance from the microperforated plate 351 to the second acoustic hole 3121. This results in a greater sound absorption effect of the microperforated plate 351 at the second acoustic hole 3122 than at the second acoustic hole 3121. Such a setting can make the second acoustic hole 3122 located on the lower side LS emit relatively less sound, reduce the interference cancellation between the sound emitted from the second acoustic hole 3122 and the sound emitted from the first acoustic hole 311 in the near field, thereby ensuring the listening effect at the ear canal opening.

[0187] 28A-28C are schematic structural diagrams of acoustic devices shown in some embodiments of this specification.

[0188] In some embodiments, referring to Figures 28A-28C , the acoustic device 1000 includes a housing 310 having a major axis Y and a minor axis Z that are perpendicular to the vibration direction of the diaphragm 320 (i.e., the thickness direction X) and are orthogonal to each other. The microperforated plate structure can be arranged in the major axis direction. For example, the side of the microperforated plate 351 facing the second acoustic cavity 340 has a certain angle with the major axis Y, which can be in the range of 0°-90°. For a detailed description of the thickness direction X, the major axis Y, and the minor axis Z, please refer to Figure 3A . It should be noted that the angle here refers to the absolute value of the angle between the side of the microperforated plate 351 and the major axis Y. For example, for the microperforated plate sound absorption structures 350 and 350′ shown in Figure 28C , the angle between the side of the microperforated plate facing the second acoustic cavity 340 and the major axis Y is 90°.

[0189] In some embodiments, the arrangement direction of the microperforated plate 351 forms a certain angle β with the long axis direction Y, where 0° ≤ β ≤ 90°. In some embodiments, as shown in FIG28A , the side of the microperforated plate 351 facing the second acoustic cavity 340 can be substantially parallel to the long axis direction Y. In some embodiments, as shown in FIG28B , the angle β between the side of the microperforated plate 351 facing the second acoustic cavity 340 and the long axis direction Y is greater than 0° and less than 90°. In some embodiments, as shown in FIG28C , the side of the microperforated plate 351 facing the second acoustic cavity 340 is substantially perpendicular to the long axis direction Y. In some embodiments, to ensure the sound absorption effect of the microperforated plate sound absorption structure, when the side of the microperforated plate 351 facing the second acoustic cavity 340 is substantially perpendicular to the long axis direction Y, the microperforated plate 351 can be positioned toward or near the second acoustic hole, thereby minimizing the distance between the microperforated plate 351 and the second acoustic hole and improving the sound absorption effect.

[0190] In some embodiments, to accommodate the wearing style of the acoustic device shown in FIG3A , where the sound-emitting portion can extend into the cavum conchae, the dimension of the sound-emitting portion along the longitudinal direction Y can be appropriately increased so that the distal end FE of the sound-emitting portion can be located in the user's cavum conchae. In some embodiments, when the acoustic device 1000 has a relatively large dimension along the longitudinal direction Y, the microperforated plate 351 is positioned proximate to the second acoustic hole to better absorb sound waves from the second acoustic hole. In some embodiments, to prevent components within the housing 310 (e.g., the diaphragm, magnetic circuit assembly, etc.) from interfering with the microperforated plate 351's absorption of sound waves from the second acoustic hole, the microperforated plate 351 is positioned substantially along the longitudinal direction Y. In some embodiments, when the diaphragm 320 cannot completely cover the second acoustic cavity 340 along the longitudinal direction Y, a partition 313 arranged along the longitudinal direction Y can be provided. The partition 313 and the diaphragm 320 together separate the interior of the housing 310 to form the first acoustic cavity 330 and the second acoustic cavity 340.

[0191] In some embodiments of this specification, by arranging the microperforated plate sound-absorbing structure generally along the longitudinal direction Y, the size of the sound-emitting portion along the longitudinal direction Y can be appropriately increased. This allows the distal end FE of the sound-emitting portion to better extend into the cavum conchae when worn, for example, as shown in FIG3A . Furthermore, when the microperforated plate sound-absorbing structure is arranged along the longitudinal direction Y, the cavity extending from the sound-emitting portion along the longitudinal direction Y can have a sufficiently large space. For example, in the thickness direction, since the extended cavity does not include the magnetic circuit component, parameters such as the position and height of the cavity within the microperforated plate sound-absorbing structure are not restricted by the magnetic circuit component. This can increase the cavity height within the microperforated plate sound-absorbing structure, improving the sound absorption effect. Alternatively, while maintaining the cavity height within the sound-absorbing structure, the microperforated plate sound-absorbing structure can be positioned upward (for example, in the positive X direction as shown in FIG28A ), thereby reducing the thickness of the sound-emitting portion.

[0192] It should be noted that the micro-perforated plate sound absorption structure shown in Figures 28A-28C is merely an example. When the micro-perforated plate sound absorption structure is arranged along the longitudinal direction Y, the position, orientation, and other parameters of the micro-perforated plate sound absorption structure are not limited to the examples shown in Figures 28A-28C. In some embodiments, when the micro-perforated plate sound absorption structure is arranged along the longitudinal direction Y, the side of the micro-perforated plate facing the second acoustic cavity 340 may also generally face other sidewalls of the housing 310, for example, generally facing the upper sidewall and / or lower sidewall where the second acoustic hole is located. This is not a limitation in this specification, as long as the micro-perforated plate primarily faces the second acoustic cavity (i.e., does not face away from the rear side of the diaphragm).

[0193] 29A-29C are schematic structural diagrams of acoustic devices shown in some embodiments of this specification.

[0194] In some embodiments, in conjunction with Figures 29A-29C, the acoustic device 1100 includes a shell 310 having a long axis direction Y and a short axis direction Z that are perpendicular to the vibration direction of the diaphragm 320 (i.e., the thickness direction X) and orthogonal to each other. The micro-perforated plate structure can be arranged in the short axis direction. For example, there is a certain angle between the side of the micro-perforated plate 351 facing the second acoustic cavity 340 and the short axis direction Z. The angle can be in the range of 0°-90°. For specific instructions on the thickness direction X, the long axis direction Y and the short axis direction Z, please refer to Figure 3A. It should be noted that, similar to the above, the angle here refers to the absolute value of the angle between the side of the micro-perforated plate 351 and the short axis direction Z.

[0195] In some embodiments, the arrangement direction of the micro-perforated plate 351 forms a certain angle γ with the short axis direction Z, where 0°≤γ≤90°. In some embodiments, as shown in FIG29A , the side of the micro-perforated plate 351 facing the second acoustic cavity 340 can be approximately parallel to the short axis direction Z. In some embodiments, as shown in FIG29B , the angle γ between the side of the micro-perforated plate 351 facing the second acoustic cavity 340 and the short axis direction Z is greater than 0° and less than 90°. In some embodiments, as shown in FIG29C , the side of the micro-perforated plate 351 facing the second acoustic cavity 340 can be approximately perpendicular to the short axis direction Z.

[0196] In some embodiments, to accommodate the wearing style of the acoustic device shown in FIG. 5 , where the sound-emitting portion can be located in the antihelix region, the size of the sound-emitting portion along the minor axis Z can be appropriately increased to allow the sound-emitting portion (e.g., the first acoustic hole) to be closer to the ear canal. In some embodiments, when the acoustic device 1100 has a relatively large size along the minor axis Z, the microperforated plate 351 is positioned near the second acoustic hole to better absorb sound waves from the second acoustic hole. In some embodiments, to prevent components within the housing 310 (e.g., the diaphragm, magnetic circuit components, etc.) from interfering with the microperforated plate 351's absorption of sound waves from the second acoustic hole, the microperforated plate 351 and the diaphragm 310 are positioned substantially along the minor axis Z. In some embodiments, when the diaphragm 320 cannot completely cover the second acoustic cavity 340 along the minor axis Z, a partition 313 arranged along the minor axis Z can be provided. The partition 313 and the diaphragm 320 together separate the interior of the housing 310 to form the first acoustic cavity 330 and the second acoustic cavity 340.

[0197] In some embodiments of this specification, by arranging the microperforated plate generally along the short-axis direction Z, the size of the sound-emitting portion along the short-axis direction Z can be appropriately increased. This allows, for example, the first acoustic hole in the sound-emitting portion to be closer to the ear canal when worn in the configuration shown in FIG5 , resulting in a better listening experience for the user. Furthermore, when the microperforated plate sound-absorbing structure is arranged along the short-axis direction Z, the cavity extending from the sound-emitting portion along the short-axis direction Z can have a sufficiently large space. For example, in the thickness direction, since the extended cavity does not include the magnetic circuit component, parameters such as the position and height of the cavity in the microperforated plate sound-absorbing structure are not restricted by the magnetic circuit component. This can increase the cavity height of the microperforated plate sound-absorbing structure, improving the sound absorption effect. Alternatively, while maintaining the cavity height of the sound-absorbing structure, the microperforated plate sound-absorbing structure can be positioned upward (for example, in the positive X direction as shown in FIG29A ), thereby reducing the thickness of the sound-emitting portion.

[0198] It should be noted that the micro-perforated plate sound-absorbing structure shown in Figures 29A-29C is merely an example. When the micro-perforated plate sound-absorbing structure is positioned along the minor axis Z, the position, orientation, and other parameters of the micro-perforated plate sound-absorbing structure are not limited to the examples shown in Figures 29A-29C. For example, the side of the micro-perforated plate 351 shown in Figures 29A-29C facing the second acoustic cavity 340 is generally oriented toward the upper sidewall where the first acoustic hole 311 is located, or the sidewall where the second acoustic hole is located (e.g., the upper sidewall or the lower sidewall). In some embodiments, when the micro-perforated plate sound-absorbing structure is positioned along the axial direction Z, the side of the micro-perforated plate facing the second acoustic cavity 340 can also be generally oriented toward other sidewalls of the housing 310, for example, toward either end of the housing 310 along the major axis Y (e.g., toward or away from the end FE). This is not a limitation in this specification, as long as the micro-perforated plate primarily faces the second acoustic cavity (i.e., does not face away from the rear side of the diaphragm).

[0199] FIG30 is a schematic structural diagram of an acoustic device shown in some other embodiments of this specification.

[0200] 30 , in some embodiments, the sound absorbing structure of the acoustic device 1200 may include multiple independently disposed sub-sound absorbing structures, for example, sub-sound absorbing structure 350a, sub-sound absorbing structure 350b, and so on. In some embodiments, each sub-sound absorbing structure includes a sub-microperforated plate and a sub-cavity. For example, sub-sound absorbing structure 350a includes a sub-microperforated plate 351a and a sub-cavity 352a, and sub-sound absorbing structure 350b includes a sub-microperforated plate 351b and a sub-cavity 352b, and so on.

[0201] In some embodiments, a relatively larger sound-absorbing structure can be replaced with multiple, smaller, independently located sub-sound-absorbing structures within the second acoustic cavity 340. In some embodiments, multiple sub-sound-absorbing structures can be placed at different locations within the second acoustic cavity 340, allowing for flexible design of their installation locations. This allows for full utilization of the space within the second acoustic cavity 340 and facilitates miniaturization of the acoustic device 1200. In some embodiments, when the acoustic device 1200 has multiple second acoustic holes, one or more sub-sound-absorbing structures can be placed corresponding to each second acoustic hole. This ensures that sound waves at each second acoustic hole are uniformly absorbed by the sound-absorbing structure, ensuring effective sound absorption. In some embodiments, the position and number of sub-sound-absorbing structures associated with each second acoustic hole can be adjusted to differentiate the sound absorption effect of the sound-absorbing structure on each second acoustic hole. For example, to reduce near-field cancellation between the second acoustic hole and the first acoustic hole, the sub-sound-absorbing structures can be placed closer to the second acoustic hole, or a larger number of sub-sound-absorbing structures can be placed around the second acoustic hole. In some embodiments, the parameter combinations of the multiple sub-sound absorbing structures may be different, so that the target frequency ranges of the sound absorption of the multiple sub-sound absorbing structures are different, thereby achieving absorption of sounds in different frequency bands.

[0202] While the basic concepts have been described above, it will be apparent to those skilled in the art that the detailed disclosure is merely illustrative and does not limit this specification. Although not explicitly stated herein, various modifications, improvements, and revisions to this specification may be made by those skilled in the art. Such modifications, improvements, and revisions are suggested in this specification and remain within the spirit and scope of the exemplary embodiments of this specification.

[0203] This specification also uses specific terms to describe the embodiments of this specification. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and noted that references to "one embodiment," "an embodiment," or "an alternative embodiment" two or more times in different locations in this specification do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics of one or more embodiments of this specification may be appropriately combined.

[0204] In addition, unless expressly stated in the claims, the order of the processing elements and sequences, the use of alphanumeric characters, or the use of other names described in this specification are not intended to limit the order of the processes and methods of this specification. Although the above disclosure discusses some of the invention embodiments currently considered useful through various examples, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the spirit and scope of the embodiments of this specification. For example, although the system components described above can be implemented by hardware devices, they can also be implemented only by software solutions, such as installing the described system on an existing server or mobile device.

[0205] Similarly, it should be noted that, in order to simplify the presentation of this specification and thus facilitate understanding of one or more embodiments of the invention, the foregoing descriptions of the embodiments of this specification sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not imply that the subject matter of this specification requires more features than those recited in the claims. In fact, an embodiment may have fewer features than all of the features of a single disclosed embodiment.

[0206] In some embodiments, numbers are used to describe the quantity of components and attributes. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise stated, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the description and claims are approximate values, which may change according to the required characteristics of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of this specification are approximate values, in specific embodiments, the settings of such numerical values ​​are as accurate as possible within the feasible range.

[0207] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, and documents, cited in this specification is hereby incorporated by reference in its entirety. This includes application history documents that are inconsistent with or conflict with the content of this specification, as well as documents (currently or subsequently attached to this specification) that limit the broadest scope of the claims of this specification. It should be noted that if the descriptions, definitions, and / or terminology used in the accompanying materials are inconsistent or conflicting with the content of this specification, the descriptions, definitions, and / or terminology used in this specification will control.

[0208] Finally, it should be understood that the embodiments described in this specification are intended only to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, by way of example and not limitation, alternative configurations of the embodiments of this specification may be considered consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly described and illustrated in this specification.

Claims

1. An acoustic device, comprising: Diaphragm; A shell, used to accommodate the diaphragm and form a first acoustic cavity and a second acoustic cavity corresponding to the front side and the rear side of the diaphragm, respectively, wherein the diaphragm radiates sound to the first acoustic cavity and the second acoustic cavity, respectively, and outputs the sound through a first acoustic hole coupled to the first acoustic cavity and a second acoustic hole coupled to the second acoustic cavity, respectively; a sound absorbing structure, the sound absorbing structure being coupled to the second acoustic cavity and being used for absorbing sound within a target frequency range transmitted to the second acoustic hole via the second acoustic cavity, wherein the sound absorbing structure comprises a micro-perforated plate and a cavity, the micro-perforated plate comprises a through hole, and the second acoustic cavity is connected to the cavity through the through hole; and The suspension structure is used to wear the shell near the user's ear canal but not to block the ear canal opening.

2. According to the acoustic device of claim 1, the ratio of the opening area of ​​the first acoustic hole to the opening area of ​​the second acoustic hole is in the range of 0.5-2. 3 . The acoustic device according to claim 1 , wherein a difference in acoustic load between the first acoustic hole and the second acoustic hole is less than 0.

15.

4. According to the acoustic device according to any one of claims 1 to 3, an angle between a normal line of the side surface of the micro-perforated plate facing the second acoustic cavity and a vibration direction of the diaphragm is in the range of 0°-90°.

5. According to the acoustic device of claim 4, the sound absorption structure is arranged in the vibration direction of the diaphragm, and the angle between the normal of the side of the micro-perforated plate facing the second acoustic cavity and the vibration direction of the diaphragm is in the range of 0°-10°.

6. The acoustic device according to claim 5, further comprising: Magnetic circuit components; as well as A coil is connected to the diaphragm and is at least partially located in the magnetic gap formed by the magnetic circuit assembly. When the coil is energized, it drives the diaphragm to vibrate to generate sound, wherein the micro-perforated plate includes an annular structure arranged around the magnetic circuit assembly.

7. According to the acoustic device of claim 6, the aperture of the through hole is in the range of 0.2mm-0.4mm, the perforation rate of the micro-perforated plate is in the range of 1%-5%, the thickness of the micro-perforated plate is in the range of 0.2mm-0.7mm, and the height of the cavity is in the range of 4mm-9mm. The acoustic device of claim 7 , wherein the target frequency range comprises 4 kHz.

9. According to the acoustic device of claim 6, the aperture of the through hole is in the range of 0.1mm-0.3mm, the perforation rate of the micro-perforated plate is in the range of 0.5%-5%, the thickness of the micro-perforated plate is in the range of 0.2mm-0.6mm, and the height of the cavity is in the range of 4mm-10mm.

10. The acoustic device of claim 9, wherein the target frequency range comprises 2 kHz-3 kHz.

11. The acoustic device according to claim 5, further comprising: Magnetic circuit components; as well as A coil is connected to the diaphragm and is at least partially located in the magnetic gap formed by the magnetic circuit assembly. When the coil is energized, it drives the diaphragm to vibrate to generate sound, wherein the micro-perforated plate and the magnetic circuit assembly are spaced apart in the vibration direction of the diaphragm.

12. According to the acoustic device of claim 11, the aperture of the through hole is in the range of 0.1mm-0.2mm, the perforation rate of the micro-perforated plate is in the range of 2%-5%, the thickness of the micro-perforated plate is in the range of 0.2mm-0.7mm, and the height of the cavity is in the range of 7mm-10mm.

13. The acoustic device of claim 12, the target frequency range comprising 4 kHz.

14. According to the acoustic device of claim 11, the aperture of the through hole is in the range of 0.1mm-0.3mm, the perforation rate of the micro-perforated plate is in the range of 0.5%-5%, the thickness of the micro-perforated plate is in the range of 0.2mm-0.6mm, and the height of the cavity is in the range of 4mm-10mm.

15. The acoustic device of claim 14, wherein the target frequency range comprises 2 kHz-3 kHz.

16. According to the acoustic device of claim 4, the shell has a long axis direction and a short axis direction that are perpendicular to the vibration direction of the diaphragm and orthogonal to each other, the sound absorption structure is arranged in the long axis direction, and the angle between the side of the micro-perforated plate facing the second acoustic cavity and the long axis direction is in the range of 0°-90°. 17 . The acoustic device according to claim 16 , wherein a side surface of the micro-perforated plate facing the second acoustic cavity is perpendicular to the long axis direction.

18. According to the acoustic device of claim 4, the shell has a long axis direction and a short axis direction that are perpendicular to the vibration direction of the diaphragm and orthogonal to each other, the sound absorption structure is arranged in the short axis direction, and the angle between the side of the micro-perforated plate facing the second acoustic cavity and the short axis direction is in the range of 0°-90°. 19 . The acoustic device according to claim 18 , wherein a side surface of the micro-perforated plate facing the second acoustic cavity is perpendicular to the short axis direction.

20. The acoustic device according to claim 1, wherein the sound absorbing structure comprises a plurality of independently arranged sub-sound absorbing structures, each of which comprises a sub-microperforated plate and a sub-cavity.

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