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

Cross-references

[0001] This specification claims the priority of 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

[0002] The present invention relates to the field of acoustics, and in particular to an acoustic device. Background Art

[0003] 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 two sound sources with opposite phases to 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 sound leakage is shorter, the distance between the two sound sources under far-field conditions cannot be ignored compared to the wavelength, resulting in the inability to cancel out the sound signals emitted by the two sound sources. 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 sound wave generation position, and additional resonance peaks will be added to the transmitted sound wave, resulting in chaotic sound field distribution and difficulty in ensuring the sound leakage reduction effect in the far field at high frequencies, and may even increase sound leakage.

[0004] Therefore, it is desirable to provide an acoustic device with a better directional sound field. Summary of the invention

[0005] 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 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 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, the sound absorbing structure is coupled to the second acoustic cavity, and is used to absorb the sound transmitted to the second acoustic hole through the second acoustic cavity within a target frequency range, 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. By setting the sound absorption structure to couple with the second acoustic cavity, the sound waves within the target frequency range are absorbed by the sound absorption structure, which can reduce or avoid the resonance of the sound waves near a specific frequency (e.g., the resonant frequency) under the action of the acoustic cavity, thereby reducing or avoiding the first sound wave on the front side of the diaphragm and the second sound wave on the back side of the diaphragm near the specific frequency of the cavity. The amplitude difference and phase difference change will cause the sound leakage reduction effect at the spatial point to deteriorate, or even the two groups of sounds will not only not cancel each other, but will interfere with each other, thereby reducing the sound leakage in the target frequency range. The first sound wave and the second sound wave outside the target frequency range can cancel each other, reducing the sound leakage at the spatial point.

[0006] In some embodiments, the difference in acoustic load between the first acoustic hole and the second acoustic hole is less than 0.15. This arrangement can make the intensity of the first sound leakage close to the intensity of the second sound leakage, thereby effectively reducing the sound leakage of the acoustic device in the far field.

[0007] 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°.

[0008] 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°. Such an arrangement can make the micro-perforated plate parallel or approximately parallel to the diaphragm, improve the fault tolerance of the assembly of the sound absorbing structure and the shell, and at the same time avoid the micro-perforated plate sound absorbing structure from needing to increase the thickness of the sound-emitting part along the vibration direction due to excessive inclination angle, thereby facilitating the reduction of the volume and / or weight of the sound-emitting part.

[0009] In some embodiments, the acoustic device further comprises 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, and when the coil is energized, it drives the diaphragm to vibrate to generate sound, wherein the micro-perforated plate comprises an annular structure arranged around the magnetic circuit assembly. Such an arrangement can effectively utilize the space around 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 miniaturized design of the acoustic device.

[0010] 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.

[0011] In some embodiments, the target frequency range includes 4 kHz. By setting parameters such as the aperture of the micro-perforated plate, the sound absorbing structure can effectively absorb sound waves around 4 kHz, thereby reducing sound leakage of the acoustic device around 4 kHz.

[0012] 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.

[0013] In some embodiments, the target frequency range includes 2kHz-3kHz. By setting parameters such as the aperture of the micro-perforated plate, the sound absorbing structure can effectively absorb sound waves around 2kHz-3kHz, thereby achieving more targeted and effective sound leakage reduction.

[0014] 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, and 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. Such a setting can improve the sound absorption effect of the micro-perforated plate sound absorption structure, and the structure is simple and easy to assemble. In addition, by spacing the micro-perforated plate and the magnetic circuit assembly in the vibration direction of the diaphragm, the parameters such as the aperture and the perforation rate can be designed more flexibly, simplifying the manufacturing process while ensuring the sound absorption effect.

[0015] 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.

[0016] In some embodiments, the target frequency range includes 4 kHz. By setting parameters such as the aperture of the micro-perforated plate, the sound absorbing structure can effectively absorb sound waves around 4 kHz, thereby reducing sound leakage of the acoustic device around 4 kHz.

[0017] 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°. The sound absorbing structure is arranged in the long axis direction, which can appropriately increase the size of the sound-emitting part along the long axis direction, so that when the sound-emitting part partially extends into the concha cavity, the end of the sound-emitting part can better extend into the concha cavity. In addition, when the micro-perforated plate sound absorbing structure is arranged along the long axis direction, the cavity extending from the sound-emitting part along the long axis direction can have a sufficiently large space. For example, in the thickness direction, since the extended cavity does not include the magnetic circuit component, the parameters such as the cavity position and height in the micro-perforated plate sound absorbing structure can be not restricted by the magnetic circuit component. Thus, the cavity height in the micro-perforated plate sound absorbing structure can be increased to improve the sound absorption effect. Or when the cavity height in the sound absorbing structure remains unchanged, the micro-perforated plate sound absorbing structure can be arranged on top to reduce the thickness of the sound-emitting part.

[0018] In some embodiments, a side of the micro-perforated plate facing the second acoustic cavity is perpendicular to the long axis direction.

[0019] 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°. By arranging the micro-perforated plate roughly along the short axis direction, the size of the sound-emitting part along the short axis direction can be appropriately increased, so that when the sound-emitting part partially covers the antihelix, the first acoustic hole on the sound-emitting part can be closer to the ear canal, so that the user's listening effect is better. In addition, when the micro-perforated plate sound absorption structure is arranged along the short axis direction, the cavity extending from the sound-emitting part along the short axis direction can have a sufficiently large space. For example, in the thickness direction, since the extended cavity does not include the magnetic circuit component, the parameters such as the cavity position and height in the micro-perforated plate sound absorption structure can be not restricted by the magnetic circuit component. In this way, the cavity height in the micro-perforated plate sound absorption structure can be increased to improve the sound absorption effect. Alternatively, when the cavity height in the sound absorbing structure remains unchanged, the micro-perforated plate sound absorbing structure can be arranged upward, thereby reducing the thickness of the sound-emitting part.

[0020] In some embodiments, a side of the micro-perforated plate facing the second acoustic cavity is perpendicular to the short axis direction.

[0021] 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. By setting a plurality of independently arranged sub-sound absorbing structures, the installation position of the sub-sound absorbing structure can be flexibly designed, so that the space in the second acoustic cavity can be fully utilized, which is conducive to the miniaturization of the acoustic device. When the acoustic device has a plurality of second acoustic holes, one or more sub-sound absorbing structures can be correspondingly arranged for each second acoustic hole, so that the sound waves at each second acoustic hole can be absorbed by the sound absorbing structure to ensure the sound absorption effect. In addition, by adjusting the position and number of the sub-sound absorbing structures corresponding to each second acoustic hole, the sound absorption effect of the sound absorbing structure on each second acoustic hole can be differentiated. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present application will be further described in the form of exemplary embodiments, which will be described in detail by way of the accompanying drawings. These embodiments are not restrictive, and in these embodiments, the same number represents the same structure, wherein:

[0023] Figure 1 is an exemplary ear schematic diagram according to some embodiments of the present specification;

[0024] Figure 2 is an exemplary structural diagram of an acoustic device according to some embodiments of this specification;

[0025] Figure 3A is an exemplary wearing diagram of an acoustic device according to some embodiments of this specification;

[0026] Figure 3B is a schematic diagram of the structure of an acoustic device in a non-wearing state according to some embodiments of this specification;

[0027] Figure 4 yes Figure 3A A schematic diagram of an acoustic cavity formed by the acoustic device shown;

[0028] Figure 5 is an exemplary wearing diagram of an acoustic device according to other embodiments of this specification;

[0029] Figure 6 yes Figure 5 A schematic diagram of an acoustic cavity formed by the acoustic device shown;

[0030] Figure 7 is a schematic diagram of an acoustic device according to some embodiments of the present specification;

[0031] Fig. 8A yes Figure 7The schematic diagram of the sound pressure level and sound field distribution of the acoustic device shown in FIG.

[0032] Figure 8B yes Figure 7 A schematic diagram of the sound pressure level sound field distribution of the acoustic device shown at high frequencies;

[0033] Fig. 9 is a schematic structural diagram of an acoustic device provided with a sound absorbing structure according to some embodiments of this specification;

[0034] Fig.10 It is a sound absorption effect diagram of the acoustic device using metal micro-perforated plates and non-metal micro-perforated plates respectively according to some embodiments of this specification;

[0035] Fig.11 The frequency response curves of the acoustic devices using metal micro-perforated plates and non-metal micro-perforated plates respectively are shown in some embodiments of this specification;

[0036] Fig.12 It 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;

[0037] Fig.13 is a curve diagram of sound absorption coefficient of a micro-perforated plate sound absorption structure with different cavity heights according to some embodiments of this specification;

[0038] Fig.14 is a comparison chart of the maximum sound absorption coefficient and the 0.5 sound absorption octave at different cavity heights according to some embodiments of this specification;

[0039] Fig.15 It is a sound absorption effect diagram of a micro-perforated plate with through-hole diameters of 0.15 mm and 0.3 mm respectively according to some embodiments of this specification;

[0040] Fig.16 It is a frequency response curve diagram of a micro-perforated plate 351 with a hole diameter of 0.15 mm and a hole diameter of 0.3 mm as shown in some embodiments of this specification;

[0041] Fig.17 is a schematic structural diagram of an acoustic device provided with a sound absorbing structure according to some embodiments of this specification;

[0042] Fig.18 is a frequency response curve diagram of the second acoustic cavity of the acoustic device corresponding to different filling material filling rates shown in some embodiments of this specification;

[0043] Fig.19is a schematic structural diagram of an acoustic device provided with a sound absorbing structure according to some embodiments of this specification;

[0044] Fig. 20 is a schematic structural diagram of another acoustic device provided with a sound absorbing structure according to some embodiments of this specification;

[0045] Fig.21 is an internal structure diagram of an acoustic device according to some embodiments of this specification;

[0046] Fig. 22 is an internal structure diagram of an acoustic device according to some embodiments of this specification;

[0047] Fig.23A is a frequency response curve diagram at the second acoustic hole of the acoustic device;

[0048] Fig. 23B is a frequency response curve diagram at another second acoustic hole of the acoustic device;

[0049] Fig.24 is an internal structure diagram of an acoustic device according to some embodiments of this specification;

[0050] Fig.25A is an internal structure diagram of an acoustic device according to some embodiments of this specification;

[0051] Fig.25B is an internal structure diagram of another acoustic device according to some embodiments of this specification;

[0052] Fig.26 yes Fig.25A and 25B A frequency response curve diagram of the second acoustic hole of the acoustic device shown;

[0053] Fig. 27 is a schematic diagram of the structure of an acoustic device shown in some embodiments of this specification;

[0054] Figure 28A-28C is a schematic diagram of the structure of an acoustic device shown in some embodiments of this specification;

[0055] Figure 29A-29C is a schematic diagram of the structure of an acoustic device shown in some embodiments of this specification;

[0056] Fig.30 It is a schematic diagram of the structure of the acoustic device shown in some embodiments of this specification. DETAILED DESCRIPTION

[0057] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0058] It should be understood that the "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 words can achieve the same purpose, the words can be replaced by other expressions.

[0059] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the terms "comprises" and "includes" only indicate the inclusion of the steps and elements that have been clearly identified, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.

[0060] Flowcharts are used in the present application to illustrate the operations performed by the system according to the embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed accurately in order. On the contrary, the various steps may be processed in reverse order or simultaneously. At the same time, other operations may also be added to these processes, or one or more operations may be removed from these processes.

[0061] Figure 1 is a schematic diagram of an exemplary ear according to some embodiments of the present application. Figure 1, the ear 100 (also referred to as the auricle) may include an external auditory canal 101, a cavum 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 cavum 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 acoustic device may be worn by other parts of the ear 100 other than the external auditory canal 101. For example, the acoustic device can be worn with the help of the cymba concha 103, the triangular fossa 104, the antihelix 105, the scaphoid 106, the helix 107 and other parts or their combination. In some embodiments, in order to improve the comfort and reliability of the acoustic device in wearing, it can also be further used with the user's earlobe 108 and other parts. By using other parts of the ear 100 other than the external auditory canal 101 to achieve the wearing of the acoustic device and the propagation of sound, the user's external auditory canal 101 can be "liberated". When the user wears the acoustic device, the acoustic device will not block the user's external auditory canal 101 (or ear canal or ear canal opening), and the user can receive both the sound from the acoustic device and the sound from the environment (for example, horn sounds, car bells, surrounding human voices, traffic control sounds, etc.), thereby reducing the probability of traffic accidents. In this specification, when the user wears it, the acoustic device that does not block the user's external auditory canal 101 (or ear canal or ear canal opening) can be called 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-generating part of the acoustic device can be worn at different positions of 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-generating part. The sound-generating part is physically connected to the suspension structure. The suspension structure can be compatible with the shape of the auricle, so that the entire or partial structure of the sound-generating part is placed on the front side of the tragus 109 (e.g., Figure 1 For another example, when the user wears the earphone, the whole or part of the structure of the sound-emitting part may be in contact with the upper part of the external auditory canal 101 (for example, the location where 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 of the helix 1071 are located). For another example, when the user wears the earphone, the whole or part of the structure of the sound-emitting part may be located in a cavity formed by one or more parts of the ear 100 (for example, the cavum concha 102, the cymba concha 103, the triangular fossa 104, etc.) (for example, Figure 1The middle dotted line encloses an area M1 that includes at least the cymba concha 103 and the triangular fossa 104 and an area M2 that includes at least the cavum concha 102).

[0062] Different users may have individual differences, resulting in different shapes, sizes and other dimensional differences in the ears. For ease of description and understanding, if not otherwise specified, this specification will mainly use an ear model with a "standard" shape and size as a reference to further describe the wearing method of the acoustic device in different embodiments on 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 the scene of most users wearing the acoustic device normally. Just as an example, the ear used as a reference can have the following relevant characteristics: the size of the projection of the auricle on the sagittal plane in the vertical axis direction can 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 can be in the range of 36.6mm-55mm. Therefore, in the present application, descriptions such as "user wears", "in a wearing state" and "in a wearing state" may refer to the acoustic device described in the present application being worn on the ear of the aforementioned simulator. Of course, considering the individual differences among different users, the structure, shape, size, thickness, etc. of one or more parts of the ear 100 may be different. In order to meet the needs of different users, the acoustic device may be designed differently. These differentiated designs may be manifested as characteristic parameters of one or more parts of the acoustic device (for example, the sound-emitting part, ear hook, etc. described below) having different ranges of values ​​to adapt to different ears.

[0063] It should be noted that in the fields of medicine and anatomy, three basic planes of the human body can be defined: 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. Among them, the sagittal plane refers to a plane perpendicular to the ground along the front-back direction of the body, which divides the human body into left and right parts; the coronal plane refers to a plane perpendicular to the ground along the left-right direction of the body, which divides the human body into front and back parts; the horizontal plane refers to a plane parallel to the ground along the vertical direction perpendicular to the body, which divides the human body into upper and lower parts. Correspondingly, the sagittal axis refers to an axis along the front-back direction of the body and perpendicular to the coronal plane, the coronal axis refers to an axis along the left-right direction of the body and perpendicular to the sagittal plane, and the vertical axis refers to an axis along the up-down direction of the body and perpendicular to the horizontal plane. Furthermore, the "front side of the ear" mentioned in this application is a concept relative to the "back side of the ear", the former refers to the side of the ear away from the head, and the latter refers to the side of the ear facing the head. Figure 1 Schematic diagram of the front profile of the ear shown.

[0064] Figure 2 is an exemplary structural diagram of an acoustic device according to some embodiments of the present specification.

[0065] like Figure 2 As shown, the acoustic device 10 may include a sound generating portion 11 and a suspension structure 12 .

[0066] 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-frequency (e.g., 30Hz to 16kHz) speaker, or any combination thereof. The low frequency, high frequency, etc. mentioned here only represent the approximate range of frequency, and different division methods may be used in different application scenarios. For example, a crossover point may be determined, the low frequency represents the frequency range below the crossover point, and the high frequency represents the frequency above the crossover point. The crossover point may be any value within the audible range of the human ear, for example, 500Hz, 700Hz, 1000Hz, etc.

[0067] like Figure 2As shown, the acoustic device 10 may include a sound generating portion 11 and a suspension structure 12 .

[0068] In some embodiments, the acoustic device 10 can wear the sound-emitting part 11 on the user's body (e.g., the head, neck, or upper torso) through the suspension structure 12. In some embodiments, the acoustic device 10 can fix the sound-emitting part 11 near the ear canal but not blocking the ear canal opening through the suspension structure 12.

[0069] In some embodiments, one end of the suspension structure 12 may be connected to the sound-emitting part 11, and the other end thereof may extend along the junction between the user's ear 100 and the head. In some embodiments, the suspension structure 12 may be an arc-shaped structure adapted to the user's auricle 100, so that the suspension structure 12 may be suspended on the user's auricle 100. For example, the suspension structure 12 may have an arc-shaped structure adapted to the junction between the user's head and the auricle 100, so that the suspension structure 12 may be suspended between the user's auricle 100 and the head. In some embodiments, the suspension structure 12 may also be a clamping structure adapted to the user's auricle 100, so that the suspension structure 12 may be clamped at 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 may be better fixed on the user to prevent the user from falling during use. In some embodiments, the acoustic device 10 may not include the suspension structure 12, and the sound-emitting part 11 may be fixed near the user's auricle 100 by hanging or clamping.

[0070] For example, when the acoustic device 10 is in a wearing state, the suspension structure 12 may be suspended between the rear side of the user's auricle 100 and the head, and the sound-generating portion 11 may be suspended between the front side of the user's auricle 100 (for example, Figure 1 region M3) or the auricle 100 (e.g., Figure 1 The suspension structure 12 or the suspension structure 12 and the sound-emitting part 11 cooperate to provide the sound-emitting part 11 with a pressing force on the front side of the auricle 100 or the auricle 100. Under the action of the pressing force, the sound-emitting part 11 can be pressed against the front side of the auricle 100 or the areas where the concha 102, the cymba concha 103, the triangular fossa 104, the antihelix 105 and other parts are located, so that the acoustic device 10 does not block the ear canal opening 101 of the auricle 100 when it is in the wearing state.

[0071] The sound-emitting part 11 can generate sound to input into the ear canal of the user. In some embodiments, the sound-emitting part 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 part 11 can be directly hung on the auricle 100 of the user. In some embodiments, the sound-emitting part 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 part 11 (for example, the projection of the sound-emitting part 11 on the plane where its inner side surface 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 with reference to the projection of the sound-emitting part on the sagittal plane. The short axis direction Z can be defined as the direction perpendicular to the long axis direction Y in the shape of the projection of the sound-emitting part 11 on the sagittal plane (for example, when the projection shape is a rectangle or a rectangle approximately, the short axis direction is the width direction of the rectangle or the rectangle approximately). The thickness direction X can be defined as the direction perpendicular to the sagittal plane, for example, consistent with the direction of the coronal axis, both pointing to the left and right directions of the body.

[0072] 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 generate 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.

[0073] 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 the sound generated by the first acoustic cavity is exported from the housing 111, and the second acoustic hole 113 opened on the housing 111 is acoustically coupled with the second acoustic cavity, and the sound generated by the second acoustic cavity is exported from the housing 111. In some embodiments, the first acoustic hole 112 can be arranged 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 guides the sound generated by the diaphragm out of the housing 111 and then transmits it to the ear canal, so that the user can hear the sound. The sound exported 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, the second acoustic hole 113 is opened on the other side of the housing 111 (for example, the side away from or away from the user's ear canal). The second acoustic hole 113 is farther away from the ear canal opening than the first acoustic hole 112. The sound propagated from the second acoustic hole 113 will form a second sound leakage in the far field. The intensity of the first sound leakage is equivalent 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 is beneficial to reduce the sound leakage of the acoustic device 10 in the far field. For more information about the sound-emitting part 11, please refer to the content elsewhere in this manual, for example, Figure 3A and Figure 3B and the corresponding instruction manual.

[0074] In some embodiments, when the user wears the acoustic device 10, the sound-emitting portion 11 may be worn near the user's ear canal but not blocking the ear canal opening 101. In some embodiments, when the acoustic device 10 is worn, 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 sagittal axis (e.g., Figure 2 At this time, the sound-generating part 11 is located in front of the user's tragus, the long axis of the sound-generating part 11 can be in a vertical or nearly 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-generating part 11 on the sagittal plane can fall on the antihelix 105 (e.g., Figure 2At this time, the sound-emitting part 11 is at least partially located at the antihelix 105, the long axis of the sound-emitting part 11 is in a horizontal or approximately horizontal state, the projection of the long axis direction Y of the sound-emitting part 11 on the sagittal plane is consistent with the direction of the sagittal axis, the projection of the short axis direction Z on the sagittal plane is consistent with the vertical axis direction, and the thickness direction X is perpendicular to the sagittal plane. In this way, it is possible to avoid the sound-emitting part 11 blocking the ear canal, thereby freeing the user's ears; it is also possible to increase the contact area between the sound-emitting part 11 and the ear 100, thereby improving the wearing comfort of the acoustic device 10. In some embodiments, in the wearing state, 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-emitting part 11 on the sagittal plane may fall within the concha cavity 102 (e.g., Figure 2 The position shown in the dotted frame B in the middle) and contacts the crus of the 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.

[0075] Exemplary, combined Figure 3A , in the wearing state, the end FE of the sound-emitting part 11 can extend into the concha cavity. Optionally, the sound-emitting part 11 and the suspension structure 12 can be configured to clamp the auricle 100 from the front and back sides of the auricle 100 area corresponding to the concha cavity 102, thereby increasing the resistance of the acoustic device 10 to fall off the ear, thereby improving the stability of the acoustic device 10 in the wearing state. For example, the end FE of the sound-emitting part is pressed in the concha cavity in the thickness direction X. For another example, the end FE abuts against the concha cavity in the major axis direction Y and / or the minor axis direction Z (for example, abuts against the inner wall of the opposite end FE of the concha cavity). It should be noted that the end FE of the sound-emitting part 11 refers to the end of the sound-emitting part 11 that is arranged opposite to the fixed end connected to the suspension structure 12, also referred to as the free end. The sound-emitting part 11 can be a regular or irregular structure, and an exemplary description is given here to further illustrate the end FE of the sound-emitting part 11. For example, when the sound-emitting part 11 is a rectangular parallelepiped structure, the end wall surface of the sound-emitting part 11 is a plane, and the end FE of the sound-emitting part 11 is an end side wall of the sound-emitting part 11 that is arranged opposite to the fixed end connected to the suspension structure 12. For another example, when the sound-emitting part 11 is a sphere, an ellipsoid or an irregular structure, the end FE of the sound-emitting part 11 may refer to a specific area away from the fixed end obtained by cutting the sound-emitting part 11 along the X-Z plane (the plane formed by the short axis direction Z and the thickness direction X), and the ratio of the size of the specific area along the long axis direction Y to the size of the sound-emitting part along the long axis direction Y may be 0.05-0.2.

[0076] Reference Figure 3A and Figure 3B Here, 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 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.

[0077] like Figure 3B As shown, 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.

[0078] By extending the sound-emitting part 11 at least partially into the concha cavity, the listening volume at the listening position (for example, at the opening of the ear canal), especially the listening volume of the mid-low frequency, can be increased, while still maintaining a good far-field sound leakage cancellation effect. As an exemplary illustration only, when the entire or partial structure of the sound-emitting part 11 extends into the concha cavity 102, the sound-emitting part 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 wall of the sound-emitting part 11 and the concha cavity 102 structure. The semi-enclosed structure makes the listening position (for example, at the opening of the ear canal) not completely sealed and isolated from the external environment, but has a leakage structure (for example, an opening, a gap, a pipe, etc.) that is acoustically connected to the external environment. When the user wears the acoustic device 10, one or more first acoustic holes 112 may be provided on the side of the shell of the sound-emitting part 11 close to or facing the ear canal of the user, and one or more second acoustic holes 113 may be provided on the other side walls of the shell of the sound-emitting part 11 (for example, the side walls away from or away from the ear canal of the user). 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. Taking the sound-emitting part 11 including a first acoustic hole 112 and a second acoustic hole 113 as an example, 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, and the sound phases of the two sound sources are opposite. The inner walls corresponding to the sound-emitting part 11 and the cavum concha 102 form a cavity-like structure, wherein the sound source corresponding to the first acoustic hole 112 is located inside the cavity-like structure, and the sound source corresponding to the second acoustic hole 113 is located outside the cavity-like structure, forming a cavity-like structure. Figure 4 The acoustic model shown.

[0079] like Figure 4As shown, the cavity-like structure 402 may include a listening position and at least one sound source 401A. Here, "include" may mean that at least one of the listening position and the sound source 401A is inside the cavity-like structure 402, or 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 may be an acoustic reference point of the ear, such as the ear reference point (ERP), the ear-drum reference point (DRP), etc., or 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 phenomenon of sound waves, thereby achieving the effect of sound leakage cancellation. 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 or reflected means. In contrast, in the absence of the cavity-like structure 402, most of the sound radiated by the sound source 401A will not reach the listening position. Therefore, the setting of the cavity structure significantly increases the volume of the sound reaching the listening position. At the same time, only a small part 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. 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 a considerable sound leakage reduction effect is still maintained.

[0080] In some embodiments of the present specification, the sound-emitting part 11 is partially or entirely extended into the concha cavity, so that a cavity-like structure communicating with the outside world is formed between the sound-emitting part 11 and the contour of the concha cavity. Furthermore, the first acoustic hole 112 is arranged at a position of the shell of the sound-emitting part facing the user's ear canal opening and close to the edge of the concha cavity to construct Figure 4The acoustic model shown in the figure enables the user to 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 the user with a sufficiently large volume, that is, a sound pressure exceeding a specific threshold can be generated in the user's ear canal.

[0081] In some embodiments, the sound-generating part may have different Figure 3A Other wearing methods that extend into the concha cavity can also achieve better sound output efficiency. Figure 5 The acoustic device 10 shown is described in detail as an example.

[0082] Figure 5 is an exemplary wearing diagram of an acoustic device according to other embodiments of the present specification.

[0083] In some embodiments, when the acoustic device 10 is worn, at least part of the sound-emitting portion 11 may cover the anti-helix region of the user. At this time, the sound-emitting portion 11 is located above the concha cavity 102 and the ear canal opening, and the ear canal opening of the user is in an open state. In some embodiments, the shell 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 with the first acoustic cavity of the acoustic device 10, and the second acoustic hole 113 is acoustically coupled with the second acoustic cavity of the acoustic device 10, wherein 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, and the sounds of the two sound sources have 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 ear canal opening of the user, and the second acoustic hole 113 is located on the side wall of the sound-emitting portion 11 away from or away from the ear canal opening of the user. At this time, the sound-emitting portion 11 and the auricle 100 of the user can be regarded as a baffle structure. 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 Figure 6 The acoustic model shown.

[0084] like Figure 6As shown, when a baffle is provided between the sound source A1 and the sound source A2, in the near field, the sound field of the sound source A2 needs to bypass the baffle to interfere with the sound wave of the sound source A1 at the listening position, which is equivalent to increasing the sound path from the sound source A2 to the listening position. Therefore, assuming that the sound source A1 and the sound source A2 have the same amplitude, the amplitude difference between the sound waves of the sound source A1 and the sound source A2 at the listening position increases compared to the case where no baffle is provided, thereby reducing the degree of cancellation of the two-way sound at the listening position, thereby increasing the volume at the listening position. In the far field, since the sound waves generated by the sound source A1 and the sound source A2 do not need to bypass the baffle to interfere in a larger spatial range (similar to the case without a baffle), the sound leakage in the far field will not increase significantly compared to the case without a baffle. Therefore, by providing a baffle structure around one of the sound sources A1 and A2, the volume at the near-field listening position can be significantly increased without significantly increasing the sound leakage volume in the far field.

[0085] In some embodiments of the present specification, by at least partially covering the anti-helix area of ​​the user with the sound-emitting part 11, the user can hear a louder listening volume when wearing the acoustic device. This method can also make the sound-emitting part 11 have a better sound output efficiency.

[0086] Figure 7 Schematic diagram of an acoustic device according to some embodiments of this specification. Figure 7 As shown, the acoustic device 200 may include a housing 210 and a diaphragm 220. The diaphragm 220 may be disposed in a cavity formed by the housing 210, and a first acoustic cavity 230 and a second acoustic cavity 240 for radiating sound are respectively disposed on the front and rear sides of the diaphragm 220. 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 with the first acoustic hole 211, and the second acoustic cavity 240 may be acoustically coupled with the second acoustic hole 212. When the user wears the acoustic device 200, the acoustic device 200 may be located near the user's auricle, and the first acoustic hole 211 may face the user's ear canal opening. The second acoustic hole 212 may be 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.

[0087] In some embodiments, the front and rear sides of the diaphragm 220 can be used 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 interfere at a spatial point (e.g., the far field), thereby effectively improving the sound leakage problem in the far field of the acoustic device 200.

[0088] Fig. 8A yes Figure 7 The acoustic device shown in Figure 1 is a schematic diagram of the sound pressure level and sound field distribution at medium and low frequencies. Fig. 8A As shown, in the mid-to-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 mid-to-low frequency range, the dual sound sources formed by 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.

[0089] Figure 8B yes Figure 7 The schematic diagram of the sound pressure level and sound field distribution of the acoustic device at high frequencies is shown in FIG. Figure 8BAs shown, in the higher frequency range, the sound field distribution of the acoustic device 200 is relatively chaotic. In some embodiments, in the higher frequency range (for example, 1500Hz-20kHz), the wavelengths of the first sound wave and the second sound wave are shorter than those in the medium and low frequency range. 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 inability of the sound waves emitted by the two sound sources to cancel each other, making it difficult to ensure the sound leakage reduction effect of the sound-emitting part in the far field in the higher frequency range, and even may increase the sound leakage, and make the sound field distribution of the sound-emitting part relatively chaotic. For example, the distance between the first acoustic hole 211 and the second acoustic hole 212 can make the sound path 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 and cancel 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.

[0090] 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 a 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.

[0091] In some embodiments, the acoustic transmission structure may have a resonant frequency, and when the frequency of the sound waves 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 waves in the acoustic transmission structure also resonate, and the resonance may change the frequency component of the transmitted sound waves (for example, adding additional resonance peaks to the transmitted sound waves), or change the phase of the sound waves transmitted in the acoustic transmission structure. Compared with when no resonance occurs, the phase and / or amplitude of the sound waves radiated from the first acoustic hole 211 and / or the second acoustic hole 212 changes, and the change in phase and / or amplitude may cause confusion in the sound field of the dual sound source structure near the resonant frequency, affecting the effect of interference and destructive interaction of the sound waves radiated from the first acoustic hole 211 and the second acoustic hole 212 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, etc.), the effect of the sound waves interfering and destructing at the spatial point is weakened, and it is difficult to achieve the effect of reducing sound leakage; or, the sound waves with a small phase difference may also be superimposed 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 sound 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 differs greatly, and the effect of the sound waves interfering and destructing at the spatial point is weakened, and it is difficult to achieve the effect of reducing sound leakage. In some embodiments, the difference in the volume of the first acoustic cavity 230 and the second acoustic cavity 240 of the sound-emitting part, the size and height of the first acoustic hole 211 and the second acoustic hole 212, etc., may lead to the inconsistency of the resonance frequency of the first acoustic cavity 230 and the second acoustic cavity 240 (also referred to as the acoustic cavity), that is, the resonance frequency of the acoustic transmission structure on the front and back sides of the acoustic device 200 is different. In some embodiments, the shielding and / or reflection of high-frequency sound waves by structures such as the auricle 100 may also cause the chaotic sound field distribution of the acoustic device 200.

[0092] based on Figure 7-8BAccording to the description, the dual sound sources have a chaotic sound field in the high-frequency range, and the sound leakage reduction effect is not good. In some cases, the sound leakage may even increase. 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.

[0093] The sound absorbing structure refers to a structure that absorbs sound waves within a specific frequency band (for example, within a target frequency range). The sound absorbing structure can be coupled with the second acoustic cavity to absorb the sound radiated from the second acoustic cavity to the second acoustic hole within the target frequency range. Accordingly, within the target frequency range, the sound pressure level at the second acoustic hole when the sound absorbing structure is not provided can be greater than the sound pressure level at the second acoustic hole when the sound absorbing structure is provided.

[0094] 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 avoid changes in the phase and / or amplitude of the second sound wave caused by the resonance of the second acoustic cavity near the resonant frequency, thereby reducing the amplitude of the sound wave 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 medium and high frequency band, for example, 2kHz-8kHz. Accordingly, the target frequency range may include the frequency of the medium and high frequency band. For example, the target frequency range may be in the range of 1kHz-10kHz. In some embodiments, in a higher frequency range, since the distance between the dual sound sources formed by the first acoustic hole and the second acoustic hole is not negligible compared to the wavelength, the first sound wave and the second sound wave cannot interfere and cancel each other at the spatial point, and may also be superimposed at the spatial point to increase the amplitude of the sound wave at the spatial point. In some embodiments, in order to reduce the amplitude of the sound wave caused by the superposition of the first sound wave and the second sound wave in the higher frequency range, the target frequency range may also include a frequency 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 may 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.

[0095] In some embodiments, the acoustic device can have different sound effects at a spatial point by setting a sound absorbing structure (for example, the position of the sound absorbing structure, the sound absorbing frequency, etc.). In some embodiments, the resonance of the first acoustic cavity will also affect the sound wave radiation of the second acoustic cavity, and produce redundant resonance peaks on the frequency response curve measured at the position of the second acoustic hole. Therefore, in order 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 may also include the resonance frequency of the first acoustic cavity. In some embodiments, another sound absorbing structure can also be set in the first acoustic cavity to absorb sound waves near the resonance frequency of the first acoustic cavity, so as to avoid interference enhancement between the sound waves near the resonance frequency of the first acoustic cavity and the sound waves of the same frequency range output by the second acoustic hole at a spatial point (for example, a spatial point), thereby reducing the amplitude of the sound waves near the resonance frequency of the first acoustic cavity received by the spatial point. In some embodiments, the sound absorbing structure can also be set in the first acoustic cavity and the second acoustic cavity at the same time, so as to absorb the sound waves near the resonance frequency in the first sound wave and the second sound wave, so as to better reduce the amplitude of the sound waves at any spatial point. In some embodiments, the sound absorbing structure can also absorb low-frequency sounds in a specific frequency range. For example, the sound absorbing structure can be disposed in the second acoustic cavity to reduce the low-frequency sounds in a specific frequency range output from the second acoustic hole, and to avoid the low-frequency sounds in the specific frequency range from interfering with the low-frequency sounds in the same frequency range output from the first acoustic hole at a spatial point (e.g., near field), thereby increasing the volume of the acoustic device in the specific frequency range in the near field (i.e., transmitted to the user's ears). In some embodiments, the sound absorbing structure can also include sub-sound absorbing structures that absorb different frequency ranges, for example, mid-high frequency bands and low frequency bands, for absorbing sounds in different frequency ranges.

[0096] In some embodiments, since 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 spatial point, thereby causing the dual sound sources formed by the two acoustic holes to weaken the sound leakage reduction effect in the high-frequency range. Therefore, in order to reduce the high-frequency output of the second acoustic cavity, the target frequency range may 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.

[0097] 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 sounds less than 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.

[0098] According to the above embodiment, the sound absorbing structure can absorb the sound waves in the target frequency range in 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 and cancel each other at the spatial point to achieve the effect of double sound source leakage reduction; the first sound wave and / or the second sound wave in 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 can weaken or absorb the additional resonance peaks 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 the present 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 the resonant frequency or higher than the resonant frequency of the acoustic transmission structure. While ensuring that the acoustic device interferes destructively in the first frequency range, the increase in the amplitude of the sound waves 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 full frequency band.

[0099] The sound absorption effect of the sound absorbing structure refers to the amount of sound that the sound absorbing structure can absorb in the target frequency range, which can be expressed by the sound pressure level of the sound. For example, the sound absorption effect of the sound absorbing structure can be expressed by the difference between the sound pressure levels measured at the same frequency and at the same position corresponding to the second acoustic cavity in the target frequency range with and without the sound absorbing structure. As an example only, the difference between the sound pressure levels at the second acoustic hole with and without the sound absorbing structure can be used to represent the difference between the sound pressure levels of the second acoustic cavity with and without the sound absorbing structure. As an example only, the sound pressure level at the second acoustic hole with and without the sound absorbing structure can be measured as follows: the test microphone is facing the second acoustic hole at a distance of about 2mm-5mm, and the sound pressure level at the second acoustic hole with and without the sound absorbing structure is tested. The test frequency is near the resonant frequency of the second acoustic cavity or near 1kHz. In some embodiments, the difference between the sound pressure levels measured at the same frequency and at the same position in the second acoustic cavity with and without the sound absorbing structure may be not less than 3dB. For example, when there is a sound absorbing structure and when there is no sound absorbing structure, the difference in the sound pressure level at the second acoustic hole measured at the same frequency is not less than 3dB. In some embodiments, the above-mentioned 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 3kHz-6kHz, the sound absorbing structure can effectively absorb sound waves in the range of 3kHz-6kHz, and the sound absorption effect is not less than 3dB, thereby improving the sound leakage of the acoustic device in the range of 3kHz-6kHz. In some embodiments, in order to further reduce the sound leakage of the acoustic device, the sound absorption effect of the sound absorbing structure may be not less than 6dB in the target frequency range. In some embodiments, in order to further reduce the sound leakage of the acoustic device, the sound absorption effect of the sound absorbing structure may be not less than 10dB in the target frequency range. In some embodiments, the sound absorption effect of the sound absorbing structure may be different in different frequency ranges. For example, in the range of 3kHz-6kHz, the sound absorption effect of the sound absorbing structure is not less than 3dB. For another example, in the range of 4kHz-6kHz, the sound absorption effect of the sound absorbing structure is not less than 6dB. For another example, within the range of 5kHz-6kHz, the sound absorption effect of the sound absorption structure is not less than 8dB, so that sound leakage can be more effectively reduced within a higher frequency range.

[0100] Since the frequency response curve of the second acoustic cavity will have a resonance peak at its specific frequency (for example, the resonant frequency), and the vibration amplitude at the resonant frequency is large, in order to obtain 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 14dB for the sound at the resonant frequency or the sound at the vibration frequency close to the resonant frequency. In this way, the sound waves at the resonant frequency or close to the resonant frequency of the second acoustic cavity can be effectively absorbed by the sound absorbing structure, reducing or avoiding the resonance of the sound waves near the resonant frequency under the action of the acoustic cavity, thereby reducing or avoiding the change in amplitude difference and phase difference between the first sound wave and the second sound wave near the resonant frequency, which leads to a deterioration of the sound leakage reduction effect at the spatial point, or even the situation where the two groups of sounds not only do not cancel each other, but interfere with each other, thereby reducing the sound leakage of the acoustic device at the far-field spatial point. In some embodiments, in order to further reduce the sound leakage of the acoustic device, the sound absorption effect of the sound absorbing structure at the resonant frequency or the sound at the vibration frequency close to the resonant frequency is not less than 18dB. In some embodiments, in order to further reduce sound leakage of the acoustic device, the sound absorption effect of the sound absorption structure on the sound at the resonance frequency or the sound with a vibration frequency close to the resonance frequency is not less than 25 dB.

[0101] In some embodiments, the sound absorbing structure may include at least one of a resistive sound absorbing structure or an anti-type sound absorbing structure. For example, the function of the sound absorbing structure may be realized by a resistive sound absorbing structure. For another example, the function of the sound absorbing structure may be realized by an anti-type sound absorbing structure. For another example, the function of the sound absorbing structure may also be realized by a resistive and anti-type mixed sound absorbing structure.

[0102] The resistive sound absorbing structure may refer to a structure that can provide acoustic resistance when sound waves pass through. 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 arranged at any position on the transmission path of the first sound wave and / or the second sound wave. For example, the porous sound absorbing material or the acoustic gauze may be attached to the inner wall of the acoustic transmission structure. For another example, the porous sound absorbing material or the acoustic gauze may constitute at least a part of the inner wall of the acoustic transmission structure. For another example, the porous sound absorbing material or the acoustic gauze may fill at least a part of the inside of the acoustic transmission structure. The anti-sound absorbing structure may refer to a structure that absorbs sound by resonance. In some embodiments, the anti-sound absorbing structure may include but is not limited to a Helmholtz sound absorbing cavity, a perforated plate sound absorbing structure, a micro-perforated plate sound absorbing structure, a thin plate, a film, a 1 / 4 wavelength resonance tube, etc. or any combination thereof. In some embodiments, the resistive sound absorbing structure and the anti-sound absorbing structure may be arranged at the same time as an impedance mixed sound absorbing structure to realize the function of the 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.

[0103] The sound absorbing structure may be coupled to the second acoustic cavity. In some embodiments, the sound absorbing structure may include a micro-perforated plate sound absorbing structure. The micro-perforated plate sound absorbing structure includes a micro-perforated plate and a cavity, wherein the micro-perforated plate includes through holes, wherein the acoustic cavity coupled to the micro-perforated plate structure is connected to the cavity through the through holes on the micro-perforated plate. For more information about the micro-perforated plate sound absorbing structure, please refer to the contents elsewhere in this specification, for example, Fig. 9 and the corresponding instruction manual.

[0104] In some embodiments of the present specification, by setting a sound-absorbing structure to couple with a second acoustic cavity, sound waves within a target frequency range are absorbed by the sound-absorbing structure, which can reduce or avoid the resonance of sound waves near a specific frequency (e.g., a resonant frequency) under the action of the acoustic cavity, thereby reducing or avoiding the change in amplitude difference and phase difference between the first sound wave and the second sound wave near the specific frequency of the cavity, which leads to a poor effect of reducing sound leakage at a spatial point, or even a situation where the two groups of sounds not only do not cancel each other, but interfere with each other, thereby reducing sound leakage within the target frequency range. The first sound wave and the second sound wave outside the target frequency range can cancel each other, reducing sound leakage at a spatial point.

[0105] In some embodiments, in order to reduce the sound leakage of the acoustic device 10 in the far field, in addition to the opposite or nearly opposite phases, 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 0.5-2. 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 1.0-1.8. 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 to 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 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, acoustic resistance nets can be respectively provided at the first acoustic hole 112 and the second acoustic hole 113, and the acoustic resistance of the acoustic resistance nets is the same or close.

[0106] In some embodiments, in order 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, in order 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, the second acoustic hole 113 can be one or more. 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.

[0107] 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 resonate. Compared with when no resonance occurs, the phase and / or amplitude of the sound waves radiated from the second acoustic hole 113 changes, and the change in the phase and / or amplitude may cause the sound field of the sound-emitting part 11 near the resonant frequency to be chaotic, affecting the effect of interference and destructive interaction 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 within 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, so as to achieve the effect of reducing far-field sound leakage. For example, a sound absorbing structure can be provided to absorb the sound waves in the second acoustic cavity within the target frequency range, so as to adjust the sound waves in the second acoustic cavity, thereby effectively reducing far-field sound leakage. In addition, in frequency bands outside the target frequency range (e.g., low frequency bands), by making the intensity of the first sound leakage close to the intensity of the second sound leakage, far-field sound leakage can be effectively reduced.

[0108] Fig. 9 It is a schematic diagram of the structure of an acoustic device provided with a sound absorbing structure according to some embodiments of the present specification.

[0109] like Fig. 9 As shown, in some embodiments, the acoustic device 300 may include a housing 310 and a diaphragm 320. The diaphragm 320 is disposed in a housing cavity formed by the housing 310, and a first acoustic cavity 330 and a second acoustic cavity 340 are respectively disposed on the front and rear sides of the diaphragm 320. The housing 310 is provided with a first acoustic hole 311 and a second acoustic hole 312, and the first acoustic cavity 330 may be acoustically coupled with the first acoustic hole 311, and the second acoustic cavity 340 may be acoustically coupled with the second acoustic hole 312.

[0110] In some embodiments, Fig. 9 As shown, the acoustic device 300 may further include a micro-perforated plate sound absorbing structure 350, and the micro-perforated plate sound absorbing structure 350 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, wherein the micro-perforated plate 351 includes through holes, wherein the second acoustic cavity 340 coupled to the micro-perforated plate structure is connected to the cavity 352 through the through holes on the micro-perforated plate. It should be noted that, as Fig. 9The acoustic device 300 shown is merely an example, and the specific configuration of the micro-perforated plate sound absorbing structure 350 may have many variations or modifications.

[0111] The sound waves of 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, and cause the resonance of 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 is close to the resonance frequency of the micro-perforated plate sound absorbing structure 350, the sound waves entering the cavity 352 cause the resonance of the micro-perforated plate sound absorbing structure 350. The air in the cavity 352 will resonate with the micro-perforated plate sound absorbing structure 350 and dissipate energy to achieve 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 resonance frequency.

[0112] 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 small, and the process of sound waves passing through the through holes 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 large, and when the aperture of the through hole is small, the process of sound waves passing through the through hole can be regarded as an isothermal process. The conduction of heat represents the enhancement of energy dissipation, so the equivalent damping of the metal plate is greater than that of the non-metal plate.

[0113] Fig.10 The diagram is a sound absorption effect diagram of the acoustic devices using metal micro-perforated plates and non-metal micro-perforated plates respectively according to some embodiments of the present specification. Fig.10 The horizontal axis represents the sound absorption frequency, the vertical axis represents the sound absorption coefficient, the curve L1 represents the sound absorption effect of the non-metallic micro-perforated plate, and the curve L2 represents the sound absorption effect of the metal micro-perforated plate. Fig.10 As shown in the figure, the maximum sound absorption coefficient of the metal microperforated plate is slightly lower than that of the non-metallic microperforated plate, but the sound absorption bandwidth of the metal microperforated plate is wider than that of the non-metallic microperforated plate. This is because the metal microperforated plate has better thermal conductivity and greater equivalent damping for sound waves passing through.

[0114] Fig.11 The frequency response curves of the acoustic devices shown in some embodiments of the present specification respectively using metal micro-perforated plates and non-metal micro-perforated plates. Fig.11 The horizontal axis represents frequency, the vertical axis represents sound pressure level, curve L3 represents the frequency response of the metal micro-perforated plate, and curve L4 represents the frequency response of the non-metal micro-perforated plate. The frequency response here refers to the frequency response at the second acoustic hole (for example, 10 mm in front of the second acoustic hole). Fig.11As shown, the metal micro-perforated plate has a better sound absorption effect than the non-metal micro-perforated plate in the low and medium frequency band (for example, less than 4kHz), and the sound leakage of the acoustic device is reduced by about 2-3dB. At this time, the metal micro-perforated plate is an aluminum plate. Although the sound absorption effect of the non-metal micro-perforated plate is slightly worse, the use of the non-metal micro-perforated plate can reduce the weight of the acoustic device, which is conducive to improving the portability of the acoustic device and reducing the cost of the acoustic device. In some embodiments, since the metal plate and the non-metal plate each have their own advantages, the metal micro-perforated plate or the non-metal micro-perforated plate can be flexibly selected according to weight, cost, corrosion resistance and other aspects.

[0115] If the natural frequency of the microperforated plate 351 installed in the acoustic device (or called 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 not easy to measure, and the natural frequency of the microperforated plate 351 in the free state can be used to characterize its natural frequency in the fixed state, wherein the free state can refer to the state when the microperforated plate 351 is not installed in the acoustic device, and the natural frequency of the microperforated plate 351 in the fixed state is much greater than the natural frequency in the free state. The method for measuring the natural frequency in the free state may be: keep the micro-perforated plate 351 in the free state, apply an excitation force with a constant amplitude and a frequency varying from low to high to the micro-perforated plate 351 through an exciter, and use a laser vibrometer to test the velocity amplitude of the micro-perforated plate 351, and record the frequency that first makes the velocity amplitude of the micro-perforated plate 351 reach a maximum value, which is the natural frequency of the micro-perforated plate 351 in the free state. In some embodiments, the sound absorption bandwidth is in the range of 3kHz-6kHz. In order to prevent the natural frequency of the micro-perforated plate in the fixed state from falling within the sound absorption bandwidth, the theoretical value of the natural frequency of the micro-perforated plate 351 in the free state may be greater than 500Hz (e.g., 500Hz-3.6kHz), so that its natural frequency in the fixed state can be much greater than the upper limit frequency of sound absorption (i.e., the maximum frequency in the sound absorption bandwidth, such as 6kHz). The natural frequency is related to the stiffness of the micro-perforated plate 351 and the mass of the micro-perforated plate 351. Therefore, the natural frequency of the micro-perforated plate 351 can be determined by setting the stiffness of the micro-perforated plate 351 and / or the mass of the micro-perforated plate 351, so that the micro-perforated plate 351 can absorb sound waves within the target frequency range. In some embodiments, the micro-perforated plate 351 of different shapes, materials, etc. has different stiffness and / or mass, resulting in different natural frequencies. In some embodiments, the micro-perforated plate 351 can be a regular shape or an irregular shape such as a circle, a fan, a rectangle, a diamond, etc. In some embodiments, the material of the micro-perforated plate 351 can be a non-metallic or metallic material.

[0116] 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, in order to make the natural frequency of the microperforated plate 351 in the free state within the range of 500Hz-3.6kHz, the Young's modulus of its material ranges from 5Gpa to 200Gpa. For example, the Young's modulus of the material ranges from 20Gpa to 150Gpa. For another example, the Young's modulus of the material ranges from 50Gpa to 100Gpa. 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, in order to make the natural frequency of the microperforated plate 351 in the free state within the range of 500Hz-3.6kHz, the thickness of the racetrack type microperforated plate may be within the range of 0.1mm-0.8mm. For example, the thickness of the racetrack type microperforated plate may be within the range of 0.3mm-0.6mm.

[0117] In some embodiments, the micro-perforated plate 351 can be a circular micro-perforated plate. With the same parameters (e.g., aperture, plate thickness, perforation rate, cavity (e.g., cavity 652) height), the natural frequency of the circular micro-perforated plate 351 is lower than that of the racetrack-type micro-perforated plate 351. Therefore, the circular micro-perforated plate needs to use a material with greater rigidity and / or a micro-perforated plate with a thicker plate thickness than the racetrack-type micro-perforated plate to ensure that its natural frequency is much greater than the upper limit frequency of sound absorption. In some embodiments, when the micro-perforated plate 351 is a circular micro-perforated plate, in order to make the natural frequency of the micro-perforated plate 351 in the free state within the range of 500Hz-3.6kHz, the Young's modulus range of the micro-perforated plate 351 material is within the range of 50Gpa-200Gpa. For example, the Young's modulus range of the circular micro-perforated plate material is within the range of 80Gpa-150Gpa. For another example, the Young's modulus range of the circular micro-perforated plate material is within the range of 100Gpa-150Gpa. In some embodiments, when the micro-perforated plate 351 is a circular perforated plate, in order to make the natural frequency of the micro-perforated plate 351 in a free state within the range of 500 Hz-3.6 kHz, the thickness of the circular micro-perforated plate needs to be within the range of 0.3 mm-1 mm. For example, the thickness of the circular micro-perforated plate needs to be within the range of 0.6 mm-0.7 mm.

[0118] By setting the Young's modulus and / or the plate thickness of the micro-perforated plate 351 and adjusting its natural frequency, it is possible to avoid the natural frequency of the micro-perforated plate 351 in a fixed state falling within the sound absorption bandwidth and affecting its sound absorption effect.

[0119] 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 for waterproofing and dustproofing. Specifically, since the aperture of the through holes of the micro-perforated plate 351 is relatively small, capillary phenomena are prone to occur, and it is difficult to discharge water after entering, which will affect the sound leakage reduction effect of the sound-absorbing structure. Therefore, it is necessary to provide a waterproof and breathable structure 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.

[0120] In some embodiments, the waterproof breathable structure may be a mesh. Fig.12 It is a frequency response curve diagram at the second acoustic hole measured when a 025HY type gauze is set on the side of the micro-perforated plate facing the diaphragm as shown in some embodiments of the present specification and when no gauze is set. Fig.12 In FIG. 1 , 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 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 in front of the second acoustic hole 312) when the gauze is not set. Fig.12 As shown, 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 great, but it can play a role of waterproof and dustproof 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 set on the side of the micro-perforated plate 351 facing the diaphragm to achieve the purpose that the micro-perforated plate sound absorption structure can be waterproof and dustproof. In some embodiments, the acoustic resistance of the 025HY type gauze is lower than 50MKSRayls. Therefore, a gauze can be set on the side of the micro-perforated plate 351 facing the diaphragm, and the acoustic resistance of the gauze can be lower than 50MKSRayls, so that it is waterproof and dustproof while hardly affecting the output effect of the acoustic device (for example, the second acoustic hole).

[0121] The cavity 352 is disposed on the side of the micro-perforated plate 351 away from the second acoustic cavity 340, and is connected to the outside only through the through holes on the micro-perforated plate 351. In some embodiments, the shape of the cavity 352 includes but is not limited to Fig. 9 The rectangular parallelepiped shown in FIG. 1 may also include regular shapes such as a sphere and a cylinder or irregular shapes such as a racetrack. In some embodiments, the cavity 352 has a certain height D (see FIG. 1 ). Fig. 9), the larger the cavity height D, the wider its sound absorption bandwidth. Therefore, in some embodiments, a larger cavity height D can be set to enhance the sound absorption effect of the micro-perforated plate sound absorption structure. It should be understood that when the shape of the cavity 352 is regular, its own height dimension is equal to the cavity height D. When the shape of the cavity 352 is irregular, its own height dimension is difficult to determine, and the equivalent height D of the cavity can be represented by the ratio between the volume of the cavity 352 and the area of ​​the micro-perforated plate 351 (that is, the area of ​​the side of the micro-perforated plate facing the cavity 352). The volume of the irregular cavity 352 can be measured by the glue injection method, and 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 by the drainage method to obtain the volume of the irregular cavity 352.

[0122] Fig.13 1 is a curve diagram of the sound absorption coefficient of the micro-perforated plate sound absorption structure with different cavity heights according to some embodiments of this specification. Fig.13 As shown in FIG. 1 , as the height D of the cavity 352 increases, the peak abscissa of the corresponding curve gradually shifts to the left, the peak of the corresponding curve gradually decreases, but the coverage width of the corresponding curve gradually increases. Therefore, the larger the cavity height D, the lower the corresponding sound absorption frequency, the smaller the maximum sound absorption coefficient, but the wider the sound absorption bandwidth.

[0123] Fig.14 This is a comparison chart of the maximum sound absorption coefficient and the 0.5 sound absorption octave at different cavity heights according to some embodiments of this specification. Among them, the 0.5 sound absorption octave refers to the octave range spanned by the sound absorption curve when the sound absorption coefficient is 0.5. The larger the octave, the wider the sound absorption bandwidth. Fig.14 As shown in the figure, as the cavity height D increases, the corresponding maximum sound absorption coefficient gradually decreases, but the 0.5 sound absorption octave gradually increases, that is, the sound absorption bandwidth gradually widens.

[0124] In summary, the larger the height D of the cavity 352 is, the wider the sound absorption bandwidth can be obtained near the desired resonant sound absorption frequency. However, the larger the cavity height is, the smaller the maximum sound absorption coefficient corresponding to the resonant sound absorption frequency will be. Therefore, in some embodiments, in order to take into account the sound absorption bandwidth and the maximum sound absorption coefficient of the micro-perforated plate sound absorption structure, the value range of the cavity height D can be 0.5mm-10mm. For example, the value range of the cavity height D can be 2mm-9mm. For another example, the value range of the cavity height D can be 7mm-10mm.

[0125] In some embodiments, a plurality of through holes may be provided on the micro-perforated plate 351, and the plurality of through holes may be spaced apart from each other. In some embodiments, the plurality of through holes may be distributed in any manner as a whole. For example, a plurality of through holes may be distributed in an array. For another example, a plurality of through holes may be distributed in a ring around a center 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.

[0126] In some embodiments, the hole spacing between the through holes may 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 hole spacing and the aperture of the through hole may be greater than 3. In some embodiments, the hole spacing may be much larger than the aperture of the through hole, and the ratio between the hole spacing and the aperture of the through hole may be greater than 10. When the hole spacing is larger than the aperture, the characteristics of transmitting sound waves between the holes may not affect each other.

[0127] In some embodiments, the hole spacing of the through holes on the micro-perforated plate can be much smaller than the wavelength of the sound in the target frequency range. In some embodiments, the ratio of the wavelength of the sound in the target frequency range to the hole spacing can be greater than 5. In some embodiments, the ratio of the wavelength of the sound in the target frequency range to the hole spacing can be greater than 10. As an example only, the target frequency range can be 3kHz-6kHz, and the wavelength of the sound in the target frequency range can be in the range of 53mm-110mm. The ratio of the wavelength of the sound in 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 inter-hole plate (the area of ​​the micro-perforated 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 inter-hole plate on the sound wave propagation process.

[0128] In some embodiments, within the effective aperture range, the smaller the aperture of the through hole, the greater the acoustic resistance when the sound wave passes through the through hole, the more energy dissipated, and the wider the sound absorption bandwidth. Therefore, the sound absorption effect of the micro-perforated plate sound absorption structure can be improved by setting a smaller through hole aperture. The effective aperture range refers to the sound absorption bandwidth of the micro-perforated plate sound absorption structure with an aperture size within this range that can meet the requirements of reducing leakage sound. 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 greatly reduced. In some embodiments, the effective aperture range can be in the range of 0.1mm-1mm. At the same time, taking into account the processing technology requirements, in some embodiments, the effective aperture range can be in the range of 0.2mm-0.4mm; for example, the effective aperture range can be in the range of 0.2mm-0.3mm. In some embodiments, the effective aperture range can be in the range of 0.1mm-0.4mm; for example, the effective aperture range can be in the range of 0.1mm-0.2mm.

[0129] Fig.15 This is a diagram of the sound absorption effect of a micro-perforated plate with through-hole diameters of 0.15 mm and 0.3 mm respectively according to some embodiments of this specification. Fig.15 The horizontal axis represents the sound absorption frequency, the vertical axis represents the sound absorption coefficient, the curve 151 represents the sound absorption effect of the micro-perforated plate 351 with a hole diameter of 0.15 mm, and the curve 152 represents the sound absorption effect of the micro-perforated plate 351 with a hole diameter of 0.3 mm. Fig.15 As shown, the width of curve 151 is greater than that of curve 152, but the heights of the curve 151 and the curve 152 are close. Therefore, it can be seen that the sound absorption bandwidth and sound absorption effect of the micro-perforated plate 351 with a hole diameter of 0.15 mm are obviously better than those of the micro-perforated plate 351 with a hole diameter of 0.3 mm.

[0130] Fig.16 It is a frequency response curve diagram of a micro-perforated plate 351 with a hole diameter of 0.15 mm and a hole diameter of 0.3 mm shown in some embodiments of this specification. Fig.16 In FIG. 1 , the horizontal axis represents frequency, the vertical axis represents sound pressure level, curve 161 represents the frequency response of the micro-perforated plate 351 with a hole diameter of 0.15 mm, and curve 162 represents the frequency response of the micro-perforated plate 351 with a hole diameter of 0.3 mm. Here, the frequency response refers to the frequency response of the sound emitted by the second acoustic hole. Fig.16 As shown, the sound leakage of curve 161 in the 2kHz-4kHz frequency band is about 6dB lower than that of curve 162. It can be seen that the sound absorption effect of the micro-perforated plate 351 with a pore size of 0.15mm in the medium and high frequency range is significantly better than that of the micro-perforated plate 351 with a pore size of 0.3mm. Therefore, in some embodiments, in order to obtain a better sound absorption effect, a micro-perforated plate 351 with a pore size of 0.15mm or close to 0.15mm can be used. For example, a micro-perforated plate 351 with a pore size in the range of 0.1mm-0.2mm is used. In some embodiments, considering the needs of dust prevention and drainage, a micro-perforated plate 351 with a pore size of 0.3mm or close to 0.3mm (for example, 0.28mm-0.35mm) can be used.

[0131] In some embodiments, in order to avoid too many through holes resulting in too small a hole spacing, which affects the characteristics of sound wave transmission between through holes, the perforation rate of the micro-perforated plate 351 can be less than 5%. The perforation rate refers to the ratio of the total area of ​​the through holes to the side area of ​​the micro-perforated plate 351 close to the second acoustic cavity 340.

[0132] 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, so the sound absorption effect of the micro-perforated plate sound absorption structure can be improved by a resistive sound absorption structure. Fig.17 Schematic diagram of an acoustic device with a sound absorbing structure according to some embodiments of this specification. Fig.17As shown, the resistive sound absorbing structure can be arranged in the cavity 352 of the micro-perforated plate sound absorbing structure. In some embodiments, the resistive sound absorbing structure may further include a filling material 354 (e.g., N′Bass particles or porous sound absorbing material). The filling material 354 may be used to increase the equivalent height of the cavity 352 of the micro-perforated plate sound absorbing structure, thereby reducing the design size of the acoustic device 1300 while improving the sound absorption effect of the micro-perforated plate sound absorbing structure. Specifically, the filling material 354 has a "sponge" effect. When the sound wave propagates, the air molecules will be adsorbed and desorbed between the pores of the filling material 354, which can be regarded as a decrease in the sound velocity in the filling material 354, which is equivalent to increasing the volume of the cavity 352, thereby achieving the purpose of widening 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 reducing the design size of the acoustic device while improving the sound absorption effect of the micro-perforated plate sound absorbing structure.

[0133] In some embodiments, the cavity 352 may be filled with N'Bass (aluminosilicate) sound absorbing particles. In some embodiments, the N'Bass sound absorbing particles may be filled in the cavity 352 in a variety of ways. For example only, the N'Bass sound absorbing particles are directly filled in the cavity 352, or the N'Bass sound absorbing particles are filled in a powder bag, which is disposed in the cavity 352, or the N'Bass sound absorbing particles are encapsulated in a gauze of a specific shape, which is disposed in the cavity 352, or the N'Bass sound absorbing particles are filled in the cavity 352 in at least two of the above filling methods.

[0134] In some embodiments, the smaller the N'Bass sound absorbing particles are, the smaller the interval between each sound absorbing particle is, that is, the stronger the adsorption effect on air molecules is. Accordingly, the smaller the particles are, the more N'Bass sound absorbing particles need to be filled, and the cost increases. Therefore, the diameter of the N'Bass sound absorbing particles can be in the range of 0.15mm-0.7mm, so as to ensure the sound absorption effect while taking into account the cost. For example, the diameter of the N'Bass sound absorbing particles can be in the range of 0.15-0.6mm. For another example, the diameter of the N'Bass sound absorbing particles can be in the range of 0.3-0.5mm.

[0135] In some embodiments, as the filling rate of the N'Bass sound absorbing particles in the cavity 352 gradually increases, the more N'Bass sound absorbing particles there are in the cavity 352, the better 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 the cavity 352. However, when the N'Bass sound absorbing particles completely fill the cavity 352, the pressure of the micro-perforated plate sound absorbing structure on the N'Bass sound absorbing particles may cause the N'Bass sound absorbing particles to break, thereby blocking the gaps between the N'Bass sound absorbing particles, which in turn reduces the sound absorption effect.

[0136] Fig.18 is a frequency response curve diagram of the second acoustic cavity of the acoustic device corresponding to different filling material filling rates shown in some embodiments of this specification. Fig.18 As shown in FIG. 1 , when the filling rate of the filling material (e.g., N′Bass sound absorbing particles) is 0%, that is, there is no filling material in the cavity of the micro-perforated plate sound absorbing structure, the frequency response curve corresponding to the second acoustic cavity of the acoustic device forms a peak near 2kHz (e.g., Fig.18 (shown by the dotted circle in the middle), indicating that the second acoustic cavity has a larger sound output at 2kHz. When the filling material filling rate is 25%, that is, 25% of the space in the cavity of the micro-perforated plate sound-absorbing structure is filled with filling material, the peak near 2kHz is absorbed in large quantities, but there are still small peaks. When the filling material filling rate is 50%, that is, 50% of the space in the cavity of the micro-perforated plate sound-absorbing structure is filled with filling material, the peak near 2kHz is further absorbed, and the corresponding frequency response curve tends to be flat. When the filling material filling rate is 75%, that is, 75% of the space in the cavity of the micro-perforated plate sound-absorbing structure is filled with filling material, the peak near 2kHz is further absorbed, but another peak is formed near 3kHz, and the sound output of the second acoustic cavity at 3kHz is slightly increased. When the filling material filling rate is 100%, that is, the cavity of the micro-perforated plate sound-absorbing structure is fully filled with filling material, the peak near 2kHz is further absorbed, but the peak near 3kHz is further increased, and the peak value is obvious, and the sound output of the second acoustic cavity near 3kHz is further increased. In order to make the frequency response curve of the second acoustic cavity smoother and avoid peaks in the curve within a preset range (e.g., 2kHz-3kHz), in some embodiments, the filling rate of the filling material may range from 30% to 100%. In some embodiments, the filling rate may range from 70% to 95%. In some embodiments, taking into account the cost of filling N'Bass sound-absorbing particles, the filling rate may range from 75% to 85%. For example, the filling rate may be 80%.

[0137] 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 gap, thereby reducing the sound absorption effect.

[0138] In some embodiments, since the diameter of the N′Bass sound absorbing particles is close to or smaller than the aperture of the through hole, in order to prevent the N′Bass sound absorbing particles from blocking the through hole, Fig.17As shown, a gauze 353 may be provided between the N'Bass sound absorbing particles and the micro-perforated plate 351. In some embodiments, the side of the micro-perforated plate 351 away from the second acoustic cavity 340 (or the diaphragm 320) may be covered with the gauze 353, and the gauze 353 covers all through holes on the micro-perforated plate 351. In some embodiments, the gauze 353 may be provided at 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.

[0139] In some embodiments, the micro-perforated plate sound absorbing structure may be disposed toward the second acoustic cavity. For example, the angle between the normal line of the side of the micro-perforated plate facing the second acoustic cavity and the vibration direction of the diaphragm (for example, Fig. 20 The angle α shown in FIG. 1 is in the range of 0°-90°, so that the sound waves of the target frequency in the second acoustic cavity can be effectively absorbed. It should be noted that the angle here refers to the absolute value of the angle between the normal line and the vibration direction of the diaphragm. For example, for Fig.28C In the micro-perforated plate sound absorbing structures 350 and 350 ′ shown, the angle between the normal line of the micro-perforated plate facing the side surface of the second acoustic cavity 340 and the vibration direction of the diaphragm is 90°.

[0140] In some embodiments, the micro-perforated plate can be arranged parallel or approximately parallel to the diaphragm. For example, 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 in the range of 0°-10°, which improves the fault tolerance of the assembly of the sound-absorbing structure and the shell, and at the same time avoids the micro-perforated plate sound-absorbing structure from increasing the thickness of the sound-emitting part along the vibration direction due to excessive inclination angle, thereby facilitating the reduction of the volume and / or weight of the sound-emitting part.

[0141] 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 inclination 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 micro-perforated 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 micro-perforated plate facing the side of the second acoustic cavity and the vibration direction of the diaphragm can be 90°, that is, the micro-perforated plate can be vertically arranged relative to the diaphragm. At this time, the micro-perforated plate sound absorption structure can be arranged at the corner position of the second acoustic cavity to avoid increasing the thickness of the sound-emitting part due to the large inclination angle of the micro-perforated plate sound absorption structure. For example only, refer to Fig.28B The micro-perforated plate can be arranged in the long axis direction of the sound-emitting part and tilted relative to the vibration direction of the diaphragm and the long axis direction Y of the sound-emitting part. Fig.29B The micro-perforated plate can be arranged in the short axis direction of the sound-emitting part and tilted relative to the vibration direction of the diaphragm and the short axis direction Z of the sound-emitting part. Figure 19-29C The embodiments in which the micro-perforated plate is arranged parallel to or tilted relative to the diaphragm are exemplified.

[0142] In some embodiments, the micro-perforated plate sound absorbing structure 350 may be arranged inside the housing of the acoustic device 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 micro-perforated plate in the micro-perforated plate sound absorbing structure 350 facing the side of the second acoustic cavity (or the plane where the micro-perforated plate is located) and the vibration direction may be in the range of 0°-10°.

[0143] Fig.19 Schematic diagram of an acoustic device with a sound absorbing structure according to some embodiments of this specification. Fig.19 As shown, the micro-perforated plate 351 included in the acoustic device 500 can be arranged in the vibration direction of the diaphragm, and the normal line of the side of the micro-perforated plate 351 facing the second acoustic cavity 340 is substantially parallel to the vibration direction of the diaphragm 320. At this time, the second acoustic hole 312 is located on the side of the second acoustic cavity 340 adjacent to the micro-perforated plate 351.

[0144] Fig. 20FIG. 1 is a schematic diagram of another acoustic device having a sound absorbing structure according to some embodiments of this specification. Fig. 20 As shown, the micro-perforated plate 351 included in the acoustic device 500 can be arranged in the vibration direction of the diaphragm, and the normal of the micro-perforated plate 351 facing the side of the second acoustic cavity 340 forms a certain angle α with the vibration direction of the diaphragm 320, and the angle α is greater than 0° and less than 10°. At this time, the second acoustic hole 312 is located on the side of the second acoustic cavity 340 adjacent to the micro-perforated plate 351.

[0145] In some embodiments of the present specification, the micro-perforated plate sound absorption structure is arranged in the vibration direction of the diaphragm, so that the space of the back cavity can be fully utilized, and the second acoustic hole located on the side of the sound-emitting part (such as the upper side wall US or the lower side wall LS) can be arranged adjacent to the micro-perforated plate sound absorption structure. Figure 3B When the upper side wall US or the lower side wall LS is shown, the micro-perforated plate sound absorption structure is arranged in the vibration direction of the diaphragm and is connected to the upper side wall US and the lower side wall LS, so that the micro-perforated plate sound absorption structure is arranged close to the second acoustic hole, thereby improving the absorption effect of the micro-perforated plate sound absorption structure on the sound at the second acoustic hole. When a plurality of second acoustic holes are arranged on the upper side wall US or the lower side wall LS of the sound-emitting part, the micro-perforated plate sound absorption structure is arranged in the vibration direction of the diaphragm so that the distance from each second acoustic hole to the micro-perforated plate sound absorption structure is relatively short, thereby ensuring the comprehensive sound absorption effect of the micro-perforated 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 within the range of 0°-10°, thereby avoiding the need for the micro-perforated plate sound absorption structure to increase the thickness of the sound-emitting part along the vibration direction due to the excessive inclination angle, thereby helping to reduce the volume and / or weight of the sound-emitting part.

[0146] In some embodiments, for using Figure 3A In the acoustic device of the wearing method shown in the figure (i.e. the sound-emitting part can partially extend into the concha cavity), when the micro-perforated plate sound-absorbing structure is arranged in the vibration direction of the diaphragm, the micro-perforated plate sound-absorbing structure can be arranged at the end away from the end FE along the long axis direction of the sound-emitting part. Such arrangement can avoid increasing the thickness of the end FE of the sound-emitting part along the vibration direction, thereby avoiding the end FE of the sound-emitting part from being unable to penetrate into the concha cavity due to excessive thickness. In some embodiments, for the use of Figure 5 For the acoustic device with the wearing method shown (i.e., the sound-emitting part can partially cover the antihelix area), when the micro-perforated plate sound-absorbing structure is set in the vibration direction of the diaphragm, the micro-perforated plate sound-absorbing structure can be specifically set at any position along the length direction or width direction of the sound-emitting part without affecting the wearing of the acoustic device.

[0147] In some embodiments, the angle between the normal line of the side of the micro-perforated plate facing the second acoustic cavity and the vibration direction may be in the range of 0°-10°, and the micro-perforated plate sound absorption structure may not be arranged in the vibration direction of the diaphragm. Fig.28A As shown, the angle between the normal line of the side of the micro-perforated plate facing the second acoustic cavity and the vibration direction can be approximately 0°, and the micro-perforated plate sound absorption structure can be arranged in the long axis direction Y of the sound-emitting part. Fig.29A As shown, the angle between the normal line of the side of the micro-perforated plate facing the second acoustic cavity and the vibration direction can be approximately 0°, and the micro-perforated plate sound absorption structure can be arranged in the short axis direction Z of the sound-emitting part. For details about how the micro-perforated plate sound absorption structure can be arranged in the long axis and / or short axis direction, please refer to Figures 28A-29C and its related description.

[0148] Fig.21 It is a diagram of the internal structure of an acoustic device according to some embodiments of the present specification. Fig. 22 It is a diagram of the internal structure of an acoustic device according to some embodiments of the present specification.

[0149] like Fig.21 and Fig. 22 As shown, the diaphragm 720 of the acoustic device 700 divides the accommodating cavity of the shell 710 into a first acoustic cavity 730 and a second acoustic cavity 740, and the acoustic device also includes a coil 722, a basin frame 723 and a magnetic circuit assembly 721. Among them, the basin frame 723 is arranged around the diaphragm 720, the coil 722 and the magnetic circuit assembly 721 to provide an installation and fixing platform. The diaphragm 720 can be connected to the shell 710 through the basin frame 723. The diaphragm 720 covers the coil 722 and the magnetic circuit assembly 721 in the vibration direction. At least part of the coil 722 extends into the magnetic gap formed by the magnetic circuit assembly 721 and is connected to the diaphragm 720. After the coil 722 is energized, the magnetic field generated interacts with the magnetic field formed by the magnetic circuit assembly 721, thereby driving the diaphragm 720 to generate mechanical vibration, and then generating sound through the propagation of a medium such as air, and the sound is output through the hole on the shell 710. The micro-perforated plate sound absorption structure can be arranged in the second acoustic cavity 740. For example, a micro-perforated plate sound absorption structure can be arranged around the magnetic circuit component 721, and the micro-perforated plate sound absorption structure includes a micro-perforated plate 751 and a filling layer 753, and the micro-perforated plate 751 is connected to the filling layer 753 on the side away from the diaphragm 720 along the vibration direction. Among them, the micro-perforated plate 751 is an annular structure, which is arranged around the magnetic circuit component 721. The filling layer 753 is filled with N'Bass sound absorbing particles or porous sound absorbing materials. In some embodiments, the shell 710 (for example, the back plate 752) can be enclosed with the magnetic circuit component 721 to form a closed cavity, that is, the cavity of the micro-perforated plate sound absorption structure, and the filling layer 753 can be filled in the cavity.

[0150] 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 connected to each other. The side of the magnet 7212 away from the magnetic plate 7211 is installed on the bottom wall of the magnetic cover 7213, and a magnetic gap is formed between the peripheral side of the magnet 7212 and the peripheral inner side wall of the magnetic cover 7213. In some embodiments, the peripheral outer side wall of the magnetic cover 7213 is connected and fixed to the basin frame 723. In some embodiments, the magnetic cover 7213 and the magnetic plate 7211 can both be made of magnetic conductive materials (such as iron, etc.).

[0151] 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 a suitable 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 of the shell 710, and it is difficult to meet the design requirements of the small size of the acoustic device. 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.

[0152] 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.

[0153] Generally, the acoustic impedance of a single through hole on the micro-perforated plate 751 is:

[0154] (1) In the formula, ρ is the air density, μ is the air kinematic viscosity, t is the plate thickness, and d is the hole diameter. When the plate thickness of the through hole is equivalent to the hole diameter, 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 a plurality of through holes, and its acoustic impedance can be equivalent to the parallel connection of the acoustic impedances of the plurality of 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:

[0155] (2) where σ is the porosity, 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 capacity, and its acoustic impedance is:

[0156] (3) In the formula, D is the cavity height. Then the acoustic impedance of the micro-perforated plate sound absorption structure can be expressed as: Z total =Z MPP +Z D (4)

[0157] After normalization:

[0158] (5) In the formula, r is the relative acoustic resistivity and m is the relative acoustic mass, which is:

[0159] When the sound wave is incident vertically, the sound absorption coefficient α of the micro-perforated plate sound absorption structure can be solved as:

[0160] The resonant frequency of the sound absorbing structure 350 is:

[0161] 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 pore size, perforation rate, plate thickness, and cavity height of the micro-perforated plate 751.

[0162] In addition, the values ​​of parameters such as aperture, perforation rate, plate thickness, cavity height, etc. can be combined with considerations such as sound absorption coefficient, sound absorption frequency range, and structural size to comprehensively determine the parameter combination. For example, the sound absorption bandwidth and the maximum sound absorption coefficient of the sound-absorbing structure restrict each other and can be balanced according to actual needs. For example, the smaller the aperture of the micro-perforated plate, the wider the sound absorption bandwidth. The wider sound absorption bandwidth corresponds to the 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 greatly reduced. For another example, a small aperture, a large perforation rate, a small plate thickness, and a cavity height are suitable for the high-frequency sound absorption range, and vice versa for the low-frequency sound absorption range.

[0163] In some embodiments, the parameter combination of the micro-perforated plate 751 can be determined according to the resonant frequency of the second acoustic cavity 740, so that the sound absorbing structure can absorb the sound waves near the resonant frequency of the second acoustic cavity 740, so as to avoid the change of 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 leakage sound. 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 the sound near the resonant frequency can be absorbed. In some embodiments, the second acoustic cavity 740 may resonate near 4kHz, and the human ear is more sensitive to the 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.

[0164] In some embodiments, the aperture of the micro-perforated plate 751 may be in the range of 0.2mm-0.4mm, the perforation rate may be in the range of 1%-5%, the plate thickness may be in the range of 0.2mm-0.7mm, and the cavity height may be in the range of 4mm-9mm. In some embodiments, the aperture of the micro-perforated plate 751 may be in the range of 0.25mm-0.35mm, the perforation rate may be in the range of 1.2%-4.5%, the plate thickness may be in the range of 0.3mm-0.6mm, and the cavity height may be in the range of 5mm-8mm. As an example only, the aperture of the micro-perforated plate 751 may be 0.25mm, the perforation rate may be 2.8%, the plate thickness may be 0.4mm, and the cavity height may be 6mm. For another example, the aperture of the micro-perforated plate 751 may be 0.3mm, the perforation rate may be 3.2%, the plate thickness may be 0.5mm, and the cavity height may be 6.5mm. For another example, the micro-perforated plate 751 may have a hole 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.

[0165] Fig.23A It is a frequency response curve diagram at the second acoustic hole of the acoustic device. Fig. 23B is a frequency response curve diagram of another second acoustic hole of the acoustic device. Fig.23A and Fig. 23BIn the figure, the horizontal axis represents frequency and the vertical axis represents sound pressure level. Curve a1 represents the frequency response of the acoustic device 200 (without a micro-perforated sound absorbing structure) at the second acoustic hole, curve a2 represents the frequency response of the acoustic device 200 at another second acoustic hole, curve b1 represents the frequency response of the acoustic device 300 (with a micro-perforated sound absorbing structure) at the second acoustic hole, curve b2 represents the frequency response of the acoustic device 300 at another second acoustic hole, curve c1 represents the frequency response of the acoustic device 400 (with a micro-perforated sound absorbing structure and N'Bass sound absorbing particles) at the second acoustic hole, and curve c2 represents the frequency response of the acoustic device 400 at another second acoustic hole. The second acoustic hole and another second acoustic hole are acoustic holes at different positions on the shell corresponding to the second acoustic cavity. Among them, curves b1, b2, c1 and c2 are all measured by the micro-perforated plate under the conditions of the above-mentioned parameter combination, which 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.

[0166] like Fig.23A and Fig. 23B As shown, curves a1 and a2 have higher resonance peaks near 4kHz, and 3.8kHz corresponds to the resonance frequency of the second acoustic cavity. After the micro-perforated plate sound absorption structure is set (curves b1 and b2), the sound pressure level in the 3kHz-6kHz frequency band is effectively reduced by 4dB-20dB, and reaches a low point near 4kHz. It can be seen that the micro-perforated plate sound absorption structure can effectively absorb sound waves in the range of 3kHz-6kHz, and the micro-perforated plate sound absorption structure absorbs sound waves near 4kHz by about 20dB, which can reduce or avoid the resonance of sound waves near the resonance frequency under the action of the second acoustic cavity, thereby reducing sound leakage at the resonance frequency. After the cavity of the micro-perforated plate sound absorption structure is filled with N′Bass sound absorption particles (curves c1 and c2), the sound absorption bandwidth can be increased. Both combined sound absorption schemes have 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.

[0167] Fig.24 It is a diagram of the internal structure of an acoustic device according to some embodiments of the present specification.

[0168] like Fig.24As shown, the acoustic device 800 includes a diaphragm 820, a magnetic circuit assembly 821, a coil (not shown in the figure) and a basin frame (not shown in the figure). The diaphragm 820 divides the accommodating cavity of the shell 810 into a first acoustic cavity 830 and a second acoustic cavity 840. The cooperation between the diaphragm 820, the magnetic circuit assembly 821, the coil and the basin frame is similar to that in the acoustic device 700. The micro-perforated plate sound absorption structure is coupled with the second acoustic cavity 840. The micro-perforated plate 851 is arranged on the side of the magnetic circuit assembly 821 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 (for example, elliptical, circular, etc.) that is adapted to the shape of the second acoustic cavity 840 or the shell 810. In some embodiments, the parameters of the micro-perforated plate 851, such as the aperture, perforation rate, and hole spacing, can be consistent with the relevant parameters of the above-mentioned micro-perforated plate (for example, the micro-perforated plate of the annular structure arranged around the magnetic circuit component). In this way, the micro-perforated plate of the panel structure has a larger area, a relatively larger number of through holes, a better sound absorption effect, and a simple structure, which is easy to assemble. In some embodiments, the parameters of the micro-perforated plate 851 may be inconsistent with the micro-perforated plate of the annular structure. For example, under the premise of maintaining a similar sound absorption frequency band, the perforation rate of the micro-perforated plate 851 spaced apart from the magnetic circuit component can be less than the perforation rate of the micro-perforated plate of the annular structure. At this time, due to the relatively large area of ​​the micro-perforated plate 851, a good sound absorption effect can still be guaranteed. For another example, under the premise of maintaining a similar sound absorption frequency band, the aperture of the micro-perforated plate 851 spaced apart from the magnetic circuit component can be greater than the aperture of the micro-perforated plate of the annular structure. At this time, due to the relatively large area of ​​the micro-perforated plate 851, a good sound absorption effect can still be guaranteed.

[0169] In some embodiments of the present specification, the micro-perforated plate and the magnetic circuit assembly are spaced apart in the vibration direction of the diaphragm, so that the sound absorption effect of the micro-perforated plate sound absorption structure can be improved, and the structure is simple and easy to assemble. In addition, by spacing the micro-perforated plate and the magnetic circuit assembly in the vibration direction of the diaphragm, the parameters such as the aperture and the perforation rate can be designed more flexibly, and the manufacturing process can be simplified while ensuring the sound absorption effect.

[0170] In some embodiments, for using Figure 5 The acoustic device with the wearing method shown (i.e., the sound-emitting part can partially cover the antihelix area) can arrange the perforated plate and the magnetic circuit assembly at intervals 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 the aperture and perforation rate without affecting the wearing of the acoustic device.

[0171] In some embodiments, the parameter combination of the micro-perforated plate 851 can be determined according to the resonant frequency of the second acoustic cavity 840, so that the sound absorbing structure can absorb the sound waves near the resonant frequency of the second acoustic cavity 840, so as to avoid the change of 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 the sound leakage. In some embodiments, the parameter combination of the micro-perforated plate 851 can be set so that the target frequency range of sound absorption includes the resonant frequency, so that the sound near the resonant frequency can be absorbed. In some embodiments, the second acoustic cavity 840 may resonate near 4kHz, and the human ear is more sensitive to the 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.

[0172] In some embodiments, the aperture of the micro-perforated plate 851 may be in the range of 0.1 mm-0.2 mm, the perforation rate may be in the range of 2%-5%, the plate thickness may be in the range of 0.2 mm-0.7 mm, and the cavity height may be in the range of 7 mm-10 mm. For example only, the aperture of the micro-perforated plate 851 may be in the range of 0.1 mm-0.2 mm, the perforation rate may be in the range of 2.18%-4.91%, the plate thickness may be in the range of 0.3 mm-0.6 mm, and the cavity height may be in the range of 7.5 mm-9.5 mm. For example, the hole diameter of the micro-perforated plate 851 can be 0.15mm, the perforation rate can be 2.18%, the plate thickness can be 0.3mm, and the cavity height can be 8mm; for another example, the hole diameter of the micro-perforated plate 851 can be 0.15mm, the perforation rate can be 2.76%, the plate thickness can be 0.4mm, and the cavity height can be 8.5mm; for another example, the hole diameter of the micro-perforated plate 851 can be 0.15mm, the perforation rate can be 3.61%, the plate thickness can be 0.5mm, and the cavity height can be 9mm.

[0173] In some embodiments of the present specification, the parameter combination of the micro-perforated plate is set to a hole 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, so that the target frequency range of the sound absorbing structure including the micro-perforated plate includes 4kHz, and the best 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.

[0174] In some embodiments, the second acoustic cavity (e.g., Fig.21 The second acoustic cavity 740 shown, Fig.24The second acoustic cavity 840 shown in the figure 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.

[0175] In some embodiments, the micro-perforated plate (e.g., micro-perforated plate 751, micro-perforated plate 851, etc.) may have an aperture in the range of 0.1 mm-0.3 mm, a perforation rate in the range of 0.5%-5%, a plate thickness in the range of 0.2 mm-0.6 mm, and a cavity height in the range of 4 mm-10 mm. For example only, the aperture of the micro-perforated plate may be in the range of 0.3 mm-0.3 mm, a perforation rate in the range of 0.7%-2.3%, a plate thickness in the range of 0.25 mm-0.55 mm, and a cavity height in the range of 4 mm-7.5 mm. For example, in order to make the sound absorption center frequency of the micro-perforated plate sound absorption structure near 3kHz, the aperture of the micro-perforated plate can be 0.2mm, the perforation rate can be 0.87%, the plate thickness can be 0.3mm, and the cavity height can be 4.5mm; for another example, in order to make the sound absorption center frequency of the micro-perforated plate sound absorption structure near 3kHz, the aperture of the micro-perforated plate can be 0.25mm, the perforation rate can be 1%, the plate thickness can be 0.4mm, and the cavity height can be 4.5mm; for another example, in order to make the sound absorption center frequency of the micro-perforated plate sound absorption structure near 3kHz, the aperture of the micro-perforated plate can be 0.3mm, the perforation rate can be 0.97%, the plate thickness can be 0.4mm, and the cavity height can be 4.5mm.

[0176] In some embodiments of the present specification, by setting the parameter combination of the micro-perforated plate to a hole 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 best sound absorption effect is achieved near 2kHz-3kHz, thereby achieving more targeted and effective sound leakage reduction.

[0177] In some embodiments, the cavity of the micro-perforated plate sound absorbing structure can be a regular shape including a sphere, a cylinder, a racetrack, or an irregular shape. For example, the cavity can be Fig.25A As shown in the figure, the ring-shaped structure is arranged around the magnetic circuit component. For another example, the cavity can be as follows Fig.25B In some embodiments, as shown in the flat plate shape Fig.25A and Fig.25B The cavity height and the cross-sectional area perpendicular to the cavity height are different, but the cavity volume is the same. Based on this, combined with Fig.26Determine the effect of cavity volume and cavity height on the sound absorption effect of the sound absorbing structure.

[0178] Fig.26 yes Fig.25A and 25B FIG. 4 is a frequency response graph of the second acoustic hole of the acoustic device shown. Fig.26 In FIG. 261 , the horizontal axis represents frequency and the vertical axis represents sound pressure level. Fig.25A The frequency response of the acoustic device shown at the second acoustic hole, curve 262 represents Fig.25B The frequency response of the acoustic device shown in the figure is at the same second acoustic hole. Curve 261 is measured by the micro-perforated plate under the parameter combination of 0.3mm aperture, 2.1% perforation rate, 0.6mm plate thickness, and 4mm cavity height. Curve 262 is measured by the micro-perforated plate under the parameter combination of 0.3mm aperture, 2.1% perforation rate, 0.6mm plate thickness, and 2mm cavity height. Fig.25A and 25B The cavities of the acoustic devices shown are filled with the same volume of N'Bass sound absorbing particles, and the cavity volumes corresponding to the two curves are the same. Fig.26 , curve 261 and curve 262 are substantially overlapped. It can be seen that the cavity height and shape are adjusted on the basis of the cavity volume of the sound absorbing structure being unchanged, and the sound absorption effect of the sound absorbing structure can be ignored. Therefore, in some embodiments, the cavity height and shape can be adjusted on the basis of the cavity volume of the sound absorbing structure being unchanged to adapt to the functional and structural requirements of the acoustic device. For example, the cavity height can be reduced on the basis of the cavity volume of the sound absorbing structure being unchanged, thereby reducing the size of the acoustic device and realizing a miniaturized design.

[0179] Fig. 27 It is a schematic diagram of the structure of the acoustic device shown in some embodiments of this specification.

[0180] like Fig. 27 As shown, in some embodiments, the arrangement direction A of the micro-perforated plate 351 can be arranged obliquely with respect to the vibration direction, that is, the normal line of the micro-perforated plate 351 facing the side of the second acoustic cavity forms a certain angle α. For example, 10°<α<90°. In some embodiments, combined with Fig. 27 The acoustic device 900 has two second acoustic holes (i.e., second acoustic holes 3121 and 3122), which can be located on opposite sides of the housing 310, for example, arranged opposite to each other in a direction perpendicular to the vibration direction, in order to destroy the high-pressure area of ​​the sound field in the second acoustic cavity to the greatest extent. Figure 3A As an example, the acoustic device 10 in which the sound-generating portion can partially extend into the concha cavity when worn is used, and combined with Fig. 27, 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. Figure 3A In the thickness direction X) shown in FIG. 1 , the distances from the second acoustic hole 3121 and the second acoustic hole 3122 to the inner side surface IS may be different. At this time, the micro-perforated plate 351 may be tilted so that the distances from the micro-perforated plate 351 (for example, the connection between the micro-perforated plate 351 and the shell 310) to the two second acoustic holes are the same or close, so that the sound absorption effect of the micro-perforated plate 351 on the two second acoustic holes is basically the same. Specifically, the line direction B of the hole centers of the two second acoustic holes is roughly parallel to the arrangement direction A of the micro-perforated plate, or the difference between the shortest distance from the centroid of the second acoustic hole 3121 to the micro-perforated plate 351 and the shortest distance from the centroid of the second acoustic hole 3122 to the micro-perforated plate 351 is within a preset range, for example, not more than 1 / 10 of the size of the sound-emitting part in the vibration direction.

[0181] In some embodiments, the distances between the second acoustic hole 3121 and the second acoustic hole 3122 and the inner side IS may also be the same. Figure 3A or Figure 5 As shown in the figure, the second acoustic hole 3122 located on the lower side surface LS may be closer to the ear canal opening. In order to avoid the sound emitted by the second acoustic hole 3122 and the sound emitted by the first acoustic hole 311 from canceling each other in the near field, the sound absorbing structure 350 can be adjusted to absorb more sound emitted by the second acoustic hole 3122. At this time, the micro-perforated plate 351 is more inclined toward the second acoustic hole 3122, so that the distance from the micro-perforated plate 351 to the second acoustic hole 3122 is less than the distance from the micro-perforated plate 351 to the second acoustic hole 3121, so that the sound absorption effect of the micro-perforated plate 351 at the second acoustic hole 3122 is greater than the sound absorption effect of the micro-perforated plate 351 at the second acoustic hole 3121. With such a configuration, the second acoustic hole 3122 located on the lower side surface LS can emit relatively less sound, reduce the interference cancellation of the sound emitted from the second acoustic hole 3122 and the sound emitted from the first acoustic hole 311 in the near field, and thus ensure the listening effect at the ear canal opening.

[0182] Figure 28A-28C It is a schematic diagram of the structure of the acoustic device shown in some embodiments of this specification.

[0183] In some embodiments, in combination Figure 28A-28C, the shell 310 included in the acoustic device 1000 has 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 are orthogonal to each other, and the micro-perforated plate structure can be arranged in the long 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 long axis direction Y, and 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 the angle here refers to the absolute value of the angle between the side of the micro-perforated plate 351 and the long axis direction Y. For example, for Fig.28C In the micro-perforated plate sound absorbing structures 350 and 350 ′ shown, the angle between the side surface of the micro-perforated plate facing the second acoustic cavity 340 and the long axis direction Y is 90°.

[0184] In some embodiments, the arrangement direction of the micro-perforated plate 351 has a certain angle β with the long axis direction Y, wherein 0°≤β≤90°. Fig.28A As shown, the side of the micro-perforated plate 351 facing the second acoustic cavity 340 may be substantially parallel to the long axis direction Y. In some embodiments, as shown in FIG. Fig.28B As shown, the angle β between the side of the micro-perforated plate 351 facing the second acoustic cavity 340 and the long axis direction Y is greater than 0° and less than 90°. Fig.28C As shown, the side of the micro-perforated plate 351 facing the second acoustic cavity 340 is substantially perpendicular to the long axis direction Y. In some embodiments, in order to ensure the sound absorption effect of the micro-perforated plate sound absorption structure, when the side of the micro-perforated plate 351 facing the second acoustic cavity 340 is substantially perpendicular to the long axis direction Y, the micro-perforated plate 351 can be arranged toward or close to the second acoustic hole, thereby reducing the distance between the micro-perforated plate 351 and the second acoustic hole as much as possible, thereby improving the sound absorption effect.

[0185] In some embodiments, to accommodate Figure 3AIn the wearing mode of the acoustic device in which the sound-emitting part can extend into the concha cavity, the size of the sound-emitting part along the long axis direction Y can be appropriately increased so that the end FE of the sound-emitting part can be located in the concha cavity of the user. In some embodiments, when the acoustic device 1000 has a relatively large size in the long axis direction Y, in order to better absorb the sound waves of the second acoustic hole, the micro-perforated plate 351 is arranged close to the second acoustic hole. In some embodiments, in order to prevent the components inside the housing 310 (such as the diaphragm, the magnetic circuit component, etc.) from affecting the micro-perforated plate 351 to absorb the sound waves of the second acoustic hole, the micro-perforated plate 351 is arranged roughly along the long axis direction Y. In some embodiments, when the diaphragm 320 cannot completely cover the second acoustic cavity 340 along the long axis direction Y, a partition 313 arranged along the long axis direction Y can be provided, and the partition 313 and the diaphragm 320 jointly separate the interior of the housing 310 to form the first acoustic cavity 330 and the second acoustic cavity 340.

[0186] In some embodiments of the present specification, by arranging the micro-perforated plate sound absorbing structure approximately along the long axis direction Y, the size of the sound-emitting part along the long axis direction Y can be appropriately increased, so that in, for example Figure 3A In the wearing mode shown, the end FE of the sound-emitting part can better extend into the concha cavity. In addition, when the micro-perforated plate sound-absorbing structure is arranged along the long axis direction Y, the cavity extending from the sound-emitting part along the long axis 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, the cavity position, height and other parameters in the micro-perforated plate sound-absorbing structure may not be restricted by the magnetic circuit component. In this way, the cavity height in the micro-perforated plate sound-absorbing structure can be increased to enhance the sound absorption effect. Alternatively, when the cavity height in the sound-absorbing structure remains unchanged, the micro-perforated plate sound-absorbing structure can be placed closer to the top (for example, Fig.28A The positive direction of the X direction shown in FIG. 1 ) is set so as to reduce the thickness dimension of the sound-emitting part.

[0187] What you need to know is, Figures 28A-28C The micro-perforated plate sound absorption structure shown is only an example. When the micro-perforated plate sound absorption structure is arranged along the long axis direction Y, the position, orientation and other parameters of the micro-perforated plate sound absorption structure may not be limited to Figures 28A-28C In some embodiments, when the micro-perforated plate sound absorption structure is arranged along the long axis direction Y, the side of the micro-perforated plate facing the second acoustic cavity 340 can also be roughly facing other side walls of the shell 310, for example, roughly facing the upper side wall and / or the lower side wall where the second acoustic hole is located, etc., as long as the micro-perforated plate is mainly facing the second acoustic cavity (that is, not facing the back side of the diaphragm), this specification does not limit this.

[0188] Figure 29A-29C It is a schematic diagram of the structure of the acoustic device shown in some embodiments of this specification.

[0189] In some embodiments, in combination Figure 29A-29C , the shell 310 included in the acoustic device 1100 has 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 are 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 surface of the micro-perforated plate 351 and the short axis direction Z.

[0190] In some embodiments, the arrangement direction of the micro-perforated plate 351 has a certain angle γ with the short axis direction Z, wherein 0°≤γ≤90°. Fig.29A As shown, the side of the micro-perforated plate 351 facing the second acoustic cavity 340 may be substantially parallel to the short axis direction Z. In some embodiments, as Fig.29B As shown, 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°. Fig.29C As shown, the larger side of the micro-perforated plate 351 facing the second acoustic cavity 340 may be substantially perpendicular to the short axis direction Z.

[0191] In some embodiments, to accommodate Figure 5 The sound-emitting part shown can be located in the wearing mode of the acoustic device in the antihelix region, and the size of the sound-emitting part along the short axis direction Z can be appropriately increased so that the sound-emitting part (for example, the first acoustic hole) can be close to the ear canal. In some embodiments, when the acoustic device 1100 has a relatively large size in the short axis direction Z, in order to better absorb the sound waves of the second acoustic hole, the micro-perforated plate 351 is arranged close to the second acoustic hole. In some embodiments, in order to prevent the components inside the shell 310 (such as the diaphragm, the magnetic circuit component, etc.) from affecting the micro-perforated plate 351 to absorb the sound waves of the second acoustic hole, the micro-perforated plate 351 is arranged roughly along the short axis direction Z. In some embodiments, when the diaphragm 320 cannot completely cover the second acoustic cavity 340 along the short axis direction Z, a partition 313 arranged along the short axis direction Z can be provided, and the partition 313 and the diaphragm 320 jointly separate the inside of the shell 310 to form the first acoustic cavity 330 and the second acoustic cavity 340.

[0192] In some embodiments of the present specification, by arranging the micro-perforated plate approximately along the short axis direction Z, the size of the sound-emitting part along the short axis direction Z can be appropriately increased, so that in, for example Figure 5In the wearing method shown, the first acoustic hole on the sound-emitting part can be closer to the ear canal, so that the user's listening effect is better. In addition, when the micro-perforated plate sound-absorbing structure is arranged along the short-axis direction Z, the cavity extending from the sound-emitting part 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, the cavity position, height and other parameters in the micro-perforated plate sound-absorbing structure may not be restricted by the magnetic circuit component. In this way, the cavity height in the micro-perforated plate sound-absorbing structure can be increased to improve the sound absorption effect. Or when the cavity height in the sound-absorbing structure remains unchanged, the micro-perforated plate sound-absorbing structure can be closer to the top (for example, Fig.29A The positive direction of the X direction shown in FIG. 1 ) is set so as to reduce the thickness dimension of the sound-emitting part.

[0193] What you need to know is, Figures 29A-29C The micro-perforated plate sound absorption structure shown is only an example. When the micro-perforated plate sound absorption structure is arranged along the short axis direction Z, the position, orientation and other parameters of the micro-perforated plate sound absorption structure may not be limited to Figures 29A-29C For example, Figures 29A-29C The side of the micro-perforated plate 351 shown facing the second acoustic cavity 340 is roughly toward the upper side wall where the first acoustic hole 311 is located or the side wall where the second acoustic hole is located (for example, the upper side wall or the lower side wall). In some embodiments, when the micro-perforated plate sound absorption structure is arranged along the axial direction Z, the side of the micro-perforated plate facing the second acoustic cavity 340 can also be roughly toward other side walls of the shell 310, for example, toward both ends of the shell 310 along the long axis direction Y (for example, toward or away from the end FE), etc. As long as the micro-perforated plate is mainly facing the second acoustic cavity (that is, not facing away from the rear side of the diaphragm), this specification does not impose any restrictions on this.

[0194] Fig.30 It is a schematic diagram of the structure of the acoustic device shown in some embodiments of this specification.

[0195] Combination Fig.30 In some embodiments, the sound absorbing structure of the acoustic device 1200 may include a plurality of independently arranged sub-sound absorbing structures, for example, sub-sound absorbing structure 350a, sub-sound absorbing structure 350b, ... 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, ...

[0196] In some embodiments, a plurality of smaller, independently arranged sub-sound absorbing structures may be used to replace a relatively larger sound absorbing structure in the second acoustic cavity 340. In some embodiments, a plurality of sub-sound absorbing structures may be arranged at different positions in the second acoustic cavity 340, and the installation positions of the sub-sound absorbing structures may be flexibly designed, so that the space in the second acoustic cavity 340 may be fully utilized, which is conducive to the miniaturization of the acoustic device 1200. In some embodiments, when the acoustic device 1200 has a plurality of second acoustic holes, one or more sub-sound absorbing structures may be arranged corresponding to each second acoustic hole, so that the sound waves at each second acoustic hole can be absorbed by the sound absorbing structure to ensure the sound absorption effect. In some embodiments, the sound absorption effect of the sound absorbing structure on each second acoustic hole may be differentiated by adjusting the position and number of the sub-sound absorbing structures corresponding to each second acoustic hole. For example, in order to reduce the cancellation of the second acoustic hole and the first acoustic hole in the near field, the sub-sound absorbing structure may be closer to the second acoustic hole, or a greater number of sub-sound absorbing structures may be arranged 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, so as to achieve absorption of sounds in different frequency bands.

[0197] The basic concepts have been described above. Obviously, for those skilled in the art, the above detailed disclosure is only for example and does not constitute a limitation of this specification. Although not explicitly stated here, those skilled in the art may make various modifications, improvements and corrections to this specification. Such modifications, improvements and corrections are suggested in this specification, so such modifications, improvements and corrections still belong to the spirit and scope of the exemplary embodiments of this specification.

[0198] At the same time, this specification uses specific words to describe the embodiments of this specification. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of this specification. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures or characteristics in one or more embodiments of this specification can be appropriately combined.

[0199] In addition, unless explicitly stated in the claims, the order of the processing elements and sequences described in this specification, the use of alphanumeric characters, or the use of other names are not intended to limit the order of the processes and methods of this specification. Although the above disclosure discusses some invention embodiments that are currently considered useful through various examples, it should be understood that such details are only for illustrative purposes, and the attached 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 essence 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.

[0200] Similarly, it should be noted that in order to simplify the description disclosed in this specification and thus help understand one or more embodiments of the invention, in the above description of the embodiments of this specification, multiple features are sometimes combined into one embodiment, figure or description thereof. However, this disclosure method does not mean that the features required by the subject matter of this specification are more than the features mentioned in the claims. In fact, the features of the embodiments are less than all the features of the single embodiment disclosed above.

[0201] In some embodiments, numbers describing the number of components and attributes are used. 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 specified, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features 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 setting of such numerical values ​​is as accurate as possible within the feasible range.

[0202] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, etc., cited in this specification are hereby incorporated by reference in their entirety. Except for application history documents that are inconsistent with or conflicting with the contents of this specification, documents that limit the broadest scope of the claims of this specification (currently or later attached to this specification) are also excluded. It should be noted that if the descriptions, definitions, and / or use of terms in the materials attached to this specification are inconsistent or conflicting with the contents described in this specification, the descriptions, definitions, and / or use of terms in this specification shall prevail.

[0203] Finally, it should be understood that the embodiments described in this specification are only used to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, as an example and not a 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 introduced and described 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 . 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. 3 . According to the acoustic device according to claim 1 or 2 , 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°.

4. According to the acoustic device of claim 3, 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°.

5. The acoustic device according to claim 4, 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.

6. According to the acoustic device of claim 5, 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 6 , wherein the target frequency range comprises 4 kHz.

8. According to the acoustic device of claim 5, 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.

9. The acoustic device according to claim 8, wherein the target frequency range comprises 2 kHz-3 kHz.

10. The acoustic device according to claim 4, 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.

11. According to the acoustic device of claim 10, 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.

12. The acoustic device of claim 11, the target frequency range comprising 4 kHz.

13. According to the acoustic device of claim 3, 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°. 14 . The acoustic device according to claim 13 , wherein a side surface of the micro-perforated plate facing the second acoustic cavity is perpendicular to the long axis direction.

15. According to the acoustic device of claim 3, the shell has a long axis direction and a short axis direction which 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°. 16 . The acoustic device according to claim 15 , wherein a side surface of the micro-perforated plate facing the second acoustic cavity is perpendicular to the short axis direction.

17. 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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