Audio equipment

Abstract

An embodiment of the present specification provides an acoustic device, the acoustic device including: a diaphragm; a housing that accommodates the diaphragm and has a first acoustic cavity and a second acoustic cavity formed corresponding to a front side and a rear side of the diaphragm, respectively; the diaphragm radiates sound to the first acoustic cavity and the second acoustic cavity, respectively, and emits sound from a first acoustic hole coupled to the first acoustic cavity and a second acoustic hole coupled to the second acoustic cavity, respectively; and a sound absorbing structure coupled to the second acoustic cavity that absorbs sound that passes through the second acoustic cavity and is transmitted to the second acoustic hole within a target frequency range including a resonant frequency of the second acoustic cavity.

Description

[Technical field]

[0001] The present disclosure relates to the field of audio devices, and more particularly to audio devices.

[0002] [Incorporated by reference] This application claims priority to an international application having application number PCT / CN2022 / 101273, filed on June 24, 2022, and a Chinese application having application number 202211455122.0, filed on November 21, 2022, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] In order to solve the sound leakage problem of an acoustic device, two or more sound sources are usually used to generate two acoustic signals with opposite phases. Under far-field conditions, the difference in acoustic distance to a certain point in the far-field of two sound sources with opposite phases can basically be ignored, so the two acoustic signals can be offset with each other to reduce far-field sound leakage. Although this method can achieve a certain degree of sound leakage reduction effect, it still has certain limitations. For example, the wavelength of high-frequency sound leakage is shorter than , and under far-field conditions, the distance between the two sound sources is not negligible relative to the wavelength, so the sound signals from the two sound sources cannot be offset. In addition, for example, when the acoustic transmission structure of the acoustic device resonates, there is a certain phase difference between the phase of the acoustic signal actually emitted from the sound outlet of the acoustic device and the original phase of the sound wave generation position, and an additional resonance peak is added to the transmitted sound wave, which may cause a disturbance in the sound field distribution, making it difficult to ensure the far-field sound leakage reduction effect at high frequencies, and thus increasing sound leakage. Summary of the Invention [Problem to be solved by the invention]

[0004] It is therefore desirable to provide an acoustic device that has excellent sound field directionality. [Means for solving the problem]

[0005] An acoustic device according to one embodiment of the present specification includes a diaphragm, and a housing that accommodates the diaphragm and has a first acoustic cavity and a second acoustic cavity formed corresponding to a front side and a rear side of the diaphragm, respectively, wherein the diaphragm radiates sound to the first acoustic cavity and the second acoustic cavity, respectively, and emits sound from a first acoustic hole coupled to the first acoustic cavity and a second acoustic hole coupled to the second acoustic cavity, respectively; and a sound absorbing structure that is coupled to the second acoustic cavity and absorbs sound that passes through the second acoustic cavity and is transmitted to the second acoustic hole within a target frequency range including the resonant frequency of the second acoustic cavity.

[0006] In some embodiments, the target frequency range further includes a resonant frequency of the first acoustic cavity.

[0007] In some embodiments, the target frequency range includes 3 kHz to 6 kHz.

[0008] In some embodiments, the sound absorbing effect of the sound absorbing structure for sounds in the target frequency range is 3 dB or greater.

[0009] In some embodiments, the sound absorbing effect of the sound absorbing structure for sound at the resonant frequency is 14 dB or more.

[0010] In some embodiments, the absorbing structure includes a micro-perforated plate and a cavity, the micro-perforated plate includes a through hole, and the second acoustic cavity coupled to the absorbing structure communicates with the cavity via the through hole.

[0011] In some embodiments, the cavity is filled with N'Bass sound absorbing particles.

[0012] In some embodiments, the N'Bass sound absorbing particles have a diameter in the range of 0.15mm to 0.7mm.

[0013] In some embodiments, the filling rate of the N'Bass sound absorbing particles in the cavity is in the range of 70% to 95%.

[0014] In some embodiments, gauze is placed between the N'Bass sound absorbing particles and the micro-perforated plate.

[0015] In some embodiments, the cavity is filled with a porous sound absorbing material, the porous sound absorbing material having a porosity greater than 70%.

[0016] In some embodiments, the ratio of the spacing between the through-holes to the diameter of the through-holes is greater than 5.

[0017] In some embodiments, the ratio of the wavelength of sound in the target frequency range to the hole spacing between the through-holes of the micro-perforated plate is greater than 5.

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

[0019] In some embodiments, the hole diameter of the through hole is in the range of 0.2 mm to 0.4 mm, the aperture ratio of the fine-perforated plate is in the range of 1% to 5%, the thickness of the fine-perforated plate is in the range of 0.2 mm to 0.7 mm, and the height of the cavity is in the range of 4 mm to 9 mm.

[0020] In some embodiments, the microperforated plate comprises a racetrack microperforated plate or a circular microperforated plate.

[0021] In some embodiments, the thickness of the micro-perforated circular plate is in the range of 0.3 mm to 1 mm.

[0022] In some embodiments, the Young's modulus of the micro-perforated plate is in the range of 5 GPa to 200 GPa.

[0023] In some embodiments, the natural frequency of the micro-perforated plate is greater than 500 Hz.

[0024] In some embodiments, the natural frequency of the micro-perforated plate is in the range of 500 Hz to 3.6 kHz.

[0025] In some embodiments, the height of the cavity is in the range of 0.5 mm to 10 mm.

[0026] In some embodiments, the micro-perforated plate comprises a metal micro-perforated plate.

[0027] In some embodiments, a waterproof ventilation structure is provided on the side of the micro-perforated plate facing the vibrating membrane.

[0028] In some embodiments, the acoustic device further includes a magnetic circuit assembly and a coil, the coil connected to the diaphragm and at least a portion of which is located in a magnetic gap formed by the magnetic circuit assembly, the coil vibrating the diaphragm to generate sound when energized, and the micro-perforated plate includes an annular structure centered around the magnetic circuit assembly.

[0029] In some embodiments, the acoustic device further includes a magnetic circuit assembly and a coil, the coil connected to the diaphragm and at least a portion of which is located in a magnetic gap formed by the magnetic circuit assembly, the coil vibrating the diaphragm to generate sound when energized, and the micro-perforated plate and the magnetic circuit assembly are spaced apart in the vibration direction of the diaphragm.

[0030] In some embodiments, the acoustic device further includes a magnetic circuit assembly and a coil, the coil connected to the diaphragm and located at least in a magnetic gap formed by the magnetic circuit assembly, the coil, when energized, vibrates the diaphragm to generate sound, and the micro-perforated plate includes a magnetic permeable element of the magnetic circuit assembly.

[0031] An acoustic device according to one embodiment of the present specification includes a diaphragm, and a housing that accommodates the diaphragm and has a first acoustic cavity and a second acoustic cavity formed corresponding to the front and rear sides of the diaphragm, respectively, wherein the diaphragm radiates sound to the first acoustic cavity and the second acoustic cavity, respectively, and emits sound from a first acoustic hole coupled to the first acoustic cavity and a second acoustic hole coupled to the second acoustic cavity, respectively, and a sound absorbing structure coupled to the second acoustic cavity and absorbing sound that passes through the second acoustic cavity within a target frequency range and is transmitted to the second acoustic hole, wherein within the target frequency range, the sound pressure level of the second acoustic hole when the sound absorbing structure is not installed is greater than the sound pressure level of the second acoustic hole when the sound absorbing structure is installed.

[0032] In some embodiments, the target frequency range includes 3 kHz to 6 kHz.

[0033] In some embodiments, within the target frequency range, the difference between the sound pressure level of the second acoustic hole when the sound absorbing structure is not installed and the sound pressure level of the second acoustic hole when the sound absorbing structure is installed is 3 dB or more.

[0034] In some embodiments, the target frequency range includes a resonant frequency of the second acoustic cavity.

[0035] In some embodiments, at the resonant frequency, the difference between the sound pressure level of the second acoustic hole when the sound absorbing structure is not installed and the sound pressure level of the second acoustic hole when the sound absorbing structure is installed is 14 dB or more.

[0036] In some embodiments, the absorbing structure includes a micro-perforated plate and a cavity, the micro-perforated plate includes a through hole, and the second acoustic cavity coupled to the absorbing structure communicates with the cavity via the through hole.

[0037] In some embodiments, the cavity is filled with N'Bass sound absorbing particles.

[0038] In some embodiments, the N'Bass sound absorbing particles have a diameter in the range of 0.15mm to 0.7mm.

[0039] In some embodiments, the filling rate of the N'Bass sound absorbing particles in the cavity is in the range of 70% to 95%.

[0040] In some embodiments, gauze is placed between the N'Bass sound absorbing particles and the micro-perforated plate.

[0041] In some embodiments, the cavity is filled with a porous sound absorbing material, the porous sound absorbing material having a porosity greater than 70%.

[0042] In some embodiments, the ratio of the spacing between the through-holes to the diameter of the through-holes is greater than 5.

[0043] In some embodiments, the ratio of the wavelength of sound in the target frequency range to the hole spacing between the through-holes of the micro-perforated plate is greater than 5.

[0044] In some embodiments, the hole diameter of the through hole is in the range of 0.1 mm to 0.2 mm, the aperture ratio of the fine-perforated plate is in the range of 2% to 5%, the thickness of the fine-perforated plate is in the range of 0.2 mm to 0.7 mm, and the height of the cavity is in the range of 7 mm to 10 mm.

[0045] In some embodiments, the hole diameter of the through hole is in the range of 0.2 mm to 0.4 mm, the aperture ratio of the fine-perforated plate is in the range of 1% to 5%, the thickness of the fine-perforated plate is in the range of 0.2 mm to 0.7 mm, and the height of the cavity is in the range of 4 mm to 9 mm.

[0046] In some embodiments, the microperforated plate comprises a racetrack microperforated plate or a circular microperforated plate.

[0047] In some embodiments, the thickness of the micro-perforated circular plate is in the range of 0.3 mm to 1 mm.

[0048] In some embodiments, the Young's modulus of the micro-perforated plate is in the range of 5 GPa to 200 GPa.

[0049] In some embodiments, the natural frequency of the micro-perforated plate is greater than 500 Hz.

[0050] In some embodiments, the natural frequency of the micro-perforated plate is in the range of 500 Hz to 3.6 kHz.

[0051] In some embodiments, the height of the cavity is in the range of 0.5 mm to 10 mm.

[0052] In some embodiments, the micro-perforated plate comprises a metal micro-perforated plate.

[0053] In some embodiments, a waterproof ventilation structure is provided on the side of the micro-perforated plate facing the vibrating membrane.

[0054] In some embodiments, the acoustic device further includes a magnetic circuit assembly and a coil, the coil connected to the diaphragm and at least a portion of which is located in a magnetic gap formed by the magnetic circuit assembly, the coil vibrating the diaphragm to generate sound when energized, and the micro-perforated plate includes an annular structure centered around the magnetic circuit assembly.

[0055] In some embodiments, the acoustic device further includes a magnetic circuit assembly and a coil, the coil connected to the diaphragm and at least a portion of which is located in a magnetic gap formed by the magnetic circuit assembly, the coil vibrating the diaphragm to generate sound when energized, and the micro-perforated plate and the magnetic circuit assembly are spaced apart in the vibration direction of the diaphragm.

[0056] In some embodiments, the acoustic device further includes a magnetic circuit assembly and a coil, the coil connected to the diaphragm and located at least in a magnetic gap formed by the magnetic circuit assembly, the coil, when energized, vibrates the diaphragm to generate sound, and the micro-perforated plate includes a magnetic permeable element of the magnetic circuit assembly.

[0057] The present application will be further illustrated by exemplary embodiments, which are not limiting and are illustrated in detail in the drawings, in which like numbers refer to like structures. [Brief description of the drawings]

[0058] [Figure 1] 1 is a schematic diagram of an acoustic device according to some embodiments of the present disclosure. [Figure 2A] 2 is a schematic diagram of a sound field distribution of low and mid-frequency sound pressure levels of the acoustic device shown in FIG. 1. [Figure 2B] 2 is a schematic diagram of a sound field distribution of high-frequency sound pressure levels of the acoustic device shown in FIG. 1. [Diagram 3] FIG. 1 is a block diagram of an audio device in accordance with some embodiments of the present disclosure. [Figure 4] 1A-1C are frequency response curve diagrams of an acoustic device with different sound absorbing structures installed, in accordance with some embodiments of the present disclosure. [Diagram 5] 1A-1C are frequency response curve diagrams of an acoustic device with different sound absorbing structures installed, in accordance with some embodiments of the present disclosure. [Figure 6]FIG. 1 is a schematic diagram of an acoustic device having a sound absorbing structure installed therein, according to some embodiments of the present disclosure. [Figure 7] 1 is a diagram showing the sound absorbing effect when an acoustic device according to some embodiments of the present specification uses a metal micro-perforated plate and a non-metal micro-perforated plate, respectively. [Figure 8] 4A and 4B are frequency response curve diagrams of an acoustic device according to some embodiments of the present specification when using a metallic micro-perforated plate and a non-metallic micro-perforated plate, respectively. [Figure 9] FIG. 11 is a frequency response curve diagram of the second acoustic hole measured when 025HY type gauze is placed on the side of the micro-perforated plate facing the speaker (or diaphragm) and when no gauze is placed, according to some embodiments of the present specification. [Figure 10] FIG. 2 is a curve diagram of sound absorption coefficient of a micro-perforated plate sound absorbing structure having different cavity heights, according to some embodiments of the present disclosure. [Figure 11] FIG. 10 is a comparison diagram of the change trend of the maximum sound absorption coefficient and the change trend of the 0.5 sound absorption octave for different cavity heights according to some embodiments of the present disclosure. [Figure 12] FIG. 13 is a diagram showing the sound absorbing effect of a micro-perforated plate having through-holes with diameters of 0.15 mm and 0.3 mm, respectively, according to some embodiments of the present specification. [Figure 13] FIG. 13 illustrates frequency response curves for a micro-perforated plate with 0.15 mm hole diameter and a micro-perforated plate with 0.3 mm hole diameter, according to some embodiments herein. [Figure 14] FIG. 13 illustrates the sound absorption effect of micro-perforated plates with different cavity heights, when the hole diameter is 0.15 mm, the aperture ratio is 2.18%, and the thickness is 0.3 mm, according to some embodiments of the present specification. [Figure 15] FIG. 10 illustrates the sound absorption effect of micro-perforated panels of different thicknesses when the hole diameter is 0.3 mm, the aperture ratio is 2.18%, and the cavity height is 5 mm according to some embodiments of the present specification. [Figure 16] FIG. 1 is a schematic diagram of an acoustic device having a sound absorbing structure installed therein, according to some embodiments of the present disclosure. [Figure 17] 11A-11C are frequency response curve diagrams of the second acoustic cavity of an acoustic device corresponding to different filling rates of the filling material, in accordance with some embodiments of the present disclosure. [Figure 18] 1A-1C are frequency response curves for several embodiments of the present specification without a micro-perforated plate, with a micro-perforated plate only, with a micro-perforated plate in combination with N'Bass sound absorbing particles, and with a micro-perforated plate in combination with a porous sound absorbing material. [Figure 19] 1 is a diagram showing the internal structure of an audio device according to some embodiments of the present disclosure; [Figure 20] 1 is a diagram showing the internal structure of an audio device according to some embodiments of the present disclosure; [Figure 21] 1 is a diagram showing the internal structure of an audio device according to some embodiments of the present disclosure; [Figure 22] 21. FIG. 22 is a frequency response curve diagram of the acoustic device shown in FIGS. 19 and 20 and the acoustic device shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0059] In order to more clearly describe the technical means of the embodiments of the present application, the drawings necessary for the description of the embodiments will be briefly described below. Obviously, the drawings described below are merely some examples or embodiments of the present application, and those skilled in the art can apply the present application to other similar scenarios based on these drawings without creative efforts. Unless otherwise clear from the language environment or described otherwise, the same numbers in the drawings indicate the same structures or operations.

[0060] It should be understood that the terms "system," "apparatus," "unit," and / or "module" used herein are ways of distinguishing between different levels of assemblies, elements, parts, portions, or constructions, however, other terms may be used in place of the above terms if they accomplish the same purpose.

[0061] As used in this application and the claims, unless the context clearly dictates otherwise, terms such as "a," "one," "one kind," and / or "the" do not specifically refer to the singular but may include the plural. In general, the terms "comprise" and "containing" are intended to indicate only the inclusion of explicitly identified steps and elements, and these steps and elements are not intended to be an exclusive listing, and a method or apparatus may also include other steps or elements.

[0062] In this application, flowcharts are used to describe the operations performed by the system according to the embodiments of this application. It should be understood that the preceding and subsequent operations are not necessarily performed in exact order. Instead, the steps may be processed in reverse order or simultaneously. Also, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0063] FIG. 1 is a schematic diagram of an audio device according to some embodiments of the present disclosure. As shown in FIG. 1, the audio device 100 may include a housing 110 and a speaker 120. The speaker 120 may be installed in a cavity formed by the housing 110, and a first audio cavity 130 and a second audio cavity 140 for emitting sound are installed on both the front and rear sides of the speaker 120, respectively. A first audio hole 111 and a second audio hole 112 are installed in the housing 110, and the first audio cavity 130 may be acoustically coupled to the first audio hole 111, and the second audio cavity 140 may be acoustically coupled to the second audio hole 112. When a user uses the audio device 100, the audio device 100 may be located near the user's auricle, and the first audio hole 111 may face the opening of the user's ear canal, so that the sound emitted from the first audio hole 111 can be transmitted to the user's ear canal. The second acoustic hole 112 may be farther away from the ear canal opening than the first acoustic hole 111, and the distance between the first acoustic hole 111 and the ear canal opening may be smaller than the distance between the second acoustic hole 112 and the ear canal opening.

[0064] In some embodiments, the front and rear sides of the speaker 120 can generate a pair of sound waves (or voices) with equal amplitudes and opposite phases as sound wave generating structures. In some embodiments, the pair of sound waves with equal amplitudes and opposite phases can be radiated to the outside from the first sound hole 111 and the second sound hole 112, respectively. When the speaker 120 outputs sound waves, the sound waves (or called the first sound waves) on the front side of the speaker 120 can pass through the first sound cavity 130 and emanate from the first sound hole 111, and the sound waves (or called the second sound waves) on the rear side of the speaker 120 can pass through the second sound cavity 140 and emanate from the second sound hole 112, thereby forming a dipole sound source including the first sound hole 111 and the second sound hole 112. The dipole sound sources can interfere and cancel each other out at a spatial point (e.g., the far field), thereby effectively improving the sound leakage problem in the far field of the audio device 100.

[0065] Fig. 2A is a schematic diagram of the sound field distribution of the sound pressure level of the mid-low frequency of the acoustic device 100 shown in Fig. 1. As shown in Fig. 2A, the sound field distribution of the acoustic device 100 shows good dipole directivity in the mid-low frequency range (for example, 50Hz to 1kHz), and the sound leakage reduction effect of the dipole sound source is remarkable. That is, in the mid-low frequency range, the dipole sound source formed by the first acoustic hole 111 and the second acoustic hole 112 of the acoustic device 100 outputs sound waves that are in opposite phase or almost in opposite phase, and according to the principle of the antiphase cancellation of sound waves, the above two sound waves are cancelled out in the far field, thereby achieving the far field sound leakage reduction effect.

[0066] Fig. 2B is a schematic diagram of a sound field distribution of high frequency sound pressure levels of the acoustic device 100 shown in Fig. 1. As shown in Fig. 2B, within the high frequency range, the sound field distribution of the acoustic device 100 is disturbed.

[0067] In some embodiments, in the high frequency range (e.g., 1500 Hz to 20 kHz), the wavelengths of the first and second sound waves are shorter than those in the mid-low frequency range. In this case, the distance between the dipole sound source formed by the first acoustic hole 111 and the second acoustic hole 112 cannot be ignored in relation to the wavelength, so the sound waves emitted from the two sound sources cannot be offset, making it difficult to ensure the effect of reducing far-field sound leakage of the acoustic device in the high frequency range, which may even increase sound leakage and cause a disturbance in the sound field distribution of the acoustic device. As merely an illustrative explanation, due to the distance between the first acoustic hole 111 and the second acoustic hole 112, the acoustic distance of the first sound wave to a particular spatial point (e.g., the far field) is different from the acoustic distance of the second sound wave to the particular spatial point, so that the phase difference between the first sound wave and the second sound wave at the spatial point is small (e.g., the phase is the same or close), and the first sound wave and the second sound wave cannot interfere and cancel each other out at the spatial point, but overlap at the spatial point, increasing the amplitude of the sound waves at the spatial point and potentially increasing sound leakage.

[0068] In some embodiments, sound waves emanating from both the front and rear sides of the speaker 120 may pass through an acoustic transmission structure and then be radiated to the outside from the first acoustic hole 111 and / or the second acoustic hole 112. The acoustic transmission structure may refer to an acoustic path through which sound waves pass when radiating from the speaker 120 to the outside environment. In some embodiments, the acoustic transmission structure may include a housing 110 between the speaker 120 and the first acoustic hole 111 and / or the second acoustic hole 112. In some embodiments, the acoustic transmission structure may include an acoustic cavity. The acoustic cavity may be an amplitude space reserved for a diaphragm (not shown) of the speaker 120, and for example, the acoustic cavity may include a cavity formed between the diaphragm of the speaker 120 and the housing 110. Also, for example, the acoustic cavity may further include a cavity formed between the diaphragm of the speaker 120 and a driving system (e.g., a magnetic circuit assembly). In some embodiments, the acoustic transmission structure may be in acoustic communication with the first acoustic hole 111 and / or the second acoustic hole 112, and the first acoustic hole 111 and / or the second acoustic hole 112 may be part of the acoustic transmission structure. In some embodiments, when the speaker 120 is far from the ear canal opening, or when the radiation direction of the sound waves generated by the speaker 120 is not in the desired direction, or away from the ear canal opening, the sound waves may be guided to the desired location by a sound conduit and then radiated to the external environment using the first acoustic hole 111 and / or the second acoustic hole 112. Thus, the acoustic transmission structure may further include a sound conduit.

[0069] In some embodiments, the acoustic transmission structure may have a resonant frequency, and when the frequency of the sound waves generated by the speaker 120 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 may also resonate, and the resonance may change the frequency components of the transmitted sound waves (e.g., add additional resonant peaks to the transmitted sound waves) or change the phase of the sound waves transmitted in the acoustic transmission structure. Compared with the case where there is no resonance, the phase and / or amplitude of the sound waves radiated from the first acoustic hole 111 and / or the second acoustic hole 112 may change, and the change in the phase and / or amplitude may cause a disturbance in the sound field near the resonant frequency of the dipole structure, and affect the interference cancellation effect at the spatial point of the sound waves radiated from the first acoustic hole 111 and the second acoustic hole 112. For example, when resonance occurs, the phase difference between the sound waves emitted from the first acoustic hole 111 and the second acoustic hole 112 changes. For example, when the phase difference between the sound waves emitted from the first acoustic hole 111 and the second acoustic hole 112 is small (e.g., less than 120°, less than 90°, or 0), the interference cancellation effect at the spatial point of the sound waves decreases, making it difficult to achieve the sound leakage reduction effect. Alternatively, sound waves with small phase differences may overlap at the spatial point, increasing the amplitude of sound waves near the resonance frequency at the spatial point (e.g., in the far field), which may increase the far-field sound leakage of the acoustic device 100. In addition, for example, the above-mentioned resonance may increase the amplitude of the transmitted sound wave near the resonance frequency of the acoustic transmission structure (for example, expressed as a resonance peak near the resonance frequency), causing a disturbance of the sound field near the resonance frequency of the dipole structure, and at this time, the difference in amplitude of the sound wave emitted from the first acoustic hole 111 and the second acoustic hole 112 is large, the interference cancellation effect at the spatial point of the sound wave is reduced, and it is difficult to achieve the effect of reducing sound leakage. In some embodiments, when parameters such as the volume of the first acoustic cavity 130 and the second acoustic cavity 140 of the acoustic device, the size and height of the first acoustic hole 111 and the second acoustic hole 112 are different, the resonance frequency of the first acoustic cavity and the second acoustic cavity (which may be abbreviated as acoustic cavity) may be different, that is, the resonance frequency of the acoustic transmission structure on both the front and rear sides of the acoustic device may be different.In some embodiments, the blocking of high frequency sound waves by structures such as the pinna 210 and / or their effect on the reflection of sound waves may cause perturbations in the sound field distribution of the acoustic device 100.

[0070] Since the first acoustic hole 111 faces the opening of the ear canal of the user and the second acoustic hole 112 is farther away from the opening of the ear canal than the first acoustic hole 111, the sound waves radiated from the second acoustic hole 112 account for the majority of the sound waves radiated from the acoustic device to the outside, that is, the sound waves radiated from the second acoustic hole 112 of the acoustic device 100 to the outside play a dominant role in the disturbed sound field distribution. Therefore, by adjusting the structure of the acoustic device 100, the output within the target frequency range of the second acoustic cavity (e.g., including the resonant frequency and high frequency range of the acoustic transmission structure) can be reduced without affecting the low frequency output of the second acoustic cavity, thereby achieving the effect of reducing sound leakage in the far field.

[0071] 3 is a block diagram of an acoustic device according to some embodiments of the present disclosure. In some embodiments, as shown in FIG. 3, an acoustic device 300 may include a housing 310, a diaphragm 321, and a sound absorbing structure 330.

[0072] The housing 310 may be a regular or irregular three-dimensional structure having an internal receiving cavity, for example, the housing 310 may be a hollow frame structure, including, but not limited to, any regular shape such as a rectangular frame, a circular frame, a regular polygon frame, and any irregular shape such as a racetrack shape. The housing 310 may house the speaker and the sound absorbing structure 330. In some embodiments, the housing 310 may be made of metal (e.g., stainless steel, copper, etc.), plastic (e.g., polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and acrylonitrile-butadiene-styrene copolymer (ABS)), composite (e.g., metal composite or non-metal composite), epoxy resin, phenolic, ceramic, polyimide, fiberglass (e.g., FR4-fiberglass), etc., or any combination thereof. The housing 310 may be provided with a first acoustic hole 111 and a second acoustic hole 112 for outputting sound waves, and the speaker 120 outputs sound waves having a phase difference from the first acoustic hole 111 and the second acoustic hole 112.

[0073] A speaker is an element that can receive an electric signal, convert it into an audio signal, and output it. In some embodiments, when distinguished according to frequency, the types of speakers may include low-frequency (e.g., 30Hz-150Hz) speakers, mid-low-frequency (e.g., 150Hz-500Hz) speakers, mid-high-frequency (e.g., 500Hz-5kHz) speakers, high-frequency (e.g., 5kHz-16kHz) speakers, or wideband (e.g., 30Hz-16kHz) speakers, or any combination thereof. Here, low frequency, high frequency, etc., represent only an approximate range of frequencies, and may have different distinction methods in different application scenarios. For example, one crossover frequency is determined, and low frequency represents a frequency range below the crossover frequency, and high frequency represents a frequency range above the crossover frequency. The crossover frequency may be any value within the audible range of the human ear, such as 500Hz, 600Hz, 700Hz, 800Hz, 1000Hz, etc.

[0074] In some embodiments, the speaker may include a vibrating membrane 321, and the speaker including the vibrating membrane 321 divides the receiving cavity of the housing 310 to form a first acoustic cavity and a second acoustic cavity. The vibrating membrane 321 may be a thin film structure having elasticity. In some embodiments, the material of the vibrating membrane 321 may include, but is not limited to, one or more of polyimide (PI), polyethylene terephthalate (PET), polyethyleneimine (PEI), polyetheretherketone (PEEK), silica gel, polycarbonate (PC), vinyl polymer (PVC), acrylonitrile-butadiene-styrene copolymer (ABS), polyethylene (PE), and parylene (PPX), and may be a multi-layer composite material made by combining the above materials. In some embodiments, the first acoustic cavity may be acoustically coupled to the first acoustic hole, and the second acoustic cavity may be acoustically coupled to the second acoustic hole. When the diaphragm 321 vibrates, sound waves may be emitted to the front and rear sides of the diaphragm 321, and the front side of the diaphragm 321 may be the side away from the driving system (e.g., magnetic circuit assembly) of the diaphragm 321, and the rear side of the diaphragm 321 may be the side toward the driving system (e.g., magnetic circuit assembly) of the diaphragm 321. The sound waves on the front side of the diaphragm 321 may pass through a first acoustic cavity and be emitted from a first acoustic hole, and the sound waves on the rear side of the diaphragm 321 may pass through a second acoustic cavity and be emitted from a second acoustic hole. When the diaphragm 321 vibrates, a pair of sound waves with a phase difference can be generated simultaneously on the front and rear sides of the diaphragm 321.

[0075] In some embodiments, a pair of sound waves with a phase difference are generated simultaneously at the front and rear sides of the vibrating membrane 321, passing through the first acoustic cavity to emit from the first acoustic hole, and passing through the second acoustic cavity to emit from the second acoustic hole. The two sound waves are superimposed and offset at a specific spatial point (e.g., the far field) outside the acoustic device, so that the far field sound leakage of the acoustic device can be reduced. The first acoustic hole 111 and the second acoustic hole 112 outputting the sound waves in this way form a dipole sound source. If the position, phase difference, etc. between the dipole sound sources meet certain conditions, the acoustic device can show different sound effects in the near field and the far field. For example, if the phases of the point sound sources corresponding to the two acoustic holes are opposite and the amplitudes are the same or nearly the same, i.e., if the absolute value of the phase difference between the two point sound sources is 180° or close to 180°, the reduction of the far field sound leakage can be realized by the principle of anti-phase offset of sound waves. Also, for example, when the phases of the point sound sources corresponding to the two acoustic holes are almost opposite, the reduction of the far-field sound leakage can be realized. As a mere example, the absolute value of the phase difference of the two point sound sources that realizes the reduction of the far-field sound leakage may be in the range of 120° to 240°.

[0076] Based on the description of Figures 1 to 2B, the dipole may disturb the sound field in the high frequency range, have a low sound leakage reduction effect, and may even increase sound leakage in some cases. In order to improve the sound leakage reduction effect in the high frequency range of the acoustic device, a sound absorbing structure 330 may be installed in the second acoustic cavity of the acoustic device, and the sound absorbing structure 330 can absorb sound waves in the target frequency range of the second acoustic cavity to reduce or avoid the first sound wave and the second sound wave from overlapping at a specific space point (e.g., far field) outside the acoustic device, reduce the amplitude of the sound wave in the target frequency range at the space point, adjust the directivity of the acoustic output device, and achieve the far field sound leakage reduction effect.

[0077] The sound absorbing structure 330 is a structure that has an absorbing effect on sound waves within a specific frequency band (e.g., within a target frequency range). The sound absorbing structure 330 is coupled to the second acoustic cavity and can absorb sound that passes through the second acoustic cavity within the target frequency range and is radiated to the second acoustic hole. Accordingly, within the target frequency range, the sound pressure level of the second acoustic hole when the sound absorbing structure 330 is not installed may be greater than the sound pressure level of the second acoustic hole when the sound absorbing structure 330 is installed.

[0078] In some embodiments, the target frequency range may include a frequency range near the resonance frequency of the second acoustic cavity. The sound absorbing structure 330 absorbs sound waves near the resonance frequency of the second acoustic cavity to avoid changes in the phase and / or amplitude of the second sound wave due to resonance near the resonance frequency of the second acoustic cavity, reduce the amplitude of the sound wave near the resonance frequency, and reduce sound leakage. In some embodiments, the resonance frequency may be in a medium-high frequency band, for example, 2 kHz to 8 kHz. Accordingly, the target frequency range may include frequencies in the medium-high frequency band. For example, the target frequency range may be 1 kHz to 10 kHz. In some embodiments, since the distance between the dipole sound source formed by the first acoustic hole and the second acoustic hole cannot be negligible with respect to the wavelength in the high frequency range, the first sound wave and the second sound wave cannot interfere and cancel each other out at the spatial point, but may overlap at the spatial point, increasing the amplitude of the sound wave at the spatial point. In some embodiments, the target frequency range may further include a frequency higher than the resonant frequency to reduce the overlap of the first and second sound waves in the high frequency range, thereby increasing the amplitude of the sound waves. In this way, the sound absorbing structure can absorb sound waves in the high frequency range to reduce or avoid the overlap of the first and second sound waves at a spatial point, and reduce the amplitude of the sound waves in the target frequency range at the spatial point. For example, the target frequency range may be 1 kHz to 20 kHz. The resonant frequency of the second acoustic cavity may be obtained by various measurement methods. As an example, when measuring a frequency response curve of a second acoustic cavity in which the sound absorbing structure 330 is not installed or is removed, the first acoustic hole is left open, and a microphone device is used to measure the frequency response curve at the position of the second acoustic hole (for example, the microphone device is placed 2 mm to 5 mm in front of the second acoustic hole), and a resonant frequency corresponding to a resonant peak of the frequency response curve is obtained. For a specific method of measuring the frequency response curve of the second acoustic cavity in which the sound absorbing structure 330 is not installed or removed, please refer to FIG. 18 and the description thereof.

[0079] In some embodiments, the acoustic device may have different sound effects at different spatial points by installing a sound absorbing structure (e.g., the position of the sound absorbing structure, the sound absorbing frequency, etc.). In some embodiments, the target frequency range may include the resonance frequency of the first acoustic cavity to avoid the resonance of the first acoustic cavity increasing additional resonance peaks in the sound waves transmitted in the second acoustic cavity because the resonance of the first acoustic cavity also affects the sound radiation of the second acoustic cavity, resulting in an extra resonance peak in the frequency response curve measured at the position of the second acoustic hole. In some embodiments, another sound absorbing structure 330 is installed in the first acoustic cavity to absorb sound waves near the resonance frequency of the first acoustic cavity, to avoid the sound waves near the resonance frequency of the first acoustic cavity and the sound waves in the same frequency range output from the second acoustic hole from interfering and being reinforced at spatial points (e.g., in the far field), thereby reducing the amplitude of the sound waves near the resonance frequency of the first acoustic cavity received at the spatial point. In some embodiments, the sound absorbing structure may be installed in both the first and second acoustic cavities, so as to absorb the sound waves near the resonant frequency of the first and second sound waves, and to better reduce the amplitude of the sound waves at any spatial point. In some embodiments, the sound absorbing structure may also absorb low-frequency sounds in a specific frequency range. For example, the sound absorbing structure may be installed in the second acoustic cavity to reduce low-frequency sounds in a specific frequency range output from the second acoustic hole, and prevent the low-frequency sounds in the specific frequency range and the low-frequency sounds in the same frequency range output from the first acoustic hole from interfering and canceling each other at a spatial point (e.g., near field), thereby increasing the volume of the sound device in the specific frequency range in the near field (i.e., transmitted to the user's ear). In some embodiments, the sound absorbing structure may further include sub-sound absorbing structures that respectively absorb sounds in different frequency ranges, for example, mid-high frequency bands and low frequency bands, in order to absorb sounds in different frequency ranges.

[0080] In some embodiments, in the high frequency range higher than the resonant frequency of the second acoustic cavity, the wavelength of the high frequency sound wave is short, so the distance between the two acoustic holes (e.g., the distance between the geometric centers of the two acoustic holes) may affect the phase difference at the spatial point of the sound wave emitted from the two acoustic holes, thereby reducing the sound leakage reduction effect in the high frequency range of the dipole sound source formed by the two acoustic holes. Thus, in order to reduce the high frequency output of the second acoustic cavity, the target frequency range may include a high frequency range higher than the resonant frequency of the second acoustic cavity, so that the sound absorbing structure 330 can absorb the high frequency sound wave to improve the problem that the sound leakage reduction effect in the high frequency range of the dipole sound source is not ideal.

[0081] Since the human ear is sensitive to sounds of 3 kHz to 6 kHz within the high frequency range around the resonant frequency, in some embodiments, the target frequency range may include a frequency range of 3 kHz to 6 kHz in order to achieve more directional and effective sound leakage reduction. In some embodiments, the target frequency range may include 4 kHz to 6 kHz. In some embodiments, the target frequency range may include 5 kHz to 6 kHz. Note that the resonant frequency here is mainly the resonant frequency of the second acoustic cavity, and in some embodiments, it may be the resonant frequency of the second acoustic cavity or the resonant frequency of the first acoustic cavity, hereinafter abbreviated as resonant frequency.

[0082] Based on the above embodiment, the sound absorbing structure can absorb the first and / or second sound waves in the target frequency range, thereby reducing the amplitude of the sound waves in the target frequency range at the spatial point. For the first and second sound waves outside the target frequency range (e.g., sound waves lower than the resonant frequency), the first and second sound waves can pass through the acoustic transmission structure and be transmitted to the spatial point to interfere with each other, and the interference can reduce the amplitude of the sound waves outside the target frequency range at the spatial point. That is, the first and second sound waves outside the target frequency range (or called the first frequency range) can interfere and cancel out at a spatial point to achieve the effect of reducing sound leakage of a dipole sound source, and the first and / or second sound waves within the target frequency range (or called the second frequency range) can be absorbed by the sound absorbing structure, thereby reducing or avoiding the first and / or second sound waves from interfering and being reinforced at the spatial point, or lowering or absorbing additional resonant peaks generated by the first or second sound waves under the action of the acoustic transmission structure to reduce the amplitude of the sound waves within the target frequency range at the spatial point. As a result, in the embodiments of the present specification, by installing a sound-absorbing structure, the acoustic device can output first and second sound waves in a first frequency range, and the output of sound waves near the resonant frequency of the acoustic transmission structure of the acoustic device (e.g., the second acoustic hole) or sound waves with a frequency higher than the resonant frequency can be reduced, ensuring interference cancellation in the first frequency range of the acoustic device, and reducing or avoiding the increase in the amplitude of sound waves in the second frequency range at a spatial point (e.g., the far field), thereby adjusting the directivity of the acoustic device and ensuring the effect of reducing sound leakage in the wideband band.

[0083] The sound absorbing effect of the sound absorbing structure 330 is the amount of sound that the sound absorbing structure 330 can absorb in a target frequency range, and can be expressed as the sound pressure level of the sound. For example, the sound absorbing effect of the sound absorbing structure 330 can be expressed as 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 330. By way of example only, the difference between the sound pressure levels of the second acoustic cavity in the presence and absence of the sound absorbing structure 330 can be expressed as the difference between the sound pressure levels of the second acoustic cavity in the presence and absence of the sound absorbing structure 330. As a mere example, the sound pressure level of the second acoustic hole in the absence of the sound absorbing structure 330 when the sound absorbing structure 330 is present can be measured by facing the second acoustic hole with a measuring microphone about 2 mm to 5 mm away from the second acoustic hole, and measuring the sound pressure level of the second acoustic hole in the absence of the sound absorbing structure 330 when the sound absorbing structure 330 is present. The measurement frequency is near the resonant frequency of the second acoustic cavity or near 1 kHz. In some embodiments, the difference between the sound pressure levels measured at the same frequency at the same position in the second acoustic cavity in the presence and absence of the sound absorbing structure 330 may be 3 dB or more. For example, the difference between the sound pressure levels of the second acoustic hole measured at the same frequency in the presence and absence of the sound absorbing structure 330 is 3 dB or more. In some embodiments, the target frequency range may be referred to as the sound absorption bandwidth of the sound absorbing structure 330. When the sound absorption bandwidth range is 3kHz to 6kHz, the sound absorbing structure 330 can effectively absorb sound waves in the range of 3kHz to 6kHz, and the sound absorption effect is 3dB or more, thereby improving the sound leakage of the acoustic device in the range of 3kHz to 6kHz. In some embodiments, the sound absorption effect of the sound absorbing structure 330 may be 5dB or more within the target frequency range to further reduce the sound leakage of the acoustic device. In some embodiments, the sound absorption effect of the sound absorbing structure 330 may be 6dB or more within the target frequency range to further reduce the sound leakage of the acoustic device. In some embodiments, the sound absorption effect of the sound absorbing structure 330 may be 8dB or more within the target frequency range to further reduce the sound leakage of the acoustic device.In some embodiments, the sound absorbing effect of the sound absorbing structure 330 may be 10 dB or more in the target frequency range to further reduce sound leakage of the acoustic device. In some embodiments, the sound absorbing effect of the sound absorbing structure 330 may be different in different frequency ranges. For example, in the range of 3 kHz to 6 kHz, the sound absorbing effect of the sound absorbing structure 330 is 3 dB or more. In addition, in the range of 4 kHz to 6 kHz, the sound absorbing effect of the sound absorbing structure 330 is 6 dB or more. Furthermore, in the range of 5 kHz to 6 kHz, the sound absorbing effect of the sound absorbing structure 330 is 8 dB or more, so that sound leakage can be more effectively reduced in higher frequency ranges.

[0084] The frequency response curve of the second acoustic cavity has a resonance peak at a certain frequency (e.g., a resonant frequency), and the vibration amplitude at the resonant frequency is large, so that the sound absorbing structure 330 needs to absorb more sounds at the resonant frequency to achieve a high sound leakage reduction effect at the resonant frequency of the second acoustic cavity. Therefore, in some embodiments, the sound absorbing effect of the sound absorbing structure 330 on the sound at the resonant frequency or the sound whose vibration frequency is near the resonant frequency is 14 dB or more. In this way, the sound waves at or near the resonant frequency of the second acoustic cavity can be effectively absorbed by the sound absorbing structure 330, and the sound waves can be reduced or avoided from resonating near the resonant frequency under the action of the acoustic cavity, so that the change in the amplitude difference and phase difference (e.g., the phase difference is not equal to 180 degrees) between the first sound wave and the second sound wave near the resonant frequency reduces the sound leakage reduction effect at the spatial point, thus reducing or avoiding the situation where the two sets of sounds not only do not cancel each other out, but also interfere and reinforce each other, thereby reducing the sound leakage at the spatial point in the far field of the acoustic device. In some embodiments, to further reduce sound leakage from the acoustic device, the sound absorbing structure 330 has a sound absorbing effect of 16 dB or more for sounds with a resonant frequency or vibration frequency near the resonant frequency. In some embodiments, to further reduce sound leakage from the acoustic device, the sound absorbing structure 330 has a sound absorbing effect of 18 dB or more for sounds with a resonant frequency or vibration frequency near the resonant frequency. In some embodiments, to further reduce sound leakage from the acoustic device, the sound absorbing structure 330 has a sound absorbing effect of 20 dB or more for sounds with a resonant frequency or vibration frequency near the resonant frequency. In some embodiments, to further reduce sound leakage from the acoustic device, the sound absorbing structure 330 has a sound absorbing effect of 22 dB or more for sounds with a resonant frequency or vibration frequency near the resonant frequency. In some embodiments, to further reduce sound leakage from the acoustic device, the sound absorbing structure 330 has a sound absorbing effect of 25 dB or more for sounds with a resonant frequency or vibration frequency near the resonant frequency.

[0085] In some embodiments, the sound absorbing structure 330 may include at least one of an absorptive sound absorbing structure or a reactive sound absorbing structure. For example, the function of the sound absorbing structure 330 can be realized by an absorptive sound absorbing structure. Also, for example, the function of the sound absorbing structure 330 can be realized by a reactive sound absorbing structure. Furthermore, for example, the function of the sound absorbing structure 330 can be realized by a sound absorbing structure that is a combination of an absorptive sound absorbing structure and a reactive sound absorbing structure.

[0086] An absorptive sound absorbing structure may refer to a structure that can provide acoustic resistance when sound waves pass through it. In some embodiments, the absorptive sound absorbing structure may include at least one of a porous sound absorbing material or an acoustic gauze. In some embodiments, the absorptive sound absorbing structure may be placed at any position of the first sound wave transmission path and / or the second sound wave transmission path. For example, the porous sound absorbing material or the acoustic gauze may be attached to an inner wall of the sound transmission structure. Also, for example, the porous sound absorbing material or the acoustic gauze may constitute at least a part of the inner wall of the sound transmission structure. Furthermore, for example, the porous sound absorbing material or the acoustic gauze may fill at least a part of the inside of the sound transmission structure. A reactive sound absorbing structure may refer to a structure that absorbs sound using a resonance effect. In some embodiments, the reactive 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 thin film, a quarter-wave resonator tube, or the like, or any combination thereof. In some embodiments, both the absorptive and reactive sound absorbing structures can be installed as the absorptive reactive composite sound absorbing structure to achieve the function of the sound absorbing structure 330. For example, the absorptive reactive composite sound absorbing structure may include a perforated plate sound absorbing structure and a porous sound absorbing material or acoustic gauze, and the porous sound absorbing material or acoustic gauze may be installed in the cavity of the perforated plate sound absorbing structure or may be installed inside the sound transmission structure. Also, for example, the absorptive reactive composite sound absorbing structure may include a quarter-wave resonator tube structure and a porous sound absorbing material or acoustic gauze, and the quarter-wave resonator tube structure may be installed inside or outside the sound transmission structure, and the porous sound absorbing material or acoustic gauze may be installed inside the sound transmission structure. Furthermore, for example, the absorptive reactive composite sound absorbing structure may include a perforated plate sound absorbing structure, a quarter-wave resonator tube structure and a porous sound absorbing material or acoustic gauze.

[0087] FIG. 4 is a frequency response curve diagram of an acoustic device with different sound absorbing structures according to some embodiments of the present disclosure. Curve 411 and curve 421 respectively show the frequency response curves of a first acoustic cavity (e.g., first acoustic cavity 130 shown in FIG. 1) and a second acoustic cavity (e.g., second acoustic cavity 140 shown in FIG. 1) when no sound absorbing structure is installed in the acoustic device. Curve 412 and curve 422 respectively show the frequency response curves of the first acoustic cavity and the second acoustic cavity when a quarter-wave resonator tube is installed in the second acoustic cavity of the acoustic device. Curve 413 and curve 423 respectively show the frequency response curves of the first acoustic cavity and the second acoustic cavity when a micro-perforated plate sound absorbing structure is installed in the second acoustic cavity of the acoustic device. As shown in FIG. 4, the frequency response of the first acoustic cavity of the acoustic device with the sound absorbing structure does not change much compared to the acoustic device without the sound absorbing structure. The frequency response of the second acoustic cavity does not change much in the low frequency range (e.g., less than 2 kHz), but can form a dip in the high frequency range (e.g., greater than 2 kHz). That is, the sound absorbing structure can reduce the amplitude of the high frequency sound waves output from the second acoustic cavity to reduce sound leakage at high frequencies. In addition, compared to the case of using a quarter-wave resonator tube, the acoustic device using the fine perforated plate sound absorbing structure has a higher effect of reducing sound leakage at high frequencies.

[0088] In some embodiments, the sound transmission structure (e.g., housing) of the acoustic device may include a perforated plate sound absorbing structure and an absorptive sound absorbing structure. The absorptive sound absorbing structure may include a porous sound absorbing material and / or an acoustic gauze. In some embodiments, the absorptive sound absorbing structure may be installed around the opening of one or more holes of the perforated plate sound absorbing structure. In some embodiments, the installation of the absorptive reactive composite sound absorbing structure not only can absorb sound by the resonance of the reactive sound absorbing structure, but also can increase the frictional wear of sound waves by the absorptive sound absorbing structure, further widen the sound absorption bandwidth, and further improve the sound leakage reduction effect within the target frequency range of the acoustic device. In some embodiments, the absorptive sound absorbing structure may be attached to the inner wall of the cavity of the perforated plate sound absorbing structure. In some embodiments, the absorptive sound absorbing structure may fill at least a portion of the cavity. In some embodiments, the absorptive sound absorbing structure may be installed inside the housing or may be a part of the housing.

[0089] FIG. 5 is a frequency response curve diagram of an acoustic device with different sound absorbing structures according to some embodiments of the present disclosure. As shown in FIG. 5, the curve L 5-1 shows the frequency response curve of the second acoustic cavity of an acoustic device without a sound absorbing structure, and curve L 5-2 shows the frequency response curve of the second acoustic cavity of the acoustic device in which the micro-perforated plate sound absorbing structure is installed, and the curve L 5-3 FIG. 1 shows the frequency response curve of the second acoustic cavity of the acoustic device in which the micro-perforated plate sound absorbing structure and the acoustic gauze are installed, and the curve L 5-4 Figure 5 shows the frequency response curves of the second acoustic cavity of the acoustic device with the micro-perforated plate sound absorbing structure, acoustic gauze and N'Bass material installed. As can be seen from Figure 5, within the low frequency range (e.g., 1kHz-2kHz), the overlapping degree of the four curves is high, which indicates that the low frequency output of the acoustic device with the four structures is almost the same. However, within the mid-high frequency range (e.g., above 2kHz), the L 5-1 When sound-absorbing structures are installed, the L 5-2 , L 5-3 and L 5-4In other words, the sound absorbing structure can reduce the high frequency output of the second acoustic cavity of the acoustic device, thereby improving the effect of reducing sound leakage at high frequencies. Within a large range (e.g., 2kHz to 5kHz), the L 5-4 is basically located below the other three curves and has the best sound leakage reduction effect. Therefore, by installing a sound absorbing structure (such as an absorbing reactive composite sound absorbing structure), the high frequency output of the second acoustic cavity of the acoustic device can be reduced, so as to suppress the sound field disturbance in the high frequency range of the acoustic device, and the sound leakage reduction effect at high frequencies can be improved.

[0090] By setting the sound absorbing structure 330 to be coupled to the second acoustic cavity, the sound waves in the target frequency range are absorbed by the sound absorbing structure 330, and the sound waves can be reduced or avoided from resonating around a certain frequency (e.g., resonant frequency) under the action of the acoustic cavity, so that the change in amplitude difference and phase difference (e.g., the phase difference is not equal to 180 degrees) between the first sound wave and the second sound wave around the certain frequency of the cavity reduces the sound leakage reduction effect at the space point, and thus reduces or avoids the situation where the two sets of sounds not only do not cancel each other, but also interfere and reinforce, thereby reducing the sound leakage in the target frequency range. The target frequency range may include a high frequency range, and the first sound wave and the second sound wave outside the target frequency range can realize the cancellation of dipoles to reduce the sound leakage at the space point.

[0091] FIG. 6 is a schematic diagram of an acoustic device having a sound absorbing structure according to some embodiments of the present disclosure.

[0092] 6, in some embodiments, an acoustic device 600 may include a housing 610 and a speaker 620. The speaker 620 is installed in a receiving cavity defined by the housing 610, and a first acoustic cavity 630 and a second acoustic cavity 640 are installed on both the front and rear sides of the speaker 620 (or a diaphragm), respectively. A first acoustic hole 611 and a second acoustic hole 612 are installed in the housing 610, and the first acoustic cavity 630 may be acoustically coupled to the first acoustic hole 611, and the second acoustic cavity 640 may be acoustically coupled to the second acoustic hole 612.

[0093] In some embodiments, as shown in FIG. 6, the acoustic device 600 may further include an absorbing structure 650, which may be coupled to the second acoustic cavity 640. In some embodiments, the absorbing structure 650 may include a micro-perforated plate absorbing structure. The micro-perforated plate absorbing structure includes a micro-perforated plate 651 and a cavity 652, the micro-perforated plate 651 includes a through hole, and the second acoustic cavity 640 coupled to the micro-perforated plate structure communicates with the cavity 652 through the through hole of the micro-perforated plate. It should be noted that the acoustic device 600 shown in FIG. 6 is merely an illustrative example, and various changes or modifications may be made to the specific installation manner of the absorbing structure 650.

[0094] The sound waves in the second acoustic cavity 640 can enter the cavity 652 of the micro-perforated sound absorbing structure through one or more through holes, and can cause the micro-perforated sound absorbing structure to resonate under certain conditions, for example, when the vibration frequency of the sound waves entering the cavity 652 is near the resonant frequency of the micro-perforated sound absorbing structure, the sound waves entering the cavity 652 will cause the micro-perforated sound absorbing structure to resonate. The air in the cavity 652 resonates with the micro-perforated sound absorbing structure to consume energy and achieve the sound absorbing effect, and the frequency of the sound waves absorbed by the micro-perforated sound absorbing structure is the same as or close to its resonant frequency.

[0095] In some embodiments, the material of the micro-perforated plate 651 may be metal (e.g., aluminum) or non-metal (e.g., acrylic, polycarbonate (PC), etc.). If the micro-perforated plate 651 is a non-metal plate, the thermal conductivity of the non-metal plate is small, and the process of the sound wave passing through the through-holes can be regarded as an adiabatic process. If the micro-perforated plate 651 is a metal plate, the thermal conductivity of the metal plate is large, and the hole diameter of the through-holes is small, and the process of the sound wave passing through the through-holes can be regarded as an isothermal process. Because the conduction of heat means an increase in energy consumption, the metal plate has a higher equivalent attenuation than the non-metal plate.

[0096] Fig. 7 is a diagram showing the sound absorption effect when the acoustic device according to some embodiments of the present specification uses a metal micro-perforated plate and a non-metal micro-perforated plate, respectively. In Fig. 7, the horizontal axis indicates the sound absorption frequency, the vertical axis indicates the sound absorption coefficient, curve 71 indicates the sound absorption effect of the non-metal micro-perforated plate, and curve 72 indicates the sound absorption effect of the metal micro-perforated plate. As shown in Fig. 7, the maximum sound absorption coefficient of the metal micro-perforated plate is slightly lower than that of the non-metal micro-perforated plate, but the sound absorption bandwidth of the metal micro-perforated plate is wider than that of the non-metal micro-perforated plate, which is because the thermal conductivity of the metal micro-perforated plate is better and the equivalent attenuation of the sound wave passing through is larger than that of the non-metal micro-perforated plate.

[0097] FIG. 8 is a frequency response curve diagram of an acoustic device according to some embodiments of the present specification when a metal micro-perforated plate and a non-metal micro-perforated plate are used. In FIG. 8, the horizontal axis indicates frequency, the vertical axis indicates sound pressure level, curve 81 indicates the frequency response when a metal micro-perforated plate is used, and curve 82 indicates the frequency response when a non-metal micro-perforated plate is used, where the frequency response is the frequency response of the second acoustic hole (for example, a point 10 mm away from the second acoustic hole). As shown in FIG. 8, the metal micro-perforated plate has a higher sound absorption effect than the non-metal micro-perforated plate in the mid-low frequency band (for example, less than 4 kHz), and the sound leakage of the acoustic device is reduced by about 2 to 3 dB. In this case, the metal micro-perforated plate is an aluminum plate, and the sound absorption effect of the non-metal micro-perforated plate is slightly reduced, but the weight of the acoustic device can be reduced by using the non-metal micro-perforated plate, which helps to improve the lightness of the acoustic device and reduce the cost of the acoustic device. In some embodiments, since metal plates and non-metal plates have their own advantages, one can flexibly choose a metal micro-perforated plate or a non-metal micro-perforated plate according to weight, cost, corrosion resistance, etc.

[0098] If the natural frequency of the micro-perforated plate 651 attached to the acoustic device (or called the fixed state) is within the target frequency range, the micro-perforated plate 651 may resonate within the target frequency range and affect the sound absorption effect. Therefore, the natural frequency of the micro-perforated plate 651 in the fixed state should be much larger than the target frequency. In some embodiments, since the natural frequency of the micro-perforated plate 651 in the fixed state is difficult to measure, the natural frequency of the fixed state can be represented by the natural frequency of the free state of the micro-perforated plate 651, where the free state may be the state when the micro-perforated plate 651 is not attached to the acoustic device, and the natural frequency of the micro-perforated plate 651 in the fixed state is much larger than the natural frequency of the free state. The method of measuring the natural frequency of the free state may be as follows. The micro-perforated plate 651 is kept in a free state, and a vibration force having a constant amplitude and a frequency varying from low to high is applied to the micro-perforated plate 651 by a vibration exciter, and the velocity amplitude of the micro-perforated plate 651 is measured and recorded using a laser vibrometer. The frequency at which the velocity width of the micro-perforated plate 651 first reaches a maximum value is defined as the natural frequency of the free state of the micro-perforated plate 651. In some embodiments, the sound absorption bandwidth is in the range of 3 kHz to 6 kHz, and in order to avoid the fixed-state natural frequency of the micro-perforated plate being within the sound absorption bandwidth, the theoretical value of the free-state natural frequency of the micro-perforated plate 651 may be greater than 500 Hz (e.g., 500 Hz to 3.6 kHz), so that the fixed-state natural frequency is much greater than the upper sound absorption limit frequency (i.e., the maximum frequency of the sound absorption bandwidth, e.g., 6 kHz). Since the natural frequency is also related to the stiffness of the micro-perforated plate 651 and the mass of the micro-perforated plate 651, the stiffness of the micro-perforated plate 651 and / or the mass of the micro-perforated plate 651 can be set to determine its natural frequency, thereby absorbing sound waves within a target frequency range. In some embodiments, micro-perforated plates 651 of different shapes, materials, etc., have different stiffness and / or mass, and therefore different natural frequencies. In some embodiments, the micro-perforated plate 651 may have a regular shape or an irregular shape, such as a circle, a sector, a rectangle, a diamond, etc. In some embodiments, the material of the micro-perforated plate 651 may be a non-metallic material or a metallic material.

[0099] In some embodiments, the micro-perforated plate 651 may be a racetrack type micro-perforated plate. In some embodiments, when the micro-perforated plate 651 is a racetrack type micro-perforated plate, the Young's modulus of the material is in the range of 5 Gpa to 200 Gpa so that the natural frequency of the free state of the micro-perforated plate 651 is in the range of 500 Hz to 3.6 kHz. For example, the Young's modulus of the material is in the range of 10 Gpa to 180 Gpa. Also, for example, the Young's modulus of the material is in the range of 20 Gpa to 150 Gpa. Furthermore, for example, the Young's modulus of the material is in the range of 50 Gpa to 100 Gpa. In some embodiments, the thickness of the micro-perforated plate 651 can affect its natural frequency. When the micro-perforated plate 651 is a racetrack type micro-perforated plate, the thickness of the racetrack type micro-perforated plate may be in the range of 0.1 mm to 0.8 mm so that the natural frequency of the free state of the micro-perforated plate 651 is in the range of 500 Hz to 3.6 kHz. For example, the thickness of the racetrack type microperforated plate may be within a range of 0.2 mm to 0.7 mm, and for example, the thickness of the racetrack type microperforated plate may be within a range of 0.3 mm to 0.6 mm.

[0100] In some embodiments, the micro-perforated plate 651 may be a circular micro-perforated plate. With the same parameters (e.g., hole size, thickness, open area ratio, height of cavity (e.g., cavity 652)), the circular micro-perforated plate 651 has a lower natural frequency than the racetrack type micro-perforated plate 651, so the circular micro-perforated plate needs to use a material with higher stiffness and / or a micro-perforated plate with a higher thickness than the racetrack type micro-perforated plate to ensure that the natural frequency of the circular micro-perforated plate is much higher than the upper sound absorption frequency. In some embodiments, when the micro-perforated plate 651 is a circular micro-perforated plate, the Young's modulus of the material of the micro-perforated plate 651 is in the range of 50 Gpa to 200 Gpa so that the natural frequency of the free state of the micro-perforated plate 651 is in the range of 500 Hz to 3.6 kHz. For example, the Young's modulus of the material of the circular micro-perforated plate is in the range of 60 Gpa to 180 Gpa. Also, for example, the Young's modulus of the material of the circular micro-perforated plate is in the range of 80 Gpa to 150 Gpa. Furthermore, for example, the Young's modulus of the material of the circular micro-perforated plate is in the range of 100 Gpa to 150 Gpa. In some embodiments, when the micro-perforated plate 651 is a circular micro-perforated plate, the thickness of the circular micro-perforated plate needs to be in the range of 0.3 mm to 1 mm so that the natural frequency of the free state of the micro-perforated plate 651 is in the range of 500 Hz to 3.6 kHz. For example, the thickness of the circular micro-perforated plate needs to be in the range of 0.4 mm to 0.9 mm. Furthermore, for example, the thickness of the circular micro-perforated plate needs to be in the range of 0.5 mm to 0.8 mm. Furthermore, for example, the thickness of the circular micro-perforated plate needs to be in the range of 0.6 mm to 0.7 mm.

[0101] By setting the Young's modulus and / or thickness of the fine-perforated plate 651 and adjusting its natural frequency, it is possible to avoid the natural frequency of the fine-perforated plate 651 in a fixed state being within the sound absorption bandwidth and affecting its sound absorption effect.

[0102] In some embodiments, a waterproof ventilation structure may be installed on the side of the micro-perforated plate 651 facing the speaker 620 (or diaphragm), and the waterproof ventilation structure can be waterproof and dustproof. Specifically, the diameter of the through-holes of the micro-perforated plate 651 is relatively small, and capillary action is likely to occur, and water is difficult to drain if it enters, which affects the sound leakage reduction effect of the sound absorbing structure, so it is necessary to install a waterproof ventilation structure at the interface between the micro-perforated plate 651 and the second acoustic cavity 640. In some embodiments, the waterproof ventilation structure may cover the entire side where the micro-perforated plate 651 and the second acoustic cavity 640 contact each other. In some embodiments, the waterproof ventilation structure may cover all the through-holes of the micro-perforated plate 651 so that the through-holes communicate with the second acoustic cavity 640 via the waterproof ventilation structure.

[0103] In some embodiments, the waterproof breathable structure may be gauze. FIG. 9 is a frequency response curve diagram of the second acoustic hole 612 measured when 025HY type gauze is installed on the side of the micro-perforated plate 651 facing the speaker 620 (or vibrating membrane) and when no gauze is installed, according to some embodiments of the present specification. In FIG. 9, the horizontal axis indicates frequency, the vertical axis indicates sound pressure level, and curve 91 indicates a frequency response curve measured at the second acoustic hole 612 (e.g., a point 10 mm away from the second acoustic hole 612) when 025HY type gauze is installed, and curve 92 indicates a frequency response curve measured at the second acoustic hole 612 (e.g., a point 10 mm away from the second acoustic hole 612) when no gauze is installed. As shown in FIG. 9, curve 91 is slightly higher than curve 92, and the difference in sound pressure level between the two is not large. As is evident, the fine perforated plate 651 with the 025HY type gauze installed has a slightly reduced sound absorbing effect compared to the fine perforated plate 651 without the gauze installed, but the effect is not large and can achieve a certain degree of waterproof and dustproofing (for example, an acoustic device using the 025HY type gauze can pass the IPX7 waterproof test). Therefore, in some embodiments, in order to achieve the purpose of waterproof and dustproofing by the fine perforated plate sound absorbing structure, the fine perforated plate 651 may have the 025HY type gauze installed on the side facing the vibration membrane. In some embodiments, the acoustic resistance of the 025HY type gauze is less than 50 MKS Rayls. Thus, the fine perforated plate 651 may have the gauze installed on the side facing the vibration membrane, and the acoustic resistance of the gauze may be less than 50 MKS Rayls, thereby providing waterproofing and dustproofing and having little effect on the output effect of the acoustic device (for example, the second acoustic hole).

[0104] The cavity 652 is a cavity separated from the second acoustic cavity 640, and communicates with the outside only through the through holes of the finely perforated plate 651. In some embodiments, the shape of the cavity 652 includes, but is not limited to, a rectangular parallelepiped as shown in FIG. 6, and may include regular shapes such as a sphere, a cylinder, or an irregular shape such as a racetrack shape. In some embodiments, the cavity 652 has a certain height D (see FIG. 6), and the larger the height D of the cavity, the wider its sound absorption bandwidth. Thus, in some embodiments, the sound absorption effect of the finely perforated plate sound absorbing structure can be improved by setting the height D of the cavity to be large.

[0105] Fig. 10 is a curve diagram of the sound absorption coefficient when the micro-perforated plate sound absorbing structure according to some embodiments of the present specification has different cavity heights. As shown in Fig. 10, with the increase of the cavity 652 height D, the horizontal coordinate of the peak of the corresponding curve gradually moves 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.

[0106] FIG. 11 is a comparison diagram of the change trend of the maximum sound absorption coefficient and the change trend of the 0.5 sound absorption octave when the cavity height is different according to some embodiments of the present specification. The 0.5 sound absorption octave refers to the octave range traversed by the sound absorption curve when the sound absorption coefficient is 0.5. The larger the octave, the wider the sound absorption bandwidth. As shown in FIG. 11, with the increase of the cavity height D, 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.

[0107] From the above, the greater the height D of the cavity 652, the wider the sound absorption bandwidth can be obtained near the desired resonant sound absorption frequency. However, the greater the height of the cavity, the smaller the maximum sound absorption coefficient corresponding to the resonant sound absorption frequency. Therefore, in some embodiments, in order to achieve both the sound absorption bandwidth and the maximum sound absorption coefficient of the fine perforated plate sound absorbing structure, the range of the cavity height D may be 0.5 mm to 10 mm. For example, the range of the cavity height D may be 2 mm to 9 mm. Also, for example, the range of the cavity height D may be 4 mm to 9 mm. Furthermore, for example, the range of the cavity height D may be 7 mm to 10 mm.

[0108] In some embodiments, the micro-perforated plate 651 may have a plurality of through-holes disposed therein, the through-holes being distributed at intervals. In some embodiments, the through-holes may be distributed in a random manner as a whole. For example, the through-holes may be distributed in an array. Also, for example, the through-holes may be distributed in an annular manner around a central point. In some embodiments, the spacing between the through-holes (abbreviated as hole spacing) may be the same or different. The spacing between the through-holes as described in the specification is the minimum distance between the edge of a through-hole and the edge of an adjacent through-hole.

[0109] In some embodiments, the hole spacing between the through-holes may be much larger than the hole diameter of the through-holes (where hole diameter is the diameter of the through-hole), and the ratio of the hole spacing to the hole diameter of the through-holes may be greater than 3. In some embodiments, the hole spacing may be much larger than the hole diameter of the through-holes, and the ratio of the hole spacing to the hole diameter of the through-holes may be greater than 5. In some embodiments, the hole spacing may be much larger than the hole diameter of the through-holes, and the ratio of the hole spacing to the hole diameter of the through-holes may be greater than 7. In some embodiments, the hole spacing may be much larger than the hole diameter of the through-holes, and the ratio of the hole spacing to the hole diameter of the through-holes may be greater than 10. When the hole spacing is greater than the hole diameter, the properties of the sound waves transmitted between each hole do not affect each other.

[0110] In some embodiments, the hole spacing of the through-holes of the fine-perforated plate may 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 may be greater than 5. In some embodiments, the ratio of the wavelength of the sound in the target frequency range to the hole spacing may be greater than 7. In some embodiments, the ratio of the wavelength of the sound in the target frequency range to the hole spacing may be greater than 10. By way of example only, the target frequency range may be 3 kHz to 6 kHz, and the wavelength of the sound in said target frequency range may be in the range of 56 mm to 110 mm. The ratio of the wavelength of the sound in said target frequency range to the hole spacing may be greater than 5, for example, the hole spacing may be in the range of 10 mm to 22 mm. When the hole spacing is much smaller than the wavelength, the reflection of the sound wave by the hole spacing plate (the area of ​​the fine-perforated plate 651 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 hole spacing on the sound wave propagation process.

[0111] In some embodiments, within the effective hole size range, the smaller the hole size of the through hole, the greater the acoustic resistance when the sound wave passes through the through hole, the greater the energy consumption, and the wider the sound absorption bandwidth. Therefore, by setting the hole size of the through hole to be smaller, the sound absorption effect of the fine perforated plate sound absorbing structure can be improved. The effective hole size range is the range in which the sound absorption bandwidth of the fine perforated plate sound absorbing structure having hole size dimensions within the effective hole size range can meet the sound leakage reduction requirements. When the hole size is within the effective hole size range, the smaller the hole size, the higher the sound absorption effect, and when the hole size is smaller than the effective hole size range, the sound absorption bandwidth is significantly narrowed. In some embodiments, the effective hole size range may be 0.1 mm to 1 mm. Considering the requirements for the processing at the same time, in some embodiments, the effective hole size range may be 0.2 mm to 0.4 mm. For example, the effective hole size range may be 0.2 mm to 0.3 mm. In some embodiments, the effective hole size range may be 0.1 mm to 0.4 mm. For example, the effective pore size range may be 0.1 mm to 0.2 mm.

[0112] FIG. 12 is a diagram showing the sound absorption effect of the micro-perforated plate 651 with through-holes having diameters of 0.15 mm and 0.3 mm, respectively, according to some embodiments of the present specification. In FIG. 12, the horizontal axis indicates the sound absorption frequency, the vertical axis indicates the sound absorption coefficient, and the curve 121 indicates the sound absorption effect of the micro-perforated plate 651 with a hole diameter of 0.15 mm, and the curve 122 indicates the sound absorption effect of the micro-perforated plate 651 with a hole diameter of 0.3 mm. As shown in FIG. 12, the curve 121 is wider than the curve 122, but the heights of the two are close. As can be seen, the sound absorption bandwidth and sound absorption effect of the micro-perforated plate 651 with a hole diameter of 0.15 mm are obviously better than those of the micro-perforated plate 651 with a hole diameter of 0.3 mm.

[0113] FIG. 13 is a frequency response curve diagram of a fine perforated plate 651 with a hole diameter of 0.15 mm and a fine perforated plate 651 with a hole diameter of 0.3 mm according to some embodiments of the present specification. In FIG. 13, the horizontal axis indicates frequency, the vertical axis indicates sound pressure level, and curve 131 indicates the frequency response when the fine perforated plate 651 with a hole diameter of 0.15 mm is used, and curve 132 indicates the frequency response when the fine perforated plate 651 with a hole diameter of 0.3 mm is used, where the frequency response is the frequency response of the sound emitted from the second sound hole. As shown in FIG. 13, the sound leakage in the frequency band of 2 kHz to 4 kHz of curve 131 is about 6 dB lower than that of curve 132. As can be seen from this, the sound absorption effect in the mid-high frequency range of the fine perforated plate 651 with a hole diameter of 0.15 mm is obviously better than that of the fine perforated plate 651 with a hole diameter of 0.3 mm. Therefore, in some embodiments, in order to achieve a higher sound absorbing effect, a finely perforated plate 651 having a hole diameter of 0.15 mm or close to 0.15 mm may be used. For example, a finely perforated plate 651 having a hole diameter in the range of 0.1 mm to 0.2 mm may be used. In some embodiments, in consideration of the needs of dust prevention and drainage, a finely perforated plate 651 having a hole diameter of 0.3 mm or close to 0.3 mm (for example, 0.28 mm to 0.35 mm) may be used.

[0114] In some embodiments, the aperture ratio of the micro-perforated plate 651 may be less than 5% to avoid too many through-holes and too small hole spacing that would affect the characteristics of the sound waves transmitted between the through-holes. The aperture ratio is a proportional relationship between the total area of ​​the through-holes and the area of ​​the side of the micro-perforated plate 651 adjacent to the second acoustic cavity 640.

[0115] As can be seen from the above, the cavity height D, the thickness of the fine-perforated plate 651, the hole diameter of the through hole, and the aperture ratio all affect the sound absorption bandwidth and sound absorption coefficient of the fine-perforated plate 651, and the comprehensive value of the above parameters can be referred to the following description.

[0116] In general, the acoustic impedance of a single through-hole in the finely perforated plate 651 is:

[0117]

number

[0118] In formula (1), ρ is air density, μ is air motion viscosity coefficient, t is thickness, and d is hole diameter. When the thickness of the through hole corresponds to the hole diameter, it is necessary to consider modifying the end of the through hole, that is, increasing the effective thickness by 0.85d. A plurality of through holes are installed in the fine perforated plate 651, and the acoustic resistance is equivalent to that when the acoustic resistances of the plurality of through holes are connected in parallel, that is, the acoustic impedance of the fine perforated plate 651 is obtained by dividing the acoustic impedance of a single through hole by the aperture ratio.

[0119]

number

[0120] In equation (2), σ is the aperture ratio, k is the wave number, and the expression is:

[0121]

number

[0122] 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 an acoustic capacitance, and its acoustic impedance is:

[0123]

number

[0124] In formula (3), D is the height of the cavity. The acoustic impedance of the micro-perforated plate sound absorbing structure may be expressed as:

[0125]

number

[0126] After normalization:

[0127]

number

[0128] In the formula (5), r is the relative acoustic impedance, and m is the relative sound quality, specifically, as follows:

[0129]

number

[0130]

number

[0131] When sound waves are incident vertically, the sound absorption coefficient α of the fine-perforated sound absorbing structure can be calculated as follows:

[0132]

number

[0133] The resonant frequency of the sound absorbing structure 650 is:

[0134]

number

[0135] As can be seen from equations (1) to (9), the sound absorption bandwidth and sound absorption coefficient of the sound absorbing structure 650 can be controlled by adjusting the hole diameter, aperture ratio, thickness, and cavity height of the finely perforated plate 651.

[0136] In addition, the parameter values ​​such as hole diameter, open area ratio, thickness, cavity height, etc. can be combined with the sound absorption coefficient, sound absorption frequency range, and structure dimensions, etc. to comprehensively determine the combination of parameters. For example, the sound absorption bandwidth and the maximum sound absorption coefficient of the sound absorbing structure 650 can be mutually constrained and balanced according to actual needs. For example, the smaller the hole diameter of the fine perforated plate 651, the wider the sound absorption bandwidth, and the wider sound absorption bandwidth corresponds to the effective hole diameter range. When the hole diameter is in the effective hole diameter range, the smaller the hole diameter, the higher the sound absorption effect, and when the hole diameter is smaller than the effective hole diameter range, the sound absorption bandwidth is greatly narrowed. In addition, for example, a small hole diameter, a large open area ratio, a small thickness, and a cavity height are suitable for a high frequency sound absorption range, and conversely, for a low frequency sound absorption range.

[0137] In some embodiments, the hole size may be in the range of 0.1 mm to 0.2 mm, the aperture ratio may be in the range of 2% to 5%, the thickness may be in the range of 0.2 mm to 0.7 mm, and the cavity height may be in the range of 7 mm to 10 mm. By way of example only, the micro-perforated plate 651 may have a hole size in the range of 0.1 mm to 0.2 mm, an aperture ratio in the range of 2.18% to 4.91%, a thickness in the range of 0.3 mm to 0.6 mm, and a cavity height in the range of 7.5 mm to 9.5 mm. For example, the micro-perforated plate 651 may have a hole size of 0.15 mm, an aperture ratio of 2.18%, a thickness of 0.3 mm, and a cavity height of 9 mm. Also, for example, the fine perforated plate 651 may have a hole diameter of 0.15 mm, a hole ratio of 2.76%, a thickness of 0.4 mm, and a cavity height of 7.5 mm. Furthermore, for example, the fine perforated plate 651 may have a hole diameter of 0.15 mm, a hole ratio of 3.61%, a thickness of 0.5 mm, and a cavity height of 9 mm.

[0138] Fig. 14 is a diagram showing the sound absorption effect of micro-perforated plate 651 with different cavity heights when the hole diameter is 0.15 mm, the aperture ratio is 2.18%, and the thickness is 0.3 mm according to some embodiments of the present specification. In Fig. 14, the horizontal axis shows the frequency, the vertical axis shows the sound absorption coefficient, curve 141 shows the sound absorption effect of micro-perforated plate 651 with a cavity height of 9 mm, curve 142 shows the sound absorption effect of micro-perforated plate 651 with a cavity height of 7.5 mm, and curve 143 shows the sound absorption effect of micro-perforated plate 651 with a cavity height of 5 mm. As shown in Fig. 14, the difference in sound absorption effect between the cavity height of 7.5mm and that of 9mm is not large, and when the cavity height is reduced to 5mm, the sound absorption center frequency (the frequency corresponding to the point where the sound absorption coefficient is the highest) of the fine perforated plate 651 shifts from 4kHz to 4.9kHz, and the sound absorption coefficient decreases obviously in the frequency band (e.g., 2kHz to 4.9kHz) lower than the sound absorption center frequency. As a result, the sound absorption effect can meet the needs for reducing sound leakage in any of the cavity heights of 9mm, 7.5mm, and 5mm, but the sound absorption effect when the cavity height is 5mm is lower than the sound absorption effect when the cavity height is 9mm and 7.5mm.

[0139] In some embodiments, the hole size may be in the range of 0.2 mm to 0.4 mm, the aperture ratio may be in the range of 1% to 5%, the thickness of the micro-perforated plate 651 may be in the range of 0.2 mm to 0.7 mm, and the cavity height may be in the range of 4 mm to 9 mm. By way of example only, the micro-perforated plate 651 may have a hole size in the range of 0.25 mm to 0.3 mm, an aperture ratio in the range of 1.11% to 4.06%, a thickness in the range of 0.3 mm to 0.6 mm, and a cavity height in the range of 4 mm to 8.5 mm. For example, the micro-perforated plate 651 may have a hole size of 0.3 mm, an aperture ratio of 2.18%, a thickness of 0.5 mm, and a cavity height of 5 mm. Also, for example, the fine perforated plate 651 may have a hole diameter of 0.25 mm, a hole ratio of 3.41%, a thickness of 0.6 mm, and a cavity height of 8.5 mm. Furthermore, for example, the fine perforated plate 651 may have a hole diameter of 0.3 mm, a hole ratio of 2.45%, a thickness of 0.5 mm, and a cavity height of 6 mm.

[0140] FIG. 15 is a diagram showing the sound absorption effect of the micro-perforated plate 651 with different thicknesses when the hole diameter is 0.3 mm, the aperture ratio is 2.18%, and the cavity height is 5 mm according to some embodiments of the present specification. In FIG. 15, the horizontal axis shows the frequency, the vertical axis shows the sound absorption coefficient, and the curve 151 shows the sound absorption effect of the micro-perforated plate 651 with a thickness of 0.6 mm, the curve 152 shows the sound absorption effect of the micro-perforated plate 651 with a thickness of 0.5 mm, and the curve 153 shows the sound absorption effect of the micro-perforated plate 651 with a thickness of 0.4 mm. As shown in FIG. 15, the sound absorption center frequency of the curves 151, 152, and 153 gradually increases, and the maximum sound absorption coefficient gradually decreases. In any of the cases of 0.4 mm, 0.5 mm, and 0.6 mm, the sound absorbing effect can meet the need for reducing sound leakage, but the sound absorbing effect of the 0.4 mm thickness is lower than that of the 0.5 mm and 0.6 mm thickness. In some embodiments, the micro-perforated plate 651 having a thickness of 0.4 mm can be used to reduce the mass of the acoustic device. Thus, the micro-perforated plate having a thickness of 0.4 mm may be used in consideration of the user's wearing experience.

[0141] By setting the above parameter combination, the sound absorption bandwidth and the sound absorption coefficient can be compatible, the sound absorbing structure can effectively absorb the sound waves within the target frequency range, and the sound leakage reduction effect within the target frequency range can be improved. In addition, different parameter combinations can meet the needs of different application scenarios.

[0142] In some embodiments, the absorbing structure can improve the sound absorbing effect of the micro-perforated plate sound absorbing structure because the process difficulty may be high if the size of the micro-holes is too small, and the size of the acoustic device may be large if the cavity depth D is too large. FIG. 16 is a schematic diagram of an acoustic device having a sound absorbing structure installed therein, according to some embodiments herein. As shown in FIG. 16, the absorbing structure may be installed in the cavity 652 of the micro-perforated plate sound absorbing structure. In some embodiments, the absorbing structure may further include a filler material 654 (e.g., N'Bass particles or a porous sound absorbing material). The filler material 654 can increase the equivalent height of the cavity 652 of the micro-perforated plate sound absorbing structure, thereby improving the sound absorbing effect of the micro-perforated plate sound absorbing structure and reducing the design size of the acoustic device 1600. Specifically, the filling material 654 has a "sponge" effect, and it can be regarded that when sound waves propagate, air molecules are adsorbed into and desorbed from the voids in the filling material 654, and the sound speed in the filling material 654 decreases, which is equivalent to increasing the volume of the cavity 652, thereby achieving the purpose of widening the sound absorption bandwidth of the fine-perforated plate 651 and increasing the sound absorption coefficient (without affecting the sound absorption center frequency), further improving the sound absorption effect of the fine-perforated plate sound absorption structure, and reducing the design dimensions of the acoustic device.

[0143] In some embodiments, cavity 652 may be filled with N'Bass (aluminosilicate) sound absorbing particles. In some embodiments, N'Bass sound absorbing particles may be filled into cavity 652 in a number of ways. By way of example only, N'Bass sound absorbing particles may be filled directly into cavity 652, or N'Bass sound absorbing particles may be loaded into a powder pack and the powder pack placed into cavity 652, or N'Bass sound absorbing particles may be potted into a gauze of a particular shape and the powder pack placed into cavity 652, or N'Bass sound absorbing particles may be filled into cavity 652 in at least two of the above filling methods.

[0144] In some embodiments, the smaller the N'Bass sound absorbing particles, the smaller the spacing between each sound absorbing particle, i.e., the stronger the adsorption effect on air molecules. Accordingly, the smaller the particles, the more N'Bass sound absorbing particles need to be packed, which increases the cost. Therefore, in order to ensure the sound absorbing effect and to take the cost into consideration, the diameter of the N'Bass sound absorbing particles may be in the range of 0.15mm to 0.7mm. For example, the diameter of the N'Bass sound absorbing particles may be in the range of 0.15mm to 0.6mm. Also, for example, the diameter of the N'Bass sound absorbing particles may be in the range of 0.2mm to 0.6mm. Furthermore, for example, the diameter of the N'Bass sound absorbing particles may be in the range of 0.3mm to 0.5mm.

[0145] In some embodiments, the filling rate of the N'Bass sound absorbing particles in the cavity 652 gradually increases, so that the more N'Bass sound absorbing particles there are in the cavity 652, the higher the sound absorbing effect becomes. The filling rate refers to the ratio of the volume of the filled N'Bass sound absorbing particles to the volume of the cavity 652. However, when the N'Bass sound absorbing particles completely fill the cavity 652, the pressure from the plate surface of the micro-perforated plate sound absorbing structure to the N'Bass sound absorbing particles may cause the N'Bass sound absorbing particles to crack, blocking the gaps between the N'Bass sound absorbing particles and reducing the sound absorbing effect.

[0146] FIG. 17 is a frequency response curve diagram of the second acoustic cavity of the acoustic device corresponding to different filling rates of the filling material according to some embodiments herein. As shown in FIG. 17, when the filling rate of the filling material (e.g., N'Bass sound absorbing particles) is 0%, i.e., when no filling material is filled in the cavity of the micro-perforated sound absorbing structure, the frequency response curve corresponding to the second acoustic cavity of the acoustic device forms one peak near 2 kHz (as shown in the dashed circle in FIG. 17), which indicates that the output sound volume of the second acoustic cavity at 2 kHz is large. When the filling rate of the filling material is 25%, i.e., when 25% of the space in the cavity of the micro-perforated sound absorbing structure is filled with the filling material, the peak near 2 kHz is absorbed more, but there is still a small peak. When the filling rate of the filling material is 50%, i.e., when 50% of the space in the cavity of the micro-perforated sound absorbing structure is filled with the filling material, the peak near 2 kHz is further absorbed, and the corresponding frequency response curve is flat. When the filling rate of the filling material is 75%, i.e., when 75% of the space in the cavity of the micro-perforated plate sound absorbing structure is filled with the filling material, the peak near 2kHz is further absorbed, but another peak is formed near 3kHz, and the output sound volume of the second acoustic cavity near 3kHz is slightly increased. When the filling rate of the filling material is 100%, i.e., when all the space in the cavity of the micro-perforated plate sound absorbing structure is filled with the filling material, the peak near 2kHz is further absorbed, but the peak near 3kHz is further increased, the peak is obvious, and the output sound volume of the second acoustic cavity near 3kHz is further increased. In order to flatten the frequency response curve of the second acoustic cavity and avoid the appearance of a peak on the curve within a preset range (e.g., 2kHz to 3kHz) as much as possible, in some embodiments, the range of the filling rate of the filling material may be 60% to 100%. In some embodiments, the filling rate may be in the range of 70% to 95%. For example, the filling rate may be in the range of 75% to 90%. Also, for example, the filling rate may be in the range of 80% to 90%. In some embodiments, considering the filling cost of N'Bass sound absorbing particles, the filling rate may be in the range of 75% to 85%. For example, the filling rate may be 80%.

[0147] By setting the filling rate of the N'Bass sound-absorbing particles within the range of 70% to 95%, the sound absorption effect can be guaranteed while avoiding a reduction in the sound absorption effect caused by gaps being blocked by pressure from the fine-perforated sound-absorbing structure to the N'Bass sound-absorbing particles.

[0148] In some embodiments, since the diameter of the N'Bass sound absorbing particles is close to or smaller than the diameter of the through holes, in order to prevent the N'Bass sound absorbing particles from blocking the through holes, gauze 653 may be placed between the N'Bass sound absorbing particles and the micro-perforated plate 651 as shown in FIG. 16. In some embodiments, the gauze 653 may be coated on the side of the micro-perforated plate 651 that is away from the second acoustic cavity 640 (or the vibrating membrane), and the gauze 653 covers all the through holes of the micro-perforated plate 651. In some embodiments, the gauze 653 may be placed in the cavity 652 between the N'Bass sound absorbing particles and the micro-perforated plate 651. Specifically, the gauze 653 may be connected to the inner wall of the cavity 652 between the N'Bass sound absorbing particles and the micro-perforated plate 651.

[0149] In some embodiments, the cavity 652 may include a porous sound absorbing material. In some embodiments, the porous sound absorbing material may include, but is not limited to, polyurethane, polypropylene, melamine sponge, wood wool board, wool felt, and the like. In some embodiments, the filling manner of the porous sound absorbing material may be similar to the filling manner of N'Bass sound absorbing particles. In some embodiments, the entire cavity 652 may be filled with the porous sound absorbing material uniformly to achieve a better sound absorbing effect. In some embodiments, the porosity of the porous sound absorbing material may be greater than 70% to achieve a better sound absorbing effect. The porosity refers to the percentage of the void volume of the porous sound absorbing material to the total volume of the porous sound absorbing material.

[0150] In some embodiments, the micro-perforated plate sound absorbing structure can effectively reduce the sound pressure level of 4dB to 20dB in the frequency band of 4kHz to 6kHz, and after the cavity 652 of the micro-perforated plate sound absorbing structure is filled with the porous sound absorbing material or N'Bass sound absorbing particles, the sound absorbing frequency band can be further extended to lower frequencies, and the sound absorbing methods of the porous sound absorbing material and the N'Bass sound absorbing particles both have excellent sound absorbing effects. For the explanation of the sound absorbing effects of the porous sound absorbing material and the N'Bass sound absorbing particles, please refer to FIG. 18.

[0151] 18 is a frequency response diagram of the micro-perforated plate 651 without the micro-perforated plate 651, the micro-perforated plate 651 alone, the micro-perforated plate 651 in combination with N′Bass sound absorbing particles, and the micro-perforated plate 651 in combination with porous sound absorbing material according to some embodiments of the present disclosure. In FIG. 18, the horizontal axis represents frequency, the vertical axis represents sound pressure level, and curve 181 represents the frequency response without the micro-perforated plate 651, curve 182 represents the frequency response with only the micro-perforated plate 651, curve 183 represents the frequency response with the micro-perforated plate 651 and filling the cavity 652 with porous sound absorbing material, and curve 184 represents the frequency response with the micro-perforated plate 651 and filling the cavity 652 with N′Bass sound absorbing particles, where the frequency response is the frequency response of the sound emanating from the second acoustic hole. As shown in Fig. 18, without the fine perforated plate 651 (curve 181), there is a very high resonance peak around 3.9kHz, and 4.2kHz corresponds to the resonance frequency of the second acoustic cavity 640. After adding the fine perforated plate sound absorbing structure (curve 182), the sound pressure level is effectively reduced by 4dB-20dB in the frequency band of 3kHz-6kHz, as can be seen, the fine perforated plate sound absorbing structure can effectively absorb sound waves within the range of 3kHz-6kHz, and the sound absorbing effect of the fine perforated plate sound absorbing structure on the sound waves of the resonance frequency is about 20dB, which can reduce or avoid the sound waves from resonating near the resonance frequency under the action of the second acoustic cavity 640, thereby reducing the sound leakage of the resonance frequency. After the cavity 652 of the micro-perforated plate sound absorbing structure is filled with porous sound absorbing material (curve 183) or filled with N'Bass sound absorbing particles (curve 184), the sound absorbing frequency band can be extended to lower frequencies, and the two combined sound absorbing methods both have excellent sound absorbing effects.

[0152] In addition, when measuring the frequency response curve without the fine-perforated plate sound absorbing structure, the through holes of the fine-perforated plate 651 of the acoustic device including the fine-perforated plate sound absorbing structure can be blocked to simulate the frequency response of the sound emitted from the second acoustic hole without the fine-perforated plate sound absorbing structure. For example, the back plate of the cavity 652 on the side away from the second acoustic cavity 640 is opened to change the cavity 652 from a closed state to an open state, which is equivalent to removing the cavity 652 of the fine-perforated plate sound absorbing structure. Furthermore, blocking the through holes of the fine-perforated plate 651 with a material such as rubber clay or adhesive is equivalent to removing the fine-perforated plate 651 of the fine-perforated plate sound absorbing structure. The above method is equivalent to removing the fine-perforated plate sound absorbing structure, and has little effect on the volume of the second acoustic cavity 640, thereby avoiding affecting the frequency response of the second acoustic cavity 640. Furthermore, the frequency response of the sound emitted from the second acoustic hole can be measured. For example, a measurement microphone is placed directly facing the second acoustic hole at a distance of about 2 mm to 5 mm from the second acoustic hole, and the method of measuring the frequency response of the first acoustic hole is similar to the method of measuring the frequency response of the second acoustic hole.

[0153] 19 and 20 are diagrams illustrating the internal structure of an audio device according to some embodiments of the present disclosure.

[0154] As shown in FIGS. 19 and 20, the speaker divides a receiving cavity of a housing 1910 into a first acoustic cavity 1930 and a second acoustic cavity 1940, and the speaker includes a diaphragm 1921, a coil 1922, a frame 1923 and a magnetic circuit assembly 1924. The frame 1923 is installed around the diaphragm 1921, the coil 1922 and the magnetic circuit assembly 1924 to provide a mounting and fixing platform, the speaker may be connected to the housing 1910 by the frame 1923, the diaphragm 1921 covers the coil 1922 and the magnetic circuit assembly 1924 in the Z direction, at least a part of the coil 1922 enters the magnetic gap formed by the magnetic circuit assembly 1924 and is connected to the diaphragm 1921, the magnetic field generated after the coil 1922 is energized interacts with the magnetic field formed by the magnetic circuit assembly 1924 to drive the diaphragm 1921 to generate mechanical vibration, and then generates sound through the propagation of a medium such as air, and the sound is output from the hole of the housing 1910. A micro-perforated plate sound absorbing structure may be installed in the second acoustic cavity 1940. For example, the micro-perforated plate absorbing structure may be disposed around the magnetic circuit assembly 1924, and the micro-perforated plate absorbing structure includes a micro-perforated plate 1951 and a packing layer 1953, and the side of the micro-perforated plate 1951 away from the diaphragm 1921 along the Z direction is connected to the packing layer 1953. The micro-perforated plate 1951 is an annular structure and disposed around the magnetic circuit assembly 1924. The packing layer 1953 is filled with N'Bass sound absorbing particles or porous sound absorbing material. In some embodiments, the housing 1910 (e.g., back plate 1952) and the magnetic circuit assembly 1924 may form a closed cavity, i.e., the cavity of the micro-perforated plate absorbing structure, and the packing layer 1953 may be filled into the cavity.

[0155] In some embodiments, the magnetic circuit assembly 1924 includes a magnetically permeable plate 19241, a magnet 19242, and a magnetically permeable cover 19243, where the magnetically permeable plate 19241 and the magnet 19242 are connected to each other, and the side of the magnet 19242 away from the magnetically permeable plate 19241 is attached to the bottom wall of the magnetically permeable cover 19243, and a magnetic gap is formed between the peripheral side of the magnet 19242 and the peripheral inner wall of the magnetically permeable cover 19243. In some embodiments, the peripheral outer wall of the magnetically permeable cover 19243 is connected and fixed to the frame 1923. In some embodiments, both the magnetically permeable cover 19243 and the magnetically permeable plate 19241 can be made of a magnetically permeable material (such as iron).

[0156] In some embodiments, the micro-drilled plate 1951 may be provided with a number of through-holes spaced around the magnet assembly to help ensure proper hole spacing and aperture ratio.

[0157] In some embodiments, since it is necessary to provide a sealed cavity with a certain height on the side of the fine perforated plate 1951 away from the diaphragm, if the fine perforated plate 1951 is provided entirely on the side of the magnetic circuit assembly away from the diaphragm, the fine perforated plate 1951 and the filling layer 1953 may occupy too much space in the housing 1910, making it difficult to meet the design requirement for miniaturization of the acoustic device. In the acoustic device 1900 according to this embodiment, the fine perforated plate 1951 is made into an annular structure centered on the magnetic circuit assembly, which not only makes it possible to effectively utilize the space in the circumferential direction of the magnetic circuit assembly, but also does not increase the thickness of the acoustic device (i.e., the dimension along the Z direction), which is helpful in designing a miniaturized acoustic device.

[0158] In some embodiments, the micro-perforated plate may be installed on the side of the magnetic circuit assembly 1924 away from the diaphragm 1921, i.e., the micro-perforated plate 1951 and the magnetic circuit assembly are installed with a gap in the Z direction (the vibration direction of the diaphragm), and the specific installation manner can be referred to FIG. 4. In some embodiments, the micro-perforated plate may be a panel (e.g., racetrack-shaped, circular, etc.) that matches the shape of the second acoustic cavity 1940 or the housing 1910. The parameters of the micro-perforated plate, such as hole diameter, aperture ratio, hole spacing, etc., may be matched with the relevant parameters of the micro-perforated plate 1951, so that the area of ​​the micro-perforated plate in the panel structure is larger, the number of through holes is larger, the sound absorption effect is higher, the structure is simple, and it is easy to assemble.

[0159] Fig. 21 is a diagram showing the internal structure of an audio device according to some embodiments of the present disclosure. The audio device 2100 and its speaker shown in Fig. 21 are similar to the audio device 1900 and its speaker shown in Fig. 19 and Fig. 20, except that there is no separate micro-perforated plate.

[0160] At least a part of the magnetic permeable element of the acoustic device 2100 may be a finely perforated plate. For example, as shown in FIG. 21, a plurality of through holes may be provided at the bottom of the magnetic permeable cover 21243 away from the diaphragm, and the finely perforated plate may be provided. The side of the magnetic permeable cover 21243 away from the diaphragm along the Z direction is connected to the cavity. In some embodiments, a filling layer may be provided in the cavity. In this embodiment, a part of the magnetic circuit assembly is directly made into a sound absorbing structure, thereby achieving the sound absorbing effect, reducing costs, and simplifying the process.

[0161] FIG. 22 is a frequency response curve diagram of the acoustic device 1900 shown in FIGS. 19 and 20 and the acoustic device 2100 shown in FIG. In FIG. 22, the horizontal axis represents frequency and the vertical axis represents sound pressure level, where curve a1 represents the frequency response of the first acoustic hole of acoustic device 2100, curve a2 represents the frequency response of the first acoustic hole of acoustic device 1900, curve b1 represents the frequency response of the first decompression hole of acoustic device 2100, curve b2 represents the frequency response of the first decompression hole of acoustic device 1900, curve c1 represents the frequency response of the second decompression hole of acoustic device 2100, curve c2 represents the frequency response of the second decompression hole of acoustic device 1900, curve d1 represents the frequency response of sound emanating from the third decompression hole of acoustic device 2100, and curve d2 represents the frequency response of sound emanating from the third decompression hole of acoustic device 1900, and the first decompression hole, the second decompression hole, and the third decompression hole are acoustic holes (i.e., second acoustic holes) located at different positions of the housing corresponding to the second acoustic cavity. 22, the curves a1, a2, b1, b2, c1, c2, d1 and d2 of the acoustic device all reach a low point around 3.9kHz, and the curves a2, b2, c2 and d2 are all lower than the corresponding curves a1, b1, c1 and d1 in the frequency band around 3.9kHz. As can be seen, the sound absorption center frequencies of the two types of installation methods of the fine-perforated plate corresponding to the acoustic device 1900 and the acoustic device 2100 are both 3.9kHz, and the sound absorption effect of the fine-perforated plate corresponding to the acoustic device 1900 is better than that of the fine-perforated plate corresponding to the acoustic device 2100. The reason is that when the magnetic permeable cover 21243 is a fine perforated plate, the fine perforated plate sound absorbing structure acts on the magnetic gap cavity between the magnetic permeable cover 21243 and the corresponding magnet (not shown) instead of acting on the second acoustic cavity (not shown) of the acoustic device 2100, so that the absorption effect of the fine perforated plate sound absorbing structure in the second acoustic cavity is limited. In some embodiments, the fine perforated plate 1951 shown in Figures 19 and 20 and the magnetic permeable cover 21243 shown in Figure 21 can both be installed to form the sound absorbing structure of the acoustic device, and in this case, the number of through holes in the sound absorbing structure is larger, and the sound absorbing effect is higher.

[0162] Although the basic concept has been described above, it is clear to those skilled in the art that the detailed disclosure above is merely presented as an example and does not limit the present specification. Although not explicitly described in the present specification, those skilled in the art can make various changes, improvements and modifications to the present specification. These changes, improvements and modifications are intended to be suggested by the present specification and therefore are within the spirit and scope of the exemplary embodiments of the present specification.

[0163] Furthermore, certain terms are used herein to describe embodiments of the present specification. For example, "one embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the present specification. Thus, it is emphasized and understood that references to two or more of "one embodiment" or "one embodiment" or "one alternative embodiment" in various parts of the present specification do not necessarily all refer to the same embodiment. Also, certain features, structures, or characteristics in one or more embodiments of the present specification may be combined as appropriate.

[0164] Additionally, unless expressly stated in the claims, the order of enumeration of processing elements or sequences described herein, the use of alphanumeric characters, or the use of other designations, does not limit the order of steps and methods herein. While the above disclosure describes through various examples what are presently believed to be various useful embodiments of the invention, it should be understood that such details are merely for purposes of illustration and that the appended claims are not limited to the disclosed embodiments, but on the contrary are intended to cover all modifications and equivalent combinations that are within the spirit and scope of the embodiments herein. For example, the system assembly described above may be implemented by a hardware device, but may also be implemented as a software-only solution, for example, by installing the described system on an existing server or mobile device.

[0165] Similarly, in the foregoing description of embodiments herein, it should be understood that various features may be grouped together in a single embodiment, figure, or description for the purpose of simplifying the description and facilitating an understanding of one or more embodiments of the invention. This method of disclosure, however, should not be interpreted as reflecting an intention that the claimed subject matter requires more features than are recited in each claim. In fact, an embodiment may include fewer than all features of a single embodiment disclosed above.

[0166] In some embodiments, numbers are used to describe the number of components and attributes, and it is understood that the numbers describing such embodiments are modified in some embodiments by the modifiers "about," "approximately," or "generally." Unless otherwise specified, "about," "approximately," or "generally" indicate that the numbers are allowed to vary by ±20%. Thus, in some embodiments, all numerical parameters used in the specification and claims are approximations that may vary depending on the characteristics required for a particular embodiment. In some embodiments, the numerical parameters should be applied with the stated number of significant digits and ordinary rounding techniques. In some embodiments, the numerical ranges and parameters for determining the ranges are approximations; however, in specific embodiments, such numerical values ​​are set as precisely as possible.

[0167] All patents, patent applications, published patent applications, and other materials, such as papers, books, specifications, publications, documents, etc., referenced herein are incorporated herein by reference in their entirety, except for prosecution history documents that are inconsistent or inconsistent with the contents of this specification, and documents that may have a limiting effect on the broadest scope of the claims of this specification (now or later related to this specification). In addition, if the explanations, definitions, and / or use of terms in the accompanying documents of this specification are inconsistent or inconsistent with the contents described herein, the explanations, definitions, and / or use of terms in this specification shall control.

[0168] Finally, it should be understood that the embodiments described herein are merely illustrative of the principles of the embodiments herein. Other variations are possible within the scope of the present specification. Thus, by way of example, and not of limitation, alternative configurations of the embodiments herein may be considered consistent with the teachings of the present specification. Thus, the embodiments herein are not limited to the embodiments expressly introduced and described herein. [Explanation of symbols]

[0169] 100 Sound equipment 110 Housing 111 1st acoustic hole 112 2nd acoustic hole 120 Speakers 130 First Acoustic Cavity 140 Second Acoustic Cavity

Claims

1. A diaphragm; a housing that accommodates the diaphragm and has a first acoustic cavity and a second acoustic cavity formed corresponding to a front side and a rear side of the diaphragm, respectively, the diaphragm radiating sound to the first acoustic cavity and the second acoustic cavity, respectively, and emitting sound from a first acoustic hole coupled to the first acoustic cavity and a second acoustic hole coupled to the second acoustic cavity, respectively; and a sound absorbing structure coupled to the second acoustic cavity for absorbing sound that passes through the second acoustic cavity and is transmitted to the second acoustic hole within a target frequency range that includes a resonant frequency of the second acoustic cavity.

2. 2. The acoustic device of claim 1, wherein the target frequency range further includes a resonant frequency of the first acoustic cavity.

3. 2. The acoustic device of claim 1, wherein the target frequency range includes 3 kHz to 6 kHz.

4. 4. The acoustic device according to claim 3, wherein the sound absorbing effect of the sound absorbing structure for sounds within the target frequency range is 3 dB or more.

5. 4. The acoustic device according to claim 3, wherein the sound absorbing effect of the sound absorbing structure with respect to the sound at the resonant frequency is 14 dB or more.

6. 2. The acoustic device of claim 1, wherein the sound absorbing structure comprises a micro-perforated plate and a cavity, the micro-perforated plate includes a through hole, and the second acoustic cavity coupled to the sound absorbing structure communicates with the cavity via the through hole.

7. 7. An acoustic device as claimed in claim 6, characterised in that the cavity is filled with N'Bass sound absorbing particles.

8. 8. An acoustic device as claimed in claim 7, characterised in that the diameter of said N'Bass sound absorbing particles is in the range of 0.15mm to 0.7mm.

9. 8. The acoustic device of claim 7, wherein the filling rate of the N'Bass sound absorbing particles in the cavity is in the range of 70% to 95%.

10. 8. The acoustic device of claim 7, wherein gauze is disposed between the N'Bass sound absorbing particles and the micro-perforated plate.

11. 7. An acoustic device according to claim 6, characterized in that the cavity is filled with a porous sound absorbing material, the porous sound absorbing material having a porosity greater than 70%.

12. 7. The acoustic device according to claim 6, wherein a ratio of a hole spacing between the through holes to a hole diameter of the through holes is greater than 5.

13. 13. The acoustic device of claim 12, wherein a ratio of a wavelength of sound in the target frequency range to a hole spacing between the through holes of the fine-perforated plate is greater than 5.

14. The acoustic device according to claim 6 or claim 13, characterized in that the hole diameter of the through hole is in the range of 0.1 mm to 0.2 mm, the aperture ratio of the fine-perforated plate is in the range of 2% to 5%, the thickness of the fine-perforated plate is in the range of 0.2 mm to 0.7 mm, and the height of the cavity is in the range of 7 mm to 10 mm.

15. The acoustic device according to claim 6 or claim 13, characterized in that the hole diameter of the through hole is in the range of 0.2 mm to 0.4 mm, the aperture ratio of the fine-perforated plate is in the range of 1% to 5%, the thickness of the fine-perforated plate is in the range of 0.2 mm to 0.7 mm, and the height of the cavity is in the range of 4 mm to 9 mm.

16. 7. The acoustic device of claim 6, wherein the micro-perforated plate comprises a racetrack micro-perforated plate or a circular micro-perforated plate.

17. 17. The acoustic device of claim 16, wherein the thickness of the circular micro-perforated plate is in the range of 0.3 mm to 1 mm.

18. 7. The acoustic device of claim 6, wherein the Young's modulus of the micro-perforated plate is in the range of 5 GPa to 200 GPa.

19. 7. The acoustic device of claim 6, wherein the natural frequency of the micro-perforated plate is greater than 500 Hz.

20. 20. The acoustic device of claim 19, wherein the natural frequency of the micro-perforated plate is in the range of 500 Hz to 3.6 kHz.

21. 7. The acoustic device of claim 6, wherein the height of the cavity is in the range of 0.5 mm to 10 mm.

22. 7. The acoustic device of claim 6, wherein the micro-perforated plate comprises a metal micro-perforated plate.

23. 7. The acoustic device according to claim 6, wherein a waterproof ventilation structure is provided on the side of the finely perforated plate facing the vibration membrane.

24. Further comprising a magnetic circuit assembly and a coil; 7. The acoustic device of claim 6, wherein the coil is connected to the diaphragm and at least a portion of the coil is located in a magnetic gap formed by the magnetic circuit assembly, the coil vibrates the diaphragm to generate sound when energized, and the micro-perforated plate includes an annular structure disposed around the magnetic circuit assembly.

25. Further comprising a magnetic circuit assembly and a coil; 7. The acoustic device of claim 6, wherein the coil is connected to the diaphragm and at least a portion of the coil is located in a magnetic gap formed by the magnetic circuit assembly, the coil vibrates the diaphragm to generate sound when energized, and the fine-perforated plate and the magnetic circuit assembly are spaced apart in the vibration direction of the diaphragm.

26. Further comprising a magnetic circuit assembly and a coil; 7. The acoustic device of claim 6, wherein the coil is connected to the diaphragm and is at least partially located in a magnetic gap formed by the magnetic circuit assembly, the coil vibrates the diaphragm to generate sound when energized, and the micro-perforated plate includes a magnetic permeable element of the magnetic circuit assembly.

27. A diaphragm; a housing that accommodates the diaphragm and has a first acoustic cavity and a second acoustic cavity formed corresponding to a front side and a rear side of the diaphragm, respectively, the diaphragm radiating sound to the first acoustic cavity and the second acoustic cavity, respectively, and emitting sound from a first acoustic hole coupled to the first acoustic cavity and a second acoustic hole coupled to the second acoustic cavity, respectively; and a sound absorbing structure coupled to the second acoustic cavity for absorbing sound that passes through the second acoustic cavity within a target frequency range and is transmitted to the second acoustic hole, wherein within the target frequency range, a sound pressure level of the second acoustic hole when the sound absorbing structure is not installed is greater than a sound pressure level of the second acoustic hole when the sound absorbing structure is installed.

28. 28. Acoustic device according to claim 27, characterized in that the target frequency range comprises 3 kHz to 6 kHz.

29. 29. The acoustic device according to claim 28, characterized in that within the target frequency range, a difference between a sound pressure level of the second acoustic hole when the sound absorbing structure is not installed and a sound pressure level of the second acoustic hole when the sound absorbing structure is installed is 3 dB or more.

30. 28. Acoustic device according to claim 27, characterized in that the target frequency range includes a resonant frequency of the second acoustic cavity.

31. 31. The acoustic device according to claim 30, characterized in that at the resonant frequency, the difference between the sound pressure level of the second acoustic hole when the sound absorbing structure is not installed and the sound pressure level of the second acoustic hole when the sound absorbing structure is installed is 14 dB or more.

32. 28. The acoustic device of claim 27, wherein the absorbing structure comprises a micro-perforated plate and a cavity, the micro-perforated plate including a through hole, and the second acoustic cavity coupled to the absorbing structure communicates with the cavity via the through hole.

33. 33. An acoustic device as claimed in claim 32, characterised in that the cavity is filled with N'Bass sound absorbing particles.

34. 34. An acoustic device as claimed in claim 33, characterised in that the diameter of said N'Bass sound absorbing particles is in the range of 0.15mm to 0.7mm.

35. 34. An acoustic device as claimed in claim 33, characterised in that the filling rate of said N'Bass sound absorbing particles in said cavity is in the range of 70% to 95%.

36. 34. The acoustic device of claim 33, wherein gauze is disposed between the N'Bass sound absorbing particles and the micro-perforated plate.

37. 33. An acoustic device according to claim 32, characterised in that the cavity is filled with a porous sound absorbing material, the porous sound absorbing material having a porosity greater than 70%.

38. 33. The acoustic device according to claim 32, wherein a ratio of a hole spacing between the through holes to a hole diameter of the through holes is greater than 5.

39. 40. The acoustic device of claim 38, wherein a ratio of a wavelength of sound in the target frequency range to a hole spacing between the through-holes of the fine-perforated plate is greater than 5.

40. The acoustic device of claim 32 or 39, characterized in that the hole diameter of the through hole is in the range of 0.1 mm to 0.2 mm, the aperture ratio of the fine-perforated plate is in the range of 2% to 5%, the thickness of the fine-perforated plate is in the range of 0.2 mm to 0.7 mm, and the height of the cavity is in the range of 7 mm to 10 mm.

41. The acoustic device of claim 32 or 39, characterized in that the hole diameter of the through hole is in the range of 0.2 mm to 0.4 mm, the aperture ratio of the fine-perforated plate is in the range of 1% to 5%, the thickness of the fine-perforated plate is in the range of 0.2 mm to 0.7 mm, and the height of the cavity is in the range of 4 mm to 9 mm.

42. 33. The acoustic device of claim 32, wherein the micro-perforated plate comprises a racetrack micro-perforated plate or a circular micro-perforated plate.

43. 43. An acoustic device according to claim 42, characterized in that the thickness of said circular micro-perforated plate is in the range of 0.3 mm to 1 mm.

44. 33. An acoustic device according to claim 32, characterized in that the Young's modulus of the micro-perforated plate is in the range of 5 GPa to 200 GPa.

45. 33. An acoustic device as claimed in claim 32, characterized in that the natural frequency of the micro-perforated plate is greater than 500 Hz.

46. 46. ​​Acoustic device according to claim 45, characterized in that the natural frequency of the micro-perforated plate is in the range of 500 Hz to 3.6 kHz.

47. 33. Acoustic device according to claim 32, characterised in that the height of the cavity is in the range of 0.5 mm to 10 mm.

48. 33. The acoustic device of claim 32, wherein the micro-perforated plate comprises a metal micro-perforated plate.

49. 33. The acoustic device according to claim 32, wherein a waterproof ventilation structure is provided on the side of the finely perforated plate facing the vibration membrane.

50. Further comprising a magnetic circuit assembly and a coil; 33. The acoustic device of claim 32, wherein the coil is connected to the diaphragm and at least a portion of the coil is located in a magnetic gap formed by the magnetic circuit assembly, the coil vibrates the diaphragm to generate sound when energized, and the micro-perforated plate includes an annular structure centered on the magnetic circuit assembly.

51. Further comprising a magnetic circuit assembly and a coil; The acoustic device of claim 32, wherein the coil is connected to the diaphragm and at least a portion of the coil is located in a magnetic gap formed by the magnetic circuit assembly, the coil vibrates the diaphragm to generate sound when energized, and the fine-perforated plate and the magnetic circuit assembly are spaced apart in the vibration direction of the diaphragm.

52. Further comprising a magnetic circuit assembly and a coil; 33. The acoustic device of claim 32, wherein the coil is connected to the diaphragm and is at least partially located in a magnetic gap formed by the magnetic circuit assembly, the coil vibrates the diaphragm to generate sound when energized, and the micro-perforated plate includes a magnetically permeable element of the magnetic circuit assembly.

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