Acoustic output device

Abstract

One or more embodiments of the present specification relate to an acoustic output device comprising: a housing; the first loudspeaker is arranged in the shell and is acoustically coupled with two hole parts arranged on the shell so as to respectively output a first sound wave and a second sound wave with phase difference; the second loudspeaker is arranged in the shell and is acoustically coupled with a hole part arranged on the shell so as to output a third sound wave; the processing circuit is configured to provide a first electric signal for the first loudspeaker and provide a second electric signal for the second loudspeaker, and in a target frequency range, the first electric signal and the second electric signal have difference in amplitude and / or phase, so that far-field radiation sound of the acoustic output device presents at least one sound pressure distribution with directivity.

Description

Acoustic output device Technical Field

[0001] This specification relates to the field of acoustics, and in particular to an acoustic output device. Background Art

[0002] To address sound leakage in acoustic output devices, two sound sources are typically used, each emitting two sets of sounds with opposite phases. In far-field conditions, the difference in acoustic path length between these two sound sources, each with its own phase opposition, is essentially negligible. Therefore, the two sets of sounds cancel each other out, reducing far-field sound leakage. While this method can achieve a certain degree of sound leakage reduction, it still has certain limitations.

[0003] Summary of the Invention

[0004] An embodiment of the present specification provides an acoustic output device, comprising: a housing; a first speaker disposed within the housing, the first speaker comprising a first diaphragm, wherein a first front cavity and a first rear cavity are respectively provided on the front and rear sides of the first diaphragm within the housing, the first front cavity and the first rear cavity being acoustically coupled to two holes provided in the housing to respectively output a first sound wave and a second sound wave having a phase difference; a second speaker disposed within the housing, the second speaker comprising a second diaphragm, wherein a second front cavity and a second rear cavity are respectively provided on the front and rear sides of the second diaphragm within the housing, only one of the second front cavity and the second rear cavity being acoustically coupled to a hole provided in the housing to output a third sound wave; and a processing circuit configured to provide a first electrical signal to the first speaker and a second electrical signal to the second speaker, wherein within a target frequency range, the first electrical signal and the second electrical signal have an amplitude and / or phase difference, such that far-field radiated sound of the acoustic output device exhibits at least one directional sound pressure distribution.

[0005] Other embodiments of the present specification further provide an acoustic output device, comprising: a housing; a first speaker disposed within the housing, the first speaker comprising a first diaphragm, wherein within the housing, a first front cavity and a first rear cavity are respectively provided on the front and rear sides of the first diaphragm, the first front cavity and the first rear cavity are acoustically coupled to two holes provided in the housing to respectively output a first sound wave and a second sound wave with a phase difference; a second speaker disposed within the housing, the second speaker comprising a second diaphragm, wherein within the housing, a second front cavity and a second rear cavity are respectively provided on the front and rear sides of the second diaphragm, only one of the second front cavity and the second rear cavity is acoustically coupled to a hole provided in the housing to output a third sound wave; and a processing circuit configured to provide a first electrical signal to the first speaker and a second electrical signal to the second speaker, the processing circuit being capable of obtaining a plurality of filter function groups, each of the filter function groups comprising a first filter function and a second filter function corresponding to the first electrical signal and the second electrical signal, respectively, the first electrical signal and the second electrical signal being modulated in response to the first filter function and the second filter function, respectively, and different filter function groups providing different sound pressure distributions for the acoustic output device at the same frequency.

[0006] Other embodiments of the present specification also provide an acoustic output device, comprising: a shell; a first speaker, disposed in the shell, the first speaker outputting sound waves outward through at least one hole on the shell, and the first speaker having a first response function in the far field; a second speaker, disposed in the shell, the second speaker outputting sound waves outward through at least one hole on the shell, and the second speaker having a second response function in the far field; a processing circuit, configured to provide a first electrical signal to the first speaker and a second electrical signal to the second speaker, the processing circuit constructing at least one set of constraint functions based on the first response function and the second response function, each set of constraint functions generating a first filter function corresponding to the first electrical signal and a second filter function corresponding to the second electrical signal, the first electrical signal and the second electrical signal respectively responding to modulation of the first filter function and the second filter function, and each set of constraint functions providing a specific sound pressure distribution for the acoustic output device. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] This specification will be further described in the form of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting, and in these embodiments, like numbers represent like structures, wherein:

[0008] FIG1 is a schematic diagram illustrating the relative positions of an acoustic output device and a user's ear according to some embodiments of this specification;

[0009] FIG2 is a schematic diagram of the sound pressure level and sound pressure distribution of the acoustic output device shown in FIG1 ;

[0010] FIG3 is a schematic block diagram of adjusting an electrical signal according to some embodiments of this specification;

[0011] FIG4 is a sound pressure level curve obtained by testing according to some embodiments of this specification;

[0012] FIG5 is a time domain and frequency domain graph of filter functions ω1 and ω2 according to some embodiments of this specification;

[0013] FIG6 is a diagram of sound pressure distribution obtained by testing according to some embodiments of this specification;

[0014] 7 to 10 are schematic diagrams of acoustic output devices with different structures according to some embodiments of this specification;

[0015] FIG11 is a schematic structural diagram of an acoustic output device according to other embodiments of this specification;

[0016] FIG. 12 is a schematic diagram of directivity according to some embodiments of this specification. DETAILED DESCRIPTION

[0017] To more clearly illustrate the technical solutions of the embodiments of this specification, the following briefly describes the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of this specification. Those skilled in the art can apply this specification to other similar scenarios based on these drawings without inventive effort. Unless otherwise apparent from the context or otherwise noted, the same reference numerals in the figures represent the same structure or operation.

[0018] It should be understood that the terms "system," "device," "unit," and / or "module" used herein are a method for distinguishing different components, elements, parts, portions, or assemblies at different levels. However, if other terms can achieve the same purpose, the terms may be replaced by other expressions.

[0019] As used in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not refer to the singular but also include the plural. Generally speaking, the terms "comprises" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0020] Flowcharts are used throughout this specification to illustrate the operations performed by systems according to embodiments of this specification. It should be understood that preceding or following operations do not necessarily need to be performed in exact order. Instead, the steps may be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more operations may be removed from these processes.

[0021] In some embodiments, to address sound leakage from an acoustic output device, two sound sources with opposite phases can be used to produce two sets of sounds with opposite phases. In far-field conditions, the difference in acoustic path length between the two sound sources with opposite phases reaching a point in the far field is essentially negligible, so the two sets of sounds can cancel each other out, reducing far-field sound leakage.

[0022] FIG1 is a schematic diagram illustrating the relative positions of an acoustic output device and a user's ear according to some embodiments of this specification. As shown in FIG1 , the acoustic output device 100 may include a housing 110 and a speaker 120. The speaker 120 may be disposed within the cavity formed by the housing 110. The speaker 120 includes a diaphragm. Within the cavity of the housing 110, the diaphragm is provided with a front cavity 130 and a rear cavity 140, respectively, for radiating sound. The housing 110 is provided with a first hole 111 and a second hole 112. The front cavity 130 may be acoustically coupled to the first hole 111, and the rear cavity 140 may be acoustically coupled to the second hole 112. The speaker 120 generates sound waves in response to an electrical signal. When the speaker 120 outputs sound waves, the sound waves on the front side of the diaphragm (or first sound waves) may be emitted from the first hole 111 through the front cavity 130, while the sound waves on the rear side of the diaphragm (or second sound waves) may be emitted from the second hole 112 through the rear cavity 140. At this time, the first hole portion 111 and the second hole portion 112 can be regarded as a set of dual sound sources, which can emit two sets of sounds with the same amplitude but opposite phases. For ease of understanding, in some embodiments of this specification, the front side of the diaphragm refers to the side of the diaphragm facing away from the magnetic circuit assembly; the back side of the diaphragm refers to the side of the diaphragm facing the magnetic circuit assembly. Of course, in some scenarios, the front side and back side of the diaphragm can be interchangeable, that is, the side of the diaphragm facing away from the magnetic circuit assembly can be regarded as the back side, and the side of the magnetic circuit assembly facing away from the diaphragm can be regarded as the front side.

[0023] In some embodiments, as shown in FIG1 , when a user wears or uses the acoustic output device 100, the acoustic output device 100 can be located near the user's auricle 200, and the first hole portion 111 can face the user's ear canal opening 201, so that sound emitted from the first hole portion 111 can be transmitted toward the user's ear canal opening 201. The second hole portion 112 can be farther away from the ear canal opening 201 than the first hole portion 111, and the distance between the first hole portion 111 and the ear canal opening is smaller than the distance between the second hole portion 112 and the ear canal opening.

[0024] In some embodiments, when the speaker 120 vibrates, the front and rear sides of the speaker 120 can each function as a sound wave generating structure, generating sound waves of equal amplitude and opposite phase. These sound waves of equal amplitude and opposite phase can radiate outward through the first hole 111 and the second hole 112, respectively, forming dual sound sources. These dual sound sources can destructively interfere with each other at a spatial point (e.g., the far field), thereby effectively improving sound leakage in the far field of the earphone 100.

[0025] Figure 2 is a schematic diagram of the sound pressure level and sound pressure distribution of the acoustic output device shown in Figure 1. As shown in Figure 2, the sound pressure distribution of the acoustic output device 100 shows obvious directivity, and its sound leakage reduction effect in certain directions is significant. Specifically, in the medium and low frequency bands, the dual sound sources formed by the first hole portion 111 and the second hole portion 112 of the acoustic output device 100 output sound waves with opposite phases (i.e., the first sound wave and the second sound wave), and the sound field forms two lobe-shaped structures in space. In the two opposite directions of the line connecting the dual sound sources, the sound pressure level is large, and in the direction perpendicular to the line connecting the dual sound sources, the sound pressure level is small, that is, the sound leakage reduction effect is better. For the two lobe-shaped structures formed in the sound field, one of the lobe-shaped structures will be away from the user's ear, resulting in a larger sound leakage, which increases the sound leakage performance of the acoustic output device.

[0026] When the two sound sources have opposite phases, the sound field distribution of the acoustic output device in the far field has clear directionality. At this time, in the direction of the connection between the two sound sources, the acoustic output device will produce a large far-field sound leakage, which brings a bad user experience to the application in a specific scenario (for example, a scenario with a high sound leakage reduction demand in the direction of the connection between the two sound sources). In some embodiments, in order to provide the acoustic output device with a flexible sound leakage reduction effect that meets the needs of specific scenarios, when using two sound sources, the amplitude and / or phase (for example, amplitude, phase, or amplitude and phase) of the first sound wave and the second sound wave can be adjusted so that the far-field sound pressure of the acoustic output device in a specific direction or within a specific direction range is within the desired range. In some alternative embodiments, multiple sound sources with more than two sound sources can be used, and by controlling the amplitude and / or phase of the sound waves emitted by each sound source respectively, the far-field sound pressure of the acoustic output device in a specific direction or within a specific direction range can also be within the desired range.

[0027] In some embodiments, in order to facilitate the adjustment of the amplitude and / or phase of the sound waves emitted by each sound source, the acoustic output device may include several speakers driven by independent electrical signals. By modulating the electrical signals driving the several speakers separately, for example, applying different filter functions to the electrical signals corresponding to the several speakers, the sound waves generated by each sound source (i.e., each hole portion coupled to the speaker on the acoustic output device) can present an amplitude and / or phase relationship that meets the conditions, thereby flexibly adjusting the sound pressure distribution formed by the acoustic output device in the far field to ensure the sound leakage reduction effect of the acoustic output device in a specific direction or within a specific direction range, meeting the different needs of users in different application scenarios. For illustrative purposes only, the following will take the acoustic output device including two speakers as an example to illustrate the method of regulating the sound pressure distribution and the corresponding structure. It should be noted that when the acoustic output device includes more speakers, the method of regulating the sound pressure distribution and the corresponding structure can be obtained by analogy with the contents disclosed in some embodiments of this specification without inventive work.

[0028] In some embodiments, the acoustic output device includes a first speaker, a second speaker, and a processing circuit. The first speaker and the second speaker are disposed within a housing. The first speaker includes a first diaphragm, the processing circuit provides a first electrical signal to the first speaker, and the first diaphragm generates sound waves in response to the first electrical signal. The second speaker includes a second diaphragm, the processing circuit provides a second electrical signal to the second speaker, and the second diaphragm generates sound waves in response to the second electrical signal.

[0029] The sound waves generated by the first diaphragm and the second diaphragm can be radiated outside the shell through one or more holes on the shell. For example, the first speaker is acoustically coupled to two holes on the shell (e.g., the first hole and the second hole) to output the first sound wave and the second sound wave with a phase difference, respectively. The second speaker is acoustically coupled to two holes provided on the shell (e.g., the third hole and the fourth hole) to output the third sound wave and the fourth sound wave with a phase difference, respectively. At this time, the first speaker and the second speaker both form dual sound sources, and the first sound wave, the second sound wave, the third sound wave and the fourth sound wave can be superimposed in the far field. For another example, the first speaker is acoustically coupled to two holes on the shell (e.g., the first hole and the second hole) to output the first sound wave and the second sound wave, respectively. The second speaker is acoustically coupled to only one hole provided on the shell (e.g., the third hole) to output the third sound wave. At this time, the first speaker forms a dual sound source, and the second speaker forms a single sound source, and the first sound wave, the second sound wave and the third sound wave can be superimposed in the far field. For another example, the first speaker is acoustically coupled only to one hole portion (e.g., the first hole portion) on the shell to output a first sound wave. The second speaker is acoustically coupled only to one hole portion (e.g., the third hole portion) provided on the shell to output a third sound wave. At this time, the first speaker and the second speaker both form a single sound source, and the first sound wave and the third sound wave can be superimposed in the far field. For relevant descriptions of the specific structure of the acoustic output device, please refer to the contents of other parts of this specification. For example, Figures 7 to 11 and their corresponding contents illustrate the specific structure of the acoustic output device by taking the first speaker forming a dual sound source and the second speaker forming a single sound source as an example.

[0030] In some embodiments, the amplitude and / or phase of the first electrical signal and the second electrical signal can be modulated so that the second electrical signal and the first electrical signal have a certain amplitude and / or phase difference within the target frequency range. When the sound waves output by the second speaker and the sound waves output by the first speaker are superimposed in the far field, the far-field radiation of the acoustic output device can present a specific sound pressure distribution. For example, the far-field sound pressure distribution of the acoustic output device can be directional, which is manifested as a lower intensity of the far-field sound pressure in a specific direction or a specific direction range, thereby improving the sound leakage problem of the acoustic output device in the far field in the specific direction or a specific direction range.

[0031] The above-mentioned target frequency range refers to the frequency range in which a specific directivity of the sound pressure distribution can be achieved. In some embodiments, the amplitude and / or phase of the first electrical signal and the second electrical signal are modulated in different ways in different frequency ranges, which can satisfy the requirement that the far-field radiation of the acoustic output device presents the desired sound pressure distribution in different frequency ranges. In some embodiments, the target frequency range may include frequency bands to which the human ear is more sensitive, including 200Hz-8000Hz. Constructing the sound pressure distribution of the acoustic output device in the far-field position within the frequency band to which the human ear is more sensitive can reduce far-field sound leakage radiated in directions where others are likely to appear, which is beneficial to reducing interference with others and protecting the privacy of the user's listening.

[0032] In some embodiments, the processing circuit of the acoustic output device includes a filter. The filter can be used to adjust the amplitude and / or phase of the electrical signal to output the desired first electrical signal and the second electrical signal to the first speaker and the second speaker respectively. In some embodiments, the filter processes the signal based on the filter function to adjust the amplitude and / or phase of the first electrical signal and the second electrical signal within the target frequency range. In some embodiments, the filter can select an infinite impulse response (IIR) filter. The IIR filter has a small amount of calculation and good real-time performance. In some embodiments, the filter can also select a finite impulse response (FIR) filter. The FIR filter has good stability and controllable phase, and can enable synchronous input signals to be output synchronously while performing amplitude selection to avoid signal distortion.

[0033] FIG3 is a schematic block diagram of adjusting an electrical signal according to some embodiments of this specification.

[0034] The processing circuit can provide one or more filter function groups, each filter function group including a first filter function ω1 and a second filter function ω2 corresponding to the first electrical signal and the second electrical signal, respectively, and the first electrical signal and the second electrical signal respond to the modulation of the first filter function ω1 and the second filter function ω2, respectively. As shown in Figure 3, the filters of the processing circuit may include a first filter and a second filter, which accept the first filter function ω1 and the second filter function ω2 from the plurality of filter function groups, filter the first electrical signal and the second electrical signal passing through, and thereby control the acoustic signals output by the first speaker and the second speaker.

[0035] In some embodiments, the amplitudes and / or phases of the first electrical signal and the second electrical signal modulated by different filter function groups are different, thereby affecting the acoustic output of the first speaker and the second speaker, and providing different sound pressure distributions for the acoustic output device.

[0036] In some embodiments, the first filter function ω1 and the second filter function ω2 can be determined based on a constraint function. The constraint function is a functional expression that constrains the sound pressure distribution of the acoustic sound-emitting device (including the first speaker and the second speaker) in the far field. The constraint function is related to the output capability of each speaker in the acoustic output device in the far field. The output capability of a speaker in the far field can be expressed as a response function of the speaker in the far field, and the response function can characterize the sound pressure level of the speaker at the far field position.

[0037] In some embodiments, the response function of the loudspeaker in the far field can be obtained by actual measurement or simulation. As an example only, a circular boundary with the acoustic output device as the center (for example, the centroid of the multiple sound sources is regarded as the center of the circle) and a sufficiently large radius is approximated as the far-field position of the acoustic output device. A microphone is set to collect microphone responses at various positions on the circular boundary. For example, on the circular boundary, the corresponding microphone response IR when the loudspeaker is excited is collected every x°. In some embodiments, when the radius is large enough, the position of the microphone can be regarded as the far-field position of the acoustic output device. At this time, the distance between the microphone and the acoustic output device is greater than a preset distance threshold, for example, greater than 25 cm. Since sound waves of different frequencies have different wavelengths, for shorter wavelengths, the far-field position of the acoustic output device can be closer to the acoustic output device. In some embodiments, when the frequency range of the excitation signal is 1000 Hz-4000 Hz, the far-field position of the acoustic output device can refer to a position that is greater than 5.5 cm away from the acoustic output device.

[0038] In some embodiments, the smaller the value of x, the more accurate the sound pressure distribution diagram drawn by the corresponding simulation. In some embodiments, in order to reduce the burden of simulation work, x° can be in the range of 5°-10°. In some embodiments, the test signal that excites the speaker can be a swept frequency signal, and the frequency range of the swept frequency signal is 200Hz-8000Hz, so as to test the sound pressure distribution of the speaker in the frequency range of 200Hz-8000Hz. In some embodiments, the swept frequency signal can refer to a signal that gradually changes from 200Hz to 8000Hz, and the swept frequency signal only includes a single frequency signal at any time, and the swept frequency signal can simulate a simple signal input. It should be noted that the method of obtaining the response function of the speaker exemplified here is not the only way to obtain the response function of the speaker. Those skilled in the art can make appropriate adjustments or changes to this method based on the purpose.

[0039] In some embodiments, in order to minimize the far-field sound pressure level of the acoustic output device in a specific direction, so as to achieve the effect of minimizing the far-field sound leakage of the acoustic output device in the specific direction, the response function of each speaker in the specific direction can be combined to construct a constraint function that characterizes the sound pressure level of the acoustic output device in the specific direction. For the convenience of description, the response function of the speaker in the β° direction is expressed as IR β By minimizing the constraint function, the sound pressure of the acoustic output device in the β° direction can be made to have a smaller intensity. Specifically, the constraint function is composed of the response function and filter function ω corresponding to each speaker. When the constraint function is minimized, the filter function ω corresponding to each speaker when the acoustic output device presents directivity in the β° direction can be obtained. In other words, when the electrical signal is modulated by the aforementioned filter function ω and then excites the speaker, the sound pressure distribution of the acoustic output device can be made to present directivity in the β° direction.

[0040] For example only, the first response function of the first loudspeaker in the β° direction is denoted as IR1 β° , the second response function of the second loudspeaker in the β° direction is recorded as IR2 β° In some embodiments, in order to adjust the sound pressure distribution of the first speaker and the second speaker radiating outward simultaneously, the sound pressure corresponding to the first speaker and the second speaker modulated by the first filter function ω1 and the second filter function ω2 are expressed as ‖ω1*IR1 β° ‖ and ‖ω2*IR2 β° ‖Combination forms constraint function‖ω1*IR1 β° +ω2*IR2 β° ‖ (also called the "first constraint function"). The first constraint function can represent the sound pressure level output by the acoustic output device in the β° direction. When minimizing the first constraint function, a first filter function ω1 and a second filter function ω2 corresponding to the acoustic output device presenting a smaller sound pressure level in the β° direction can be obtained.

[0041] In some embodiments, the first filter is used to filter the first electrical signal based on the first filter function ω1, and the second filter is used to filter the second electrical signal based on the second filter function ω2, and the first electrical signal and the second electrical signal generated after the processing are used to excite the first speaker and the second speaker respectively, so as to achieve the directivity of the acoustic output device in the β° direction, that is, the sound pressure in the β° direction has a smaller intensity. For example, taking a dual sound source as an example, when the directivity of the acoustic output device in the direction of the dual sound source connection (for example, the 180° direction described in the relevant content of Figures 7 to 11 of this specification, that is, the direction from the first hole 311 to the second hole 312 (also called the second direction)) is to be achieved, it is necessary to set the response functions of the first speaker and the second speaker in the 180° direction to IR1, respectively.180° and IR2 180° Substitute the first constraint function to obtain the first constraint function ‖ω1*IR1 180° +ω2*IR2 180° ‖.

[0042] In some embodiments, based on ‖ω1*IR1 180° +ω2*IR2 180° ‖The first filter function ω1 and the second filter function ω2 are obtained, and the first electrical signal and the second electrical signal processed based on the first filter function ω1 and the second filter function ω2 are used to simultaneously excite the first loudspeaker and the second loudspeaker. The sound pressure level curve obtained by the test is shown in FIG4. FIG4 is a sound pressure level curve obtained by testing according to some embodiments of the present specification. As shown in FIG4, the horizontal axis represents the frequency in Hz, and the vertical axis represents the sound pressure level in dB. Curve 61 is the sound pressure level curve of the acoustic output device in the opposite direction of 180°, that is, in the 0° direction (that is, the first direction described in the relevant contents of FIG7 to FIG11 of this specification, that is, the direction in which the second hole portion 312 points to the first hole portion 311) under the excitation signal of 200Hz-8000Hz. Curve 62 is the sound pressure level curve of the acoustic output device in the 180° direction under the excitation signal of 200Hz-8000Hz. As can be seen from FIG4, after the sound pressure level is determined based on ‖ω1*IR1 180° +ω2*IR2 180° ‖Under the excitation of the first electric signal and the second electric signal modulated by the obtained first filter function ω1 and the second filter function ω2, the difference in sound pressure level between the 0° direction and the 180° direction can be achieved to be 12dB-25dB, and the far-field sound pressure level in the 180° direction is effectively reduced, showing good directivity and effective sound leakage reduction in the 180° direction. Moreover, the difference in sound pressure level under the excitation of electric signals of different frequencies is different, that is, the sound leakage reduction effect at different frequencies is different. It can be seen that the filter functions ω1 and ω2 obtained by the above method can provide a specific sound pressure distribution for the acoustic output device to achieve the directivity of the acoustic output device in a specific direction.

[0043] In some embodiments, by constructing a specific constraint function and performing a minimization process, the acoustic output device can have a smaller far-field sound pressure within a specific direction range, that is, the average sound pressure level within the specific direction range is smaller. The specific direction range mentioned here refers to the direction range between one angular direction and another angular direction, or refers to the direction range near an angular direction, and the direction range directly refers to all directions within a fan-shaped area. The direction range here can be understood as the area range with an angle less than a certain degree with a certain direction. As an example only, for ease of description, the direction in the acoustic output device shown in Figures 7 to 11 is taken as an example, that is, the direction of the first hole portion 311 pointing to the second hole portion 312 is taken as the 180° direction (also called the second direction), and the direction of the second hole portion 312 pointing to the first hole portion 311 is taken as the 0° direction (also called the first direction). At this time, the specific direction range can be a 135° to 225° direction range, which refers to all directions in the fan-shaped area between the 135° direction and the 225° direction, or refers to all directions in the fan-shaped area composed of two angular directions with an angle less than 45° with the 180° direction.

[0044] As an example only, to achieve the directivity of the first speaker and the second speaker in the direction range of α° to β°, the sound pressure corresponding to the first speaker and the second speaker in the direction range of α° to β° are expressed as ‖ω1*(IR1 α° +…+IR1 β° )‖ and‖ω2*(IR2 α° +…+IR2 β° )‖ can form another set of constraint functions‖ω1*(IR1 α° +…+IR1 β° )+ω2*(IR2 α° +…+IR2 β° )‖ (also called the "second constraint function"). The second constraint function can represent the average sound pressure level of the acoustic output device within the α° to β° direction range. When minimizing the second constraint function, two filter functions ω1 and ω2 corresponding to minimizing the average sound pressure of the acoustic output device within the α° to β° direction range can be obtained.

[0045] In some embodiments, after obtaining the first filter function ω1 and the second filter function ω2 based on the second constraint function, the first filter can filter the first electrical signal based on the first filter function ω1, and the second filter can filter the second electrical signal based on the second filter function ω2, and the first electrical signal and the second electrical signal generated after processing can respectively excite the first loudspeaker and the second loudspeaker, so as to achieve the directivity of the acoustic output device in the direction range of α° to β°, that is, the average sound pressure in the direction range of α° to β° is minimized. For example, when the directivity of the acoustic output device in the direction range of 135° to 225° is to be achieved, the second constraint function is constructed as ‖ω1*(IR1 135° +…+IR1 225° )+ω2*(IR2 135° +…+IR2 225° )‖, minimize the second constraint function to obtain the corresponding first filter function ω1 and second filter function ω2, and make the first electric signal and the second electric signal modulated by the first filter function ω1 and the second filter function ω2 respectively excite the first loudspeaker and the second loudspeaker, so as to realize the directivity of the acoustic output device in the direction range of 135° to 225°.

[0046] FIG5 is a time domain and frequency domain graph of the filter functions ω1 and ω2 according to some embodiments of this specification. In some embodiments, based on the first constraint function ‖ω1*IR1 180° +ω2*IR2 180°The minimum value of ‖ can obtain the first filter function ω1 and the second filter function ω2, as shown in (a) of Figure 5. Wherein, the horizontal axis of (a) of Figure 5 represents the period (T / 64s), the vertical axis represents the normalized amplitude (1), and T is the time of one period of the sampling signal. The first electrical signal and the second electrical signal processed based on the first filter function ω1 and the second filter function ω2 respectively excite the first speaker and the second speaker, and the sound pressure level of the acoustic output device obtained by testing is shown in (b) of Figure 5. Wherein, the horizontal axis of (b) of Figure 5 represents the frequency in Hz, and the vertical axis represents the sound pressure level in dB. Figure 6 is a sound pressure distribution diagram obtained by testing according to some embodiments of this specification. As shown in Figure 6, curve 81 represents the sound pressure distribution with the minimum sound pressure level in the 180° direction, and curve 82 represents the sound pressure distribution with the minimum average sound pressure level in the direction range of 135° to 225°. By comparing curve 81 and curve 82, it can be seen that the first filter function ω1 and the second filter function ω2 obtained based on the first constraint function can enable the acoustic output device to achieve directivity in a specific direction, for example, the sound pressure level in the 180° direction is the minimum and the sound pressure level in the 0° direction is the maximum, while the first filter function ω1 and the second filter function ω2 obtained based on the second constraint function can enable the acoustic output device to achieve the minimum average sound pressure level in different directions within the direction range of 135° to 225°. This means that the ω1 and ω2 obtained based on the first constraint function make the acoustic output device have a stronger sound leakage reduction effect in the 180° direction, but the range of sound leakage reduction is narrower, while the ω1 and ω2 obtained based on the second constraint function weaken the sound leakage reduction effect of the acoustic output device in a specific direction, but expand the directional range of sound leakage reduction. In other words, the first constraint function and the second constraint function can meet the needs of different user application scenarios and improve the sound leakage reduction effect in a targeted manner according to different environments. Figures a, b, c, d, e, and f in Figure 6 represent the sound pressure distributions for excitation signals of 500 Hz, 1000 Hz, 2000 Hz, 3000 Hz, 4000 Hz, and 5000 Hz, respectively. As can be seen from Figures a, b, c, d, e, and f in Figure 6, by constructing a constraint function, the acoustic output device can achieve the desired sound pressure distribution at different frequencies.

[0047] In some embodiments, the processing circuit can provide multiple sets of constraint functions, and different sets of constraint functions can provide different sound pressure distributions for the acoustic output device. For example, at the same frequency, different sets of constraint functions can make the minimum far-field sound pressure levels of the acoustic output device correspond to different directions. Among them, the different directions corresponding to the minimum far-field sound pressure level can refer to the pointing direction of the acoustic output device or the direction range corresponding to the directivity within a specific direction range (hereinafter referred to as the pointing direction range). In other words, the pointing direction or pointing direction range of the acoustic output device can be adjusted at the same frequency based on different sets of constraint functions. In order to achieve this purpose, different first constraint functions or second constraint functions corresponding to different directions can be determined, and the first constraint function or the second constraint function can be minimized to obtain different sets of first filter functions and second filter functions. Based on the modulation of the electrical signal by the first filter function and the second filter function, the pointing direction or pointing direction range of the acoustic output device can be adjusted at the same frequency. In some embodiments, due to the different wearing angles of the acoustic output device, the direction of the acoustic output device's sound leakage reduction needs to be adjusted accordingly. At this time, the pointing direction of the acoustic output device can be adjusted at the same frequency based on the constraint function, and the direction corresponding to the minimum far-field sound pressure level of the acoustic output device is adjusted to the opposite direction of the user's ear. In some embodiments, for different user application scenarios, the acoustic output device needs to adjust different sound leakage reduction ranges. For example, in relatively quiet usage scenarios such as libraries and offices, the filter function can be selected according to the different requirements for sound leakage reduction direction, and the direction corresponding to the minimum far-field sound pressure level of the acoustic output device can be adjusted to the direction of other people around. For example, it can be a direction range with an angle of 30 degrees, 40 degrees, 50 degrees, etc. with the sagittal axis of the human body, so as to avoid the interference of sound leakage on other people. For another example, the direction corresponding to the minimum far-field sound pressure level of the acoustic output device can be adjusted based on the filter function according to the different requirements for sound leakage reduction direction corresponding to the use time period of the acoustic output device.

[0048] In some embodiments, the acoustic output device can present different sound pressure distributions at different frequencies. At this time, the processing circuit can provide the speaker with different sets of constraint functions at two different frequencies within the target frequency range. In some embodiments, the pointing direction or pointing direction range of the acoustic output device can be adjusted at two different frequencies based on different sets of constraint functions. In order to achieve this purpose, different first constraint functions or second constraint functions corresponding to different directions can be determined, and the first constraint function or the second constraint function can be minimized to obtain different sets of first filter functions and second filter functions. Based on the modulation of the first electric signal and the second electric signal by the first filter function and the second filter function respectively, the pointing direction or pointing direction range of the acoustic output device can be adjusted at different frequencies. For example, according to the different requirements for the sound leakage reduction effect corresponding to different frequency ranges, the direction corresponding to the minimum far-field sound pressure level of the acoustic output device can be adjusted based on the filter function. Specifically, in the listening frequency band to which the human ear is more sensitive, for example, 2000 Hz-4000 Hz, the minimum far-field sound pressure level of the acoustic output device can be adjusted to point in the opposite direction of the user's ear, while in the listening frequency band to which the human ear is relatively insensitive, for example, 200 Hz-400 Hz, the minimum far-field sound pressure level of the acoustic output device can be adjusted to other directions.

[0049] In some embodiments, the constraint function can be determined based on user input. The processing circuit adjusts the constraint function in real time based on the user input. In some embodiments, the information input by the user is different, the constraint function constructed by the processing circuit is different, and the filter function obtained after minimizing the constraint function is different. In some embodiments, the user can output instructions to the processing circuit to adjust the constraint function and the filter function based on their own needs through the user input module to adjust the sound pressure distribution of the acoustic output device. In some embodiments, the user input may include input methods such as instruction input and voice input. Among them, the instruction input can be implemented based on touch, pressing, etc. For example, the user can input instructions through touch for a time greater than a threshold. For another example, the user can activate the voice input mode of the acoustic output device through touch or the like, and then input instructions verbally.

[0050] As an example, a user can select a mode based on their environment (i.e., the application environment of the acoustic output device). The modes may include noisy environments, quiet environments, etc., or may include first-level environments, second-level environments, and third-level environments. Here, the first, second, and third levels may indicate the sound pressure level of the environment, or the user may directly enter information about the application scenario, such as the application scenario name (office, outdoor, reading, etc.) and the sound pressure level of the environment. In response to the user's mode selection or input information, the processing circuit may process and obtain a new filter function, and use the new filter function to modulate the corresponding electrical signal to adjust the sound pressure distribution. For example, if the user is in a quiet environment or enters the application scenario information of "office", the processing circuit may use a first constraint function to minimize the sound pressure of the acoustic output device in a specific direction. For noisy environments, the processing circuit may use a second constraint function to minimize the sound pressure of the acoustic output device within a specific direction range.

[0051] In some embodiments, the constraint function can also be obtained by responding to signals detected by sensors on the acoustic output device, and the processing circuit adjusts the direction corresponding to the constraint function based on the detection results. For example, if the detection results indicate that the surrounding human voices primarily originate from a direction 180° from the acoustic output device, the constraint function is constructed to reduce the far-field sound pressure level of the acoustic output device in the 180° direction. In some embodiments, different detection results result in different constraint functions adjusted by the processing circuit, and different filter functions are obtained after minimizing the constraint function. In some embodiments, the acoustic output device can automatically identify the user's environment and obtain detection results. The processing circuit adjusts the filter function based on the detection results to adjust the sound pressure distribution of the acoustic output device.

[0052] As just one example, an acoustic output device can use a sensor to identify its environment (e.g., the sound pressure level of the environment), using the information obtained by the sensor as a detection result. In response to the detection result, the processing circuit adjusts a new filter function and uses the new filter function to modulate the corresponding electrical signal, thereby adjusting the sound pressure distribution. In some embodiments, when the application environment of the acoustic output device changes, the sensor can identify the change in the application environment and further identify new information in the new application environment to update the detection result. The processing circuit adjusts the filter function in response to the updated detection result and uses the new filter function to modulate the corresponding electrical signal, thereby adjusting the sound pressure distribution.

[0053] In some embodiments of the present specification, different filter function groups can be determined based on different groups of constraint functions, and the electrical signal can be filtered to generate a first electrical signal and a second electrical signal, respectively, so that the acoustic output device can present different sound pressure distributions to meet the needs of different usage scenarios of the acoustic output device. The following is an illustrative description of the possible sound pressure distributions of the acoustic output device. It should be noted that by setting the filter function, the acoustic output device can present at least one of the different sound pressure distributions described below. In addition, by adjusting the filter function, the acoustic output device can switch between the multiple sound pressure distributions described below to meet the needs of different scenarios. Of course, the following description of the sound pressure distribution is only an example and does not constitute a limitation on other possible sound pressure distribution methods.

[0054] In some embodiments, in conjunction with curve 81 shown in FIG6 , the acoustic output device has a first sound pressure level in the far field in the first direction (the 0° direction shown in FIG6 ), and has a second sound pressure level in the far field in the second direction (the 180° direction shown in FIG6 ). In some embodiments, the first direction and the second direction are related to the positions of the dual or multiple sound sources, that is, the positions of the holes on the acoustic output device. For more relevant descriptions, please refer to FIG7-FIG11 and their related descriptions. The filter function at this time is obtained by minimizing the first constraint function ‖ω1*IR1 associated with the far-field sound pressure in the second direction 180° +ω2*IR2 180° Obtaining, filtering the electrical signal based on the obtained filter function can make the second sound pressure level of the acoustic output device in the 180° direction the minimum far-field sound pressure level. The first direction is close to the user's ear canal opening, and the second direction is away from the user's ear canal opening. When the first sound pressure level is high, the sound volume received by the user is high, which can improve the user's listening experience. When the second sound pressure level is low, the sound leakage volume of the acoustic output device is low, which can improve the sound leakage reduction effect of the acoustic output device.

[0055] In some embodiments, the difference between the first and second sound pressure levels can be used to reflect the sound leakage reduction effect of the acoustic output device. In some embodiments, the direction range near the second direction also has a moderate sound leakage reduction effect. Therefore, the sound leakage reduction range of the acoustic output device can be equivalently considered to be a direction within a fan-shaped area with an angle less than 30° with the second direction.

[0056] In some embodiments, the difference between the first sound pressure level and the second sound pressure level of the acoustic output device is greater than 12dB. This can ensure that the volume of the radiated sound transmitted by the acoustic output device to the user's ear canal opening is large, and the sound leakage of the acoustic output device is small. In some embodiments, at a first frequency, the difference between the first sound pressure level and the second sound pressure level of the acoustic output device is greater than 12dB, and the difference between the far-field sound pressure level in any direction with an angle less than 30° with the second direction and the second sound pressure level is not less than 6dB. Under this sound pressure distribution, the acoustic output device can achieve a strong sound leakage reduction effect in a specific direction, and at the same time, a better sound leakage reduction effect can be achieved within a smaller range of directions. It can be understood that this sound pressure distribution corresponds to the minimum sound pressure level of the acoustic output device in a specific direction as described above. In some embodiments, to further enhance the sound leakage reduction effect of the acoustic output device, the difference between the first sound pressure level and the second sound pressure level of the acoustic output device at the first frequency may be greater than 18 dB, and the difference between the far-field sound pressure level in any direction with an angle less than 30° with the second direction and the second sound pressure level may be no less than 6 dB. In some embodiments, to further enhance the sound leakage reduction effect of the acoustic output device, the difference between the first sound pressure level and the second sound pressure level of the acoustic output device at the first frequency may be greater than 12 dB, and the difference between the far-field sound pressure level in any direction with an angle less than 25° with the second direction and the second sound pressure level may be no less than 6 dB. In some embodiments, to further enhance the sound leakage reduction effect of the acoustic output device, the difference between the first sound pressure level and the second sound pressure level of the acoustic output device at the first frequency may be greater than 12 dB, and the difference between the far-field sound pressure level in any direction with an angle less than 30° with the second direction and the second sound pressure level may be no less than 8 dB. In some embodiments, the first frequency may be in the range of 1000 Hz to 8000 Hz.

[0057] The sound pressure distribution provided in some embodiments of this specification, which achieves a strong sound leakage reduction effect within a smaller directional range, can be applied to scenarios where it is necessary to significantly enhance sound leakage reduction within a smaller directional angle range. For example, it can be used to achieve focused enhancement of sound leakage reduction within a certain directional range to the side of the user while riding public transportation or in relatively fixed application scenarios such as libraries and offices, so as to prevent the leakage of sound output by the acoustic output device from interfering with people within a certain directional range to the side, while also improving the privacy of listening or talking.

[0058] In some embodiments, in conjunction with the curve 82 shown in FIG6 , the acoustic output device has a first sound pressure level in the far field of the first direction, and has a second sound pressure level in the far field of the second direction. The filter function in this case is obtained by minimizing the constraint function ‖ω1*(IR1 135° +…+IR1225° )+ω2*(IR2 135° +…+IR2 225° )‖ is obtained, and filtering the electrical signal based on the obtained filter function can reduce the sound pressure level of the acoustic output device in the directional range of 135° to 225°, thereby improving the sound leakage reduction effect. In some embodiments, the directional ranges near the 135° direction and the 225° direction can also achieve a moderate sound leakage reduction effect. Therefore, in this case, the sound leakage reduction range of the acoustic output device can be equivalently regarded as the directional range of a fan-shaped area with an angle greater than 45° formed with the second direction.

[0059] In some embodiments, the difference between the first and second sound pressure levels of the acoustic output device is greater than 9dB, which can ensure that the volume of the sound radiated by the acoustic output device is greater than 9dB when delivered to the user's ear canal opening, and that the acoustic output device has less sound leakage. In some embodiments, at a second frequency, the difference between the first and second sound pressure levels of the acoustic output device is greater than 9dB, and the angle formed by the direction with a far-field sound pressure level 6dB higher than the second sound pressure level with the second direction is greater than 45°. That is, the sound pressure level within a directional range with an angle less than 45° with the second direction can be 6dB higher than the second sound pressure level. Under this sound pressure distribution, the acoustic output device can achieve a good sound leakage reduction effect over a relatively large directional range. It can be understood that this sound pressure distribution corresponds to the previously described low average sound pressure level of the acoustic output device within a specific directional range. The filter function in this case is obtained by minimizing the constraint function within the directional range with an angle less than 45° with the second direction. In some embodiments, to further enhance the sound leakage reduction effect of the acoustic output device, the difference between the first and second sound pressure levels of the acoustic output device at the second frequency can be greater than 12dB, and the angle formed by the direction having a far-field sound pressure level 6dB higher than the second sound pressure level and the second direction can be greater than 50°. In some embodiments, to further enhance the sound leakage reduction effect of the acoustic output device, the difference between the first and second sound pressure levels of the acoustic output device at the second frequency can be greater than 15dB, and the angle formed by the direction having a far-field sound pressure level 6dB higher than the second sound pressure level and the second direction can be greater than 45°. In some embodiments, to further enhance the sound leakage reduction effect of the acoustic output device, the difference between the first and second sound pressure levels of the acoustic output device at the second frequency can be greater than 12dB, and the angle formed by the direction having a far-field sound pressure level 8dB higher than the second sound pressure level and the second direction can be greater than 45°. In some embodiments, the second frequency can be within the range of 200Hz to 1000Hz.

[0060] The sound pressure distribution that achieves a relatively strong sound leakage reduction effect in a relatively large directional range provided by some embodiments of this specification can be applied to scenarios where enhanced sound leakage reduction is required within a larger directional angle range. For example, it can be applied to scenarios where the crowd around the user is widely and irregularly distributed or where the crowd around the user is far away (such as sports scenes, street scenes, etc.). In such scenarios, it is not necessary to ensure that the acoustic output device has the best sound leakage reduction effect in a specific direction, but the acoustic output device can achieve a certain sound leakage reduction effect within a larger directional range.

[0061] In some embodiments, when an acoustic output device presents a sound field distribution that minimizes the far-field sound pressure level in a specific direction, the directions of the minimum far-field sound pressure level of the acoustic output device can be different at two different frequencies within a target frequency range. In some embodiments, the directions corresponding to the minimum far-field sound pressure level of the acoustic output device at different frequencies can be adjusted by using first constraint functions corresponding to different directions. For example, by constructing different first constraint functions, at one frequency, the far-field sound pressure level of the acoustic output device can be minimized in a direction 180° away; while at another frequency, the far-field sound pressure level of the acoustic output device can be minimized in a direction different from 180°.

[0062] The acoustic output device provided in some embodiments of this specification has different directivities or directions of sound leakage reduction at two different frequencies within the target frequency range, which can be applied to the selection of directivities at different frequencies. As an example only, in the frequency band to which the human ear is more sensitive (e.g., 2000Hz-4000Hz), the direction corresponding to the minimum far-field sound pressure level of the acoustic output device can be made 180°, with special attention paid to the sound leakage reduction within the lateral range of the acoustic output device. In the frequency band to which the human ear is not sensitive (e.g., 5000Hz-8000Hz), the direction corresponding to the minimum far-field sound pressure level of the acoustic output device can be other directions other than the 180° direction, for example, 160°, 200°, etc.

[0063] In some embodiments, when the acoustic output device is actually worn, the direction of the required sound leakage reduction may change due to different wearing angles or other reasons. Therefore, the sound leakage reduction direction of the acoustic output device needs to be adjusted to the actual required sound leakage reduction direction, i.e., the fourth direction. The direction opposite to the fourth direction is the third direction. Based on the constraint function, the direction of the acoustic output device can be adjusted to the direction corresponding to the minimum far-field sound pressure level of the acoustic output device to the fourth direction. The filter function in this case can be obtained by minimizing the constraint function.

[0064] In some embodiments, at the third frequency, the angle formed by the fourth direction and the second direction is greater than 15°, and the difference between the second sound pressure level of the acoustic output device in the second direction and the minimum far-field sound pressure level is greater than 6dB. The sound leakage reduction effect can be guaranteed within a direction range that deviates from the second direction by a large angle. In some embodiments, the angle formed by the fourth direction and the second direction can be greater than 25° at the third frequency, and the difference between the first sound pressure level and the second sound pressure level of the acoustic output device is greater than 6dB. In some embodiments, the angle formed by the fourth direction and the second direction can be adjusted according to the required direction range of sound leakage reduction. For example, the angle formed by the fourth direction and the second direction can be adjusted to be greater than 45° according to the required direction range of sound leakage reduction. In some embodiments, the third frequency can be in the range of 200Hz to 8000Hz.

[0065] Some embodiments of the present specification can provide a sound pressure distribution that ensures a sound leakage reduction effect within a directional range that deviates from the second direction at a large angle. This sound pressure distribution can be applied to scenarios where the sound leakage reduction effect is enhanced within a directional range that deviates from the side of the acoustic output device. For example, it can be applied when a specific person is located in front of or behind the user, and the sound leakage reduction effect is enhanced within the front or rear lateral range to avoid the sound output by the acoustic output device from leaking out and interfering with the person in front or behind. For another example, it can be applied when the side of the acoustic output device is inconsistent with the side of the user due to wearing problems, that is, the side of the acoustic output device points to the second direction and the side of the user points to the fourth direction, and the sound leakage reduction effect can be enhanced within the user's side range to avoid the sound output by the acoustic output device from interfering with the person on the user's side. For another example, it can be applied to scenarios where the user needs to move. During the user's movement, the directional range in which the sound leakage reduction effect needs to be achieved also changes. In this case, the sound leakage reduction effect needs to be achieved within a larger directional range to meet the sound leakage reduction needs.

[0066] By constructing a constraint function to adjust the amplitude and / or phase of the first and second electrical signals, the above-mentioned method adjusts the sound pressure distribution formed by the second speaker and the first speaker, making the far-field radiation of the acoustic output device directional, thereby improving the sound leakage problem of the acoustic output device in the far field. By adjusting the amplitude and / or phase of the first and second electrical signals respectively through the first filter function and the second filter function, the purpose of flexibly adjusting the directionality of the acoustic output device can be achieved. The first and second speakers included in the acoustic output device can have various structural forms, which will be exemplified below with reference to Figures 7-12.

[0067] 7 to 10 are schematic structural diagrams of acoustic output devices of different structures according to some embodiments of this specification.

[0068] As shown in Figures 7-10, the acoustic output device 300 includes a housing 310, a first speaker 320, and a second speaker 350. The first speaker 320 and the second speaker 350 are disposed within the housing 310. The first speaker 320 includes a first diaphragm 321. A first front cavity 330 and a first rear cavity 340 are disposed on the front and rear sides of the first diaphragm 321, respectively. The first front cavity 330 and the first rear cavity 340 are acoustically coupled to the first hole 311 and the second hole 312 in the housing 310, respectively. Driven by a first electrical signal, the first speaker 320 outputs a first sound wave and a second sound wave with a phase difference through the first hole 311 and the second hole 312, respectively. The second speaker 350 includes a second diaphragm 351. A second front cavity 360 and a second rear cavity 370 are disposed on the front and rear sides of the second diaphragm 351, respectively. One of the second front cavity 360 and the second rear cavity 370 is the same cavity as the first rear cavity 340. As shown in Figures 7 and 9, the second rear cavity 370 forms the same cavity as the first rear cavity 340. As shown in Figures 8 and 10, the second front cavity 360 forms the same cavity as the first rear cavity 340. The second front cavity 360 or the second rear cavity 370 forming the same cavity as the first rear cavity 340 is acoustically coupled with the second hole portion 312 on the shell 310, and the second speaker 350 outputs the third sound wave through the second hole portion 312 under the drive of the second electrical signal. It should be noted that in the above example, the third hole portion of the second speaker refers to the second hole portion 312, but in other embodiments, the third hole portion of the second speaker can be another hole portion different from the first hole portion 311 and the second hole portion 312.

[0069] Continuing to refer to Figures 7 to 10, in some embodiments, the vibration directions of the first diaphragm 321 and the second diaphragm 351 (for example, the up and down directions in Figures 7 to 10) are the same or close. In some embodiments, the first diaphragm 321 and the second diaphragm 351 can be arranged at intervals along the vibration direction, that is, the first speaker 320 and the second speaker 350 are arranged at intervals along the vibration direction (as shown in Figures 7 to 8); the first diaphragm 321 and the second diaphragm 351 can also be arranged at intervals along a direction perpendicular to the vibration direction, that is, the first speaker 320 and the second speaker 350 are arranged at intervals along a direction perpendicular to the vibration direction (as shown in Figures 9 to 10). It should be noted that the vibration directions of the first diaphragm 321 and the second diaphragm 351 being close can mean that the angle between the vibration directions of the first diaphragm 321 and the second diaphragm 351 can be less than a certain specific value (for example, 10°, etc.).

[0070] In some embodiments, the orientation of the first diaphragm 321 can be the same as or opposite to the orientation of the second diaphragm 351. In some embodiments, as shown in FIG7 , the orientation of the first diaphragm 321 is opposite to the orientation of the second diaphragm 351, the first diaphragm 321 and the second diaphragm 351 are spaced apart along the vibration direction, the first rear cavity 340 and the second rear cavity 370 are connected to form a common cavity, and the second front cavity 360 remains closed. In some embodiments, as shown in FIG8 , the orientation of the first diaphragm 321 is the same as the orientation of the second diaphragm 351, the first diaphragm 321 and the second diaphragm 351 are spaced apart along the vibration direction, the first rear cavity 340 and the second front cavity 360 are connected to form a common cavity, and the second rear cavity 370 remains closed. In some embodiments, as shown in FIG9 , the orientation of the first diaphragm 321 is the same as that of the second diaphragm 351, the first diaphragm 321 and the second diaphragm 351 are spaced apart in a direction perpendicular to the vibration direction, the first rear cavity 340 and the second rear cavity 370 communicate with each other to form a common cavity, and the second front cavity 360 remains closed. In some embodiments, as shown in FIG10 , the orientation of the first diaphragm 321 is opposite to that of the second diaphragm 351, the first diaphragm 321 and the second diaphragm 351 are spaced apart in a direction perpendicular to the vibration direction, the first rear cavity 340 and the second front cavity 360 communicate with each other to form a common cavity, and the second rear cavity 370 remains closed.

[0071] The far-field sound radiation from the acoustic output device 300 shown in Figures 7-10 exhibits directionality. When a user wears the acoustic output device 300, the direction from the second hole portion 312 to the first hole portion 311 is toward the user's ear canal opening. That is, the direction from the second hole portion 312 to the first hole portion 311 is the 0° direction shown in Figure 6, which is the first direction. The direction from the first hole portion 311 to the second hole portion 312 is away from the user's ear canal opening. That is, the direction from the first hole portion 311 to the second hole portion 312 is the 180° direction shown in Figure 6, which is the second direction.

[0072] FIG11 is a schematic diagram of the structure of an acoustic output device according to another embodiment of the present disclosure. As shown in FIG11 , the acoustic output device 400 includes a housing 410, a first speaker 420, and a second speaker 450. The first speaker 420 includes a first diaphragm 421, with a first front cavity 430 and a first rear cavity 440 provided on its front and rear sides, respectively. The housing 410 includes a first hole 411 acoustically coupled to the first front cavity 430, and a second hole 412 acoustically coupled to the first rear cavity 440. The first hole 411 and the second hole 412 serve as sound outlets for the first speaker 420, forming a dual sound source. The second speaker 450 includes a second diaphragm 451, with a second front cavity 460 and a second rear cavity 470 provided on its front and rear sides, respectively. The housing 410 includes a third hole 413 acoustically coupled to the second rear cavity 470. The third hole 413 is different from the first hole 411 and the second hole 412. The second front cavity 460 serves as a closed cavity. The third hole 413 serves as the sound outlet for the second speaker 450, forming a single sound source. It should be understood that the positions of the second front cavity 460 and the second rear cavity 470 can be interchanged. The second front cavity 460 and the third hole 413 are acoustically coupled, and the second rear cavity 470 serves as a closed cavity.

[0073] In some embodiments, a partition 414 is disposed within the housing 410, separating the second rear cavity 470 (or second front cavity 460) acoustically coupled to the third hole 413 from the first rear cavity 440 via the partition 414. The second hole 412 and the third hole 413 are located on either side of the partition 414. The first speaker 420 and the second speaker 450 do not share the same cavity, so that the sound waves radiated by the first speaker 420 and the second speaker 450 do not interfere with each other, thereby reducing mutual radiation impedance.

[0074] In some embodiments of the present specification, the cavities of the first speaker and the second speaker are independently provided to avoid the first speaker and the second speaker sharing the same cavity, so that the sound waves radiated by the first speaker and the second speaker do not interfere with each other, thereby reducing the mutual radiation impedance.

[0075] When the third hole portion is a different hole portion from the first hole portion and the second hole portion, in order to determine the first direction and the second direction, it is necessary to determine the equivalent hole portion formed between the third hole portion and the first hole portion and the second hole portion. The position of the equivalent hole portion can be determined by connecting the center points of adjacent hole portions in sequence to form a line segment, polygon or polyhedron, and taking the midpoint of the line segment, the centroid of the polygon or polyhedron as the center point of the equivalent hole portion. The center point of the equivalent hole portion can be used to represent the position of the equivalent hole portion. As shown in Figure 11, the second hole portion 412 is adjacent to the third hole portion 413, and a line segment is formed by connecting the center of the second hole portion 412 and the center of the third hole portion 413. The center point M of the line segment is regarded as the position of the equivalent hole portion of the second hole portion 412 and the third hole portion 413.

[0076] The far-field sound radiation from the acoustic output device 400 shown in Figure 11 exhibits directionality. When a user wears the acoustic output device 400, the equivalent hole portion points toward the user's ear canal opening in the direction of the first hole portion 411. That is, the direction in which the equivalent hole portion points toward the first hole portion 411 is the 0° direction shown in Figure 6, which is the first direction. The direction in which the first hole portion 411 points toward the equivalent hole portion is away from the user's ear canal opening. That is, the direction in which the first hole portion 411 points toward the equivalent hole portion is the 180° direction shown in Figure 6, which is the second direction.

[0077] FIG12 is a schematic diagram of directivity according to some embodiments of this specification. Referring to FIG12 , the acoustic output device shown in FIG12 is in a worn state, wherein AS1 represents the first hole portion of the acoustic output device, and AS2 represents the second hole portion of the acoustic output device. In some embodiments, the far-field radiation of the acoustic output device is directive, which means that the output sound direction of the acoustic output device is within a specific direction range, that is, the far-field radiation of the acoustic output device within the specific direction range is significantly greater or less than the far-field radiation outside the specific direction range. For example, the acoustic output device is directional in the first direction or the second direction (the first direction and the second direction are collinear).

[0078] In some embodiments, when the acoustic output device is worn, the direction X1 and directions near X1 (e.g., directions X2 and X3) from the second hole AS2 for sound emission corresponding to the rear cavity of the acoustic output device to the first hole AS1 for sound emission corresponding to the front cavity are directed toward the user's ear canal opening 201. The direction X1' and directions near X1' (e.g., directions X2' and X3') from the first hole AS1 to the second hole AS2 are directed away from the user's ear canal opening 201. Direction X1 is a first direction, and direction X1' is a second direction. In some embodiments, directions near direction X1' can be understood as directions or a range of directions whose angle with direction X1' is less than a preset angle. The preset angle can be 10°, 15°, 25°, 30°, 35°, etc. In some embodiments, the far-field radiation of the acoustic output device in the first direction is significantly greater than the far-field radiation in other directional ranges (e.g., directions perpendicular to the first direction, directions opposite to the first direction, etc.).

[0079] In some embodiments, the directivity of the acoustic output device can be expressed as follows: the absolute value of the sound pressure level difference at the corresponding far-field position in a specific direction of the acoustic output device and its opposite direction is not less than a preset sound pressure level difference threshold. In the worn state, the specific direction may refer to the direction in which the acoustic output device is away from the user's ear canal opening, and the opposite direction may refer to the direction in which the acoustic output device is pointing toward the user's ear canal. In some embodiments, the preset sound pressure level difference threshold may be 6dB, 8dB, 10dB, 12dB, 16dB, 18dB, etc. It should be noted that for the purpose of facilitating the understanding of directivity, only two hole portions, AS1 and AS2, are used for exemplary explanation. When the acoustic output device has more different hole portions, AS1 can be understood as an equivalent hole portion formed by some of the hole portions, and AS2 can be understood as an equivalent hole portion formed by another part of the hole portions. At this time, the direction of the directivity can be determined by the position of the equivalent hole portion. In some embodiments, the position of an equivalent hole portion formed by multiple hole portions can be determined by connecting the center points of adjacent hole portions in sequence to form a polygon, and the centroid of the polygon is the center point of the equivalent hole portion, which can be used to indicate the position of the equivalent hole portion.

[0080] In some embodiments, the far-field radiation of the acoustic output device can exhibit a cardioid directivity similar to curve 81 in Figure 6 , characterized by the absolute value of the sound pressure level difference between the far-field radiation of the acoustic output device in at least one pair of opposite directions (e.g., a first direction and a second direction) being no less than a preset sound pressure level difference threshold. The at least one pair of opposite directions can each fall within the directional range of the aforementioned specific direction and its opposite direction. In some embodiments, the at least one pair of opposite directions includes a pair of opposite directions corresponding to the line connecting the first aperture AS1 and the second aperture AS2. The cardioid directivity of the acoustic output device can be characterized by a significant difference in sound field intensity between a pair of opposite or nearly opposite directions within the aforementioned specific direction and its opposite direction. For example, the pair of opposite or nearly opposite directions can be one direction located near direction X1' from the first aperture to the second aperture, and the other direction located near direction X1 from the second aperture to the first aperture. For example, direction X1' can be opposite or nearly opposite to direction X1, direction X2, or direction X3.

[0081] Through the cardioid directivity setting of the far-field radiation of the acoustic output device, the sound output by the acoustic output device can be transmitted more concentratedly toward the direction of the user's ear canal opening, reducing the transmission of sound in other directions, improving the sound leakage problem of the acoustic output device, and enhancing the user's listening experience.

[0082] The basic concepts have been described above. It will be apparent to those skilled in the art that the detailed disclosure above is merely illustrative and does not limit the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and amendments to the present application. Such modifications, improvements, and amendments are suggested in the present application and remain within the spirit and scope of the exemplary embodiments of the present application.

[0083] At the same time, this application uses specific terms to describe the embodiments of this application. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "one embodiment," "an embodiment," or "an alternative embodiment" mentioned twice or multiple times in different locations in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application may be appropriately combined.

[0084] In addition, it will be understood by those skilled in the art that various aspects of the present application can be illustrated and described by a number of patentable categories or situations, including any new and useful process, machine, product or combination of substances, or any new and useful improvements thereto. Accordingly, various aspects of the present application can be performed entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The above hardware or software may all be referred to as "data blocks", "modules", "engines", "units", "components" or "systems". In addition, various aspects of the present application may be represented as a computer product located in one or more computer-readable media, which includes computer-readable program code.

[0085] A computer storage medium may include a propagated data signal embodying the computer program code, for example, in baseband or as part of a carrier wave. The propagated signal may be in a variety of forms, including electromagnetic, optical, or any suitable combination thereof. A computer storage medium may be any computer-readable medium other than a computer-readable storage medium that can be connected to an instruction execution system, apparatus, or device to communicate, propagate, or transfer the program for use. The program code on the computer storage medium may be transmitted via any suitable medium, including radio, cable, fiber optic cable, RF, or similar media, or any combination of these.

[0086] In addition, unless expressly stated in the claims, the order of the processing elements and sequences described in this application, the use of alphanumeric characters, or the use of other names are not intended to limit the order of the processes and methods of this application. Although the above disclosure discusses some of the invention embodiments currently considered useful through various examples, it should be understood that such details are only for illustrative purposes, and the appended claims are not limited to the disclosed embodiments. On the contrary, the claims are intended to cover all modifications and equivalent combinations that are consistent with the essence and scope of the embodiments of this application. For example, although the system components described above can be implemented by hardware devices, they can also be implemented only by software solutions, such as installing the described system on an existing processing device or mobile device.

[0087] Similarly, it should be noted that, in order to simplify the presentation of this application and thus facilitate understanding of one or more embodiments of the invention, the foregoing descriptions of the embodiments of this application sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not mean that the subject matter of this application requires more features than those recited in the claims. In fact, an embodiment may have fewer features than all of the features of a single embodiment disclosed above.

[0088] In some embodiments, numbers are used to describe the quantity of components and attributes. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about", "approximately" or "substantially" in some examples. Unless otherwise stated, "about", "approximately" or "substantially" indicate that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the description and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the settings of such numerical values ​​are as accurate as possible within the feasible range.

[0089] Each patent, patent application, patent application disclosure, and other materials, such as articles, books, specifications, publications, documents, etc., cited in this application is hereby incorporated by reference in its entirety. This includes application history documents that are inconsistent with or conflict with the content of this application, as well as documents (currently or subsequently attached to this application) that limit the broadest scope of the claims of this application. It should be noted that if the descriptions, definitions, and / or use of terms in the accompanying materials of this application are inconsistent or conflicting with the content of this application, the descriptions, definitions, and / or use of terms in this application shall prevail.

[0090] Finally, it should be understood that the embodiments described in this application are merely illustrative of the principles of the embodiments of this application. Other variations may also fall within the scope of this application. Therefore, by way of example and not limitation, alternative configurations of the embodiments of this application may be considered consistent with the teachings of this application. Accordingly, the embodiments of this application are not limited to the embodiments explicitly introduced and described in this application.

Claims

1. An acoustic output device, comprising: a housing; a first speaker disposed within the housing, the first speaker including a first diaphragm, within the housing, a first front cavity and a first rear cavity are respectively provided on the front and rear sides of the first diaphragm, the first front cavity and the first rear cavity are respectively acoustically coupled to two hole portions provided on the housing to respectively output a first sound wave and a second sound wave having a phase difference; a second speaker disposed within the housing, the second speaker including a second diaphragm, within the housing, a second front cavity and a second rear cavity are respectively provided on the front and rear sides of the second diaphragm, only one of the second front cavity and the second rear cavity is acoustically coupled to a hole portion provided on the housing to output a third sound wave; a processing circuit configured to provide a first electrical signal to the first speaker and a second electrical signal to the second speaker, within a target frequency range, there are differences in amplitude and / or phase between the first electrical signal and the second electrical signal, so that the far-field radiated sound of the acoustic output device presents at least one directional sound pressure distribution.

2. The acoustic output device according to claim 1, wherein, the target frequency range includes 200 Hz to 8000 Hz.

3. The acoustic output device according to claim 2, wherein, the first front cavity and the first rear cavity are respectively coupled to a first hole portion and a second hole portion provided on the housing, one of the second front cavity and the second rear cavity is the same cavity as the first rear cavity, the second front cavity or the second rear cavity that forms the same cavity with the first rear cavity outputs the third sound wave through the second hole portion, the direction of the second hole portion pointing to the first hole portion is the first direction, and the direction of the first hole portion pointing to the second hole portion is the second direction.

4. The acoustic output device according to claim 2, wherein, the first front cavity and the first rear cavity are respectively coupled to a first hole portion and a second hole portion provided on the housing, one of the second front cavity and the second rear cavity is coupled to a third hole portion on the housing, the third hole portion is different from the first hole portion and the second hole portion, the second hole portion and the third hole portion have an equivalent hole portion, the direction of the equivalent hole portion pointing to the first hole portion is the first direction, and the direction of the first hole portion pointing to the equivalent hole portion is the second direction.

5. The acoustic output device according to claim 3 or 4, wherein, the at least one directional sound pressure distribution includes: at a first frequency, the difference in far-field sound pressure level between the first direction and the second direction of the acoustic output device is greater than 12 dB, and the difference in far-field sound pressure level between any direction within an angle less than 30° formed with the second direction and the far-field sound pressure level of the second direction is not less than 6 dB.

6. The acoustic output device according to claim 3 or 4, wherein, The at least one directional sound pressure distribution includes: at a second frequency, the difference in the far-field sound pressure levels of the acoustic output device in the first direction and the second direction is greater than 9 dB, and the angle formed between the direction having a far-field sound pressure level 6 dB higher than the far-field sound pressure level in the second direction and the second direction is greater than 45°.

7. The acoustic output device according to claim 3 or 4, wherein, the at least one directional sound pressure distribution includes: at a third frequency, the angle formed between the direction corresponding to the minimum far-field sound pressure level of the acoustic output device and the second direction is greater than 15°, and the difference between the far-field sound pressure level in the second direction and the minimum far-field sound pressure level is greater than 6 dB.

8. The acoustic output device according to claim 3 or 4, wherein, the at least one directional sound pressure distribution includes: the minimum far-field sound pressure levels in the sound pressure distributions corresponding to two different frequencies within the target frequency range respectively correspond to different directions.

9. The acoustic output device according to claim 3 or 4, wherein, the processing circuit is capable of acquiring a plurality of filter function groups, each filter function group includes a first filter function and a second filter function corresponding to the first electrical signal and the second electrical signal respectively, the first electrical signal and the second electrical signal are respectively modulated in response to the first filter function and the second filter function, and different filter function groups provide different sound pressure distributions for the acoustic output device at the same frequency.

10. The acoustic output device according to claim 9, wherein, under the modulation of different filter function groups, the minimum far-field sound pressure levels in the sound pressure distributions generated by the acoustic output device at the same frequency correspond to different directions.

11. The acoustic output device according to claim 9, wherein, the processing circuit adjusts the filter function group in real time according to user input.

12. An acoustic output device, comprising: a housing; a first speaker disposed within the housing, the first speaker includes a first diaphragm, within the housing, a first front cavity and a first rear cavity are respectively provided on the front and rear sides of the first diaphragm, and the first front cavity and the first rear cavity are respectively acoustically coupled to two hole portions provided on the housing to respectively output a first sound wave and a second sound wave having a phase difference; a second speaker disposed within the housing, the second speaker includes a second diaphragm, within the housing, a second front cavity and a second rear cavity are respectively provided on the front and rear sides of the second diaphragm, and only one of the second front cavity and the second rear cavity is acoustically coupled to a hole portion provided on the housing to output a third sound wave; A processing circuit configured to provide a first electrical signal to the first speaker and a second electrical signal to the second speaker, the processing circuit being capable of acquiring a plurality of filter function groups, each filter function group including a first filter function and a second filter function corresponding to the first electrical signal and the second electrical signal respectively, the first electrical signal and the second electrical signal being modulated in response to the first filter function and the second filter function respectively, and different filter function groups providing different sound pressure distributions for the acoustic output device at the same frequency.

13. The acoustic output device according to claim 12, wherein, under the modulation of different filter function groups, the minimum far-field sound pressure levels in the sound pressure distributions generated by the acoustic output device at the same frequency correspond to different directions.

14. The acoustic output device according to claim 12, wherein, the processing circuit adjusts the filter function groups in real time according to user input.

15. The acoustic output device according to claim 12, wherein, within a target frequency range, there are differences in amplitude and / or phase between the first electrical signal and the second electrical signal, so that the far-field radiated sound of the acoustic output device presents at least one directional sound pressure distribution.

16. The acoustic output device according to claim 15, wherein, the target frequency range includes 200 Hz to 8000 Hz.

17. The acoustic output device according to claim 16, wherein, the first front cavity and the first rear cavity are respectively coupled to a first hole portion and a second hole portion provided on the housing, one of the second front cavity and the second rear cavity is the same cavity as the first rear cavity, and the second front cavity or the second rear cavity that forms the same cavity as the first rear cavity outputs the third sound wave through the second hole portion, the direction of the second hole portion pointing to the first hole portion is the first direction, and the direction of the first hole portion pointing to the second hole portion is the second direction.

18. The acoustic output device according to claim 16, wherein, the first front cavity and the first rear cavity are respectively coupled to a first hole portion and a second hole portion provided on the housing, one of the second front cavity and the second rear cavity is coupled to a third hole portion on the housing, the third hole portion is different from the first hole portion and the second hole portion, the second hole portion and the third hole portion have an equivalent hole portion, the direction of the equivalent hole portion pointing to the first hole portion is the first direction, and the direction of the first hole portion pointing to the equivalent hole portion is the second direction.

19. The acoustic output device according to claim 17 or 18, wherein, the at least one directional sound pressure distribution includes: at a first frequency, the difference in far-field sound pressure levels between the first direction and the second direction of the acoustic output device is greater than 12 dB, and the difference in far-field sound pressure levels between any direction within an angle less than 30° formed with the second direction and the far-field sound pressure level of the second direction is not less than 6 dB.

20. The acoustic output device according to claim 17 or 18, wherein, the at least one directional sound pressure distribution includes: at a second frequency, the difference in the far-field sound pressure levels of the acoustic output device in the first direction and the second direction is greater than 9 dB, and the angle formed between the direction having a far-field sound pressure level 6 dB higher than that in the second direction and the second direction is greater than 45°.

21. The acoustic output device according to claim 17 or 18, wherein, the at least one directional sound pressure distribution includes: at a third frequency, the angle formed between the direction corresponding to the minimum far-field sound pressure level of the acoustic output device and the second direction is greater than 15°, and the difference between the far-field sound pressure level in the second direction and the minimum far-field sound pressure level is greater than 6 dB.

22. The acoustic output device according to claim 17 or 18, wherein, the at least one directional sound pressure distribution includes: the minimum far-field sound pressure levels in the sound pressure distributions corresponding to two different frequencies within the target frequency range respectively correspond to different directions.

23. The acoustic output device according to claim 17 or 18, wherein, that different filter function groups provide different sound pressure distributions for the acoustic output device at the same frequency includes: at the same frequency, after being modulated by one filter function group among different filter function groups, the difference in the far-field sound pressure levels of the acoustic output device in the first direction and the second direction is greater than 12 dB, and the difference between the far-field sound pressure level in any direction forming an angle less than 30° with the second direction and the far-field sound pressure level in the second direction is not less than 6 dB; after being modulated by another filter function group among different filter function groups, the difference in the far-field sound pressure levels of the acoustic output device in the first direction and the second direction is greater than 9 dB, and the angle formed between the direction having a far-field sound pressure level 6 dB higher than that in the second direction and the second direction is greater than 45°.

24. An acoustic output device, comprising: a housing; a first speaker disposed within the housing, the first speaker outputting sound waves outward through at least one hole in the housing, the first speaker having a first response function in the far field; a second speaker disposed within the housing, the second speaker outputting sound waves outward through at least one hole in the housing, the second speaker having a second response function in the far field; a processing circuit configured to provide a first electrical signal to the first speaker and a second electrical signal to the second speaker, the processing circuit constructing at least one set of constraint functions based on the first response function and the second response function, each set of constraint functions generating a first filter function corresponding to the first electrical signal and a second filter function corresponding to the second electrical signal, the first electrical signal and the second electrical signal respectively responding to the modulation of the first filter function and the second filter function, and each set of constraint functions providing a specific sound pressure distribution for the acoustic output device.

25. The acoustic output device according to claim 24, wherein, the at least one set of constraint functions includes a plurality of constraint functions, and each set of constraint functions provides a specific sound pressure distribution for the acoustic output device, including: at the same frequency, different sets of constraint functions provide different sound pressure distributions for the acoustic output device, and the minimum far-field sound pressure levels in the different sound pressure distributions respectively correspond to different directions.

26. The acoustic output device according to claim 24, wherein, the at least one set of constraint functions includes a plurality of constraint functions, and each set of constraint functions provides a specific sound pressure distribution for the acoustic output device, including: two different frequencies within a target frequency range respectively correspond to different sets of constraint functions, the different sets of constraint functions provide different sound pressure distributions for the acoustic output device at the two different frequencies, and the minimum far-field sound pressure levels in the different sound pressure distributions respectively correspond to different directions.

27. The acoustic output device according to claim 24, wherein, the processing circuit adjusts the constraint functions in real time according to user input.

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