Audio output device

Abstract

One or more embodiments of this specification relate to an acoustic output device, the acoustic output device comprising: a housing; a first speaker installed within the housing and acoustically coupled to two holes installed in the housing to output a first sound wave and a second sound wave having a phase difference, respectively; a second speaker installed within the housing and acoustically coupled to one hole installed 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 the first electrical signal and the second electrical signal have an amplitude and / or phase difference within a target frequency range such that the far-field radiated sound of the acoustic output device exhibits at least one directional sound pressure distribution.

Description

Technical Field

[0001] This specification relates to the field of acoustics, and particularly to an acoustic output device.

Background Art

[0002] To solve the sound leakage problem of an acoustic output device, usually, two sound sources are used to emit two sets of sounds with opposite phases. Under the conditions of the far-field, since the acoustic distance difference between two sound sources with opposite phases to a specific point in the far-field can basically be ignored, the two sets of sounds can cancel each other out to reduce the sound leakage in the far-field. Although this method can achieve a certain sound leakage reduction effect, there are still certain limitations.

Summary of the Invention

Means for Solving the Problems

[0003] The acoustic output device according to an embodiment of this specification includes a housing, and is installed in the housing, including a first diaphragm. In the housing, a first front cavity and a first rear cavity are correspondingly installed on the front side and the rear side of the first diaphragm respectively. The first front cavity and the first rear cavity are acoustically coupled to two holes installed in the housing respectively to output a first sound wave and a second sound wave having a phase difference respectively, a first speaker; installed in the housing, including a second diaphragm. In the housing, a second front cavity and a second rear cavity are installed on the front side and the rear side of the second diaphragm respectively. Only one of the second front cavity and the second rear cavity is acoustically coupled to one hole installed in the housing to output a third sound wave, a second speaker; 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 first electrical signal and the second electrical signal have a difference in amplitude and / or phase within a target frequency range so that the far-field radiated sound of the acoustic output device shows at least one sound pressure distribution having directivity.

[0004] Some other embodiments of this specification of an acoustic output device include a housing, a first speaker installed within the housing and including a first diaphragm, wherein a first front cavity and a first rear cavity are installed correspondingly on the front and rear sides of the first diaphragm, respectively, and the first front cavity and the first rear cavity are acoustically coupled to two holes installed in the housing, respectively, to output a first sound wave and a second sound wave having a phase difference, respectively, and a second speaker installed within the housing and including a second diaphragm, wherein a second front cavity and a second rear cavity are installed on the front and rear sides of the second diaphragm, respectively, and the second front cavity and the second The device includes a second speaker that outputs a third sound wave, with only one of the rear cavities acoustically coupled to a single hole in the housing, 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 the processing circuit is capable of acquiring a plurality of filter function groups, each of which 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 respond to the modulation of the first filter function and the second filter function, respectively, and different filter function groups provide different sound pressure distributions to the acoustic output device at the same frequency.

[0005] A sound output device according to some other embodiments of this specification includes a housing; a first speaker installed within the housing and outputting sound waves to the outside through at least one hole of the housing and having a first response function in the far field; a second speaker installed within the housing and outputting sound waves to the outside through at least one hole of the housing and having a second response function in the far field; 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 the processing circuit constructs 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 responding to the modulation of the first filter function and the second filter function, respectively, and each set of constraint functions provides the sound output device with a specific sound pressure distribution.

[0006] This specification will be further described by exemplary embodiments, which will be described in detail with reference to the drawings. These embodiments are not limiting, and in these embodiments, the same numbers indicate the same structure. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram showing the relative positions of an acoustic output device according to some embodiments of this specification and the user's ear. [Figure 2] Figure 1 is a schematic diagram of the sound pressure distribution of the sound pressure level of the acoustic output device shown. [Figure 3] This is a schematic block diagram illustrating the adjustment of electrical signals according to some embodiments of this specification. [Figure 4] These are sound pressure level curves obtained from tests relating to some of the examples described herein. [Figure 5] These are time-domain and frequency-domain curve diagrams of filter functions ω1 and ω2 according to some embodiments of this specification. [Figure 6] This is a sound pressure distribution diagram obtained from tests relating to some of the embodiments described herein. [Figure 7] This is a schematic diagram of different acoustic output devices according to some embodiments of this specification. [Figure 8] This is a schematic diagram of different acoustic output devices according to some embodiments of this specification. [Figure 9] This is a schematic diagram of different acoustic output devices according to some embodiments of this specification. [Figure 10] This is a schematic diagram of different acoustic output devices according to some embodiments of this specification. [Figure 11] This is a schematic diagram of an acoustic output device according to some other embodiments of this specification. [Figure 12] This is a schematic diagram of the directivity according to some embodiments of this specification. [Modes for carrying out the invention]

[0008] To more clearly illustrate the technical means of the embodiments described herein, the drawings necessary for describing the embodiments are briefly described below. Clearly, the drawings described below are only a part of the examples or embodiments of this specification, and those skilled in the art can apply this specification to other similar scenarios based on these drawings without requiring any creative effort. Unless otherwise stated or otherwise evident from the context, the same numbers in the figures represent the same structure or operation.

[0009] It should be understood that the terms “system,” “apparatus,” “unit,” and / or “module” as used herein are ways of distinguishing various assemblies, elements, components, parts, or assemblies of different levels. However, other terms may be used in place of the above terms if they can achieve the same purpose.

[0010] As provided herein and in the claims, unless the context explicitly indicates otherwise, terms such as “one,” “one,” “one kind,” and / or “the” do not specifically refer to the singular form, but may include the plural form. Generally, the terms “includes” and “contains” merely indicate the inclusion of clearly identified steps and elements, which are not an exclusive list, and the method or apparatus may also include other steps or elements.

[0011] This specification uses flowcharts to illustrate the operations performed by the systems according to the embodiments described herein. It should be understood that the preceding and succeeding operations are not necessarily performed in exact order. Instead, each step may be performed 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.

[0012] In some embodiments, to solve the sound leakage problem of an acoustic output device, two sound sources with opposite phases can be used to emit two sets of sounds with opposite phases. Under far-field conditions, the difference in acoustic distance to a specific point in the far field between the two sound sources with opposite phases is essentially negligible, so the two sets of sounds can cancel each other out, reducing far-field sound leakage.

[0013] Figure 1 is a schematic diagram of the relative positions of an acoustic output device and a user's ear according to some embodiments of this specification. As shown in Figure 1, the acoustic output device 100 may include a housing 110 and a speaker 120. The speaker 120 may be installed in a cavity formed by the housing 110, and the speaker 120 includes a diaphragm, and the cavity of the housing 110 is provided with a front cavity 130 and a rear cavity 140 that radiate sound on the front and rear sides of the diaphragm, respectively. The housing 110 is provided with a first hole 111 and a second hole 112, and 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 (referred to as the first sound wave) may pass through the front cavity 130 and be emitted from the first hole 111, and the sound waves on the rear side of the diaphragm (referred to as the second sound wave) may pass through the rear cavity 140 and be emitted from the second hole 112. In this case, the first hole 111 and the second hole 112 can be considered as a pair of dual sound sources, and can emit two sets of sound waves with the same amplitude but opposite phase. For ease of understanding, in some embodiments of this specification, the front side of the diaphragm refers to the side of the diaphragm away from the magnetic circuit assembly, and the rear side of the diaphragm refers to the side of the diaphragm facing the magnetic circuit assembly. Naturally, in certain scenarios, the front and rear sides of the diaphragm may be interchangeable; that is, the side of the diaphragm away from the magnetic circuit assembly may be the rear side, and the side of the magnetic circuit assembly away from the diaphragm may be the front side.

[0014] In some embodiments, as shown in FIG. 1, when the user wears or uses the acoustic output device 100, the acoustic output device 100 may be located near the user's auricle 200, and the first hole 111 may face the user's ear canal opening 201, so that the sound emitted from the first hole 111 can be transmitted to the user's ear canal opening 201. The second hole 112 may be farther from the ear canal opening 201 than the first hole 111, and the distance between the first hole 111 and the ear canal opening is smaller than the distance between the second hole 112 and the ear canal opening.

[0015] In some embodiments, when the speaker 120 vibrates, the front side and the rear side of the speaker 120 can generate sound waves with equal amplitudes and opposite phases as sound wave generation structures, respectively. The sound waves with equal amplitudes and opposite phases are radiated to the outside from the first hole 111 and the second hole 112, respectively, to form a dual sound source. The dual sound source can interfere and cancel each other at a spatial point (e.g., the far field), thereby effectively improving the sound leakage problem of the earphone 100 in the far field.

[0016] FIG. 2 is a schematic diagram of the sound pressure distribution of the sound pressure level of the acoustic output device shown in FIG. 1. As shown in FIG. 2, the sound pressure distribution of the acoustic output device 100 shows a clear directivity, and the sound leakage reduction effect in a certain direction is remarkable. Specifically, in the mid-low frequency band, the dual sound source composed of the first hole 111 and the second hole 112 of the acoustic output device 100 outputs sound waves with opposite phases (i.e., the first sound wave and the second sound wave), and the sound field has a distribution form of two lobe-like structures in space. In the two opposite directions of the connection line of the dual sound source, the sound pressure level is large, and in the direction perpendicular to the connection line of the dual sound source, the sound pressure level is small, that is, the sound leakage reduction effect is high. Regarding the two lobe-like structures formed in the sound field, one lobe-like structure is far from the user's ear and forms a large sound leakage, increasing the sound leakage of the acoustic output device.

[0017] When dual sound sources have opposite phases, the acoustic output device exhibits clear directivity in the far-field sound distribution. In this case, the acoustic output device generates significant far-field sound leakage in the direction of the connection line between the dual sound sources, resulting in a poor user experience in certain scenarios (e.g., scenarios where there is a high demand for sound leakage reduction in the direction of the connection line between the dual sound sources). In some embodiments, when using dual sound sources, the amplitude and / or phase (e.g., amplitude, phase, or amplitude and phase) of the first and second sound waves can be adjusted so that the far-field sound pressure in a specific direction or range of a specific direction of the acoustic output device is within a desired range, in order to provide a flexible sound leakage reduction effect that meets the needs of specific scenarios. In some alternative embodiments, multiple sound sources beyond two can also be used, and the amplitude and / or phase of the sound waves emitted by each sound source can be controlled to bring the far-field sound pressure in a specific direction or range of a specific direction of the acoustic output device within a desired range.

[0018] In some embodiments, the acoustic output device may include multiple speakers, each driven by an independent electrical signal, to facilitate adjustment of the amplitude and / or phase of sound waves emitted by each sound source. By modulating the electrical signals driving each of the multiple speakers, for example by applying different filter functions to the electrical signals corresponding to each of the multiple speakers, it is possible to establish a satisfactory amplitude and / or phase relationship between the sound waves generated by each sound source (i.e., the holes coupled to each speaker in the acoustic output device), thereby flexibly adjusting the sound pressure distribution formed by the acoustic output device in the far field, ensuring a sound leakage reduction effect in a specific direction or within a specific directional range of the acoustic output device, and meeting the different needs of users in different application scenarios. For illustrative purposes only, the following will exemplify the method of adjusting the sound pressure distribution and the corresponding structure, etc., using an acoustic output device including two speakers as an example. Note that if the acoustic output device includes more speakers, the method of adjusting the sound pressure distribution and the corresponding structure, etc., can be obtained by analogy from the contents disclosed in some embodiments of this specification without requiring creative effort.

[0019] 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 installed in a housing. The first speaker includes a first diaphragm, and 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, and 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.

[0020] The sound waves generated by the first and second diaphragms are radiated to the outside of the housing through one or more holes in the housing. For example, the first speaker is acoustically coupled to two holes in the housing (e.g., the first and second holes) and outputs a first and second sound wave with a phase difference, respectively, while the second speaker is acoustically coupled to two holes in the housing (e.g., the third and fourth holes) and outputs a third and fourth sound wave with a phase difference, respectively. In this case, both the first and second speakers form dual sound sources, and the first, second, third, and fourth sound waves can be superimposed in the far field. Furthermore, for example, the first speaker is acoustically coupled to two holes in the housing (e.g., a first hole and a second hole), outputting a first sound wave and a second sound wave, respectively, while the second speaker is acoustically coupled to only one hole in the housing (e.g., a third hole), outputting a third sound wave. In this case, the first speaker forms a dual sound source, the second speaker forms a single sound source, and the first, second, and third sound waves can be superimposed in the far field. Alternatively, for example, the first speaker is acoustically coupled to only one hole in the housing (e.g., a first hole), outputting a first sound wave. The second speaker is acoustically coupled to only one hole in the housing (e.g., a third hole), outputting a third sound wave. In this case, both the first and second speakers form single sound sources, and the first and third sound waves can be superimposed in the far field. For a detailed description of the structure of the acoustic output device, please refer to other parts of this specification. For example, Figures 7 to 11 and their corresponding contents illustrate the specific structure of an audio output device using a first speaker that forms a dual sound source and a second speaker that forms a single sound source as examples.

[0021] In some embodiments, the amplitude and / or phase of the first and second electrical signals can be modulated such that they have a constant amplitude and / or phase difference within a target frequency range. After the sound waves output from the second speaker and the sound waves output from the first speaker are superimposed in the far field, the far-field radiation of the acoustic output device can exhibit a specific sound pressure distribution. For example, the far-field sound pressure distribution of the acoustic output device can be directional and expressed such that the far-field sound pressure has a low intensity in a specific direction or within a specific directional range, thereby improving the far-field sound leakage problem of the acoustic output device in that specific direction or within a specific directional range.

[0022] The above-mentioned target frequency range is the frequency range of a sound pressure distribution that can achieve a specific directivity. In some embodiments, by modulating the amplitude and / or phase of the first and second electrical signals in different ways within different frequency ranges, it is possible to satisfy the requirement that the far-field radiation of the acoustic output device exhibits a desired sound pressure distribution within different frequency ranges. In some embodiments, the target frequency range may include a frequency band sensitive to the human ear, including 200 Hz to 8000 Hz. By constructing a sound pressure distribution at the far-field location of the acoustic output device in a frequency band sensitive to the human ear, it is possible to reduce far-field sound leakage that is easily radiated towards others, thereby reducing interference with others and protecting the privacy of the user's listening.

[0023] In some embodiments, the processing circuit of the audio output device includes a filter. The filter adjusts the amplitude and / or phase of the electrical signal so that a desired first electrical signal and a second electrical signal can be output to a first speaker and a second speaker, respectively. In some embodiments, the filter processes the signal based on a filter function to adjust the amplitude and / or phase of the first and second electrical signals within a target frequency range. In some embodiments, an infinite impulse response (IIR) filter can be selected as the filter. IIR filters have low computational complexity and excellent real-time performance. In some embodiments, a finite impulse response (FIR) filter can be selected as the filter. FIR filters have high stability, controllable phase, and can perform amplitude selection, as well as synchronously input and output signals, thus avoiding signal distortion.

[0024] Figure 3 is a schematic block diagram illustrating the adjustment of electrical signals according to some embodiments of this specification.

[0025] The processing circuit can provide one or more sets of filter functions, each set of filter functions including a first filter function ω1 and a second filter function ω2 corresponding to a first electrical signal and a second electrical signal, respectively, and the first and second electrical signals respond to the modulation of the first filter function ω1 and the second filter function ω2, respectively. As shown in Figure 3, the filter of the processing circuit may include a first filter and a second filter, the first filter and the second filter receiving the first filter function ω1 and the second filter function ω2 from the set of filter functions, performing filtering on the passed first and second electrical signals, and further controlling the acoustic signals output from the first and second speakers.

[0026] In some embodiments, the amplitudes and / or phases of the first and second electrical signals modulated by different filter functions differ, affecting the acoustic output of the first and second speakers and providing different sound pressure distributions to the acoustic output device.

[0027] In some embodiments, the first filter function ω1 and the second filter function ω2 may be determined based on a constraint function. The constraint function is a functional expression that constrains the far-field sound pressure distribution of the acoustic sound generating device (including the first and second speakers). The constraint function relates to the far-field output capability of each speaker in the acoustic output device. The far-field output capability of a speaker can be expressed as the far-field response function of the speaker, and the response function can represent the sound pressure level at the far-field position of the speaker.

[0028] In some embodiments, the far-field response function of a speaker can be obtained by methods such as measurement or simulation. As a simple example, the acoustic output device is assumed to be the center of a circle (for example, the centroid of a multi-source system is assumed to be the center of the circle), and a circular boundary with a sufficiently large radius is approximated as the far-field position of the acoustic output device. A microphone is positioned to collect the microphone response at each position on the circular boundary. For example, the corresponding microphone response IR is collected at every x° interval when the speaker is excited on the circular boundary. In some embodiments, if the radius is sufficiently large, the microphone position can be considered the far-field position of the acoustic output device. In this case, the distance between the microphone and the acoustic output device is greater than a predetermined distance threshold, for example, greater than 25 cm. Since sound waves of different frequencies have different wavelengths, the distance between the far-field position of the acoustic output device and the acoustic output device can be made smaller for shorter wavelengths. In some embodiments, when the frequency range of the excitation signal is 1000 Hz to 4000 Hz, the far-field position of the acoustic output device may be a position where the distance from the acoustic output device is greater than 5.5 cm.

[0029] In some embodiments, the smaller the value of x, the more accurate the sound pressure distribution diagram created by the simulation. In some embodiments, to reduce the burden of the simulation work, x° may be in the range of 5° to 10°. In some embodiments, the test signal that excites the speaker may be a sweep signal, the frequency range of the sweep signal is 200Hz to 8000Hz, and the sound pressure distribution of the speaker is tested within the frequency range of 200Hz to 8000Hz. In some embodiments, the sweep signal may be a signal that gradually changes from 200Hz to 8000Hz, the sweep signal may contain only a single frequency signal at any given time, and the sweep signal can simulate a simple signal input. Note that the method for obtaining the speaker response function exemplified here is not the only method for obtaining the speaker response function, and those skilled in the art can make appropriate adjustments or modifications to this method depending on the purpose.

[0030] In some embodiments, in order to minimize the far-field sound pressure level of the acoustic output device in a particular direction and thereby minimize far-field sound leakage from the acoustic output device in that particular direction, a constraint function representing the sound pressure level of the acoustic output device in that particular direction can be constructed in combination with the response function of each speaker in that particular direction. For convenience of explanation, the response function of the speaker in the β° direction is IR β This is expressed as follows. By performing a minimization operation on the constraint function, the sound pressure in the β° direction of the acoustic output device can be made to have a low intensity. Specifically, the constraint function consists of a response function and a filter function ω corresponding to each speaker, and by performing a minimization operation on the constraint function, the filter function ω corresponding to each speaker is obtained when the acoustic output device exhibits directivity in the β° direction. In other words, when an electrical signal is modulated by the above filter function ω and then the speaker is excited, the sound pressure distribution of the acoustic output device can exhibit directivity in the β° direction.

[0031] As a simple example, the first response function of the first speaker in the β° direction is IR1 β°The second response function of the second speaker in the β° direction is defined as IR2 β° In some embodiments, in order to adjust the sound pressure distribution radiated simultaneously to the outside by the first and second speakers, the sound pressure representations corresponding to the first and second speakers, modulated by the first filter function ω1 and the second filter function ω2, are used.

[0032]

number

[0033] and

[0034]

number

[0035] Combining constraint functions

[0036]

number

[0037] This forms a constraint function (also called the "first constraint function"). The first constraint function can represent the magnitude of the sound pressure level output by the sound output device in the β° direction. By minimizing the first constraint function, we can obtain the first filter function ω1 and the second filter function ω2, which correspond to the case where the sound output device exhibits a small sound pressure level in the β° direction.

[0038] In some embodiments, the first filter filters the first electrical signal based on the first filter function ω1, and the second filter filters the second electrical signal based on the second filter function ω2. The first and second electrical signals generated after processing excite the first and second speakers, respectively, thereby achieving directivity in the β° direction of the acoustic output device, that is, having a low intensity of sound pressure in the β° direction. For example, taking a dual sound source as an example, if we try to achieve directivity of the acoustic output device in the direction of the connection line of the dual sound source (for example, the 180° direction as described in the relevant parts of Figures 7 to 11 of this specification, i.e., the direction from the first hole 311 to the second hole 312 (also called the second direction)), the response functions of the first speaker and the second speaker in the 180° direction are set to IR1, respectively. 180° and IR2 180° Substitute this into the first constraint function, and the first constraint function

[0039]

number

[0040] We need to obtain it.

[0041] In some examples,

[0042]

number

[0043] Based on this, a first filter function ω1 and a second filter function ω2 are obtained, and the first speaker and the second speaker are simultaneously excited by the first and second electrical signals processed based on the first and second filter functions ω1 and ω2, respectively, and the sound pressure level curves obtained by the test are shown in Figure 4. Figure 4 is a sound pressure level curve obtained by a test according to some embodiments of this specification. As shown in Figure 4, the horizontal coordinate represents frequency in Hz, and the vertical coordinate represents sound pressure level in dB. Curve 61 is the sound pressure level curve in the opposite direction of the 180° direction of the acoustic output device, i.e., the 0° direction (i.e., the first direction described in the relevant contents of Figures 7 to 11 of this specification, i.e., the direction from the second hole 312 to the first hole 311) for excitation signals of 200 Hz to 8000 Hz, and curve 62 is the sound pressure level curve in the 180° direction of the acoustic output device for excitation signals of 200 Hz to 8000 Hz. As can be seen from Figure 4,

[0044]

number

[0045] Based on the first filter function ω1 and the second filter function ω2 obtained, the excitation of the first and second electrical signals modulated by these functions results in a sound pressure level difference of 12dB to 25dB between the 0° and 180° directions. This effectively reduces the far-field sound pressure level in the 180° direction, achieving good directivity and effective sound leakage reduction in that direction. Furthermore, the sound pressure level difference differs for electrical signal excitations of different frequencies, meaning that the sound leakage reduction effect differs at different frequencies. As can be seen from this, the filter functions ω1 and ω2 obtained by the above method can provide a specific sound pressure distribution to an acoustic output device, thereby achieving directivity in a specific direction for the acoustic output device.

[0046] In some embodiments, by constructing and minimizing a specific constraint function, the acoustic output device can be made to have low far-field sound pressure within a specific directional range, that is, to have a low average sound pressure level within that specific directional range. Here, the specific directional range refers to the range between one angular direction and another, or the range near one angular direction, and the directional range directly refers to all directions within a single sector region. Here, the directional range can be understood as the range of regions where the angle with a certain direction is less than a certain degree. For the sake of explanation and as a simple example, the directions in the acoustic output device shown in Figures 7 to 11 will be used as an example. Specifically, the direction from the first hole 311 to the second hole 312 will be called the 180° direction (also called the second direction), and the direction from the second hole 312 to the first hole 311 will be called the 0° direction (also called the first direction). In this case, the specific direction range may be the 135° to 225° direction range, and refers to all directions within the sector region between the 135° direction and the 225° direction, or all directions within the sector region consisting of two angular directions whose angle with the 180° direction is less than 45°.

[0047] As a simple example, in order to achieve directivity within the α°~β° directional range of the first and second speakers, the sound pressure expression corresponding to the α°~β° directional range of the first and second speakers is...

[0048]

number

[0049] and

[0050]

number

[0051] This is another set of constraint functions

[0052]

number

[0053] A second constraint function (also called the "second constraint function") can be formed. The second constraint function can represent the magnitude of the average sound pressure level within the α°~β° range of the sound output device. By performing a minimization operation on the second constraint function, two filter functions ω1 and ω2 can be obtained that minimize the average sound pressure within the α°~β° range of the sound output device.

[0054] 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 performs filtering on the first electrical signal based on the first filter function ω1, and the second filter performs filtering on the second electrical signal based on the second filter function ω2. The first and second electrical signals generated after processing can excite the first speaker and the second speaker, respectively, thereby achieving directivity within the α°~β° directional range of the acoustic output device, i.e., minimizing the average sound pressure within the α°~β° directional range. For example, when trying to achieve directivity within the 135°~225° directional range of the acoustic output device, the second constraint function is

[0055]

number

[0056] By constructing the system and performing a minimization process on the second constraint function, the corresponding first filter function ω1 and second filter function ω2 are obtained. The first and second speakers are then excited by the first and second electrical signals modulated based on the first and second filter functions ω1 and ω2, respectively, thereby achieving directivity within a 135° to 225° directional range for the acoustic output device.

[0057] Figure 5 shows the time-domain and frequency-domain curves of filter functions ω1 and ω2 according to some embodiments of this specification. In some embodiments, as shown in Figure 5(a), the first constraint function

[0058]

number

[0059] Based on the minimum value of , the first filter function ω1 and the second filter function ω2 can be obtained. In Figure 5(a), the horizontal axis represents the period (T / 64s), the vertical axis represents the normalized amplitude (1), and T is the time of one period of the sampled signal. The first and second electrical signals processed based on the first filter function ω1 and the second filter function ω2 excite the first speaker and the second speaker, respectively, and the sound pressure level of the acoustic output device obtained by the test is shown in Figure 5(b). In Figure 5(b), the horizontal coordinate represents the frequency in Hz, and the vertical coordinate represents the sound pressure level in dB. Figure 6 is a sound pressure distribution diagram obtained by tests according to some embodiments of this specification. As shown in Figure 6, curve 81 shows the sound pressure distribution where the sound pressure level is minimized in the 180° direction, and curve 82 shows the sound pressure distribution where the average sound pressure level is minimized in the 135° to 225° direction range. As can be seen by comparing curves 81 and 82, the first filter function ω1 and the second filter function ω2 obtained based on the first constraint function allow the acoustic output device to achieve directivity in a specific direction, for example, with the sound pressure level at 180° being the minimum and the sound pressure level at 0° being the maximum. The first filter function ω1 and the second filter function ω2 obtained based on the second constraint function allow the acoustic output device to achieve the minimum average sound pressure level in different directions within the 135° to 225° range. This means that ω1 and ω2 obtained based on the first constraint function enhance the sound leakage reduction effect of the acoustic output device in the 180° direction, but narrow the range of sound leakage reduction, while 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 widen the directional range of sound leakage reduction. In other words, the first and second constraint functions can meet the application scenario needs of different users and improve the sound leakage reduction effect according to different environments. Figures 6, a, b, c, d, e, and f show the sound pressure distributions for excitation signals at 500 Hz, 1000 Hz, 2000 Hz, 3000 Hz, 4000 Hz, and 5000 Hz, respectively. As can be seen from Figures 6, a, b, c, d, e, and f, by constructing constraint functions, an acoustic output device can exhibit the desired sound pressure distribution at different frequencies.

[0060] 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 to the acoustic output device. For example, at the same frequency, different sets of constraint functions can correspond the minimum far-field sound pressure level of the acoustic output device to different directions. Here, the different directions corresponding to the minimum far-field sound pressure level may be the directivity direction of the acoustic output device or the directivity range within a specific directional range (hereinafter abbreviated as the directivity range). In other words, the directivity direction or directivity range of the acoustic output device can be adjusted at the same frequency based on different sets of constraint functions. To achieve this objective, different first or second constraint functions corresponding to different directions can be determined, and a minimization process can be performed on the first or second constraint function to obtain different sets of first and second filter functions. Based on the modulation of the electrical signal by the first and second filter functions, the directivity direction or directivity range of the acoustic output device can be adjusted at the same frequency. In some embodiments, the mounting angle of the acoustic output device differs, requiring adjustment of the sound leakage reduction direction accordingly. In this case, based on a constraint function, the directional direction of the acoustic output device can be adjusted at the same frequency, and the direction corresponding to the minimum far-field sound pressure level of the acoustic output device can be adjusted in the opposite direction to the direction in which the user's ear is located. In some embodiments, the acoustic output device needs to adjust different sound leakage reduction ranges for different user application scenarios. For example, in relatively quiet usage scenarios such as libraries and offices, a filter function can be selected according to the need 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 in which other people are located. For example, this may be a directional range where the angle with the sagittal axis of the human body is 30 degrees, 40 degrees, 50 degrees, etc., thereby avoiding sound leakage interfering with others. Also, for example, depending on the need for sound leakage reduction direction corresponding to the time of day the acoustic output device is used, the direction corresponding to the minimum far-field sound pressure level of the acoustic output device can be adjusted based on a filter function.

[0061] In some embodiments, the acoustic output device can exhibit different sound pressure distributions at different frequencies. In this case, the processing circuit can provide the speaker with different sets of constraint functions at two different frequencies within a target frequency range. In some embodiments, the directivity direction or directivity range of the acoustic output device can be adjusted at two different frequencies based on different sets of constraint functions. To achieve this, different first or second constraint functions corresponding to different directions can be determined, and a minimization process can be performed on the first or second constraint function to obtain different sets of first and second filter functions. Based on the modulation of the first and second electrical signals by the first and second filter functions, respectively, the directivity direction or directivity range of the acoustic output device can be adjusted at different frequencies. For example, depending on the need for sound leakage reduction effects 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 range in which the human ear is more sensitive, for example, 2000Hz to 4000Hz, the minimum far-field sound pressure level of the acoustic output device can be adjusted in the opposite direction to the direction in which the user's ear is located, while in the listening frequency range in which the human ear is relatively less sensitive, for example, 200Hz to 400Hz, the minimum far-field sound pressure level of the acoustic output device can be adjusted in the other direction.

[0062] In some embodiments, the constraint function may 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 differs, the constraint function constructed by the processing circuit differs, and the filter function obtained by minimizing the constraint function differs. In some embodiments, the user can adjust the sound pressure distribution of the acoustic output device by outputting commands via a user input module based on their needs, causing the processing circuit to adjust the constraint function and filter function. In some embodiments, the user input may include input methods such as command input and voice input. Here, command input can be implemented based on methods such as touch and pressure. For example, the user can input a command by touching for a duration exceeding a threshold. Alternatively, for example, the user can activate the voice input mode of the acoustic output device by touch and then input a command verbally.

[0063] As a simple example, a user can select a mode according to the environment in which they are located (i.e., the application environment of the sound output device), and the mode may include noisy environments, quiet environments, etc., and may also include first-level environments, second-level environments, third-level environments, etc., where the first level, second level, and third level can indicate the sound pressure level of the environment. Alternatively, the user can directly input information about the application scenario, such as the application scenario name (office, outdoors, reading, etc.) and the sound pressure level of the environment. The processing circuit can then process and obtain a new filter function in response to the user's mode selection or input information, and use the new filter function to modulate the corresponding electrical signal, thereby achieving adjustment of the sound pressure distribution. For example, if the user is in a quiet environment or inputs the application scenario information "office", the processing circuit can use a first constraint function to minimize the sound pressure in a specific direction of the sound output device, and for a noisy environment, the processing circuit can use a second constraint function to minimize the sound pressure within a specific directional range of the sound output device.

[0064] In some embodiments, the constraint function may be obtained in response to a signal detected by a sensor of the acoustic output device, and the processing circuit adjusts the direction corresponding to the constraint function based on the detection result. For example, if the detection result indicates that ambient human voices are mainly coming from a 180° direction from the acoustic output device, the constraint function is constructed to reduce the far-field sound pressure level in a 180° direction from the acoustic output device. In some embodiments, the detection result will differ, the constraint function adjusted by the processing circuit will differ, and the filter function obtained by minimizing the constraint function will differ. In some embodiments, the acoustic output device can automatically identify the environment in which the user is located, obtain a detection result, and the processing circuit can adjust the filter function based on the detection result to adjust the sound pressure distribution of the acoustic output device.

[0065] As a simple example, an acoustic output device can use a sensor to identify the environment in which it is located (e.g., the sound pressure level of the environment), and the information identified by the sensor is used as a detection result. A processing circuit can then adjust a new filter function in response to the detection result and use the new filter function to modulate the corresponding electrical signal to achieve adjustment of the sound pressure distribution. In some embodiments, if the application environment in which the acoustic output device is located changes, the sensor can identify the change in the application environment, further identify new information in the new application environment and update the detection result. A processing circuit can then adjust the filter function in response to the updated detection result and use the new filter function to modulate the corresponding electrical signal to achieve adjustment of the sound pressure distribution.

[0066] In some embodiments of this specification, by determining different sets of filter functions based on different sets of constraint functions and applying filtering to the electrical signals to generate a first and second electrical signal, the acoustic output device can exhibit different sound pressure distributions, thereby meeting the needs of different usage scenarios for the acoustic output device. The following describes illustrative examples of sound pressure distributions that the acoustic output device may take. The acoustic output device can exhibit at least one of the different sound pressure distributions described below by setting the filter function. Furthermore, the acoustic output device can switch between the multiple sound pressure distributions described below by adjusting the filter function, thereby meeting the needs of different scenarios. Of course, the following descriptions of sound pressure distributions are merely illustrative and do not limit other possible sound pressure distribution schemes.

[0067] In some embodiments, by combining the curve 81 shown in Figure 6, the sound output device has a first sound pressure level in the far field in the first direction (0° direction shown in Figure 6), and a second sound pressure level in the far field in the second direction (180° direction shown in Figure 6). In some embodiments, the first and second directions relate to the positions of dual or multi-source sound sources, i.e., the positions of the holes in the sound output device, and further explanation can be found in Figures 7 to 11 and their related explanations. The filter function in this case is the first constraint function related to the far field sound pressure in the second direction.

[0068]

number

[0069] By minimizing the obtained filter function and applying filtering to the electrical signal based on the obtained filter function, the second sound pressure level in a 180° direction of the acoustic output device can be made to the minimum sound pressure level in the far field. If the first direction is close to the user's ear canal and the second direction is far from the user's ear canal, and the first sound pressure level is large, the volume of the sound received by the user will be large, improving the user's listening experience. If the second sound pressure level is small, the sound leakage volume of the acoustic output device will be small, improving the sound leakage reduction effect of the acoustic output device.

[0070] In some embodiments, the difference between the first sound pressure level and the second sound pressure level may be used to reflect the strength of the sound leakage reduction effect of the sound output device. In some embodiments, the directional range near the second direction also has an appropriate amount of sound leakage reduction effect, in which case the sound leakage reduction range of the sound output device can be considered equivalent to the direction within a sector-shaped region where the angle with respect to the second direction is less than 30°.

[0071] In some embodiments, the difference between the first and second sound pressure levels of the acoustic output device is greater than 12 dB. This increases the volume of sound radiated by the acoustic output device transmitted to the user's ear canal and reduces sound leakage from the acoustic output device. In some embodiments, at the first frequency, the difference between the first and second sound pressure levels of the acoustic output device is greater than 12 dB, and the difference between the far-field sound pressure level and the second sound pressure level in any direction with an angle of less than 30° to the second direction is 6 dB or more. In such a sound pressure distribution, the acoustic output device can achieve a strong sound leakage reduction effect in a specific direction, as well as a good sound leakage reduction effect within a range of smaller directions. As can be understood, such a sound pressure distribution corresponds to the sound pressure level being minimized in a specific direction of the acoustic output device. In some embodiments, to further improve the sound leakage reduction effect of the sound output device, at the first frequency, the difference between the first and second sound pressure levels of the sound output device can be made greater than 18 dB, and the difference between the far-field sound pressure level and the second sound pressure level in any direction with an angle of less than 30° with respect to the second direction can be made 6 dB or more. In some embodiments, to further improve the sound leakage reduction effect of the sound output device, at the first frequency, the difference between the first and second sound pressure levels of the sound output device can be made greater than 12 dB, and the difference between the far-field sound pressure level and the second sound pressure level in any direction with an angle of less than 25° with respect to the second direction can be made 6 dB or more. In some embodiments, to further improve the sound leakage reduction effect of the sound output device, at the first frequency, the difference between the first and second sound pressure levels of the sound output device can be made greater than 12 dB, and the difference between the far-field sound pressure level and the second sound pressure level in any direction with an angle of less than 30° with respect to the second direction can be made 8 dB or more. In some embodiments, the first frequency may be within the range of 1000Hz to 8000Hz.

[0072] The sound pressure distributions described in some embodiments of this specification, which achieve a strong sound leakage reduction effect within a small directional range, can be applied to scenarios where it is necessary to significantly enhance sound leakage reduction within a small directional angular range. For example, they can be applied to application scenarios where the orientation is relatively fixed, such as when riding public transport or in libraries or offices, prioritizing sound leakage reduction within a certain directional range to the side of the user, preventing sound leakage from the sound output device from interfering with people within that directional range to the side, and improving listening or call privacy.

[0073] In some embodiments, by combining the curve 82 shown in Figure 6, the sound output device has a first sound pressure level in the far field in the first direction, and the sound output device has a second sound pressure level in the far field in the second direction. The filter function in this case is a constraint function related to the far field sound pressure in the directional range where the angle with respect to the 180° direction is less than 45°.

[0074]

number

[0075] By minimizing the obtained filter function and performing filtering on the electrical signal based on the obtained filter function, the sound pressure level in the 135° to 225° directional range of the acoustic output device can be reduced, improving the sound leakage reduction effect. In some embodiments, an appropriate amount of sound leakage reduction effect can also be achieved in the directional ranges near 135° and near 225°. In this case, the sound leakage reduction range of the acoustic output device can be considered equivalent to the directional range of a sector-shaped region where the angle with the second direction is greater than 45°.

[0076] In some embodiments, the difference between the first and second sound pressure levels of the acoustic output device is greater than 9 dB, increasing the volume of sound transmitted to the user's ear canal from the acoustic output device and reducing sound leakage from the acoustic output device. 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 9 dB, and the angle between the second direction and the direction having a far-field sound pressure level 6 dB higher than the second sound pressure level is greater than 45°. That is, the sound pressure level in the directional range where the angle with the second direction is less than 45° may be 6 dB higher than the second sound pressure level. In such a sound pressure distribution, within a relatively large directional range, all acoustic output devices can achieve a good sound leakage reduction effect. As can be understood, such a sound pressure distribution corresponds to a small average sound pressure level within a certain directional range of the acoustic output device. The filter function in this case is obtained by minimizing the constraint function in the directional range where the angle with the second direction is less than 45°. In some embodiments, to further improve the sound leakage reduction effect of the sound output device, at the second frequency, the difference between the first and second sound pressure levels of the sound output device can be made greater than 12 dB, and the angle between the direction having a far-field sound pressure level 6 dB higher than the second sound pressure level and the second direction can be made greater than 50°. In some embodiments, to further improve the sound leakage reduction effect of the sound output device, at the second frequency, the difference between the first and second sound pressure levels of the sound output device can be made greater than 15 dB, and the angle between the direction having a far-field sound pressure level 6 dB higher than the second sound pressure level and the second direction can be made greater than 45°. In some embodiments, to further improve the sound leakage reduction effect of the sound output device, at the second frequency, the difference between the first and second sound pressure levels of the sound output device can be made greater than 12 dB, and the angle between the direction having a far-field sound pressure level 8 dB higher than the second sound pressure level and the second direction can be made greater than 45°. In some embodiments, the second frequency may be within the range of 200 Hz to 1000 Hz.

[0077] The sound pressure distributions described in some embodiments of this specification, which achieve a relatively strong sound leakage reduction effect over a relatively large directional range, can be applied to scenarios where enhanced sound leakage reduction is required over a large directional angular range. For example, they can be applied to scenarios where the crowd distribution around the user is widespread and irregular, or where the crowd distribution around the user is far away (e.g., sports scenarios, street scenarios, etc.). In such scenarios, it is not necessary to guarantee that the acoustic output device has an optimal sound leakage reduction effect in a particular direction, but the acoustic output device can achieve a certain sound leakage reduction effect over a large directional range.

[0078] In some embodiments, when an acoustic output device exhibits a sound field distribution that minimizes the far-field sound pressure level in a particular direction, it is possible to achieve different directions for the minimum far-field sound pressure level of the acoustic output device at two different frequencies within a target frequency range. In some embodiments, it is possible to adjust the direction corresponding to the minimum far-field sound pressure level of the acoustic output device at different frequencies based on a first constraint function corresponding to the different directions. For example, by constructing different first constraint functions, it is possible to minimize the far-field sound pressure level in the 180° direction of the acoustic output device at one frequency, and to minimize the far-field sound pressure level in a different direction from 180° at another frequency.

[0079] The directivity or different sound leakage reduction directions at two different frequencies within the target frequency range of an acoustic output device according to some embodiments of this specification can be applied to the selection of directivity at different frequencies. As just one example, in the frequency band sensitive to the human ear (e.g., 2000Hz to 4000Hz), the direction corresponding to the minimum far-field sound pressure level of the acoustic output device can be set to 180°, focusing on sound leakage reduction within the lateral range of the acoustic output device. In the frequency band not sensitive to the human ear (e.g., 5000Hz to 8000Hz), the direction corresponding to the minimum far-field sound pressure level of the acoustic output device may be a direction other than 180°, such as 160° or 200°.

[0080] In some embodiments, when actually mounting the acoustic output device, the direction in which sound leakage needs to be reduced changes due to differences in mounting angle or other reasons, and the sound leakage reduction direction of the acoustic output device needs to be adjusted to the actually required sound leakage reduction direction, i.e., the fourth direction, and the opposite direction of the fourth direction is the third direction. Based on the constraint function, the directivity direction of the acoustic output device can be adjusted, and the direction corresponding to the minimum far-field sound pressure level of the acoustic output device can be adjusted to the fourth direction. The filter function at this time can be obtained by minimizing the constraint function.

[0081] In some embodiments, at the third frequency, the angle between the fourth direction and the second direction is greater than 15°, and the difference between the second sound pressure level and the minimum far-field sound pressure level in the second direction of the sound output device is greater than 6dB. This ensures a sound leakage reduction effect within a directional range far from the second direction. In some embodiments, at the third frequency, the angle between the fourth direction and the second direction can be made greater than 25°, and the difference between the first sound pressure level and the second sound pressure level of the sound output device can be made greater than 6dB. In some embodiments, the angle between the fourth direction and the second direction can be adjusted according to the required directional range of sound leakage reduction; for example, the angle between the fourth direction and the second direction can be adjusted to be greater than 45° depending on the required directional range of sound leakage reduction. In some embodiments, the third frequency may be within the range of 200Hz to 8000Hz.

[0082] Some embodiments of this specification can provide a sound pressure distribution that guarantees a sound leakage reduction effect in a directional range far from the second direction, and such a sound pressure distribution can be applied to scenarios where the sound leakage reduction effect is enhanced in a directional range far from the side of the acoustic output device. For example, it can be applied when a specific person is located to the front or rear of the user, and by enhancing the sound leakage reduction effect in the front or rear range, it is possible to avoid interference from the sound leakage from the acoustic output device to the person in the front or rear. It can also be applied, for example, when, due to mounting issues, the side of the acoustic output device and the side of the user do not coincide, i.e., the side of the acoustic output device faces the second direction and the side of the user faces the fourth direction, and by enhancing the sound leakage reduction effect within the user's lateral range, it is possible to avoid interference from the sound output device to the person to the side of the user. Furthermore, it can be applied, for example, to scenarios where the user needs to move, and as the user moves, the directional range in which sound leakage reduction needs to be achieved also changes, and in this case, it is necessary to achieve a sound leakage reduction effect in a larger directional range to meet the need for sound leakage reduction.

[0083] By constructing the constraint function described above, the amplitude and / or phase of the first and second electrical signals are adjusted to control the sound pressure distribution formed by the second and first speakers together, thereby enabling the far-field radiation of the acoustic output device to exhibit directionality and further improving the problem of sound leakage in the far field of the acoustic output device. By adjusting the amplitude and / or phase of the first and second electrical signals, respectively, using the first and second filter functions, the objective of flexibly adjusting the directivity of the acoustic output device can be achieved. The first and second speakers included in the acoustic output device may have various structural forms, which will be illustrated below using a combination of Figures 7 to 12.

[0084] Figures 7 to 10 are schematic diagrams of different acoustic output devices according to some embodiments of this specification.

[0085] As shown in Figures 7 to 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 being installed inside the housing 310. The first speaker 320 includes a first diaphragm 321, with a first front cavity 330 and a first rear cavity 340 installed 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 a first hole 311 and a 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 having a phase difference through the first hole 311 and the second hole 312, respectively. The second speaker 350 includes a second diaphragm 351, with a second front cavity 360 and a second rear cavity 370 positioned in front of and behind 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 that forms the same cavity as the first rear cavity 340 is acoustically coupled to a second hole 312 in the housing 310, and the second speaker 350 outputs a third sound wave through the second hole 312 by driving a second electrical signal. In the above example, the third hole of the second speaker refers to the second hole 312, but in some other embodiments, the third hole of the second speaker may be a different hole from the first hole 311 and the second hole 312.

[0086] Next, as shown in Figures 7 to 10, in some embodiments, the vibration directions of the first vibrating membrane 321 and the second vibrating membrane 351 (for example, the vertical direction in Figures 7 to 10) are the same or close. In some embodiments, the first vibrating membrane 321 and the second vibrating membrane 351 may be spaced apart along the vibration direction, that is, the first speaker 320 and the second speaker 350 may be spaced apart along the vibration direction (as shown in Figures 7 to 8), and the first vibrating membrane 321 and the second vibrating membrane 351 may be spaced apart along a direction perpendicular to the vibration direction, that is, the first speaker 320 and the second speaker 350 may be spaced apart along a direction perpendicular to the vibration direction (as shown in Figures 9 to 10). Note that "close vibration directions" between the first vibrating membrane 321 and the second vibrating membrane 351 may mean that the angle of vibration between the first vibrating membrane 321 and the second vibrating membrane 351 may be smaller than a certain value (for example, 10°).

[0087] In some embodiments, the orientation of the first vibrating membrane 321 may be the same as or opposite to the orientation of the second vibrating membrane 351. In some embodiments, as shown in Figure 7, the orientation of the first vibrating membrane 321 and the orientation of the second vibrating membrane 351 are opposite, the first vibrating membrane 321 and the second vibrating membrane 351 are spaced apart along the vibration direction, the first rear cavity 340 and the second rear cavity 370 communicate to form the same cavity, and the second front cavity 360 is sealed. In some embodiments, as shown in Figure 8, the orientation of the first vibrating membrane 321 and the orientation of the second vibrating membrane 351 are the same, the first vibrating membrane 321 and the second vibrating membrane 351 are spaced apart along the vibration direction, the first rear cavity 340 and the second front cavity 360 communicate to form the same cavity, and the second rear cavity 370 is sealed. In some embodiments, as shown in Figure 9, the orientation of the first vibrating membrane 321 and the orientation of the second vibrating membrane 351 are the same, the first vibrating membrane 321 and the second vibrating membrane 351 are spaced apart along a direction perpendicular to the vibration direction, the first rear cavity 340 and the second rear cavity 370 communicate to form the same cavity, and the second front cavity 360 is sealed. In some embodiments, as shown in Figure 10, the orientation of the first vibrating membrane 321 and the orientation of the second vibrating membrane 351 are opposite, the first vibrating membrane 321 and the second vibrating membrane 351 are spaced apart along a direction perpendicular to the vibration direction, the first rear cavity 340 and the second front cavity 360 communicate to form the same cavity, and the second rear cavity 370 is sealed.

[0088] The far-field radiated sound from the acoustic output device 300 shown in Figures 7 to 10 exhibits directionality. When a user is wearing the acoustic output device 300, the direction from the second hole 312 to the first hole 311 is toward the user's ear canal, that is, the direction from the second hole 312 to the first hole 311 is the 0° direction shown in Figure 6, i.e., the first direction. The direction from the first hole 311 to the second hole 312 is toward the user's ear canal, that is, the direction from the first hole 311 to the second hole 312 is the 180° direction shown in Figure 6, i.e., the second direction.

[0089] Figure 11 is a schematic diagram of an acoustic output device according to some other embodiments of this specification. As shown in Figure 11, 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 located on the front and rear sides of the first diaphragm, 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 form a dual sound source as sound emission holes of the first speaker 420. The second speaker 450 includes a second diaphragm 451, with a second front cavity 460 and a second rear cavity 470 located on the front and rear sides of the second diaphragm 451, respectively. The housing 410 is provided with a third hole 413 that is acoustically coupled to the second rear cavity 470, and the third hole 413 is a different hole from the first hole 411 and the second hole 412. The second front cavity 460 is a sealed cavity. The third hole 413 forms a single sound source as the sound emission hole of the second speaker 450. The positions of the second front cavity 460 and the second rear cavity 470 are interchangeable, with the second front cavity 460 being acoustically coupled to the third hole 413 and the second rear cavity 470 being a sealed cavity.

[0090] In some embodiments, a partition plate 414 is installed inside the housing 410, and the partition plate 414 separates the second rear cavity 470 (or second front cavity 460), which is acoustically coupled to the third hole 413, from the first rear cavity 440, with the second hole 412 and the third hole 413 located on either side of the partition plate 414. Since the first speaker 420 and the second speaker 450 do not share the same cavity, the sound waves radiated from the first speaker 420 and the second speaker 450 do not interfere with each other, reducing the mutual radiated impedance.

[0091] In some embodiments of this specification, by independently installing the cavities for the first speaker and the second speaker, the first and second speakers avoid sharing the same cavity, thereby preventing sound waves radiated from the first and second speakers from interfering with each other and reducing mutual radiation impedance.

[0092] If the third hole is different from the first and second holes, it is necessary to determine the equivalent hole formed between the third hole and the first and second holes in order to determine the first and second directions. The position of the equivalent hole can be determined by the following method: connect the center points of adjacent holes in order to form a line segment, polygon, or polyhedron, and use the midpoint of the line segment, the centroid of the polygon, or the polyhedron as the center point of the equivalent hole, so that the center point of the equivalent hole represents the position of the equivalent hole. As shown in Figure 11, the second hole 412 and the third hole 413 are adjacent, and connect the center of the second hole 412 and the center of the third hole 413 to form a line segment, and the center point M of the line segment is considered to be the position of the equivalent hole between the second hole 412 and the third hole 413.

[0093] The far-field radiated sound from the acoustic output device 400 shown in Figure 11 exhibits directionality. When a user is wearing the acoustic output device 400, the direction from the equivalent hole to the first hole 411 is toward the user's ear canal, i.e., the direction from the equivalent hole to the first hole 411 is the 0° direction shown in Figure 6, i.e., the first direction. The direction from the first hole 411 to the equivalent hole is toward the user's ear canal, i.e., the direction from the first hole 411 to the equivalent hole is the 180° direction shown in Figure 6, i.e., the second direction.

[0094] Figure 12 is a schematic diagram of the directivity according to some embodiments of this specification. As shown in Figure 12, the acoustic output device shown in Figure 12 is in a mounted state, AS1 indicates the first hole of the acoustic output device, and AS2 indicates the second hole of the acoustic output device. In some embodiments, the far-field radiation of the acoustic output device exhibits directivity, meaning that the sound output direction of the acoustic output device is within a specific directional range, that is, the far-field radiation within the above-mentioned specific directional range of the acoustic output device is clearly larger or smaller than the far-field radiation outside the above-mentioned specific directional range. For example, the acoustic output device exhibits directivity in the first or second direction (the first and second directions are collinear).

[0095] In some embodiments, with the acoustic output device installed, the directions X1 and near X1 (e.g., directions X2, X3) from the second sound-emitting hole AS2 corresponding to the rear cavity of the acoustic output device to the first sound-emitting hole AS1 corresponding to the front cavity are directed toward the user's ear canal 201, while the directions X1' and near X1' (e.g., directions X2', X3') from the first hole AS1 to the second hole AS2 are directed toward the user's ear canal 201. Direction X1 is the first direction, and direction X1' is the second direction. In some embodiments, the directions near direction X1' may be understood as directions or directions within a range where the angle with direction X1' is smaller than a predetermined angle. The predetermined angle may be 10°, 15°, 25°, 30°, 35°, etc. In some embodiments, the far-field radiation from 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.).

[0096] In some embodiments, the directivity of the acoustic output device may be expressed such that the absolute value of the sound pressure level difference at the corresponding far-field position in a specific direction and the opposite direction of the acoustic output device is greater than or equal to a predetermined sound pressure level difference threshold. When worn, the specific direction may refer to the direction away from the user's ear canal, and the opposite direction may refer to the direction from the acoustic output device toward the user's ear canal. In some embodiments, the predetermined sound pressure level difference threshold may be 6dB, 8dB, 10dB, 12dB, 16dB, 18dB, etc. For the sake of easier understanding of directivity, only two holes, AS1 and AS2, are used as illustrative examples here. If the acoustic output device has many different holes, AS1 can be understood as an equivalent hole formed by some of the holes, and AS2 can be understood as an equivalent hole formed by other holes, in which case the direction of directivity may be determined by the position of the equivalent holes. In some embodiments, the position of an equivalent hole formed by multiple holes can be determined by the following method: connecting the center points of adjacent holes in sequence to form a polygon, the centroid of the polygon being the center point of the equivalent hole, and thus representing the position of the equivalent hole.

[0097] In some embodiments, the far-field radiation of the acoustic output device can exhibit heart-shaped directivity similar to curve 81 in Figure 6, and is expressed such that the absolute value of the sound pressure level difference in at least one pair of opposite directions (e.g., a first direction and a second direction) of the far-field radiated sound of the acoustic output device is greater than or equal to a predetermined sound pressure level difference threshold. Here, the at least one pair of opposite directions may each be within the directional range of the 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 connection line between the first hole AS1 and the second hole AS2. The heart-shaped directivity of the acoustic output device may be expressed such that there is a large difference in sound field intensity between a pair of opposite or nearly opposite directions within the directional range of the specific direction and its opposite direction. Exemplaryly, the pair of opposite or nearly opposite directions may refer to one direction located near the direction X1' from the first hole to the second hole, and the other direction located near the direction X1 from the second hole to the first hole. For example, direction X1' may be opposite or nearly opposite to directions X1, X2, and X3.

[0098] By positioning the acoustic output device so that its far-field radiation exhibits a heart-shaped directivity, the sound output from the device can be concentrated and transmitted towards the user's ear canal, reducing the transmission of sound in other directions, improving the problem of sound leakage from the acoustic output device, and enhancing the user's listening experience.

[0099] Having explained the basic concepts above, it will be clear to those skilled in the art that the above detailed disclosure is merely illustrative and does not limit the present application. Although not explicitly stated in the present application, those skilled in the art can make various changes, improvements, and modifications to the present application. These changes, improvements, and modifications are suggested by the present application and still remain within the spirit and scope of the exemplary embodiments of the present application.

[0100] Furthermore, certain terms are used in this Application to describe embodiments thereof. For example, “one embodiment,” “one embodiment,” and / or “several embodiments” mean certain features, structures, or properties relating to at least one embodiment of this Application. Therefore, it should be emphasized and understood that two or more references to “one embodiment,” “one embodiment,” or “one alternative embodiment” in various parts of this Specification do not necessarily refer to the same embodiment. Also, certain features, structures, or properties in one or more embodiments of this Application may be appropriately combined.

[0101] Furthermore, as will be understood by those skilled in the art, each aspect of this Application may be illustrated and described in several patentable classes or contexts, including any novel and useful combination of processes, machines, products or materials, or any novel and useful improvement thereto. Thus, each aspect of this Application may be executed entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. Any of the above hardware or software may be referred to as “data blocks,” “modules,” “engines,” “units,” “assemblies,” or “systems.” Also, each aspect of this Application may take the form of a computer program product embodied in one or more computer-readable media, including computer-readable program code.

[0102] A computer storage medium may include propagated data signals that are propagated over a baseband or as part of a carrier wave for carrying computer program code. These propagated signals may take various forms, such as electromagnetic signals, optical signals, or appropriate combinations thereof. The computer storage medium may be any computer-readable medium other than a computer-readable storage medium, which, when connected to an instruction execution system, device, or apparatus, can enable communication, propagation, or transmission of the program being used. Program code on the computer storage medium can be propagated via any appropriate medium, including wireless, cable, fiber optic cable, RF, or similar media, or any combination of the above media.

[0103] Furthermore, unless explicitly stated in the claims, the enumerated order, use of alphanumeric characters, or use of other names of the processing elements or sequences described herein is not limited to the order of the procedures and methods of this application. While the above disclosure illustrates various examples that are currently considered useful embodiments of the invention, such details are for illustrative purposes only, and it should be understood that the attached claims are not limited to the disclosed embodiments, but rather are intended to cover all modifications and equivalent combinations that fall within the spirit and scope of the embodiments of this application. For example, the system assembly described above may be implemented by a hardware device, but it may also be implemented by a software-only solution, such as by installing the described system on an existing processing device or mobile device.

[0104] Similarly, in the foregoing description of the embodiments of this application, please understand that various features may be combined into a single embodiment, drawing, or description in order to simplify the expressions disclosed herein and to aid in understanding one or more embodiments of the invention. However, such a method of disclosure does not mean that the features required for the subject matter of this application are greater than the features described in the claims. In fact, the features of an embodiment may be fewer than all the features of a single embodiment disclosed above.

[0105] In some embodiments, numbers are used to describe the number of components and attributes, and it should be understood that in some cases these numbers describing such embodiments are modified by the modifiers “about,” “approximately,” or “generally.” Unless otherwise specified, “about,” “approximately,” or “generally” indicates that the above numbers are allowed to vary by ±20%. Therefore, in some embodiments, the numerical parameters used in the specification and claims are all approximations that may vary depending on the characteristics required for the individual embodiment. In some embodiments, the numerical parameters should be treated with regard to the specified number of significant figures, and the usual place-keep method should be applied. In some embodiments of this application, the numerical ranges and parameters used to determine the range are approximations, but in specific embodiments, such numbers should be set as precisely as possible.

[0106] All patents, patent applications, published patent gazettes, and other materials such as articles, books, specifications, publications, and documents referenced herein are incorporated in their entirety by reference, with the exception of any prosecution history documents that are inconsistent with or contradict the content of this Application, and any documents that may have a limited effect on the broadest scope of the claims of this Application (currently or later relating to this Application). In the event of any inconsistency or contradiction between the descriptions, definitions, and / or use of terms in the appendices to this Application and the content of this Application, the descriptions, definitions, and / or use of terms in this Application shall prevail.

[0107] Finally, it should be understood that the embodiments described herein are merely illustrative of the principles of the embodiments herein. Other modifications may also be within the scope of this application. Therefore, alternative configurations of the embodiments herein may be considered consistent with the teachings herein, not as an extension but as an example. Accordingly, the embodiments herein are not limited to those explicitly introduced and described herein. [Explanation of Symbols]

[0108] 100, 300, 400 Audio Output Devices 110, 310, 410 Housing 111, 311, 411 1st hole 112, 312, 412 2nd hole 120 speakers 130 Front Cavity 140 Rear Cavity 320, 420 1st speaker 321, 421 First vibrating membrane 330, 430 First Front Cavity 340, 440 1st rear cavity 350, 450 2nd Speaker 351, 451 Second diaphragm 360, 460 Second Front Cavity 370, 470 Second rear cavity 413 3rd hole

Claims

1. It is an audio output device, Housing and A first speaker is installed within the housing and includes a first diaphragm, the housing having a first front cavity and a first rear cavity correspondingly installed 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 installed in the housing, respectively, to output a first sound wave and a second sound wave having a phase difference, A second speaker is installed within the housing and includes a second diaphragm, the housing having a second front cavity and a second rear cavity 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 single hole in the housing, thereby outputting a third sound wave. The system includes a processing circuit configured to provide a first electrical signal to the first speaker and a second electrical signal to the second speaker, An acoustic output device in which the first electrical signal and the second electrical signal have differences in amplitude and / or phase within a target frequency range such that the far-field radiated sound of the acoustic output device exhibits 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 connected to a first hole and a second hole installed in 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 which is the same cavity as the first rear cavity outputs the third sound wave through the second hole, the direction from the second hole to the first hole is the first direction, and the direction from the first hole to the second hole is the second direction.

4. The acoustic output device according to claim 2, wherein the first front cavity and the first rear cavity are connected to a first hole and a second hole installed in the housing, respectively, and one of the second front cavity and the second rear cavity is connected to a third hole in the housing, the third hole is different from the first hole and the second hole, the second hole and the third hole have an equivalent hole, the direction from the equivalent hole to the first hole is the first direction, and the direction from the first hole to the equivalent hole 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 between the far-field sound pressure level in the first direction of the acoustic output device and the far-field sound pressure level in the second direction is greater than 12 dB, and the difference between the far-field sound pressure level in any direction with an angle of less than 30° with respect to the second direction and the far-field sound pressure level in the second direction is 6 dB or more.

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 between the far-field sound pressure level in the first direction and the far-field sound pressure level in the second direction of the acoustic output device is greater than 9 dB, and the angle between the direction having a far-field sound pressure level 6 dB greater 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, an angle between the direction corresponding to the minimum far-field sound pressure level of the acoustic output device and the second direction being 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 being 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 level in the sound pressure distributions corresponding to two different frequencies within the target frequency range corresponding to different directions.

9. The processing circuit is capable of acquiring a plurality of filter function groups, each of which 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 respond to the modulation of the first filter function and the second filter function, respectively, and different filter function groups provide different sound pressure distributions to the sound output device at the same frequency, as described in claim 3 or 4.

10. The acoustic output device according to claim 9, wherein, under modulation of different sets of filter functions, the minimum far-field sound pressure level in the sound pressure distribution generated by the acoustic output device at the same frequency corresponds to different directions.

11. The sound output device according to claim 9, wherein the processing circuit adjusts the group of filter functions in real time based on user input.

12. It is an audio output device, Housing and A first speaker is installed within the housing and includes a first diaphragm, the housing having a first front cavity and a first rear cavity correspondingly installed 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 installed in the housing, respectively, to output a first sound wave and a second sound wave having a phase difference, A second speaker is installed within the housing and includes a second diaphragm, the housing having a second front cavity and a second rear cavity 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 single hole in the housing, thereby outputting a third sound wave. The system includes 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 is capable of acquiring a plurality of filter function groups, each of which includes a first filter function and a second filter function 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 and the second filter function, respectively, and different filter function groups provide different sound pressure distributions to the sound output device at the same frequency, in the sound output device.

13. The acoustic output device according to claim 12, wherein, under modulation of different sets of filter functions, the minimum far-field sound pressure level in the sound pressure distribution generated by the acoustic output device at the same frequency corresponds to different directions.

14. The sound output device according to claim 12, wherein the processing circuit adjusts the group of filter functions in real time based on user input.

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

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 connected to a first hole and a second hole installed in 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 which is the same cavity as the first rear cavity outputs the third sound wave through the second hole, the direction from the second hole to the first hole is the first direction, and the direction from the first hole to the second hole is the second direction.

18. The acoustic output device according to claim 16, wherein the first front cavity and the first rear cavity are connected to a first hole and a second hole installed in the housing, respectively, and one of the second front cavity and the second rear cavity is connected to a third hole in the housing, the third hole is different from the first hole and the second hole, the second hole and the third hole have an equivalent hole, the direction from the equivalent hole to the first hole is the first direction, and the direction from the first hole to the equivalent hole 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 between the far-field sound pressure level in the first direction of the acoustic output device and the far-field sound pressure level in the second direction being greater than 12 dB, and the difference between the far-field sound pressure level in any direction with an angle of less than 30° with respect to the second direction and the far-field sound pressure level in the second direction being 6 dB or more.

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 between the far-field sound pressure level in the first direction of the acoustic output device and the far-field sound pressure level in the second direction is greater than 9 dB, and the angle between the direction having a far-field sound pressure level 6 dB greater than the far-field sound pressure level 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, an angle between the direction corresponding to the minimum far-field sound pressure level of the acoustic output device and the second direction being 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 being 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 level in the sound pressure distribution corresponding to two different frequencies within the target frequency range corresponding to different directions.

23. The acoustic output device according to claim 17 or 18, wherein different groups of filter functions provide different sound pressure distributions to the acoustic output device at the same frequency, and the modulation of one of the different groups of filter functions at the same frequency causes the difference between the far-field sound pressure level in the first direction and the far-field sound pressure level in the second direction of the acoustic output device to be greater than 12 dB, and the difference between the far-field sound pressure level in any direction with an angle of less than 30° with respect to the second direction and the far-field sound pressure level in the second direction to be 6 dB or more, and the modulation of another group of filter functions at the different groups of filter functions causes the difference between the far-field sound pressure level in the first direction and the far-field sound pressure level in the second direction of the acoustic output device to be greater than 9 dB, and the angle between the direction having a far-field sound pressure level 6 dB greater than the far-field sound pressure level in the second direction and the second direction to be greater than 45°.

24. It is an audio output device, Housing and A first speaker is installed within the housing, outputs sound waves to the outside through at least one hole in the housing, and has a first response function in the far field. A second speaker is installed within the housing, outputs sound waves to the outside through at least one hole in the housing, and has a second response function in the far field. The system includes 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 constructs at least one set of constraint functions based on the first response function and the second response function, each set of constraint functions generates 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 respond to the modulation of the first filter function and the second filter function, respectively, and each set of constraint functions provides the acoustic output device with a specific sound pressure distribution.

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

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

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

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