Audio output device, sound image adjustment method, and volume adjustment method

Abstract

To provide a sound image adjustment method and a volume adjustment method for correcting the offset of a sound image sensed by a user, and an audio output device and a volume adjustment method for correcting the volume difference between left and right speakers caused by the mass difference of the mechanical structures of the speakers placed against the left and right ears.SOLUTION: A sound image adjustment method obtains a volume difference between a first sound wave and a second sound wave, and adjusts a time difference between the first sound wave and the second sound wave. The volume adjustment method obtains a volume difference between the first sound wave and the second sound wave, and adjusts an amplitude difference between the first excitation and the second excitation. An audio output device corrects an offset of the sound image perceived by a user due to a mass difference between the first mechanical structure and the second mechanical structure. The audio output device also corrects a volume difference between the first speaker and the second speaker due to a mass difference between the first mechanical structure and the second mechanical structure.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present application relates to the field of acoustics, and more particularly to an audio output device, a sound image adjustment method, and a volume adjustment method. [Background technology]

[0002] When bone conduction earphones are in operation, there is a positive correlation between the vibration amplitude of the bone conduction speaker and the volume it generates. The mass of the bone conduction speaker housing has a significant impact on its vibration amplitude, which in turn affects the volume generated by the speaker. In the product design of bone conduction earphones, it may be necessary to place an additional functional module, such as a headset microphone (a microphone with an extension rod attached) or buttons, on one side of the bone conduction speaker. Buttons on the bone conduction speaker affect the volume generated by the speaker by changing the mass distribution of the bone conduction speaker. Furthermore, if functional modules such as a headset microphone or buttons are placed only on one side and not the other, the volume levels of the two speakers will not match (the volume of the speaker placed on one ear will be high, while the volume of the speaker placed on the other ear will be low), causing a sound image offset. A large volume difference between the left and right speakers may damage the user's hearing after long-term use. Therefore, it is necessary to adjust the sound image to center the sound image and / or adjust the volume levels of the speakers on both sides of the earphone to match the volume levels of the two speakers. Summary of the Invention

[0003] The following provides a brief summary of the present application in order to provide a basic understanding of some aspects of the present application. It should be understood that this summary is not intended to identify key or important parts of the present application, nor is it intended to limit the scope of the present application. Its sole purpose is to briefly introduce some concepts in the present application. More details are described in detail in other parts of the present application. [Problem to be solved by the invention]

[0004] As mentioned above, in bone conduction earphones, the functional module attached to one bone conduction speaker increases the mass of the housing of the bone conduction speaker, which reduces the volume of the speaker on that side, resulting in a difference in volume between the left and right bone conduction earphones. If the volume difference between the left and right earphones is large, an obvious offset will occur in the sound image of the earphones, which will eventually damage hearing after long-term use. [Means for solving the problem]

[0005] In order to solve the technical problems of volume difference and sound image offset caused by mass unevenness between speakers on both sides of a bone conduction earphone, the audio output device disclosed in this application includes: a signal processing circuit that generates a first electric signal and a second electric signal based on target audio information during operation; a first speaker that is electrically connected to the signal processing circuit and that receives the first electric signal from the signal processing circuit during operation and converts the first electric signal into a first sound wave; and a second speaker that is electrically connected to the signal processing circuit and that receives the second electric signal from the signal processing circuit during operation and converts the second electric signal into a second sound wave, wherein the audio output device requires a first time length to convert the target audio information into the first sound wave and a second time length to convert the target audio information into the second sound wave, and the first time length is shorter than the second time length by one time difference.

[0006] In some embodiments, when an electrical signal having the same amplitude and frequency is input, the volume of the sound waves output from the first speaker is smaller than the volume of the sound waves output from the second speaker.

[0007] In some embodiments, when electrical signals having the same amplitude and frequency are input, the difference in volume between the first sound wave and the second sound wave is 3 dB or less.

[0008] In some embodiments, the first speaker generates the first sound wave by exciting a first mechanical structure, and the second speaker generates the second sound wave by exciting a second mechanical structure, and because the mass of the first mechanical structure is greater than the mass of the second mechanical structure, when an electrical signal having the same amplitude and frequency is input, the volume of the sound wave output from the first speaker is smaller than the volume of the sound wave output from the second speaker.

[0009] In some embodiments, the first speaker includes at least one of a first bone conduction speaker and a first air conduction speaker, and the second speaker includes at least one of a second bone conduction speaker and a second air conduction speaker.

[0010] In some embodiments, the time difference occurs during the process of converting the target audio information into the first electrical signal and the second electrical signal by the audio output device.

[0011] In some embodiments, the time difference occurs when the first speaker converts the first electrical signal into the first sound wave and the second speaker converts the second electrical signal into a second sound wave.

[0012] In some embodiments, the time difference is less than or equal to 3 ms.

[0013] The present application also discloses an audio output device that includes: a signal processing circuit that generates a first electrical signal and a second electrical signal based on target audio information during operation; a first speaker that is electrically connected to the signal processing circuit and that receives the first electrical signal from the signal processing circuit during operation and converts the first electrical signal into a first excitation to excite a first mechanical structure, thereby generating a first sound wave; and a second speaker that is electrically connected to the signal processing circuit and that receives a second electrical signal from the signal processing circuit during operation and converts the second electrical signal into a second excitation to excite a second mechanical structure, thereby generating a second sound wave, wherein the volume of the first sound wave is the same as the volume of the second sound wave, and the volume generated by the first mechanical structure under the same excitation is smaller than the volume generated by the second mechanical structure.

[0014] In some embodiments, the mass of the first mechanical structure is greater than the mass of the second mechanical structure, so that under the same excitation, the volume generated by the first mechanical structure is smaller than the volume generated by the second mechanical structure.

[0015] In some embodiments, the first speaker includes at least one of a first bone conduction speaker and a first air conduction speaker, and the second speaker includes at least one of a second bone conduction speaker and a second air conduction speaker.

[0016] In some embodiments, the first speaker further includes a first electromagnetic excitation device that generates the first excitation, which excites the first mechanical structure to vibrate, thereby generating the first sound wave; and the second speaker further includes a second electromagnetic excitation device that generates the second excitation, which excites the second mechanical structure to vibrate, thereby generating the second sound wave.

[0017] In some embodiments, the first electromagnetic excitation device includes a first coil and the second electromagnetic excitation device includes a second coil, and a diameter of the winding of the first coil is larger than a diameter of the winding of the second coil.

[0018] In some embodiments, the first electromagnetic excitation device includes a first coil and the second electromagnetic excitation device includes a second coil, and the resistivity of the first coil is less than the resistivity of the second coil.

[0019] In some embodiments, for the same input current, the first excitation generated by the first electromagnetic excitation device is greater than the second excitation generated by the second electromagnetic excitation device.

[0020] In some embodiments, the first speaker includes a first resistor and the second speaker includes a second resistor, the first resistor being smaller than the second resistor.

[0021] In some embodiments, the audio output device further includes a power amplifier circuit connected to the first speaker and the signal processing circuit, the power amplifier circuit amplifying the first electrical signal, and the first speaker receiving the amplified first electrical signal.

[0022] In some embodiments, the audio output device further includes a power attenuation circuit connected to the second speaker and the signal processing circuit, the power attenuation circuit attenuating the second electrical signal, and the second speaker receiving the attenuated second electrical signal.

[0023] The present application also discloses a sound image adjustment method configured to adjust sound images of a first speaker and a second speaker of an audio output device, the sound image adjustment method including the steps of obtaining a volume difference between the first sound wave and the second sound wave and adjusting the time difference.

[0024] In some embodiments, the difference in volume between the first sound wave and the second sound wave is 3 dB or less.

[0025] In some embodiments, adjusting the time difference between the first sound wave and the second sound wave includes adjusting a phase difference between the first sound wave and the second sound wave.

[0026] The present application also discloses a volume adjustment method configured to adjust volumes of a first speaker and a second speaker of an audio output device, the volume adjustment method including the steps of obtaining a volume difference between the first sound wave and the second sound wave, and adjusting an amplitude difference between the first excitation and the second excitation. [Effects of the Invention]

[0027] In light of the above, in response to the technical problems of volume differences and sound image offsets caused by uneven mass between the speakers on both sides of bone conduction earphones, the audio output device and sound image adjustment method of the present application correct the sound image offset perceived by the user due to the mass difference between the first mechanical structure and the second mechanical structure by setting a time difference between the first sound wave and the second sound wave.

[0028] The audio output device and volume adjustment method of the present application correct the volume difference between the left and right speakers caused by the mass difference of the mechanical structures of the speakers placed against the left and right ears by setting different coil resistivities, coil winding diameters, magnetic field strengths, and / or resistances. [Brief explanation of the drawings]

[0029] Exemplary embodiments disclosed herein will now be described in detail with reference to the drawings. The same reference numerals represent similar structures in the various views of the drawings. As will be understood by those skilled in the art, these embodiments are non-limiting, exemplary embodiments, and the drawings are for illustration and explanation purposes only and are not intended to limit the scope of the present disclosure, and other forms of embodiments can also achieve the inventive intent of the present application. It should be understood that the drawings are not drawn to scale.

[0030] [Figure 1] 1 shows a schematic diagram of the appearance of an audio output device according to some embodiments of the present application. [Figure 2] 1 shows a schematic configuration diagram of an audio output device according to some embodiments of the present application; [Figure 3] 1 shows a schematic diagram of an electromagnetic excitation device according to some embodiments of the present application; [Figure 4] 1 shows a schematic diagram of a bone conduction speaker according to some embodiments of the present application; [Figure 5] 1 shows a schematic diagram of a vibration model of a bone conduction speaker according to some embodiments of the present application; [Figure 6] 10 illustrates vibration test results of a housing during operation according to some embodiments of the present application. [Figure 7] 1 shows a schematic diagram of a moving coil speaker according to some embodiments of the present application; [Figure 8] 1 shows a flowchart of a volume adjustment method according to an embodiment of the present application. [Figure 9] 1 shows a flowchart of a sound image adjustment method according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0031] The following description is presented to enable one skilled in the art to make and use the subject matter of the present disclosure and is provided in the context of particular applications of the present disclosure and their requirements. These and other features of the present disclosure, the operation and function of associated elements of structure, and the combination of parts and economies of manufacture, can be significantly improved in light of the following description. Reference is now made to the drawings, all of which constitute a part of this disclosure. It is to be clearly understood, however, that the drawings are for purposes of illustration and description only and are not intended to limit the scope of the present disclosure. Various modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the claims.

[0032] In this application, bone-conducted sound waves refer to sound waves in which mechanical vibrations are conducted into the ear via the bones (also called bone-conducted sound), and air-conducted sound waves refer to sound waves in which mechanical vibrations are conducted into the ear via gas (also called air-conducted sound).

[0033] The present application provides a volume adjustment method. The volume adjustment method can adjust the volume of sound waves output from an audio output device. The sound waves may include bone-conducted sound waves and / or air-conducted sound waves. The audio output device may include, but is not limited to, earphones, hearing aids, helmets, etc. The earphones may include, but are not limited to, wired earphones, wireless earphones, Bluetooth® earphones, etc. The earphones may include, but are not limited to, bone-conducted speakers and air-conducted speakers.

[0034] Fig. 1 shows a schematic external view of an audio output device 300 according to an embodiment of the present application. Fig. 2 shows a schematic configuration diagram of the audio output device 300 according to an embodiment of the present application. As shown in Fig. 2, the audio output device 300 may include a first speaker 310, a second speaker 320, and a signal processing circuit 330.

[0035] The signal processing circuit 330 can receive the target audio information 10 and process the target audio information 10 to generate a first electrical signal 11 and a second electrical signal 12 .

[0036] The target audio information 10 may include a video file, an audio file, or data or files that can be converted into audio by a specific method. The target audio information 10 may be from a storage assembly of the audio output device 300 itself, or from an information generation, storage, or transmission system other than the audio output device 300. The target audio information 10 may include one or a combination of electrical signals, optical signals, magnetic signals, mechanical signals, etc. The target audio information 10 may be from one signal source or multiple signal sources. The multiple signal sources may be correlated or uncorrelated. In some embodiments, the signal processing circuit 330 may acquire the target audio information 10 in multiple different ways. The acquisition of the target audio information 10 may be wired or wireless, and may be real-time or delayed. For example, the audio output device 300 may receive the target audio information 10 via a wired or wireless method, or may acquire data directly from a storage medium to generate the target audio signal 10. For example, the audio output device 300 may include an assembly with an audio collection function, which picks up sounds in the environment, converts the mechanical vibrations of the sounds into electrical signals, and obtains electrical signals that meet specific requirements after passing through an amplification processor. In some embodiments, the wired connection may include a metal cable, an optical cable, or a metal-optical hybrid cable, such as one or more of a coaxial cable, a communication cable, a flexible cable, a spiral cable, a non-metallic sheath cable, a metal sheath cable, a multi-core cable, a twisted pair cable, a ribbon cable, a shielded cable, an electric core cable, a paired cable, a two-core parallel wiring, a twisted pair, etc. The above examples are for ease of explanation only, and the medium of the wired connection may be of another type, such as a transmission carrier of another electrical signal or an optical signal. The wireless connection may include wireless communication, free-space optical communication, audio communication, electromagnetic induction, etc.Wireless communications may include IEEE 802.11 standards, IEEE 802.15 standards (e.g., Bluetooth technology and cellular technology), first generation mobile communications technologies, second generation mobile communications technologies (e.g., FDMA, TDMA, SDMA, CDMA, and SSMA), general packet radio service technologies, third generation mobile communications technologies (e.g., CDMA2000, WCDMA, TD-SCDMA, and WiMAX), fourth generation mobile communications technologies (e.g., TD-LTE and FDD-LTE), satellite communications (e.g., GPS technology), near field communication (NFC) and other operating in other ISM bands (e.g., 2.4 GHz), free space optical communications may include visible light signals, infrared signals, etc., voice communications may include sound waves, ultrasonic signals, etc., electromagnetic induction may include near field communication technologies, etc. The above example is merely for ease of explanation, and the medium of wireless connection may be of other types, such as Z-wave technology, other paid radio frequency bands for civil or military use, etc. For example, in some application scenarios of the present application, the audio output device 300 may obtain the target audio information 10 from other devices through Bluetooth technology.

[0037] In some embodiments, in order to cause the first sound wave 21 and the second sound wave 22 to have specific output characteristics (e.g., frequency, phase, amplitude, etc.), the signal processing circuit 330 may process the target sound information 10 so that the first electrical signal 11 and the second electrical signal 12 output from the signal processing circuit 330 each contain specific frequency components.

[0038] In some embodiments, the signal processing circuit 330 may include multiple filters / filter banks 331. The multiple filters / filter banks 331 may process the received electrical signal and output an electrical signal containing different frequencies. The filter / filter bank 331 may include, but is not limited to, analog filters, digital filters, passive filters, active filters, etc. In some embodiments, the signal processing circuit 330 may include a dynamic range controller 332. The dynamic range controller 332 may be configured to compress and amplify the input signal so that the sound appears softer or louder. In some embodiments, the signal processing circuit 330 may include an active sound leakage reduction circuit 333 to reduce sound leakage from the audio output device 300. In some embodiments, the signal processing circuit 330 may include a feedback circuit 334. The feedback circuit 334 may feed back sound field information to the signal processing circuit 330. In some embodiments, the signal processing circuit 330 may include a power adjustment circuit 335 that adjusts the amplitude of the received electrical signal. The power conditioning circuit 335 may include a power amplifier circuit to amplify the signal amplitude of the first electrical signal 11 and / or the second electrical signal 12. The power conditioning circuit 335 may further include a power attenuation circuit to attenuate the signal amplitude of the first electrical signal 11 and / or the second electrical signal 12. In some embodiments, an equalizer 338 may be provided in the signal processing circuit 330. The equalizer 338 may be configured to apply individual gain or attenuation to the received signal according to a specific frequency band. In some embodiments, the signal processing circuit 330 may include a frequency division circuit 339. The frequency division circuit may divide the received electrical signal into high-frequency signal components and low-frequency signal components.

[0039] The first speaker 310 is electrically connected to the signal processing circuit 330. The first speaker 310 may receive a first electrical signal 11 from the signal processing circuit 330 and convert the first electrical signal 11 into a first sound wave 21. The first speaker 310 may be a transducer. In some embodiments, the first speaker 310 may convert the received first electrical signal 11 into mechanical vibrations. Furthermore, the first sound wave 21 is generated by the mechanical vibrations. For example, the first speaker 310 may include a first mechanical structure 311 and a first excitation device 312. In some embodiments, the first speaker 310 may be a bone conduction speaker, an air conduction speaker, or a combination of a bone conduction speaker and an air conduction speaker.

[0040] The first excitation device 312 may be the input end of the transducer. The first excitation device 312 receives the first electric signal 11 from the signal processing circuit 330 and converts the first electric signal 11 into a first excitation. The first excitation excites the first mechanical structure 311 to vibrate. That is, through the first excitation device 312 and the first mechanical structure 311, the first speaker 310 converts the electrical energy of the received first electric signal 11 into mechanical vibration energy of the first mechanical structure 311.

[0041] The first excitation device 412 excites the first mechanical structure 411 to vibrate by generating the first excitation. In some embodiments, the first excitation device 412 may be an electromagnetic excitation device. The first excitation may be a magnetic field force, an electromagnetic force, and / or an Ampere force generated by the electromagnetic excitation device. Of course, the first excitation device 412 may also be another type of excitation device, and is not specifically limited herein. The excitation device receives the first electrical signal 11 from the signal processing circuit 430 and generates the first excitation. The manner in which the excitation device generates the first excitation may include, but is not limited to, a moving coil type, an electrostatic type, a piezoelectric type, a balanced armature type, a pneumatic type, an electromagnetic type, etc.

[0042] For example, Fig. 3 shows a schematic diagram of a first excitation device 412 according to an embodiment of the present application. The first excitation device 412 shown in Fig. 3 may be an electromagnetic excitation device. Specifically, the first excitation device 412 may include a magnetic member 610 and a coil 620.

[0043] The magnetic member 610 may generate a magnetic field. For example, the magnetic member 610 may have a magnetic property. In some embodiments, the magnetic property may be constant. The magnetic member 610 may include or be manufactured from a permanent magnet. The permanent magnet may be a natural magnet or an artificial magnet. For example, the permanent magnet may include, but is not limited to, a neodymium-iron-boron magnet, a samarium-cobalt magnet, an alnico magnet, etc. The permanent magnet should have as high a coercivity, remanence, and maximum magnetic energy product as possible to ensure that the permanent magnet has stable magnetic properties and can store maximum magnetic energy.

[0044] The coil 620 may be a wire wound in a certain direction. The coil 620 may be placed in a magnetic field generated by the magnetic member 610. The coil 620 may include a first end 621 and a second end 622. An electrical signal in the form of a current may enter the coil 620 from the first end 621, flow through the coil 620, and exit from the second end 622.

[0045] As can be understood from electromagnetic knowledge, the energized coil 620 is subjected to an Ampere force in a magnetic field. The magnitude of the Ampere force may be determined by F = BIL. Here, F represents the magnitude of the Ampere force applied to the coil 620, and the direction of F may be determined based on Ampere's law. F drives the coil 620 to vibrate. The coil 620 may be connected to a mechanical structure 630, and the coil 620 drives the mechanical structure 630 to vibrate. For example, the mechanical structure 630 may be the first mechanical structure 311 that generates the first acoustic wave 21. That is, F may be an external excitation signal that excites the first mechanical structure 311 to vibrate.

[0046] B is the magnetic field strength of the magnetic field generated by the magnetic member 610. The magnitude of the magnetic field strength of the magnetic member 610 is correlated with the material of the magnetic member 610. In some embodiments, the magnitude of the magnetic field strength B generated by the magnetic member 610 is positively correlated with the coercivity, remanence, and maximum magnetic energy product of the magnetic member 610.

[0047] I is the magnitude of the current flowing through the coil 620. I is correlated with the electrical signal received by the first excitation device 412. Typically, the electrical signal is input to the coil 620 in the form of a pulse voltage. The magnitude of the pulse voltage between the first end 621 and the second end 622 of the coil 620 (i.e., the electrical signal input to the electromagnetic excitation device 600) is expressed as U. t In this case, the current I flowing through the coil 620 is expressed as I=U t / R, where R represents the magnitude of the resistance between the first end 621 and the second end 622. Furthermore, as can be understood from physics, the magnitude of the resistance between the first end 621 and the second end 622 may be calculated based on R=ρL / S, where ρ represents the resistivity of the winding of the coil 620, L represents the length of the coil 620, and S represents the diameter of the winding of the coil 620.

[0048] From the above, the magnitude of the excitation F (ie, the Ampere force received by the coil) generated by the first excitation device 412 may be as follows:

number

[0049] Further, as shown in FIG. 2 , the first mechanical structure 311 may be the output end of the energy conversion device. The first mechanical structure 311 vibrates to generate a first sound wave 21. The first mechanical structure 311 may generate mechanical vibrations under the action of a first excitation, and the first sound wave 21 is generated based on the mechanical vibration. In some embodiments, the first mechanical structure 311 may be a member that directly emits sound by vibration after being excited. For example, if the first speaker is a bone conduction speaker, the first mechanical structure 311 may be a housing of the bone conduction speaker. On the other hand, if the first speaker is a moving coil air conduction speaker, the first mechanical structure 311 may include a wool cone or a paper cone of the moving coil air conduction speaker.

[0050] Since the first sound wave 21 is generated by the vibration of the first mechanical structure 311, it is necessary to analyze the vibration process of the first mechanical structure 311 in order to analyze the characteristics of the first sound wave 21. Next, in this application, the vibration process of the first mechanical structure 311 will be analyzed using an example in which the first speaker 310 is a bone conduction speaker.

[0051] 4 shows a schematic configuration diagram of a bone conduction speaker 100 according to some embodiments of the present application. The bone conduction speaker 100 may include a housing 120 and a magnetic circuit 130.

[0052] The magnetic circuit 130 may act as an excitation device to generate an excitation f. The magnetic circuit 130 and the housing 120 are connected by a vibration transmission sheet 140.

[0053] The housing 120 may be connected to the ear hook 110. Point P, which is the tip of the ear hook 110, fits well with the head. Therefore, point P, which is the tip, may be considered a fixed point. When the bone conduction speaker 100 is operating, the housing 120 vibrates under the action of excitation f and can generate sound waves. Due to the interaction of forces, as the housing 120 vibrates, the magnetic circuit 130 also receives a biasing force that is equal in magnitude to f but opposite in direction (i.e., "-f" shown in the figure). To facilitate analysis of the relationship between the sound waves generated by the bone conduction speaker 100 and the housing 120 and magnetic circuit 130, the housing 120 and magnetic circuit 130 may be simplified as a two-degree-of-freedom vibration system.

[0054] FIG. 5 shows a model of a two-degree-of-freedom vibration system according to an embodiment of the present application. In the model shown in FIG. 5, mass block m1 may represent the housing 120, mass block m2 may represent the magnetic circuit 130, elastic connecting member k1 may represent the vibration-transmitting sheet 140, and elastic connecting member k2 may represent the ear hook 110. The damping of elastic connecting members k1 and k2 is c1 and c2, respectively. The housing 120 and magnetic circuit 130 vibrate under the action of forces f and -f, respectively. f is the magnitude of the excitation of the system, and the direction of f is as shown in FIG. 5. The complex vibration system consisting of the housing 120, magnetic circuit 130, vibration-transmitting sheet 140, and ear hook 110 is fixed to point P, which is the tip of the ear hook 110.

[0055] By performing dynamic analysis on the housing 120 and the magnetic circuit 130, the following dynamic equations of the two-degree-of-freedom vibration model shown in FIG. 5 can be obtained.

number

[0056] As can be seen from the Fourier transform, any excitation f can be expressed in the frequency domain as the sum of a series of simple harmonic motions, so

number

number

number

[0057] Substituting F and X into equation (2) gives the following equation (3).

number

[0058] The following mechanical impedance matrix Z(ω) is introduced:

number

[0059] The amplitude of the response of the vibration system can be calculated by substituting the mechanical impedance matrix Z(ω) into equation (3) as follows:

number

number

[0060] This allows us to obtain the amplitude of the response of the vibration system:

number

[0061] The housing 120 vibrates and generates sound waves. Therefore, we analyze the housing 120 (i.e., mass block m1). By substituting the mechanical impedance matrix Z(ω) into equation (4), the amplitude of the response of the housing 120 is obtained as follows:

number

[0062] As can be seen from equation (6), during forced vibration, the vibration amplitude X1 of the housing 120 is simultaneously affected by the following parameters: the frequency of the excitation f (whose magnitude is equal to 1 / ω), the amplitude F0 of the excitation f, the mass m1 of the housing 120, the mass m2 of the magnetic circuit 130, the stiffness k1 and damping c1 of the vibration transmission sheet 140, and the stiffness k2 and damping c2 of the ear hook portion 110. For example, if the other parameters are kept constant, the amplitude F0 of the excitation f and the vibration amplitude X1 of the housing 120 are directly proportional to each other. The larger the amplitude F0 of the excitation f, the larger the amplitude X1 of the housing 120. Also, for example, if the other parameters are kept constant, the larger the mass m1 of the housing 120 of the bone conduction speaker 100, the smaller the amplitude X1 of the housing 120, and the larger the mass m2 of the magnetic circuit 130, the larger the amplitude X1 of the housing 120. Therefore, if the above parameters change, the amplitude X1 of the housing 120 changes accordingly. When differences in transmission media and transmission distances are not taken into consideration, the amplitude X1 of the housing 120 is positively correlated with the volume of the sound waves generated by the vibration of the housing 120. The larger the amplitude X1, the larger the volume of the sound waves, and the smaller the amplitude X1, the smaller the volume of the sound waves.

[0063] FIG. 6 shows the results of a vibration test of the housing 120 when the bone-conduction speaker 100 according to some embodiments of the present application is operating. In the vibration test, physical quantities for evaluating the magnitude of the vibration or volume may include, but are not limited to, the velocity, displacement, and sound pressure level of the vibration source. As an example, in the vibration test shown in FIG. 6, the acceleration level (in dB) of the vibration source is used as the physical quantity for evaluating the vibration. In FIG. 6, the solid line indicates a curve showing how the vibration acceleration level of the bone-conduction speaker 100 changes depending on the frequency of the excitation f when the mass of the housing 120 is m1, and the dashed line indicates a curve showing how the vibration acceleration level of the bone-conduction speaker 100 changes depending on the frequency of the excitation f after the mass m1 of the housing 120 is increased by 50%.

[0064] As can be seen from Figure 6, the vibration acceleration level of the housing 120 is correlated with frequency and mass. When the mass m1 of the housing 120 becomes 1.5 m1 relative to the initial mass m1 of the housing, the vibration acceleration level of the housing does not decrease significantly only in the low frequency band below 160 Hz, but decreases by about 3 to 4 dB in both the mid-frequency band and the high-frequency band. In other words, when the mass of the housing 120 increases by 0.5 times in the mid-frequency band and the high-frequency band, the vibration amplitude of the housing 120 decreases by 3 to 4 dB.

[0065] The above conclusions are the results obtained by modeling speakers. Within the audible range of the human ear, low frequency may refer to a frequency range of approximately 20 Hz to 150 Hz, mid frequency may refer to a frequency range of approximately 150 Hz to 5 kHz, high frequency may refer to a frequency range of approximately 5 kHz to 20 kHz, mid-low frequency may refer to a frequency range of approximately 150 Hz to 500 Hz, and mid-high frequency refers to a frequency range of 500 Hz to 5 kHz. As will be understood by those skilled in the art, the above frequency band distinctions are merely examples that provide approximate intervals. The definitions of the above frequency bands may be changed according to different industries, different application scenarios, and different classification standards. For example, in some other application scenarios, low frequency may refer to a frequency band of approximately 20Hz to 80Hz, mid-low frequency may refer to a frequency band of approximately 80Hz to 160Hz, mid frequency may refer to a frequency band of approximately 160Hz to 1280Hz, mid-high frequency may refer to a frequency band of approximately 1280Hz to 2560Hz, and high frequency band may refer to a frequency band of approximately 2560Hz to 20KHz.

[0066] Although the above description only discusses the relationship between the volume generated by a bone conduction speaker and the mass of the housing, the first speaker 310 according to the present application is not limited to a bone conduction speaker. For example, in the case of an air conduction speaker, the expression of the first speaker 310 still satisfies the above analysis.

[0067] 7 shows a schematic diagram of a moving coil speaker 500 according to an embodiment of the present application. The moving coil speaker shown in FIG. 7 may be an air conduction speaker. Specifically, the moving coil speaker 500 may include a magnetic circuit assembly 520, a vibration assembly 530, and a support auxiliary assembly 510.

[0068] The support auxiliary assembly 510 may provide support for the vibration assembly 530 and the magnetic circuit assembly 520. The support auxiliary assembly 510 may include an elastic member 511. The vibration assembly 530 may be fixed to the upper surface of the support auxiliary assembly 510 by the elastic member 511.

[0069] The magnetic circuit assembly 520 may convert the electrical signal into an excitation F. The excitation F may act on the vibration assembly 530.

[0070] The vibrating assembly 530 may vibrate under the influence of excitation F to generate acoustic waves.

[0071] The following can be obtained through dynamic analysis: Similar to the bone conduction speaker 100, the vibration amplitude of the vibrating assembly 530 in the moving coil speaker 500 under the action of excitation F is correlated with the equivalent mass m, excitation F, damping c, and stiffness k of the vibrating assembly 530. When other parameters do not change, the larger the equivalent mass of the vibrating assembly 530, the smaller the vibration amplitude. When other parameters do not change, the larger the excitation F, the larger the vibration amplitude. For the sake of brevity, the process of dynamic analysis will not be described.

[0072] As can be seen from the above, the volume of the first sound wave 21 generated by the vibration of the first mechanical structure 311 is correlated with the frequency of the first electrical signal 11 and the mass of the first mechanical structure 311. The larger the mass of the first mechanical structure 311, the smaller the volume of the first sound wave 21.

[0073] As further shown in FIG. 2 , the second speaker 320 is electrically connected to the signal processing circuit 330. The second speaker 320 may receive a second electrical signal 12 from the signal processing circuit 330 and convert the second electrical signal 12 into a second sound wave 22. The second speaker 320 may be a transducer. In some embodiments, the second speaker 320 may convert the received electrical signal into a mechanical vibration. The second sound wave 22 is generated by the mechanical vibration. In some embodiments, the second speaker 320 may include a second mechanical structure 321 and a second excitation device 322. The structure and function of the second mechanical structure 321 may be the same as or similar to the first mechanical structure 311, and the structure and function of the second excitation device 322 may be the same as or similar to the first excitation device 312. For brevity, the structure and function of the second mechanical structure 321 and the second excitation device 322 will not be described.

[0074] Similar to the first speaker 310, the volume of the second sound waves 22 generated by the vibration of the second mechanical structure 321 in the second speaker 320 is correlated with the frequency of the second electrical signal 21 and the mass of the second mechanical structure 321. The larger the mass of the second mechanical structure 321, the smaller the volume of the second sound waves 22.

[0075] As further shown in FIG. 1 , in some embodiments, an additional device 940 is installed at one end of the first speaker 310. For example, the additional device 940 may include a function button installed on one side of the housing of the bone conduction earphone. For example, the additional device 940 may include a headset microphone installed on one side of the housing of the bone conduction earphone. The headset microphone may include, but is not limited to, components such as a base, a microphone stick, and a microphone. The installation of the headset microphone can improve the call quality of the bone conduction earphone. The mass of the additional device 940 is not negligible compared to the mass of the audio output device 300. Because the additional device 940 is installed on one side of the audio output device 300 (i.e., on one side of the first speaker 310), the mass of the first mechanical structure 311 of the first speaker 310 is greater than the mass of the second mechanical structure 311 of the second speaker 310. For example, the mass of the housing of the bone conduction speaker on one side where the headset microphone is installed is greater than the mass of the housing of the bone conduction speaker on the other side where the headset microphone is not installed.

[0076] As can be seen from the above explanation, if differences in damping, stiffness, etc. are not taken into consideration, when the same electrical signal is input, the fact that the mass of the first mechanical structure 311 is greater than the mass of the second mechanical structure 321 will cause the vibration amplitude of the first mechanical structure 311 to be smaller than the vibration amplitude of the second mechanical structure 321. If differences in transmission media and transmission distance are not taken into consideration, the volume of the first sound wave emitted from the first speaker 310 that the user hears will be smaller than the volume of the second sound wave emitted from the second speaker 320.

[0077] If a difference in volume between the first sound wave and the second sound wave heard by a user (hereinafter referred to as the volume difference) exists for a long period of time, it can damage the user's hearing. (For example, if the difference in volume between sounds heard by a user's both ears is greater than 3 dB for a long period of time, it can damage the user's both ears.) Furthermore, if there is a volume difference between the first sound wave and the second sound wave heard by a user, it can also cause an offset between the sound image perceived by the user and the actual sound image. Therefore, it is necessary to adjust the volumes of the first sound wave and the second sound wave so that the volume of the first sound wave matches the volume of the second sound wave as closely as possible, thereby avoiding hearing damage and sound image offset due to the volume difference.

[0078] 8 shows a flowchart of a volume adjustment method S200 according to an embodiment of the present application. The process S200 can adjust the volume of the sound output from the first speaker 310 and the second speaker 320 of the audio output device 300. In addition, the process S200 can adjust the sound image of the audio output device 300 perceived by a user. Specifically, the process S200 may include S210 of obtaining a volume difference between the first sound wave and the second sound wave, and S220 of adjusting an amplitude difference between the first excitation and the second excitation.

[0079] At S210, a volume difference between the first sound wave and the second sound wave is obtained. In some embodiments, the volume difference is greater than 3 dB.

[0080] In S220, the amplitude difference between the first excitation and the second excitation is adjusted. As can be seen from the above description, when the mass of the first mechanical structure is greater than the mass of the second mechanical structure, the vibration amplitude of the first mechanical structure is smaller than the vibration amplitude of the second mechanical structure, which further causes the volume of the first sound wave to be smaller than the volume of the second sound wave. Therefore, the amplitude of the first mechanical structure is adjusted by adjusting the amplitude of the first excitation, and the amplitude of the second mechanical structure is adjusted by adjusting the amplitude of the second excitation, and the volume difference due to the mass difference between the first mechanical structure and the second mechanical structure can be corrected.

[0081] For ease of understanding, in the following description of the present application, F1 represents the magnitude of the first excitation, F2 represents the magnitude of the second excitation, M1 represents the mass of the first mechanical structure, M2 represents the mass of the second mechanical structure, S1 represents the cross-sectional area of ​​the winding of the first coil, S2 represents the cross-sectional area of ​​the winding of the second coil, ρ1 represents the resistivity of the winding of the first coil, ρ2 represents the resistivity of the winding of the second coil, B1 represents the magnetic field strength of the first magnetic member, B2 represents the magnetic field strength of the second magnetic member, R1 represents the resistance of the winding of the first coil (hereinafter abbreviated as the first resistance), and R2 represents the resistance of the winding of the second coil (hereinafter abbreviated as the second resistance).

[0082] Referring to equations (1) and (6), by adjusting the magnitude of the first excitation F1 and / or the second excitation F2, the vibration amplitude X1 of the first mechanical structure 311 can be matched with the vibration amplitude X2 of the second mechanical structure 321, and further the volume of the first sound wave 21 can be matched with the volume of the second sound wave 22.

[0083] In some embodiments, the diameter of the winding of the first coil and / or the diameter of the winding of the second coil can be adjusted to obtain different magnitudes of the first excitation F1 and the second excitation F2, and the volume of the first sound wave 21 can be matched to the volume of the second sound wave 22. Since M1 > M2, increasing the diameter of the winding of the first coil and / or decreasing the diameter of the winding of the second coil can make S1 > S2. According to Equation (1), the first excitation F1 generated by the first excitation device 312 is greater than the second excitation F2 generated by the second excitation device 422. In combination with Equation (6), when the first excitation F1 is greater than the second excitation F2, X1 can be matched to X2. In this case, the power of the first sound wave 21 is the same as the power of the second sound wave 22, and the volume of the first sound wave 21 heard by the user is the same as the volume of the second sound wave 22. In this way, it is possible to correct the volume difference caused by the mass difference (M1>M2) between the first mechanical structure 311 and the second mechanical structure 321. Furthermore, it is also possible to avoid an offset in the sound image caused by the volume difference.

[0084] Furthermore, adjusting the coil diameter to adjust the volume allows the output volume to be consistent while keeping the overall dimensions of the coil constant, thus keeping the structure and dimensions of each component in the audio output device constant.

[0085] For example, if the maximum volume required for the earphone is relatively high, the bone conduction speaker on the side with the add-on device uses a coil with a larger wire diameter than the wire diameter of the wire of the speaker on the side without the add-on device. For example, the ratio of the larger wire diameter used in the coil of the speaker on the side with the add-on device to the wire diameter used in the coil of the speaker on the side without the add-on device is equal to or greater than any value of 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, and 2.0, or is in a range between any two values.

[0086] For example, if the power consumption required for the earphone is relatively low, the bone conduction speaker on the side without the add-on device may use a coil with a thinner wire diameter than the wire diameter of the speaker on the side with the add-on device. For example, the ratio of the thinner wire diameter used in the coil of the speaker on the side without the add-on device to the wire diameter used in the coil of the speaker on the side with the add-on device may be less than or equal to any of the following values: 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, and 0.99.

[0087] Furthermore, by adjusting the resistivity of the first coil and / or the resistivity of the second coil, different magnitudes of the first excitation F1 and the second excitation F2 can be obtained, further matching the volume of the first sound wave 21 with the volume of the second sound wave 22. Since M1 > M2, ρ1 < ρ2 can be achieved by decreasing the resistivity ρ1 of the first coil and / or increasing the resistivity ρ2 of the second coil. For example, ρ1 < ρ2 can be achieved by selecting a specific winding material. When other independent variables are unchanged, according to Equation (1), the first excitation F1 generated by the first excitation device 312 is greater than the second excitation F2 generated by the second excitation device 422. In combination with Equation (6), when the first excitation F1 is greater than the second excitation F2, X1 can be matched to X2. In this case, the power of the first sound wave 21 is the same as the power of the second sound wave 22, and the volume of the first sound wave 21 heard by the user is the same as the volume of the second sound wave 22. In this way, the volume difference due to the mass difference (M1>M2) between the first mechanical structure 311 and the second mechanical structure 321 is corrected. Furthermore, the offset of the sound image due to the volume difference is also corrected.

[0088] Furthermore, by adjusting the magnetic field strength B1 of the first magnetic member and / or the magnetic field strength B2 of the second magnetic member, the first excitation F1 and the second excitation F2 of different magnitudes can be obtained, and the volume of the first sound wave 21 can be made to match the volume of the second sound wave 22. Since M1 > M2, increasing the magnetic field strength B1 of the first magnetic member and / or decreasing the magnetic field strength B2 of the second magnetic member can make B1 > B2. When other independent variables do not change, according to equation (1), the first excitation F1 generated by the first excitation device 312 is greater than the second excitation F2 generated by the second excitation device 422. In combination with equation (6), when the first excitation F1 is greater than the second excitation F2, X1 can be made to match X2. In this case, the power of the first sound wave 21 is the same as the power of the second sound wave 22, and the volume of the first sound wave 21 heard by the user is the same as the volume of the second sound wave 22. In this way, the volume difference due to the mass difference (M1>M2) between the first mechanical structure 311 and the second mechanical structure 321 is corrected. Furthermore, the offset of the sound image due to the volume difference is also corrected.

[0089] Furthermore, by increasing the size of the first magnetic member and / or decreasing the size of the second magnetic member, it is possible to make B1>B2.

[0090] For example, B1>B2 can be achieved by selecting magnetic members made of materials with different magnetic properties. For example, a first magnetic member may be made of a material with stronger magnetic properties, and a second magnetic member may be made of a material with weaker magnetic properties. In some embodiments, the remanence of the first magnetic member is greater than the remanence of the second magnetic member, so that the magnetic field strength B1 generated by the first electromagnetic excitation device is greater than the magnetic field strength B2 generated by the second electromagnetic excitation device. In some embodiments, the coercivity of the first magnetic member is greater than the coercivity of the second magnetic member, so that the magnetic field strength B1 generated by the first electromagnetic excitation device is greater than the magnetic field strength B2 generated by the second electromagnetic excitation device. In some embodiments, the magnetic energy product of the first magnetic member is greater than the magnetic energy product of the second magnetic member, so that the magnetic field strength B1 generated by the first electromagnetic excitation device is greater than the magnetic field strength B2 generated by the second electromagnetic excitation device.

[0091] In some embodiments, by adjusting the magnitudes of the first resistor R1 and / or the second resistor R2, first excitation F1 and second excitation F2 with different magnitudes can be obtained, and furthermore, the volume of the first sound wave 21 can be made to match the volume of the second sound wave 22. In the present application, the above-mentioned first resistor R1 refers to the overall resistance of the first speaker, including the internal resistance of the first speaker and possible additional resistances, and the second resistor R2 refers to the overall resistance of the second speaker, including the internal resistance of the second speaker and possible additional resistances. Since M1>M2, by reducing the first resistor R1 and / or increasing the second resistor R2, R1<R2 can be achieved. When other independent variables do not change, according to Equation (1), the first excitation F1 generated by the first excitation device 312 is greater than the second excitation F2 generated by the second excitation device 422. In combination with Equation (6), when the first excitation F1 is greater than the second excitation F2, X1 can be made to match X2. In that case, the power of the first sound wave 21 is the same as the power of the second sound wave 22, and the volume of the first sound wave 21 heard by the user is the same as the volume of the second sound wave 22. Thus, the volume difference due to the mass difference (M1>M2) between the first mechanical structure 311 and the second mechanical structure 321 is corrected. As an example, for earphones, when there are no particularly strict requirements for the maximum volume and power consumption, one resistor is connected in series to the bone conduction speaker on the side without an additional device (for example, a headset microphone). As an example, the resistance value of the resistor connected in series to the bone conduction speaker on the side without an additional device is 1Ω or more. Note that the resistor connected in series does not necessarily have to be an individual resistor element, and the same effect can also be achieved by the resistance of the wire material (for example, the rear-mounted wire) used in the control circuit.

[0092] Furthermore, by connecting a resistor in series outside the above-mentioned second coil, the first resistor R1 can be made smaller than the second resistor R2 (that is, R1<R2), and furthermore, the volume difference due to the mass difference between the first mechanical structure 311 and the second mechanical structure 321 may be corrected. Further, when using the method of connecting an external resistor in series, there is no need to increase the materials in the manufacturing and design processes, and the influence on manufacturing and design is small.

[0093] Further, by directly reducing the resistance R1 of the first coil and / or increasing the resistance R2 of the second coil, the first resistance R1 is made smaller than the second resistance R2 (i.e., R1 < R2), and the volume difference due to the mass difference between the first mechanical structure 311 and the second mechanical structure 321 may be corrected. According to the formula R = ρL / S, in some embodiments, the resistance of the first coil may be made smaller than the resistance of the second coil by reducing the resistivity of the first coil and / or increasing the resistivity of the second coil. In some embodiments, the resistance of the first coil may be made smaller than the resistance of the second coil by increasing the winding length of the first coil and / or reducing the winding length of the second coil. In some embodiments, the resistance of the first coil may be made smaller than the resistance of the second coil by reducing the winding diameter of the first coil and / or increasing the winding diameter of the second coil. Note that when increasing and / or reducing the resistivity, winding length, and / or winding diameter of the first coil and / or the second coil, the mass of the first coil and / or the second coil may also change. Also, the masses of the first coil and the second coil also affect the vibration of the first mechanical structure and the second mechanical structure. Therefore, when adjusting parameters such as resistivity, winding length, and / or winding diameter, it is also necessary to match the final vibration amplitude of the first mechanical structure 311 with the vibration amplitude of the second mechanical structure 321 by considering the influence of other parameters.

[0094] Referring to Equation (6), in some embodiments, further, by adjusting the amplitude of the first electrical signal 11 and / or the second electrical signal 12, first excitation F1 and second excitation F2 with different amplitudes may be obtained, and further, the volume of the first sound wave 21 may be made to match the volume of the second sound wave 22.

[0095] For example, since M1>M2, a power amplifier circuit may be provided in the signal processing circuit 330. For example, the power adjustment circuit 335 may be the above-mentioned power amplifier circuit. The power amplifier circuit amplifies the first electrical signal 11 so that the power of the first electrical signal 11 is greater than the power of the second electrical signal 12. In this way, if the amplitudes of the first electrical signal 11 and the second electrical signal 12 are the same before passing through the power adjustment circuit 335, the amplitude of the first electrical signal 11 is greater than the amplitude of the second electrical signal 12 after passing through the power adjustment circuit 335. Because the first speaker 310 receives the amplified first electrical signal, the magnitude of the first excitation F1 generated by the first speaker 310 is greater than the magnitude of the second excitation F2 generated by the second speaker 320 (i.e., F1>F2).

[0096] For example, since M1>M2, a power attenuation circuit may be installed in the signal processing circuit 330. For example, the power adjustment circuit 335 may be the power attenuation circuit. The power attenuation circuit can attenuate the second electrical signal 12. In this way, the amplitude of the first electrical signal 11 is greater than the amplitude of the second electrical signal 12. The second speaker 320 receives the attenuated second electrical signal 12. In this way, if the amplitudes of the first electrical signal 11 and the second electrical signal 12 are the same before passing through the power adjustment circuit 335, the second excitation F2 generated by the second speaker 320 based on the attenuated second electrical signal 12 after passing through the power adjustment circuit 335 is smaller than the first excitation F1 (i.e., F1>F2). When other independent variables do not change, in combination with Equation (6), if the first excitation F1 is greater than the second excitation F2, X1 can be made equal to X2. In this case, the power of the first sound wave 21 is the same as the power of the second sound wave 22, and the volume of the first sound wave 21 heard by the user is the same as the volume of the second sound wave 22. In this way, the volume difference caused by the mass difference (M1>M2) between the first mechanical structure 311 and the second mechanical structure 321 is corrected. For example, the chip control software in the bone conduction earphone may further adjust the gain of the audio signal of the bone conduction speakers on both sides of the bone conduction earphone to match the volume on both sides of the bone conduction earphone.

[0097] In some embodiments, the mass of the first mechanical structure 311 and / or the second mechanical structure 321 may be directly adjusted to match the mass of the first mechanical structure 311 with the mass of the second mechanical structure 321, thereby compensating for the volume difference between the first sound wave 21 and the second sound wave 22 due to the mass difference. For example, if the mass of the first mechanical structure 311 is greater than the mass of the second mechanical structure 321 because a headset microphone, function buttons, etc. are installed on one side of the first speaker 310, the mass of the second mechanical structure 321 can be increased until it is the same as the mass of the first mechanical structure 311 by adding a weight to one side of the second speaker 320. In this way, the masses of the first mechanical structure 311 and the second mechanical structure 321 are the same, and ultimately, the volume of the first sound wave 21 is the same as the volume of the second sound wave 22.

[0098] Note that the volume and power referred to in the above volume adjustment solutions and / or embodiments refer to the volume and power of the sound emitted from the earphone speaker, not the power consumption of the earphone. The above volume adjustment solutions and / or embodiments are not isolated. The above volume adjustment solutions and / or embodiments may be used alone to adjust the volume at both ends of the audio output device 300. The above volume adjustment solutions and / or embodiments may be used in combination to adjust the volume at both ends of the audio output device 300. For example, mass adjustment and excitation adjustment may be performed simultaneously. For example, if M1 > M2, the volumes of the first speaker 310 and the second speaker 320 may be matched by combining solutions such as "increasing the mass of the second mechanical structure 311," "increasing the first excitation," and "increasing the diameter of the first coil."

[0099] The above solutions and / or embodiments achieve favorable technical effects in actual manufacturing. For example, the following are test results for three earphone samples. In Sample 1, the bone conduction speaker on the low-volume side uses a coil with a thicker wire diameter, while the other side uses a standard coil. In Sample 2, the bone conduction speaker on the high-volume side uses a coil with a thinner wire diameter, while the other side uses a standard coil. In Sample 3, a resistor with a fixed resistance is connected in series to the bone conduction speaker on the high-volume side. In all three samples, the same functional module is installed on one side of the bone conduction speaker, while the other side does not. A white noise signal is played using a mobile phone, and the earphone samples under test are connected via Bluetooth®. The total current at the battery end of each earphone is tested at the same volume. The test results are shown in Table 1. During the test, the output voltage at the battery end remains almost constant (4.0-4.2V). [Table 1]

[0100] As can be seen from the test results in Table 1, the total current at the battery end of the three earphone samples (Sample 1, Sample 2, and Sample 3) with additional functional modules increases compared to standard earphones at the same listening volume. Of the three samples, Sample 2 (the speaker on the louder side uses a coil with a thinner wire diameter, and the other side uses a standard coil) has the smallest total current, while Sample 1 (the speaker on the quieter side uses a coil with a thicker wire diameter, and the other side uses a standard coil) has the largest total current. For Sample 3 (the bone conduction speaker on the louder side has a resistor with a fixed resistance connected in series), the effect of connecting resistors in series can be achieved by simply connecting one resistor in series on the circuit board or by other means, eliminating the need for additional materials in the manufacturing and design processes and minimizing the impact on manufacturing and design.

[0101] In addition, the battery life of different samples was tested. Testing was performed at the same listening volume (85dB), a white noise signal was played using a mobile phone, and the earphone samples under test were connected via Bluetooth. The different earphone samples used batteries with the same capacity, and the batteries were all fully charged when the test began. The actual usage times of different samples are shown in Table 2. [Table 2]

[0102] As can be seen from the test results in Table 2, at the same listening volume, the battery life of the three samples is significantly shorter than that of the normal sample, with sample 1 having the shortest battery life and sample 3 being slightly shorter than sample 2, but not by much. These results are consistent with the previous battery current test results.

[0103] As can be seen from the above description, when the volume of the first sound wave 21 heard by the user is smaller than the volume of the second sound wave 22 heard by the user, the volume difference between the two earphones can be compensated for by adjusting the design structure of the earphones. In addition, the sound image formed by the earphones can be further adjusted to address the volume difference between the earphones.

[0104] A sound image refers to the position of sound generation in a sound field of a sound source, i.e., the sound image is the direction of sound. For a user, the user's brain determines that the position of sound generation of the target sound information (i.e., the sound image perceived by the user) is biased toward the second speaker 320, which is the side of the second sound wave 22 with a louder volume. In reality, the first speaker 310 and the second speaker 320 are considered to be at the same distance from the user, i.e., the actual sound image of the target sound information 10 is located in the center (i.e., directly in front of or directly behind the user). This results in an offset between the sound image perceived by the user and the actual sound image. The present application provides a sound image adjustment method that can make the sound image perceived by the user as close as possible to the actual sound image, thereby reducing the offset between the sound image perceived by the user and the actual sound image. The above sound image adjustment method may be applied independently to the earphones of the present application or may be combined with the above volume correction solution and / or embodiment.

[0105] 9 shows a flowchart of a sound image adjustment method S100 according to an embodiment of the present application. The process S100 can adjust the sound images output from the first speaker 310 and the second speaker 320 of the audio output device 300. Specifically, the process S100 may include S110 of obtaining a volume difference between the first sound wave and the second sound wave, and S120 of adjusting a sound generation time difference between the first sound wave and the second sound wave.

[0106] The "binaural effect" refers to the effect of people discerning the direction of a sound based on the differences in volume, time, phase, and timbre between the two ears. Because there is a certain distance between the left and right ears, the same sound from other directions, in addition to sounds from directly in front and directly behind, arrive at each ear at different volumes, times, phases, and timbres, resulting in differences in volume, time, phase, and timbre. For example, if a sound source is biased to the right, the sound will always arrive at the right ear before the left ear. The more the sound is biased to one side, the greater the time difference. For example, if a sound source is biased to the right, the sound source is closer to the right ear than to the left ear, and the volume arriving at the right ear is louder than that to the left ear. The more the sound is biased to one side, the greater the volume difference. For example, sound propagates in the form of waves, and the phase of sound waves at different locations in space is different. Due to the spatial distance between the two ears, there may be differences in the phase at which sound waves arrive at each ear. The eardrum in the ear vibrates along with the sound waves. This phase difference in vibration also becomes a factor in the user's brain determining the direction of the sound source.

[0107] People's brains determine the location of sound sources (i.e., sound images) through the "binaural effect."

[0108] If a sound is heard first in the left ear, the listener's brain will perceive the sound as coming from the left side (the side where the sound is heard first), meaning that the sound image perceived by the listener's brain will be biased to the left, and vice versa. This phenomenon is called the "time lag effect" between the left and right ears.

[0109] If the sound heard by the left ear is louder than that heard by the right ear, the listener's brain will think the sound is coming from the left side, and vice versa. This phenomenon is called the "volume difference effect" between the left and right ears. As mentioned above, the offset of the sound image due to the difference in mass between the first mechanical structure and the second mechanical structure can also be understood as essentially the "volume difference effect."

[0110] Therefore, the "time difference" and / or "phase difference" can be used to adjust the offset of the sound image perceived by the user due to the "volume difference."

[0111] In S110, the volume difference between the first sound wave and the second sound wave is obtained. First, the volume difference between the first sound wave 21 and the second sound wave 22 is obtained. Based on the volume difference, the offset value of the sound image due to the volume difference can be obtained. For example, if the volume of the first sound wave 21 is smaller than the volume of the second sound wave 22, the sound image perceived by the user is offset by δ from the center position toward the second speaker 320.

[0112] In S120, the sound generation time difference between the first sound wave and the second sound wave is adjusted.

[0113] In some embodiments, the offset of the sound image perceived by the user due to the mass difference between the first mechanical structure 311 and the second mechanical structure may be adjusted by adjusting the time difference between the sound waves 21 and 22 being emitted.

[0114] Take for example a case where the volume of the first sound wave 21 is smaller than the volume of the second sound wave 22. The audio output device 300 requires a first time length t1 to convert the target audio information 10 into the first sound wave 21, and a second time length t2 to convert the target audio information 10 into the second sound wave 22, where the first time length t1 is shorter than the second time length t2. Thus, the pronunciation time of the first speaker 310 is earlier than the pronunciation time of the second speaker 320 with respect to the target audio information 10. In some embodiments, the pronunciation time of the first speaker 310 is earlier than the pronunciation time of the second speaker 320 by one time difference. In some embodiments, the time difference is 3 ms or less. Specifically, the time difference may be any value among the following: 0.1 ms, 0.2 ms, 0.3 ms, 0.4 ms, 0.5 ms, 0.6 ms, 0.7 ms, 0.8 ms, 0.9 ms, 1.0 ms, 1.1 ms, 1.2 ms, 1.3 ms, 1.4 ms, 1.5 ms, 1.6 ms, 1.7 ms, 1.8 ms, 1.9 ms, 2.0 ms, 2.1 ms, 2.2 ms, 2.3 ms, 2.4 ms, 2.5 ms, 2.6 ms, 2.7 ms, 2.8 ms, 2.9 ms, and 3.0 ms, or any value between any two of these values. Assume that the first sound wave 21 and the second sound wave 22 have the same information except for the sound generation time. Given the same transmission medium and transmission distance, the first sound wave 21 heard by the user's left ear will be earlier than the second sound wave 22 heard by the user's right ear. Based on the binaural effect, the user's brain determines that the sound source position of the target audio information 10 is biased to the left side of the user, which is the side of the first sound wave 21 that is emitted earlier. In this way, when simultaneously considering the offset of the sound image to the right caused by the volume of the first sound wave 21 being smaller than the volume of the second sound wave 22, the sound source position of the target audio information 10 heard by the user (i.e., the sound image perceived by the user) is finally adjusted to a middle position in the same way. In this way, the offset of the sound image to the right caused by the mass of the first mechanical structure 311 being larger than the mass of the second mechanical structure 321 is eliminated.

[0115] In some embodiments, the position of the sound image of the earphone may be adjusted by controlling the time difference between the audio signals of both speakers (i.e., the time difference between the left and right channels of the audio signal). For example, the position of the sound image of the earphone may be adjusted by controlling the time difference between the sound waves output from both speakers. For example, due to the action of the first speaker and the action of the second speaker, the first sound wave output from the first speaker is advanced relative to the second sound wave output from the second speaker. In some embodiments, the first sound wave is advanced relative to the second sound wave by one time difference. In some embodiments, the time difference is 3 ms or less. Specifically, the time difference may be any value selected from the following numerical values: 0.1 ms, 0.2 ms, 0.3 ms, 0.4 ms, 0.5 ms, 0.6 ms, 0.7 ms, 0.8 ms, 0.9 ms, 1.0 ms, 1.1 ms, 1.2 ms, 1.3 ms, 1.4 ms, 1.5 ms, 1.6 ms, 1.7 ms, 1.8 ms, 1.9 ms, 2.0 ms, 2.1 ms, 2.2 ms, 2.3 ms, 2.4 ms, 2.5 ms, 2.6 ms, 2.7 ms, 2.8 ms, 2.9 ms, 3.0 ms, or any value between any two of these numerical values. For example, the time difference may be 1.0 ms or a value slightly greater than 1.0 ms.

[0116] In some embodiments, the position of the sound image of the earphone may be adjusted by controlling the time difference between the audio signals input to the two speakers (i.e., the time difference between the first electrical signal and the second electrical signal). For example, the first electrical signal input to the first speaker may be advanced relative to the second electrical signal input to the second speaker by the action of a signal processing circuit. In some embodiments, the first electrical signal may be advanced relative to the second electrical signal by one time difference. In some embodiments, the time difference is 3 ms or less. Specifically, the time difference may be any value selected from the following numerical values: 0.1 ms, 0.2 ms, 0.3 ms, 0.4 ms, 0.5 ms, 0.6 ms, 0.7 ms, 0.8 ms, 0.9 ms, 1.0 ms, 1.1 ms, 1.2 ms, 1.3 ms, 1.4 ms, 1.5 ms, 1.6 ms, 1.7 ms, 1.8 ms, 1.9 ms, 2.0 ms, 2.1 ms, 2.2 ms, 2.3 ms, 2.4 ms, 2.5 ms, 2.6 ms, 2.7 ms, 2.8 ms, 2.9 ms, 3.0 ms, or any value between any two of these numerical values. For example, the time difference may be 1.0 ms or a value slightly greater than 1.0 ms.

[0117] In addition, the sound image perceived by the user can be adjusted and centered by obtaining an offset value δ of the sound image perceived by the user and further adjusting the phase difference between the first sound wave 21 and the second sound wave 22. For example, it is assumed that the sound image can be offset by δ in the direction of the first sound wave 21 only by making the phase of the first sound wave 21 larger than the phase of the second sound wave 22 by δw2.

[0118] A phase delay circuit may be installed in the signal processing circuit 330 and / or the first speaker 310 and / or the second speaker 320 to make the phase of the first sound wave 21 greater than the phase of the second sound wave 22 by δw2.

[0119] For example, a phase delay circuit may be installed in the second speaker 320 to make the phase of the first sound wave 21 greater than the phase of the second sound wave 22 by δw2. For example, the signal processing circuit 330 processes the target sound information 10 to make the generated first electrical signal 11 and second electrical signal 12 the same in phase. A phase delay circuit may be installed in the second speaker 320. The second speaker 320 can delay the phase of the second electrical signal 12 by δw2 and generate a second sound wave 22 whose phase is also delayed by δw2. That is, ultimately, the phase of the first sound wave 21 is greater than the phase of the second sound wave 22 by δw2. Based on the binaural effect, the sound image perceived by the user is offset in the direction of the first sound wave 21, which has a larger phase. In this way, it is possible to cancel out the offset of the sound image in the direction of the second sound wave 22 due to the mass m1 of the first mechanical structure 311 being larger than the mass m2 of the second mechanical structure 321. Ultimately, the sound image perceived by the user is central.

[0120] For example, a phase delay circuit may be further installed in the signal processing circuit 330 to make the phase of the first sound wave 21 larger than the phase of the second sound wave 22 by δw2. For example, the signal processing circuit 330 can process the target sound information 10 to obtain a first electric signal 11 and a second electric signal 12. The phase of the first electric signal 11 is larger than the phase of the second electric signal 12 by δw1. Furthermore, δw1 = δw2. The first speaker 310 performs the same phase processing on the first electric signal 11, and the second speaker 320 performs the same phase processing on the phase of the second electric signal 12 (for example, the first speaker 310 does not process the phase of the first electric signal 11, and the second speaker 320 does not process the phase of the second electric signal 12). Thus, the phase of the first sound wave 21 generated by the first speaker 310 is ultimately greater than the phase of the second sound wave 22 generated by the second speaker 320 by δw2. Based on the binaural effect, the sound image perceived by the user is offset in the direction of the first sound wave 21, which has a greater phase. In this way, the offset of the sound image in the direction of the second sound wave 22, which is caused by the mass m1 of the first mechanical structure 311 being greater than the mass m2 of the second mechanical structure 321, can be canceled out. Ultimately, the sound image perceived by the user is central.

[0121] In some embodiments, the volume difference between the first sound wave and the second sound wave is 3 dB or less. In this way, by adjusting the offset of the sound image perceived by the user due to the volume difference using the "time difference" and / or the "phase difference," the sound image perceived by the user is adjusted on the one hand, while the user's hearing is not affected on the other hand. This is because adjusting the phase difference / time difference to center the sound image only adjusts the sound image perceived by the user, and does not change the volume of the first sound wave and the second sound wave actually heard by the left and right ears. If the volume difference between the sound waves actually heard by the left and right ears is too large, long-term use may cause damage to both ears of the listener.

[0122] In view of the above, the present application provides a sound image adjustment method S100 and a volume adjustment method S200. The sound image adjustment method S100 according to the present application includes S110 of acquiring a volume difference between the first sound wave and the second sound wave, and S120 of adjusting a sound generation time difference between the first sound wave and the second sound wave. The volume adjustment method S200 according to the present application includes S210 of acquiring a volume difference between the first sound wave and the second sound wave, and S220 of adjusting an amplitude difference between the first excitation and the second excitation. The sound image adjustment method S100 according to the present application corrects an offset in the sound image perceived by the user, which is caused by a mass difference between the first mechanical structure and the second mechanical structure, by setting a time difference between the first sound wave and the second sound wave. The volume adjustment method S200 of the present application compensates for the volume difference between the first speaker and the second speaker due to the mass difference between the first mechanical structure and the second mechanical structure by setting different coil resistivities, coil winding diameters, magnetic field strengths and / or resistances.

[0123] As can be seen from the above explanation, without considering differences in transmission media and transmission distances, the volume of sound waves generated by a speaker is positively correlated with the amplitude of the mechanical structure in the speaker. The larger the amplitude of the mechanical structure, the louder the volume of the sound waves. Furthermore, the amplitude of the mechanical structure is positively correlated with the excitation received by the mechanical structure. For the same mechanical structure, the greater the excitation received by the mechanical structure, the larger the amplitude of the mechanical structure.

[0124] In some embodiments, under the same excitation, the volume of a first sound wave generated by a first mechanical structure in an audio output device is different from the volume of a second sound wave generated by a second mechanical structure. For example, in the audio output device 300 shown in FIG. 1 , due to the installation of the additional device 940, the mass of the first mechanical structure 311 is greater than the mass of the second mechanical structure 321 (i.e., M1>M2). Referring to Equation (6), under the same excitation f, the vibration amplitude of the first mechanical structure is smaller than the vibration amplitude of the second mechanical structure. Disregarding differences in transmission media and transmission distances, the volume of the first sound wave perceived by a user is smaller than the volume of the second sound wave. Of course, in some embodiments, the difference in volume of the output sound waves at both ends of the audio output device may be caused by other factors. For example, in a typical earphone without a headset microphone, the mass difference at both ends may occur due to water intrusion or other causes, which ultimately leads to a difference in the volume of the sound emitted from both ends of the earphone. For ease of understanding, the following description will be given taking a bone conduction speaker as an example.

[0125] In practice, in order to avoid affecting the user's experience, it is necessary to make the volume of the sound heard by both ears of the user as consistent as possible. As can be seen from the above explanation, the volume of the sound waves generated by the speaker in the audio output device is correlated with the excitation generated based on the electrical signal, the mass M of the mechanical structure generating the vibration, the damping C and stiffness K of the vibration system, etc.

[0126] For example, taking the bone conduction speaker 100 as an example, according to equation (6), the volume of the sound waves generated by the bone conduction speaker 100 is simultaneously affected by the following parameters: the frequency of the excitation f (the magnitude of which is equal to 1 / ω), the amplitude F0 of the excitation f, the mass m1 of the housing 120, the mass m2 of the magnetic circuit 130, the stiffness k1 and damping c1 of the vibration transmission sheet 140, and the stiffness k2 and damping c2 of the ear hook part 110. For example, if the other parameters are kept constant, the amplitude F0 of the excitation f and the vibration amplitude X1 of the housing 120 are directly proportional to each other. The larger the amplitude F0 of the excitation f, the larger the amplitude X1 of the housing 120. Also, for example, if the other parameters are kept constant, the larger the mass m1 of the housing 120 of the bone conduction speaker 100, the smaller the amplitude X1 of the housing 120. Therefore, if the above parameters change, the amplitude X1 of the housing 120 changes accordingly. When differences in transmission media and transmission distances are not taken into consideration, the amplitude X1 of the housing 120 is positively correlated with the volume of the sound waves generated by the vibration of the housing 120. The larger the amplitude X1, the larger the volume of the sound waves, and the smaller the amplitude X1, the smaller the volume of the sound waves.

[0127] Therefore, if the excitation F and the mass M of the mechanical structure can be reasonably balanced, the desired vibration amplitude X can be obtained. Even if there is a difference in the mass of the mechanical structure at both ends of the audio output device (for example, a headset microphone is installed on one side of a bone conduction earphone), the volume output from both ends of the audio output device can be matched.

[0128] Therefore, the present application also provides an audio output device. The audio output device may include, but is not limited to, earphones, hearing aids, helmets, etc. The earphones may include, but are not limited to, wired earphones, wireless earphones, Bluetooth earphones, etc. Specifically, the audio output device may include a first speaker, a second speaker, and a signal processing circuit.

[0129] The signal processing circuitry is capable of receiving target audio information, processing the target audio information, and generating a first electrical signal and a second electrical signal.

[0130] The first speaker is electrically connected to the signal processing circuit. The first speaker can receive a first electrical signal from the signal processing circuit and convert the first electrical signal into a first sound wave. In some embodiments, the first speaker includes a first bone conduction speaker, and the first sound wave includes a first bone conduction sound wave. In some embodiments, the first speaker can convert the received first electrical signal into a mechanical vibration. Furthermore, the first sound wave is generated by the mechanical vibration. In some embodiments, the first speaker can include a first mechanical structure and a first excitation device. The first excitation device generates a first excitation based on the first electrical signal. The first excitation serves as an external force to excite the first mechanical structure to vibrate, and the first mechanical structure vibrates to generate a first sound wave.

[0131] The second speaker is electrically connected to the signal processing circuit. The second speaker can receive a second electrical signal from the signal processing circuit and convert the second electrical signal into a second sound wave. In some embodiments, the second speaker includes a second bone conduction speaker, and the second sound wave includes a second bone conduction sound wave. In some embodiments, the second speaker can convert the received second electrical signal into a mechanical vibration. Furthermore, the second sound wave is generated by the mechanical vibration. In some embodiments, the second speaker can include a second mechanical structure and a second excitation device. The second excitation device generates a second excitation based on the second electrical signal. The second excitation serves as an external force to excite the second mechanical structure to vibrate, and the second mechanical structure vibrates to generate a second sound wave.

[0132] In some embodiments, the first excitation device and the second excitation device may be electromagnetic excitation devices, and the magnitude of the first excitation and the magnitude of the second excitation can be calculated using Equation (1), and the vibration process of the first mechanical structure and the second mechanical structure can be expressed by Equation (6).

[0133] For ease of explanation, in the following description of the present application, F1 represents the magnitude of the first excitation, F2 represents the magnitude of the second excitation, M1 represents the mass of the first mechanical structure, M2 represents the mass of the second mechanical structure, S1 represents the cross-sectional area of ​​the winding of the first coil, S2 represents the cross-sectional area of ​​the winding of the second coil, ρ1 represents the resistivity of the winding of the first coil, ρ2 represents the resistivity of the winding of the second coil, B1 represents the magnetic field strength of the first magnetic member, B2 represents the magnetic field strength of the second magnetic member, R1 represents the resistance of the winding of the first coil (hereinafter abbreviated as the first resistance), R2 represents the resistance of the winding of the second coil (hereinafter abbreviated as the second resistance), X1 represents the vibration amplitude of the first mechanical structure, and X2 represents the vibration amplitude of the second mechanical structure.

[0134]

[0023] Under the same excitation, the volume of sound generated by the first mechanical structure is smaller than the volume of sound generated by the second mechanical structure. For example, in some embodiments, since the mass M1 of the first mechanical structure is larger than the mass M2 of the second mechanical structure, under the same excitation, the volume of a first sound wave generated by the vibration of the first mechanical structure is smaller than the volume of a second sound wave generated by the vibration of the second mechanical structure. Referring to Equation (1) and Equation (6), assuming that the first electrical signal and the second electrical signal are the same (U1=U2), and the first excitation device and the second excitation device are the same (i.e., B1=B2, S1=S2, ρ1=ρ2, R1=R2), and not considering the difference in damping and stiffness (i.e., C1=C2, K1=K2), it can be obtained based on Equation (1) and Equation (6) that the first excitation F1 and the second excitation F2 are the same (F1=F2). Based on the above assumption, M1>M2, and therefore, as can be seen from the relationship between mass and amplitude, the vibration amplitude of the first mechanical structure is smaller than that of the second mechanical structure. If the propagation medium and propagation distance are the same, the volume of the sound waves emitted from the first speaker heard by the user will be smaller than the volume of the sound waves emitted from the second speaker.

[0135] The volume of the first sound wave is the same as the volume of the second sound wave.

[0136] For ease of explanation, an example will be taken in which a first sound wave is heard by a user's left ear and a second sound wave is heard by a user's right ear. Generally, it is desirable that the volume of the first sound wave heard by the user's left ear and the volume of the second sound wave heard by the user's right ear be as similar as possible to avoid damage to both ears due to volume differences. That is, when the transmission distance and transmission medium are the same, it is desirable that the vibration amplitude of the first mechanical structure be as similar as possible to the vibration amplitude of the second mechanical structure.

[0137] In some embodiments, the diameter of the winding of the first coil is larger than the diameter of the winding of the second coil, i.e., S1>S2. According to Equations (1) and (6), the first excitation F1 generated by the first excitation device is larger than the second excitation F2 generated by the second excitation device, and thus X1 can be made equal to X2. In this case, the power of the first sound wave is the same as the power of the second sound wave, and the volume of the first sound wave heard by the user is the same as the volume of the second sound wave. In this way, the volume difference due to the mass difference (M1>M2) between the first mechanical structure and the second mechanical structure is compensated.

[0138] In some embodiments, the resistivity of the first coil is smaller than the resistivity of the second coil, i.e., ρ1<ρ2. According to Equations (1) and (6), the first excitation F1 generated by the first excitation device is greater than the second excitation F2 generated by the second excitation device, and X1 can be equal to X2. In this case, the power of the first sound wave is the same as the power of the second sound wave, and the volume of the first sound wave heard by the user is the same as the volume of the second sound wave. In this way, the volume difference due to the mass difference between the first mechanical structure and the second mechanical structure is compensated for.

[0139] In some embodiments, with the same input current, the magnetic field strength B1 generated by the first electromagnetic excitation device is greater than the magnetic field strength B2 generated by the second electromagnetic excitation device. According to Equations (1) and (6), the first excitation F1 generated by the first excitation device is greater than the second excitation F2 generated by the second excitation device, and X1 can be equal to X2. In this case, the power of the first sound wave is the same as the power of the second sound wave, and the volume of the first sound wave heard by the user is the same as the volume of the second sound wave. In this way, the volume difference due to the mass difference between the first mechanical structure and the second mechanical structure is compensated. In some embodiments, the remanence of the first magnetic member is greater than the remanence of the second magnetic member, so that the magnetic field strength B1 generated by the first electromagnetic excitation device is greater than the magnetic field strength B2 generated by the second electromagnetic excitation device. In some embodiments, the coercive force of the first magnetic member is greater than the coercive force of the second magnetic member, so that the magnetic field strength B1 generated by the first electromagnetic excitation device is greater than the magnetic field strength B2 generated by the second electromagnetic excitation device. In some embodiments, the magnetic energy product of the first magnetic member is greater than the magnetic energy product of the second magnetic member, so that the magnetic field strength B1 generated by the first electromagnetic excitation device is greater than the magnetic field strength B2 generated by the second electromagnetic excitation device.

[0140] In some embodiments, the first resistance R1 is smaller than the second resistance R2. According to Equations (1) and (6), the first excitation F1 generated by the first excitation device is larger than the second excitation F2 generated by the second excitation device, and X1 can be equal to X2. In this case, the power of the first sound wave is the same as the power of the second sound wave, and the volume of the first sound wave heard by the user is the same as the volume of the second sound wave. In this way, the volume difference due to the mass difference between the first mechanical structure and the second mechanical structure is compensated for.

[0141] In some embodiments, a resistor may be connected in series outside the second coil to make the first resistor R1 smaller than the second resistor R2, further compensating for volume differences due to mass differences between the first and second mechanical structures.

[0142] In some embodiments, the resistance R1 of the first coil may be made smaller than the resistance R2 of the second coil by reducing the resistance R1 of the first coil and / or increasing the resistance R2 of the second coil, further compensating for volume differences due to mass differences between the first and second mechanical structures.

[0143] According to the formula R=ρL / S, in some embodiments, the resistance of the first coil may be made smaller than the resistance of the second coil by increasing the resistivity of the first coil and / or decreasing the resistivity of the second coil.

[0144] According to the formula R=ρL / S, in some embodiments, the resistance of the first coil may be made smaller than the resistance of the second coil by increasing the length of the windings of the first coil and / or decreasing the length of the windings of the second coil.

[0145] According to the formula R=ρL / S, in some embodiments, the resistance of the first coil may be made smaller than the resistance of the second coil by reducing the diameter of the windings of the first coil and / or increasing the diameter of the windings of the second coil.

[0146] It should be noted that increasing and / or decreasing the resistivity, winding length, and / or winding diameter of the first coil and / or the second coil may also change the mass of the first coil and / or the second coil. The mass of the coil also affects the vibration of the first mechanical structure. Therefore, when adjusting parameters such as the resistivity, winding length, and / or winding diameter, it is necessary to consider the influence of other parameters to ultimately match the vibration amplitude of the first mechanical structure with the vibration amplitude of the second mechanical structure.

[0147] In some embodiments, a power amplifier circuit may be installed in the audio output device. The power amplifier circuit may be installed between the first speaker and the signal processing circuit. A first electrical signal output from the signal processing circuit passes through the power amplifier circuit. The power amplifier circuit amplifies the first electrical signal and outputs it to the first speaker. The first speaker receives the amplified first electrical signal. In this manner, the magnitude of the first excitation F1 generated by the first speaker is greater than the magnitude of the second excitation F2 generated by the second speaker (i.e., F1>F2). In combination with Equation (6), when the first excitation F1 is greater than the second excitation F2, X1 can be made to match X2. In this case, the power of the first sound wave is the same as the power of the second sound wave, and the volume of the first sound wave heard by the user is the same as the volume of the second sound wave. In this way, the volume difference due to the mass difference between the first mechanical structure and the second mechanical structure is compensated for.

[0148] In some embodiments, a power attenuation circuit may be provided in the audio output device. The power attenuation circuit may be provided between the second speaker and the signal processing circuit. A second electrical signal output from the signal processing circuit passes through the power attenuation circuit. The power attenuation circuit attenuates the second electrical signal and outputs it to the second speaker. The second speaker receives the attenuated second electrical signal. In this manner, the magnitude of the second excitation F2 generated by the second speaker is smaller than the magnitude of the first excitation F1 generated by the first speaker (i.e., F1>F2). In combination with Equation (6), if the first excitation F1 is larger than the second excitation F2, X1 can be made equal to X2. In this case, the power of the first sound wave is the same as the power of the second sound wave, and the volume of the first sound wave heard by the user is the same as the volume of the second sound wave. In this way, the volume difference due to the mass difference between the first mechanical structure and the second mechanical structure is compensated for.

[0149] As can be seen from the above description, if there is a volume difference between both ends of the earphone, an offset in the sound image perceived by the user occurs. Therefore, it is necessary to rationally design the audio output device so that the offset in the sound image output from the audio output device is minimized.

[0150] Therefore, the present application also provides an audio output device. The audio output device may include, but is not limited to, earphones, hearing aids, helmets, etc. The earphones may include, but are not limited to, wired earphones, wireless earphones, Bluetooth earphones, etc. Specifically, the audio output device may include a first speaker, a second speaker, and a signal processing circuit.

[0151] The signal processing circuitry is capable of receiving target audio information, processing the target audio information, and generating a first electrical signal and a second electrical signal.

[0152] The first speaker is electrically connected to the signal processing circuit. The first speaker can receive a first electrical signal from the signal processing circuit and convert the first electrical signal into a first sound wave. In some embodiments, the first speaker includes a first bone conduction speaker, and the first sound wave includes a first bone conduction sound wave. In some embodiments, the first speaker can convert the received first electrical signal into a mechanical vibration. Furthermore, the first sound wave is generated by the mechanical vibration. In some embodiments, the first speaker can include a first mechanical structure and a first excitation device. The first excitation device generates a first excitation based on the first electrical signal. The first excitation serves as an external force to excite the first mechanical structure to vibrate, and the first mechanical structure vibrates to generate a first sound wave.

[0153] The second speaker is electrically connected to the signal processing circuit. The second speaker can receive a second electrical signal from the signal processing circuit and convert the second electrical signal into a second sound wave. In some embodiments, the second speaker includes a second bone conduction speaker, and the second sound wave includes a second bone conduction sound wave. In some embodiments, the second speaker can convert the received second electrical signal into a mechanical vibration. Furthermore, the second sound wave is generated by the mechanical vibration. In some embodiments, the second speaker can include a second mechanical structure and a second excitation device. The second excitation device generates a second excitation based on the second electrical signal. The second excitation serves as an external force to excite the second mechanical structure to vibrate, and the second mechanical structure vibrates to generate a second sound wave.

[0154] In some embodiments, the first excitation device and the second excitation device may be electromagnetic excitation devices, and the magnitude of the first excitation and the magnitude of the second excitation can be calculated using Equation (1), and the vibration process of the first mechanical structure and the second mechanical structure can be expressed by Equation (6).

[0155] For ease of explanation, in the following description of the present application, F1 represents the magnitude of the first excitation, F2 represents the magnitude of the second excitation, M1 represents the mass of the first mechanical structure, M2 represents the mass of the second mechanical structure, S1 represents the cross-sectional area of ​​the winding of the first coil, S2 represents the cross-sectional area of ​​the winding of the second coil, ρ1 represents the resistivity of the winding of the first coil, ρ2 represents the resistivity of the winding of the second coil, B1 represents the magnetic field strength of the first magnetic member, B2 represents the magnetic field strength of the second magnetic member, R1 represents the resistance of the winding of the first coil (hereinafter abbreviated as the first resistance), R2 represents the resistance of the winding of the second coil (hereinafter abbreviated as the second resistance), X1 represents the vibration amplitude of the first mechanical structure, and X2 represents the vibration amplitude of the second mechanical structure.

[0156] When an electrical signal having the same amplitude and frequency is input, the volume of the sound waves output from the first speaker is smaller than the volume of the sound waves output from the second speaker. For example, in some embodiments, the mass M1 of the first mechanical structure is larger than the mass M2 of the second mechanical structure, so when an electrical signal having the same amplitude and frequency is input, the volume of the sound waves output from the first speaker is smaller than the volume of the sound waves output from the second speaker. Referring to Equations (1) and (6), assuming that the amplitude and frequency of the first electrical signal and the second electrical signal are the same (i.e., U1 = U2), and that the first excitation device and the second excitation device are the same (i.e., B1 = B2, S1 = S2, ρ1 = ρ2, R1 = R2), and disregarding differences in damping and stiffness (i.e., C1 = C2, K1 = K2), Equations (1) and (6) can be used to determine that the first excitation F1 and the second excitation F2 are the same (F1 = F2). Based on the above assumption, since M1 > M2, the vibration amplitude of the first mechanical structure is smaller than that of the second mechanical structure, as can be seen from the relationship between mass and amplitude. When the propagation medium and propagation distance are the same, the volume of the sound waves emitted from the first speaker heard by the user is smaller than the volume of the sound waves emitted from the second speaker. For example, when electrical signals having the same amplitude and frequency are input, the difference in volume between the first sound wave and the second sound wave is 3 dB or less.

[0157] For ease of explanation, the following description of the present application will take as an example a case where a first sound wave is transmitted to a user's left ear and a second sound wave is transmitted to a user's right ear to describe a user's perception of target audio information. Assuming that the first sound wave and the second sound wave have the same information except for volume, and based on the binaural effect, if the volume of the first sound wave heard by the user's left ear is lower than the volume of the second sound wave heard by the user's right ear, the user's brain will determine that the pronunciation position of the target audio information (i.e., the sound image perceived by the user) is biased toward the right side, the side of the second sound wave with a louder volume.

[0158] Based on the binaural effect, the "phase difference" and / or "time difference" can be used to cancel the offset of the sound image due to the "volume difference."

[0159] In some embodiments, the audio output device 300 requires a first time length t1 to convert the target audio information 10 into a first sound wave 21, and a second time length t2 to convert the target audio information 10 into a second sound wave 22, where the first time length t1 is shorter than the second time length t2 by a time difference δt. Thus, with respect to the target audio information 10, the pronunciation time of the first speaker 310 is earlier than the pronunciation time of the second speaker 320 by the time difference δt. In some embodiments, the time difference δt is 3 ms or less. Specifically, the time difference δt may be any value selected from the following: 0.1 ms, 0.2 ms, 0.3 ms, 0.4 ms, 0.5 ms, 0.6 ms, 0.7 ms, 0.8 ms, 0.9 ms, 1.0 ms, 1.1 ms, 1.2 ms, 1.3 ms, 1.4 ms, 1.5 ms, 1.6 ms, 1.7 ms, 1.8 ms, 1.9 ms, 2.0 ms, 2.1 ms, 2.2 ms, 2.3 ms, 2.4 ms, 2.5 ms, 2.6 ms, 2.7 ms, 2.8 ms, 2.9 ms, and 3.0 ms, or any value between any two of these values. For example, the time difference δt may be 1.0 ms or a value slightly greater than 1.0 ms. Assume that the first sound wave 21 and the second sound wave 22 have the same information except for the sounding time. When the transmission medium and transmission distance are the same, the first sound wave 21 heard by the user's left ear is earlier in time than the second sound wave 22 heard by the user's right ear. Based on the binaural effect, the sound source position of the target audio information 10 heard by the user (i.e., the sound image perceived by the user) is corrected.

[0160] In some embodiments, the time difference occurs during a process in which the first speaker converts the first electrical signal into the first sound wave and the second speaker converts the second electrical signal into a second sound wave. For example, a time advance circuit may be installed in the first speaker and / or a time delay circuit may be installed in the second speaker, so that the first sound wave output from the first speaker is earlier than the second sound wave output from the second speaker. In some embodiments, the first sound wave is earlier than the second sound wave by a time difference δt.

[0161] In some embodiments, the time difference occurs during the process in which the audio output device converts the target audio information into the first electrical signal and the second electrical signal. For example, a time processing circuit may be installed in the signal processing circuit to advance the first electrical signal input to the first speaker relative to the second electrical signal input to the second speaker. In some embodiments, the first electrical signal is advanced by a time difference δt relative to the second electrical signal.

[0162] In some embodiments, there is a first phase difference δw1 between the second sound wave and the first sound wave. In some embodiments, the phase of the first sound wave is greater than the phase of the second sound wave by δw1. Assuming that the first sound wave and the second sound wave have the same information except for their phases, based on the binaural effect, the user's brain determines that the sound source position of the target sound information (i.e., the sound image perceived by the user) is biased to the left side of the user, which is the side of the first sound wave with the greater phase. In this way, taking into account the offset of the sound image to the right due to the volume of the first sound wave being smaller than the volume of the second sound wave, the sound source position of the target sound information heard by the user is ultimately adjusted to a neutral position. In this way, the offset of the sound image due to the mass of the first mechanical structure being greater than the mass of the second mechanical structure is eliminated.

[0163] In some embodiments, the second electrical signal and the first electrical signal have the same phase. For example, the signal processing circuit may process target sound information to make the generated first electrical signal and the generated second electrical signal have the same phase. Furthermore, a phase delay circuit may be installed in the second speaker. The phase delay circuit may delay the phase of the second electrical signal by δw1 and generate a second sound wave similarly phase-delayed by δw1. In this way, the phase of the first sound wave can be made larger than the phase of the second sound wave by δw1. In this way, it is possible to eliminate a sound image offset caused by the mass of the first mechanical structure being larger than the mass of the second mechanical structure.

[0164] In some embodiments, there is a second phase difference δw2 between the second electrical signal and the first electrical signal, and the second phase difference δw2 is the same as the first phase difference δw1. For example, a phase delay circuit may be provided in the signal processing circuit. The signal processing circuit may process target audio information to obtain the first electrical signal and the second electrical signal. Furthermore, there is a second phase difference δw2 between the first electrical signal and the second electrical signal. For example, the phase of the first electrical signal is greater than the phase of the second electrical signal by δw2. Because the first speaker and the second speaker do not change the phase of the first electrical signal and the phase of the second electrical signal, the first sound wave generated by the first speaker is greater than the phase of the second sound wave generated by the second speaker by δw2. Furthermore, δw2 is the same as δw1, i.e., ultimately, the phase of the first sound wave is greater than the phase of the second sound wave by δw1. In this way, it is also possible to eliminate the offset of the sound image caused by the mass of the first mechanical structure being greater than the mass of the second mechanical structure.

[0165] In this way, the sound source time of the first speaker is made earlier than the sound source time of the second speaker for the target sound information. It is assumed that the first sound wave and the second sound wave have the same information except for the sound source time. When the transmission medium and transmission distance are the same, the time when the first sound wave is heard by the user's left ear is made earlier than the time when the second sound wave is heard by the right ear. Based on the binaural effect, the user's brain determines that the sound source position of the target sound information is biased toward the left side of the user, which is the side of the first sound wave that is heard earlier. In this way, by simultaneously taking into account the offset to the right of the sound image caused by the volume of the first sound wave being smaller than the volume of the second sound wave, the sound source position of the target sound information heard by the user (i.e., the sound image perceived by the user) is ultimately adjusted to a neutral position. In this way, the offset to the right of the sound image caused by the mass of the first mechanical structure being larger than the mass of the second mechanical structure is eliminated.

[0166] Based on the above, the present application provides a sound image adjustment method S100, a volume adjustment method S200, and two types of audio output devices. The sound image adjustment method S100 according to the present application includes S110 acquiring a volume difference between the first sound wave and the second sound wave, and S120 adjusting a sound generation time difference between the first sound wave and the second sound wave. The volume adjustment method S200 according to the present application includes S210 acquiring a volume difference between the first sound wave and the second sound wave, and S220 adjusting an amplitude difference between the first excitation and the second excitation. The audio output device and sound image adjustment method S100 according to the present application correct an offset in the sound image perceived by the user, which is caused by a mass difference between the first mechanical structure and the second mechanical structure, by setting a time difference between the first sound wave and the second sound wave. The audio output device and volume adjustment method of the present application compensate for the volume difference between the first speaker and the second speaker due to the mass difference between the first mechanical structure and the second mechanical structure by setting different coil resistivities, coil winding diameters, magnetic field strengths, and / or resistances.

[0167] It should be noted that the propagation medium of the first and / or second acoustic waves according to the present application does not limit the scope of the present application. The first and / or second acoustic waves according to the present application may propagate through a solid (e.g., a skeleton), and the first and / or second acoustic waves may propagate through a gas (e.g., air). In some embodiments, the propagation medium may include one or a combination of air and a skeleton.

[0168] In actual design and manufacturing, the volume control method of the present application, the above-described sound image control method, and the audio output device may be used in combination to achieve a desired control effect. For example, in some embodiments, the sound image control method S100 may be used alone to control the sound image output from the audio output device. For example, in some embodiments, the volume control method S200 and the sound image control method S100 may be used simultaneously to control the sound image and volume of the audio output from the audio output device.

[0169] For example, the mass and excitation may be adjusted simultaneously. For example, if M1>M2, the volumes of the first speaker 310 and the second speaker 320 may be matched by simultaneously using methods such as "increasing the mass of the second mechanical structure 311," "increasing the first excitation," and "increasing the diameter of the first coil."

[0170] For example, when M1>M2, methods such as "increasing the mass of the second mechanical structure 311," "increasing the first excitation," and "reducing the diameter of the second coil" may be simultaneously used to maintain the volume difference between the first speaker 310 and the second speaker 320 within the target volume difference range, and then the sound image may be adjusted simultaneously using a method for setting the phase difference.

[0171] It should be noted that the term "matching" or "equalizing" the volume of the first speaker and the volume of the second speaker in this application is merely for analytical purposes and does not limit the scope of protection of this application. Matching or equalizing the volume of the first speaker and the volume of the second speaker may mean maintaining the volume difference between the first speaker and the second speaker within a target volume difference range.

[0172] Note that the "centering" of the sound image of the audio output device according to the present application is merely for analytical purposes and does not limit the scope of protection of the present application. The centering of the sound image may also mean maintaining the sound image within a target position range.

[0173] From the foregoing, after reading this detailed disclosure, it will be apparent to those skilled in the art that the foregoing detailed disclosure has been presented by way of example only, and not by way of limitation. Although not expressly set forth herein, those skilled in the art will understand that the present application is intended to include various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are intended to be suggested by the present disclosure and are within the spirit and scope of the exemplary embodiments of the present disclosure.

[0174] The terms used herein are for the purpose of describing particular exemplary embodiments only and are not limiting. For example, the singular forms "a," "one," "the," and "the" as used herein may include the plural unless the context clearly dictates otherwise. As used herein, the terms "comprise," "comprise," and / or "comprising" refer to the presence of associated integers, steps, operations, elements, components, and / or groups thereof, but do not exclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups thereof, or may add other features, integers, steps, operations, elements, components, and / or groups thereof to the system / method. As used herein, the term "A is located on B" may mean that A is directly adjacent to (located above or below) B, or that A is indirectly adjacent to B (i.e., sandwiched between A and B by a material), and the term "A is located within B" may mean that A is entirely located within B, or that a portion of A is within B.

[0175] Furthermore, certain terms in this application are used to describe embodiments of the present disclosure. For example, "one embodiment," "embodiment," and / or "some embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present disclosure. Therefore, it should be emphasized and understood that two or more references to "an embodiment" or "one embodiment" or "alternative embodiments" in various parts of this specification do not necessarily all refer to the same embodiment. Furthermore, certain features, structures, or characteristics may be combined as appropriate in one or more embodiments of the present disclosure.

[0176] In the above description of the embodiments of the present disclosure, it should be understood that for the purpose of simplifying the disclosure and facilitating understanding of a single feature, the present application may group various features into a single embodiment, drawing, or description thereof. Alternatively, the present application may also distribute various features across multiple embodiments of the present invention. However, this does not mean that the combination of these features is essential, and those skilled in the art may be able to extract some of the features and understand them as separate embodiments when reading the present application. In other words, the embodiments in the present application may also be understood as a combination of multiple subembodiments. Furthermore, the content of each subembodiment may be valid even if it contains fewer than all of the features of a single, previously disclosed embodiment.

[0177] In some embodiments, numerals expressing numbers or properties for describing and claiming some embodiments of the present application are understood to be modified in some instances by the terms "about," "approximately," or "substantially." For example, unless otherwise specified, "about," "approximately," or "substantially" may indicate a variation of ±20% of the recited value. Thus, in some embodiments, the numerical parameters recited in the specification and appended claims are approximations that may vary depending on the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding the broad ranges of numerical ranges and parameters recited to describe some embodiments of the present application are approximations, the specific examples all recite the most precise numerical values ​​possible.

[0178] Each patent, patent application, patent application publication, and other materials, such as articles, books, specifications, publications, documents, articles, and the like, referenced herein are hereby incorporated by reference in their entirety for all purposes, excluding any related prosecution file history, and any that may be inconsistent or contradictory with this specification or that may have a limiting effect on the broadest scope of the claims, whether now or later related to this specification. For example, in the event of any inconsistency or contradiction between the description, definition, and / or use of a term in connection with any material incorporated herein and the description, definition, and / or use of a term in connection with this specification, the term in this specification shall control.

[0179] Finally, it should be understood that the embodiments of the present application disclosed herein are intended to illustrate the principles of the embodiments of the present application. Other modified embodiments are also within the scope of the present application. Therefore, the embodiments disclosed in the present application are merely illustrative and not limiting. Those skilled in the art can implement the invention of the present application using alternative configurations based on the embodiments of the present application. Therefore, the embodiments of the present application are not limited to the embodiments precisely described in the application.

Claims

1. a signal processing circuit that generates a first electrical signal and a second electrical signal based on the target audio information; a first speaker electrically connected to the signal processing circuit, configured to receive a first electrical signal from the signal processing circuit, and convert the first electrical signal into a first excitation to excite a first mechanical structure to generate a first sound wave corresponding to a first ear of a user; a second speaker electrically connected to the signal processing circuit to receive a second electrical signal from the signal processing circuit and convert the second electrical signal into a second excitation to excite a second mechanical structure to generate a second sound wave corresponding to a second ear of the user; a mass of the first mechanical structure is greater than a mass of the second mechanical structure; the first mechanical structure generates a smaller volume of sound than the second mechanical structure under the same excitation; 10. An audio output device, wherein the first excitation is different from the second excitation, such that the volume of the first sound waves is the same as the volume of the second sound waves.

2. the first speaker further includes a first electromagnetic excitation device that generates the first excitation, the first excitation exciting the first mechanical structure to vibrate, thereby generating the first sound wave; 2. The audio output device of claim 1, wherein the second speaker further includes a second electromagnetic excitation device that generates the second excitation, and the second excitation excites the second mechanical structure to vibrate, thereby generating the second sound wave.

3. the first electromagnetic excitation device includes a first coil; the second electromagnetic excitation device includes a second coil; 3. The audio output device according to claim 2, wherein the diameter of the winding of the first coil is larger than the diameter of the winding of the second coil.

4. the first electromagnetic excitation device includes a first coil; the second electromagnetic excitation device includes a second coil; 3. The audio output device according to claim 2, wherein the resistivity of the first coil is smaller than the resistivity of the second coil.

5. 3. The audio output device according to claim 2, wherein the first excitation generated by the first electromagnetic excitation device is greater than the second excitation generated by the second electromagnetic excitation device with the same input current.

6. the first speaker includes a first resistor; the second speaker includes a second resistor; 3. The audio output device according to claim 2, wherein the first resistance is smaller than the second resistance.

7. further comprising a power amplifier circuit connected to the first speaker and the signal processing circuit; the power amplifier circuit amplifies the first electrical signal; The audio output device according to claim 2 , wherein the first speaker receives the first electrical signal after amplification.

8. a power attenuation circuit connected to the second speaker and the signal processing circuit; the power attenuation circuit attenuates the second electrical signal; The audio output device according to claim 2 , wherein the second speaker receives the second electrical signal after attenuation.

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