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

Abstract

The present application provides an audio output device and a sound image adjustment method, as well as an audio output device and a volume adjustment method. The sound image adjustment method according to the present application includes the steps of obtaining a volume difference between the first sound wave and the second sound wave and adjusting a sound generation time difference between the first sound wave and the second sound wave. The volume adjustment method according to the present application includes 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. The audio output device and the sound image adjustment method according to the present application can correct an offset in a sound image perceived by a user due to a mass difference between a first mechanical structure and a second mechanical structure. The audio output device and the volume adjustment method according to the present application can correct a volume difference between a first speaker and a second speaker due to a mass difference between the first mechanical structure and a second mechanical structure.

Description

[Technical field]

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

[0002] When the bone conduction earphone works, there is a positive correlation between the vibration amplitude of the bone conduction speaker and the volume generated by it. The mass of the housing of the bone conduction speaker has an obvious effect on its vibration amplitude, which in turn affects the volume generated by the speaker. In the product design of the bone conduction earphone, it may be necessary to place an additional functional module, such as a headset microphone (a microphone with an additional extension rod), a button, etc., on the bone conduction speaker on one side. The button placed on the bone conduction speaker affects the volume generated by the speaker by changing the mass distribution of the bone conduction speaker. At the same time, since the functional module such as the headset microphone or the button needs to be placed only on one side and not on the other side, the volume of the speakers on both sides does not match (the volume of the speaker placed on one ear is large, while the volume of the speaker placed on the other ear is small), which causes an offset of the sound image. If the volume difference between the left and right speakers is large, it 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 of the speakers on both sides of the earphone to match the volume of the speakers on both sides. 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 section is not intended to determine key or critical 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, for bone conduction earphones, the functional module attached to the bone conduction speaker on one side increases the mass of the housing of the bone conduction speaker, so the volume of the speaker on that side decreases, and the volume of the left and right bone conduction earphones is different. If the volume difference between the left and right earphones is large, there will be an obvious offset in the sound image of the earphone, 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 of speakers on both sides of a bone conduction earphone, the audio output device disclosed in the present 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 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 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 between the volume of the first sound wave and the volume of the second sound wave is less than 3 dB.

[0008] In some embodiments, the first speaker generates the first sound waves by exciting a first mechanical structure, and the second speaker generates the second sound waves 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 waves output from the first speaker is smaller than the volume of the sound waves 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 a 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 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.

[0012] In some embodiments, the time difference is less than 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 to generate 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 to generate a second sound wave, wherein the volume of the first sound wave is the same as the volume of the second sound wave, and under the same excitation, the volume generated by the first mechanical structure 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 sound generated by the first mechanical structure is smaller than the sound 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 and thereby generates the first sound waves, and the second speaker further includes a second electromagnetic excitation device that generates the second excitation, which excites the second mechanical structure to vibrate and thereby generates the second sound waves.

[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 windings of the first coil is greater than a diameter of the windings 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, the resistivity of the first coil being 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 less than 3 dB.

[0025] In some embodiments, adjusting a time difference between the first sound wave and the second sound wave comprises 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 comprising 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. Effect of the Invention

[0027] In view of the above, in response to the technical problems of volume difference and sound image offset caused by uneven mass of the speakers on both sides of a bone conduction earphone, 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 compensate for 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 description of the drawings]

[0029] Hereinafter, exemplary embodiments disclosed in the present application will 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 description 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 external view of an audio output device according to some embodiments of the present application. [Diagram 2] FIG. 1 shows a schematic configuration diagram of an audio output device according to some embodiments of the present application. [Diagram 3] 1 shows a schematic diagram of an electromagnetic excitation device according to some embodiments of the present application; [Figure 4] FIG. 1 shows a schematic diagram of a bone conduction speaker according to some embodiments of the present application. [Diagram 5] FIG. 2 shows a schematic diagram of a vibration model of a bone conduction speaker according to some embodiments of the present application. [Figure 6] 13 illustrates vibration test results of a housing during operation according to some embodiments of the present application. [Figure 7] FIG. 1 shows a schematic diagram of a moving coil speaker according to some embodiments of the present application. [Figure 8] 2 shows a flowchart of a volume adjustment method according to an embodiment of the present application. [Figure 9] 2 shows a flowchart of a sound image adjustment method according to an embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The following description is presented to enable one skilled in the art to make and use the subject matter of the present application, and is provided in the context of specific applications of the present application and the requirements of those applications. In view of the following description, these and other features of the present disclosure, the operation and function of the associated elements of the structure, and the combination of parts and the economy of manufacture can be significantly improved. Please refer to the drawings, all of which form part of this disclosure. However, it is to be clearly understood that the drawings are for the purpose 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. Thus, the present disclosure is not 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 control method. The volume control method can adjust the volume of sound waves output from an audio output device. The sound waves may include bone conduction sound waves and / or air conduction 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 conduction speakers and air conduction speakers.

[0034] Fig. 1 is a schematic diagram showing the appearance of an audio output device 300 according to an embodiment of the present application. Fig. 2 is a schematic diagram showing the configuration 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 is capable of receiving the target sound information 10 and processing the target sound 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, having a specific data format. The target audio information 10 may be from a storage assembly of the audio output device 300 itself, or from an information generating, storing, or transmitting system other than the audio output device 300. The target audio information 10 may include one or more combinations of electrical signals, optical signals, magnetic signals, mechanical signals, and the like. 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 obtain 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 in a wired or wireless manner, or may directly obtain data 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 the sound in the environment, converts the mechanical vibration of the sound into an electrical signal, and obtains an electrical signal that meets a specific requirement 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 combinations 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 only for ease of explanation, and the medium of the wired connection may be of other types, such as a transmission carrier of other electrical signals or optical signals. The wireless connection may include wireless communication, free space optical communication, voice communication, electromagnetic induction, etc.The wireless communication may include IEEE 802.11 standards, IEEE 802.15 standards (e.g., Bluetooth technology and cellular technology), first generation mobile communication technologies, second generation mobile communication technologies (e.g., FDMA, TDMA, SDMA, CDMA, and SSMA), general packet radio service technologies, third generation mobile communication technologies (e.g., CDMA2000, WCDMA, TD-SCDMA, and WiMAX), fourth generation mobile communication technologies (e.g., TD-LTE and FDD-LTE), satellite communication (e.g., GPS technology), near field communication (NFC) and other operating in other ISM bands (e.g., 2.4 GHz), free space optical communication may include visible light signals, infrared signals, etc., voice communication may include sound waves, ultrasonic signals, etc., electromagnetic induction may include near field communication technologies, etc. The above example is only 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 above 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 be provided with a plurality of filters / filter banks 331. The plurality of filters / filter banks 331 may process the received electrical signal and output an electrical signal containing different frequencies. The filters / filter banks 331 may include, but are not limited to, analog filters, digital filters, passive filters, active filters, etc. In some embodiments, the signal processing circuit 330 may be provided with a dynamic range controller 332. The dynamic range controller 332 may be configured to compress and amplify the input signal so that the sound sounds softer or louder. In some embodiments, the signal processing circuit 330 may be provided with an active sound leakage reduction circuit 333 to reduce sound leakage of the audio output device 300. In some embodiments, the signal processing circuit 330 may be provided with 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 be provided with a power adjustment circuit 335 to adjust 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 provide individual gain or attenuation to the received signal depending on 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 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 a mechanical vibration. Furthermore, the first sound wave 21 is generated by the mechanical vibration. 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, or the first speaker 310 may include 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 an 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, the first speaker 310 converts the electric energy of the received first electric signal 11 into the mechanical vibration energy of the first mechanical structure 311 through the first excitation device 312 and 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 other types of excitation devices, which are not specifically limited in the present application. The excitation device receives the first electric signal 11 from the signal processing circuit 430 and generates a 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, and the like.

[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 with a permanent magnet. The permanent magnet may be a natural magnet or an artificial magnet. By way of example, the permanent magnet may include, but is not limited to, a neodymium iron boron magnet, a samarium cobalt magnet, an alnico magnet, and the like. The permanent magnet should have as high a coercivity, remanence, and maximum magnetic energy product as possible to ensure that the permanent magnet has a stable magnetic property and can store maximum magnetic energy.

[0044] The coil 620 may be a winding of 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 may enter the coil 620 at the first end 621, flow through the coil 620, and exit at the second end 622 in the form of an electrical current.

[0045] As can be seen 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 that the coil 620 is subjected to, 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. As an example, the mechanical structure 630 may be the first mechanical structure 311 that generates the first sound 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 field generated by 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 related to 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 defined as U. t In this case, the current I flowing through the coil 620 is expressed as I=U t The resistance between the first end 621 and the second end 622 may be expressed as R=ρL / S, where R represents the magnitude of the resistance between the first end 621 and the second end 622. 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 an 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 is analyzed by taking as an example that 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 a vibration exciter to generate an excitation f. The magnetic circuit 130 and the housing 120 are connected by a vibration transmitting 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 to be a fixed point. When the bone conduction speaker 100 operates, the housing 120 can vibrate under the action of excitation f and generate sound waves. Due to force interaction, in the process of the housing 120 vibrating, 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 the magnetic circuit 130, the housing 120 and the 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 transmission sheet 140, and elastic connecting member k2 may represent the ear hook 110. The damping of the elastic connecting members k1 and k2 is c1 and c2, respectively. The housing 120 and the magnetic circuit 130 vibrate under the action of force f and force -f, respectively. f is the magnitude of the excitation of the system, and the direction of f is as shown in FIG. 5. The composite vibration system consisting of the housing 120, the magnetic circuit 130, the vibration transmission sheet 140, and the ear hook 110 is fixed to point P, which is the tip of the ear hook 110.

[0055] By performing a dynamic analysis on the housing 120 and the magnetic circuit 130, respectively, 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), we obtain the following equation (3).

number

[0058] We introduce the following mechanical impedance matrix Z(ω):

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., the mass block m1). The amplitude of the response of the housing 120 obtained by substituting the mechanical impedance matrix Z(ω) into equation (4) is:

number

[0062] As can be seen from formula (6), in the forced vibration, the vibration amplitude X1 of the housing 120 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, when the other parameters are kept constant, the amplitude F0 of the excitation f and the vibration amplitude X1 of the housing 120 are in a directly proportional relationship. The larger the amplitude F0 of the excitation f, the larger the amplitude X1 of the housing 120. Also, for example, when 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, when 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 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 a vibration test result of the housing 120 when the bone-conduction speaker 100 according to some embodiments of the present application is operating. In the vibration test, the physical quantity for evaluating the magnitude of the vibration or sound volume may include, but is not limited to, the speed, displacement, and sound pressure level of the vibration source. As an example, in the vibration test shown in FIG. 6, the acceleration level (unit: dB) of the vibration source is taken as the physical quantity for evaluating the vibration. In FIG. 6, the solid line shows a curve in which the vibration acceleration level of the bone-conduction speaker 100 changes according to the frequency of the excitation f when the mass of the housing 120 is m1, and the dashed line shows a curve in which the vibration acceleration level of the bone-conduction speaker 100 changes according to the frequency of the excitation f after the mass m1 of the housing 120 is increased by 50%.

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

[0065] The above conclusion is a result obtained by modeling the speaker. Within the audible range of the human ear, the low frequency may refer to a frequency band of approximately 20Hz to 150Hz, the mid frequency may refer to a frequency band of approximately 150Hz to 5KHz, the high frequency band may refer to a frequency band of approximately 5KHz to 20KHz, the low-mid frequency may refer to a frequency band of approximately 150Hz to 500Hz, and the high-mid frequency refers to a frequency band of 500Hz to 5KHz. As will be understood by those skilled in the art, the above frequency bands are merely examples that give 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, low-mid frequency may refer to a frequency band of approximately 80Hz to 160Hz, medium frequency may refer to a frequency band of approximately 160Hz to 1280Hz, high-mid 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] In the above description, only the relationship between the volume generated by the bone conduction speaker and the mass of the housing is described, but 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] For example, Fig. 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 an 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 action of an excitation F to generate acoustic waves.

[0071] Through dynamic analysis, the following can be obtained: 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 the excitation F is correlated with the equivalent mass m, excitation F, damping c and stiffness k of the vibrating assembly 530. If other parameters do not change, the larger the equivalent mass of the vibrating assembly 530, the smaller the vibration amplitude. If 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 is omitted.

[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 the second electric signal 12 from the signal processing circuit 330 and convert the second electric 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 electric signal into a mechanical vibration. Furthermore, 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 or similar to that of the first mechanical structure 311, and the structure and function of the second excitation device 322 may be the same or similar to that of the first excitation device 312. For the sake of brevity, the structure and function of the second mechanical structure 321 and the second excitation device 322 are omitted from the description.

[0074] Similar to the first speaker 310, the volume of the second sound wave 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 wave 22.

[0075] Further, as 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 cannot be ignored compared with the mass of the audio output device 300. Since 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 in the first speaker 310 is larger than the mass of the second mechanical structure 311 in 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 larger 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 description, if differences in attenuation, stiffness, etc. are not taken into consideration, when the same electrical signal is input, the mass of the first mechanical structure 311 being larger than the mass of the second mechanical structure 321 causes 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 the transmission medium and transmission distance are not taken into consideration, the volume of the first sound wave emitted from the first speaker 310 heard by the user is smaller than the volume of the second sound wave emitted from the second speaker 320.

[0077] If a difference between the volume of the first sound wave and the volume of the second sound wave heard by the user (hereinafter referred to as volume difference) exists for a long period of time, it will damage the user's hearing. (For example, if the volume difference between the sounds heard by the user's both ears is greater than 3 dB for a long period of time, it will damage the user's both ears.) Also, if there is a volume difference between the first sound wave and the second sound wave heard by the user, it will cause an offset between the sound image sensed 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 to match the volume of the first sound wave with the volume of the second sound wave as much as possible, thereby avoiding hearing damage and offset of the sound image due to the volume difference.

[0078] 8 shows a flow chart 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 sensed 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 larger than the mass of the second mechanical structure, it causes the vibration amplitude of the first mechanical structure to be smaller than the vibration amplitude of the second mechanical structure, and 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 caused by 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 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, the diameter of the winding of the first coil can be increased and / or the diameter of the winding of the second coil can be decreased to 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 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. In this way, the difference in volume is corrected due to the mass difference (M1>M2) between the first mechanical structure 311 and the second mechanical structure 321. Furthermore, the offset of the sound image due to the difference in volume is also avoided.

[0084] Furthermore, adjusting the coil diameter to adjust the volume keeps the overall dimensions of the coil unchanged while still matching the output volume, thus keeping the structure and dimensions of each component in the audio output device unchanged.

[0085] For example, when the maximum volume required for the earphone is relatively large, the bone conduction speaker on the side with the additional device uses a coil with a wire diameter larger than that of the speaker on the side without the additional device. For example, the ratio of the wire diameter of the wire used for the coil of the speaker on the side with the additional device to that of the speaker on the side without the additional device is equal to or larger than any value of 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 2.0, or between any two of these values.

[0086] For example, when the power consumption required for the earphone is relatively small, the bone conduction speaker on the side without the additional device uses a coil with a thinner wire diameter than the wire diameter of the speaker on the side with the additional device. For example, the ratio of the thinner wire used in the coil of the speaker on the side without the additional device to the wire diameter used in the coil of the speaker on the side with the additional device is less than or equal to any value of 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99 or between any two of these values.

[0087] Moreover, the resistivity of the first coil and / or the resistivity of the second coil may be adjusted to obtain first excitation F1 and second excitation F2 with different magnitudes, and the volume of the first sound wave 21 may be made to match the volume of the second sound wave 22. Since M1>M2, ρ1<ρ2 can be obtained by decreasing the resistivity ρ1 of the first coil and / or increasing the resistivity ρ2 of the second coil. As an example, ρ1<ρ2 can be obtained by selecting a specific winding material. When other independent variables are not changed, 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), X1 can be made to match X2 when the first excitation F1 is greater than the second excitation F2. 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. Furthermore, the offset of the sound image caused by the volume difference is also corrected.

[0088] Furthermore, the magnetic field strength B1 of the first magnetic member and / or the magnetic field strength B2 of the second magnetic member may be adjusted to obtain the first excitation F1 and the second excitation F2 of different magnitudes, and the volume of the first sound wave 21 may be made to match the volume of the second sound wave 22. Since M1>M2, the magnetic field strength B1 of the first magnetic member may be increased and / or the magnetic field strength B2 of the second magnetic member may be decreased to make B1>B2. When other independent variables do not change, according to formula (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 formula (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 caused by 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 caused by 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 material with stronger magnetic properties is selected for the first magnetic member, and a material with weaker magnetic properties is selected for the second magnetic member. In some embodiments, the remanence of the first magnetic member is greater than that 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 that 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 that 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 magnitude 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. 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. As an example, in the case of earphones where 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 1 Ω or more. It should be noted that the resistor connected in series is not necessarily 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 to make the first resistor R1 smaller than the second resistor R2 (that is, R1 < R2), the volume difference due to the mass difference between the first mechanical structure 311 and the second mechanical structure 321 may be corrected. Furthermore, 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 impact on manufacturing and design is small.

[0093] Furthermore, 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). Further, 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 decreasing 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 decreasing 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 vibrations 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 make the vibration amplitude of the final first mechanical structure 311 coincide 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 amplitudes 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 coincide with the volume of the second sound wave 22.

[0095] For example, since M1>M2, a power amplifier circuit may be installed in the signal processing circuit 330. For example, the power conditioning circuit 335 may be the above-mentioned power amplifier circuit. The above-mentioned power amplifier circuit can amplify the first electric signal 11 to make the power of the first electric signal 11 greater than the power of the second electric signal 12. In this way, if the amplitudes of the first electric signal 11 and the second electric signal 12 are the same when not passing through the power conditioning circuit 335, the amplitude of the first electric signal 11 is greater than the amplitude of the second electric signal 12 after passing through the power conditioning circuit 335. Since the first speaker 310 receives the amplified first electric 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] As an 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 may attenuate the second electric signal 12. In this way, the amplitude of the first electric signal 11 is greater than the amplitude of the second electric signal 12. The second speaker 320 receives the attenuated second electric signal 12. In this way, if the amplitudes of the first electric signal 11 and the second electric signal 12 are the same when not passing through the power adjustment circuit 335, the second excitation F2 generated by the second speaker 320 based on the attenuated second electric signal 12 after passing through the power adjustment circuit 335 is smaller than the first excitation F1 (i.e., F1>F2). In combination with equation (6), when other independent variables do not change, X1 can be matched with X2 when the first excitation F1 is greater than the second excitation F2. 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. 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 correcting 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 larger than the mass of the second mechanical structure 321 because a headset microphone, a function button, 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 increasing the weight on 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 finally, the volume of the first sound wave 21 is the same as the volume of the second sound wave 22.

[0098] It should be noted that the volume and power mentioned in the above volume adjustment solutions and / or embodiments are the volume and power of the sound emitted from the speaker of the earphone, 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, the mass adjustment and the excitation adjustment may be performed simultaneously. For example, when M1>M2, the volume of the first speaker 310 and the second speaker 320 may be matched by a method of simultaneously using a combination of 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 good technical effects in actual production. As an example, the following lists the results of testing three earphone samples. In sample 1, the bone conduction speaker on the low volume side uses a coil with a thicker wire diameter, and the other side uses a normal coil; in sample 2, the bone conduction speaker on the high volume side uses a coil with a thinner wire diameter, and the other side uses a normal coil; and in sample 3, a resistor with a certain resistance value 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 the bone conduction speaker on one side, and there is no functional module on the other side. A white noise signal is played using a mobile phone, and the earphone sample to be tested is connected to the test sample via Bluetooth (registered trademark), and the total current at the battery end of each earphone at the same volume is tested. The test results are shown in Table 1. During the test process, the output voltage at the battery end is almost unchanged (4.0 to 4.2V). [Table 1]

[0100] As can be seen from the test results in Table 1, at the same listening volume, the total current at the battery end of the three earphone samples (sample 1, sample 2, sample 3) with additional function modules is increased compared to the normal earphone. Among the three samples, the total current of sample 2 (the speaker on the louder side uses a coil with a smaller wire diameter, and the other side uses a normal coil) is the smallest, and the total current of sample 1 (the speaker on the quieter side uses a coil with a larger wire diameter, and the other side uses a normal coil) is the largest. Sample 3 (the bone conduction speaker on the louder side is connected in series with a resistor with a certain resistance value) only requires connecting one resistor in series to the circuit board or other methods to achieve the effect of connecting resistors in series, and does not require increasing materials in the manufacturing and design process, which has a small impact on manufacturing and design.

[0101] In addition, the battery usage time of different samples is tested. Testing is performed at the same listening volume (85dB), using a mobile phone to play white noise signals, connecting to the earphone samples under test through Bluetooth, using the same capacity batteries for the different earphone samples, and when the test begins, the batteries are all in a fully charged state, and the actual usage time of different samples is 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 having a slightly shorter battery life than sample 2, but not by much. The above 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 design structure of the earphones can be adjusted to compensate for the volume difference between the two earphones. In addition, the sound image formed by the earphones can be further adjusted to address the volume difference between the earphones.

[0104] The sound image refers to the position of sound generation in the sound field of the sound source, that is, the sound image is the direction of the sound. For the user, the user's brain determines that the position of sound generation of the target sound information (i.e., the sound image sensed by the user) is biased toward the second speaker 320 side, which is the side of the second sound wave 22 with a larger volume. In contrast, in reality, the distances of the first speaker 310 and the second speaker 320 from the user are considered to be the same, that is, the actual sound image of the target sound information 10 is in the center (i.e., in front of or directly behind the user). That is, an offset occurs between the sound image sensed by the user and the actual sound image. The present application provides a sound image adjustment method, which can make the sound image sensed by the user as close as possible to the actual sound image, thereby reducing the offset between the sound image sensed by the user and the actual sound image. The above sound image adjustment method may be applied independently to the earphone according to the present application, or may be combined with the above-mentioned 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 a sound image 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 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.

[0106] The "binaural effect" is an effect in which people distinguish the direction of a sound by the difference in volume, time, phase and timbre between the two ears. Because there is a certain distance between the left and right ears, the volume, time, phase and timbre of the same sound from other directions, in addition to the sound from directly in front and directly behind, are different when they reach both ears, causing volume differences, time differences, phase differences and timbre differences. For example, if the sound source is biased to the right, the sound always reaches the left ear after reaching the right ear. The more the sound is biased to one side, the greater the time difference. For example, if the sound source is biased to the right, the distance of the sound source from the right ear is closer than that from the left ear, and the volume reaching the right ear is greater 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 the sound waves at different positions in space is different. Due to the distance in space between the two ears, there may be a difference in the phase at which the sound waves reach both ears. The eardrum in the ear membrane vibrates with the sound waves. This phase difference in vibration also helps the user's brain determine the direction of the sound source.

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

[0108] If a sound is heard first by 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), i.e. 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 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 before, the offset of the sound image due to the difference between the mass of the first mechanical structure and the mass of the second mechanical structure can also be understood as the "volume difference effect" in essence.

[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, when the volume of the first sound wave 21 is smaller than the volume of the second sound wave 22, the sound image sensed by the user is offset by δ from the center position in the direction of 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 produced.

[0114] Take for example that the volume of the first sound wave 21 is smaller than the volume of the second sound wave 22. The audio output device 300 needs a first time length t1 to convert the target audio information 10 into the first sound wave 21, and the audio output device 300 needs a second time length t2 to convert the target audio information 10 into the second sound wave 22, and the first time length t1 is shorter than the second time length t2. Thus, for the target audio information 10, the pronunciation time of the first speaker 310 is advanced relative to the pronunciation time of the second speaker 320. In some embodiments, the pronunciation time of the first speaker 310 is advanced relative to the pronunciation time of the second speaker 320 by one time difference. In some embodiments, the time difference is less than or equal to 3 ms. Specifically, the time difference may be any value among the following values: 0.1ms, 0.2ms, 0.3ms, 0.4ms, 0.5ms, 0.6ms, 0.7ms, 0.8ms, 0.9ms, 1.0ms, 1.1ms, 1.2ms, 1.3ms, 1.4ms, 1.5ms, 1.6ms, 1.7ms, 1.8ms, 1.9ms, 2.0ms, 2.1ms, 2.2ms, 2.3ms, 2.4ms, 2.5ms, 2.6ms, 2.7ms, 2.8ms, 2.9ms, 3.0ms, or any value between any two values. It is assumed 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 the transmission distance are the same, the time of the first sound wave 21 heard by the user's left ear is advanced relative to the time of 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 sound information 10 is biased toward the left side of the user, which is the side of the first sound wave 21 that is pronounced earlier. In this way, when 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 is simultaneously taken into consideration, the sound source position of the target sound information 10 heard by the user (i.e., the sound image perceived by the user) is finally adjusted to a middle position as well. 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 signals). 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 less than or equal to 3 ms. Specifically, the time difference may be any value among the following 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 the following values. For example, the time difference may be 1.0 ms, or a value slightly larger 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 and second electrical signals). For example, the first electrical signal input to the first speaker is advanced by the action of the signal processing circuit relative to the second electrical signal input to the second speaker. In some embodiments, the first electrical signal is advanced by one time difference relative to the second electrical signal. In some embodiments, the time difference is less than or equal to 3 ms. Specifically, the time difference may be any value among the following 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 the following values. For example, the time difference may be 1.0 ms, or a value slightly larger 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. As an 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] In order to make the phase of the first sound wave 21 greater than the phase of the second sound wave 22 by δw2, 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.

[0119] For example, the second speaker 320 may be provided with a phase delay circuit to make the phase of the first sound wave 21 larger than that of the second sound wave 22 by δw2. For example, the signal processing circuit 330 processes the target sound information 10 to make the phases of the generated first electric signal 11 and second electric signal 12 the same. The second speaker 320 may be provided with a phase delay circuit. The second speaker 320 may delay the phase of the second electric signal 12 by δw2 and generate a second sound wave 22 whose phase is similarly delayed by δw2. That is, finally, the phase of the first sound wave 21 is larger than that of the second sound wave 22 by δw2. Based on the binaural effect, the sound image sensed by the user is offset in the direction of the first sound wave 21 whose phase is larger. 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, the signal processing circuit 330 may further include a phase delay circuit 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 may process the target sound information 10 to obtain the first electric signal 11 and the 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. Also, 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 finally larger 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 sensed by the user is offset in the direction of the first sound wave 21, which has a larger phase. In this way, the offset of the sound image in the direction of the second sound wave 22 caused by the mass m1 of the first mechanical structure 311 being larger than the mass m2 of the second mechanical structure 321 can be canceled out. Finally, the sound image sensed by the user is in the center.

[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, the time difference and / or phase difference are used to adjust the offset of the sound image perceived by the user due to the volume difference, thereby adjusting the sound image perceived by the user on the one hand, and not affecting the user's hearing on the other hand. This is because the phase difference / time difference is adjusted to center the sound image, and only the sound image perceived by the user is adjusted, and the volume of the first sound wave and the second sound wave actually heard by the left and right ears is not changed. 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] From 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 of a sound image sensed by a user due to a mass difference between a first mechanical structure and a 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 and second speakers due to the mass difference between the first and second mechanical structures by setting different coil resistivities, coil winding diameters, magnetic field strengths and / or resistances.

[0123] As can be seen from the above explanation, when differences in transmission media and transmission distances are not taken into consideration, 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. In addition, the amplitude of the mechanical structure is positively correlated with the excitation that the mechanical structure receives. For the same mechanical structure, the greater the excitation that the mechanical structure receives, the larger the amplitude of the mechanical structure.

[0124] In some embodiments, under the same excitation, the volume of the first sound wave generated by the first mechanical structure in the audio output device is different from the volume of the second sound wave generated by the 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 larger than the mass of the second mechanical structure 321 (i.e., M1>M2). Referring to formula (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. If the difference in the transmission medium and the transmission distance is not taken into account, the volume of the first sound wave sensed by the user is smaller than the volume of the second sound wave. Of course, in some embodiments, the cause of the difference in the volume of the output sound wave at both ends of the audio output device may be other, for example, a normal earphone without a headset microphone may have a difference in the mass at both ends due to water intrusion or other causes, which ultimately causes 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 usage 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 wave generated by the speaker in the audio output device is correlated with the excitation generated based on the electric signal, the mass M of the mechanical structure in which the vibration occurs, 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 formula (6), the volume of the sound wave generated by the bone conduction speaker 100 is simultaneously affected by the following parameters: frequency of excitation f (magnitude is equal to 1 / ω), amplitude F0 of excitation f, mass m1 of the housing 120, mass m2 of the magnetic circuit 130, stiffness k1 and damping c1 of the vibration transmission sheet 140, and stiffness k2 and damping c2 of the ear hook part 110. For example, when other parameters are kept constant, the amplitude F0 of excitation f and the vibration amplitude X1 of the housing 120 are in a direct proportional relationship. The larger the amplitude F0 of excitation f, the larger the amplitude X1 of the housing 120. Also, for example, when 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, when 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 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, an earphone, a hearing aid, a helmet, etc. The earphone may include, but is not limited to, a wired earphone, a wireless earphone, a Bluetooth earphone, 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 sound information, processing the target sound 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 excites the first mechanical structure to vibrate as an external force, 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 excites the second mechanical structure to vibrate as an external force, 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 according to 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] Under the same excitation, the volume of the sound generated by the first mechanical structure is smaller than the volume of the sound generated by the second mechanical structure. 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 that under the same excitation, the volume of the first sound wave generated by the vibration of the first mechanical structure is smaller than the volume of the second sound wave generated by the vibration of the second mechanical structure. Referring to Equation (1) and Equation (6), assuming that the first electric signal and the second electric 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 that the first excitation F1 and the second excitation F2 are the same (F1=F2) based on Equation (1) and Equation (6). 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.

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

[0136] For ease of explanation, a first sound wave is heard by the user's left ear and a second sound wave is heard by the user's right ear. In general, it is desired 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 are as similar as possible to avoid damage to both ears due to the volume difference. That is, when the transmission distance and transmission medium are the same, it is desired that the vibration amplitude of the first mechanical structure is 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 to match X2. In that 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 that 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 larger than the second excitation F2 generated by the second excitation device, and X1 can be equal to X2. In that 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.

[0139] In some embodiments, with the same input current, the magnetic field intensity B1 generated by the first electromagnetic excitation device is greater than the magnetic field intensity B2 generated by the second electromagnetic excitation device. According to formula (1) and formula (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 made equal to X2. In that 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 caused by the mass difference between the first mechanical structure and the second mechanical structure is corrected. In some embodiments, the residual magnetism of the first magnetic member is greater than the residual magnetism of the second magnetic member, so that the magnetic field intensity B1 generated by the first electromagnetic excitation device is greater than the magnetic field intensity B2 generated by the second electromagnetic excitation device. In some embodiments, 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 because the coercive force of the first magnetic member is greater than the coercive force of the second magnetic member. In some embodiments, 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 because the magnetic energy product of the first magnetic member is greater than the magnetic energy product of the second magnetic member.

[0140] In some embodiments, the first resistance R1 is smaller than the second resistance R2. According to formula (1) and formula (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 that 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 caused by the mass difference between the first mechanical structure and the second mechanical structure is corrected.

[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 the volume difference due to the mass difference between the first mechanical structure and the second mechanical structure.

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

[0143] According to the equation 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 equation 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 equation 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 when the resistivity, the length of the winding and / or the diameter of the winding of the first coil and / or the second coil are increased and / or decreased, the mass of the first coil and / or the second coil may also change. The mass of the coil also affects the vibration of the first mechanical structure. Therefore, when adjusting parameters such as the resistivity, the length of the winding and / or the diameter of the winding, it is also necessary to consider the influence of other parameters to finally 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 electric signal output from the signal processing circuit passes through the power amplifier circuit. The power amplifier circuit amplifies the first electric signal and outputs it to the first speaker. The first speaker receives the amplified first electric signal. In this way, 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 matched with X2. In that 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 corrected.

[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. The 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 way, 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), when the first excitation F1 is larger than the second excitation F2, X1 can be matched with X2. In that 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 caused by the mass difference between the first mechanical structure and the second mechanical structure is corrected.

[0149] As can be seen from the above description, when a volume difference occurs between both ends of the earphone, an offset of the sound image perceived by the user occurs. Therefore, it is necessary to rationally design the sound output device so that the offset of the sound image output from the sound 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, an earphone, a hearing aid, a helmet, etc. The earphone may include, but is not limited to, a wired earphone, a wireless earphone, a Bluetooth earphone, 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 sound information, processing the target sound 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 excites the first mechanical structure to vibrate as an external force, 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 excites the second mechanical structure to vibrate as an external force, 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 according to 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 wave output from the first speaker is smaller than the volume of the sound wave 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 that 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. Referring to formula (1) and formula (6), assuming that the amplitude and frequency of the first electric signal and the second electric signal are both the same (i.e., 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 that the first excitation F1 and the second excitation F2 are the same (F1=F2) based on formula (1) and formula (6). Based on the above assumption, since M1>M2, as can be seen from the relationship between mass and amplitude, the vibration amplitude of the first mechanical structure is smaller than the vibration amplitude of the second mechanical structure. When the propagation medium and propagation distance are the same, the volume of the sound wave emitted from the first speaker heard by the user is smaller than the volume of the sound wave 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, in the following description of the present application, a first sound wave is transmitted to the user's left ear and a second sound wave is transmitted to the user's right ear to explain the user's perception of the target sound information. It is assumed that the first sound wave and the second sound wave have the same information except for the volume, and based on the binaural effect, when the volume of the first sound wave heard by the user's left ear is smaller than the volume of the second sound wave heard by the user's right ear, the user's brain determines that the pronunciation position of the target sound information (i.e., the sound image sensed by the user) is biased to the right side, that is, the side of the second sound wave with a larger volume.

[0158] Based on the binaural effect, the offset of the sound image due to the "volume difference" can be eliminated by using the "phase difference" and / or the "time 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, the first time length t1 being shorter than the second time length t2 by one time difference δt. Thus, for 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 equal to or less than 3 ms. Specifically, the time difference δt may be any value among the following values: 0.1ms, 0.2ms, 0.3ms, 0.4ms, 0.5ms, 0.6ms, 0.7ms, 0.8ms, 0.9ms, 1.0ms, 1.1ms, 1.2ms, 1.3ms, 1.4ms, 1.5ms, 1.6ms, 1.7ms, 1.8ms, 1.9ms, 2.0ms, 2.1ms, 2.2ms, 2.3ms, 2.4ms, 2.5ms, 2.6ms, 2.7ms, 2.8ms, 2.9ms, 3.0ms, or any value between any two values. For example, the time difference δt may be 1.0ms or a value slightly larger than 1.0ms. It is assumed 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 time of the first sound wave 21 heard by the user's left ear is earlier than the time of the second sound wave 22 heard by the user's right ear. Based on the binaural effect, the sound source position of the target sound 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 the 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 the second sound wave. For example, the first sound wave output from the first speaker may be advanced relative to the second sound wave output from the second speaker by providing a time advance circuit in the first speaker and / or a time delay circuit in the second speaker. In some embodiments, the first sound wave is advanced relative to the second sound wave by one 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 one 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 larger 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 other than the phase, 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 sensed by the user) is biased to the left side of the user, which is the first sound wave side with a larger 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 finally adjusted to a middle position. In this way, the offset of the sound image due to the mass of the first mechanical structure being larger 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 the target sound information to make the generated first electrical signal and the 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 whose phase is also delayed by δw1. In this way, the phase of the first sound wave may be made larger than the phase of the second sound wave by δw1. In this way, the offset of the sound image caused by the mass of the first mechanical structure being larger than the mass of the second mechanical structure may be eliminated.

[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 installed in the signal processing circuit. The signal processing circuit can process the target sound information to obtain the first electrical signal and the second electrical signal. And 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 larger than the phase of the second electrical signal by δw2. Since 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 larger than the phase of the second sound wave generated by the second speaker by δw2. And δw2 is the same as δw1, that is, finally, the phase of the first sound wave is larger 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 larger 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 other than the sound source time. When the transmission medium and the transmission distance are the same, the time of the first sound wave heard by the user's left ear is made earlier than the time of the second sound wave 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 to the left side of the user, which is the side of the first sound wave that sounds earlier. In this way, when the offset of the sound image to the right caused by the volume of the first sound wave being smaller than the volume of the second sound wave is simultaneously considered, the sound source position of the target sound information heard by the user (i.e., the sound image perceived by the user) is finally adjusted to the middle position as well. In this way, the offset of the sound image to the right caused by the mass of the first mechanical structure being larger than the mass of the second mechanical structure is eliminated.

[0166] From the above, the present application provides a sound image adjustment method S100, a volume adjustment method S200, and two types of sound output devices. 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 output device and the sound image adjustment method S100 according to the present application correct the offset of the sound image sensed 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. 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 sound waves according to the present application does not limit the scope of the present application. The first and / or second sound waves according to the present application may propagate through a solid (e.g., a skeleton), and the first and / or second sound waves may propagate through a gas (e.g., air). In some embodiments, the propagation medium may include one of air and a skeleton, or a combination thereof.

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

[0169] For example, the mass and the excitation may be adjusted simultaneously. For example, when 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 used simultaneously to maintain the volume difference between the first speaker 310 and the second speaker 320 within a target volume difference range, and then the sound image may be adjusted simultaneously using a method for setting a phase difference.

[0171] In addition, the term "matching" or "making the same" the volume of the first speaker and the volume of the second speaker in the present application is merely for the purpose of analysis and does not limit the scope of protection of the present application. Matching or making the same 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] In addition, the "centering" of the sound image of the sound output device according to the present application is merely for the purpose of analysis and does not limit the scope of protection of the present application. The centering of the sound image may be maintaining the sound image within a target position range.

[0173] From the above, after reading this detailed disclosure, it will be apparent to those skilled in the art that the above detailed disclosure is presented by way of example only and is not limiting. Although not explicitly described 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 this disclosure and are within the spirit and scope of the exemplary embodiments of the present disclosure.

[0174] The terms used herein are merely for the purpose of describing certain exemplary embodiments 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, 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 on or below) B, or that A is indirectly adjacent to B (i.e., sandwiching a material between A and B), and the term "A is located within B" may mean that A is entirely located within B, or that a part of A is within B.

[0175] In addition, some terms in this application are used to describe embodiments of the present disclosure. For example, "one embodiment," "embodiment," and / or "some embodiments" mean 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 is 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. Also, 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 to facilitate understanding of one feature, the present application may group various features together in a single embodiment, drawing, or description thereof. Alternatively, the present application also distributes various features to multiple embodiments of the present invention. However, this does not mean that the combination of these features is essential, and it is entirely possible for a person skilled in the art to extract some of the features when reading the present application and understand them as separate embodiments. That is, an embodiment in the present application can also be understood as a combination of multiple sub-embodiments. Also, the content of each sub-embodiment is valid even when it has less than all the features of a single above-disclosed embodiment.

[0177] In some embodiments, the numerals expressing numbers or properties for describing and claiming some embodiments of the present application are understood to be modified in some cases 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 for describing some embodiments of the present application are approximations, in specific examples, the precise numerical values ​​are all recited as possible.

[0178] Each patent, patent application, patent application publication, and other materials such as papers, books, specifications, publications, documents, articles, etc., referenced herein are incorporated herein by reference in their entirety for all purposes, excluding any relevant prosecution file history, and any that may be inconsistent or contradictory with the present specification or that may have a limiting effect on the broadest scope of the claims, whether now or later relating to this specification. For example, in the event of any inconsistency or discrepancy between the description, definition and / or use of a term relating to any material incorporated herein and the description, definition and / or use of a term relating to 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 illustrative of 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 in the present application using alternative configurations based on the embodiments in the present application. Therefore, the embodiments of the present application are not limited to the embodiments exactly 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 sound information during operation; a first speaker electrically connected to the signal processing circuit, the first speaker being operable to receive a first electrical signal from the signal processing circuit and convert the first electrical signal into a first sound wave corresponding to a first ear of a user; a second speaker electrically connected to the signal processing circuit, the second speaker being operable to receive a second electrical signal from the signal processing circuit and convert the second electrical signal into a second sound wave corresponding to a second ear of the user; When the input signal is the same, 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, an audio output device that requires a first length of time to convert the target audio information into the first sound wave and a second length of time to convert the target audio information into the second sound wave; An audio output device, characterized in that the first time length is shorter than the second time length by one time difference so as to adjust an offset of a sound image caused by a volume difference between the first sound wave and the second sound wave.

2. the first speaker includes at least one of a first bone conduction speaker and a first air conduction speaker; The audio output device according to claim 1 , wherein the second speaker comprises at least one of a second bone conduction speaker and a second air conduction speaker.

3. the first speaker generates the first sound waves by exciting a first mechanical structure; the second speaker generates second sound waves by exciting a second mechanical structure; The audio output device of claim 1, characterized in that since 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 waves output from the first speaker is smaller than the volume of the sound waves output from the second speaker.

4. The time difference occurs during a process in which the audio output device converts the target audio information into the first electrical signal and the second electrical signal; or 2. The audio output device of claim 1, wherein 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.

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