A multi-speaker electromagnetic interference cancellation system, cancellation method and electronic musical instrument

Abstract

This invention belongs to the field of musical instruments, specifically relating to a multi-speaker electromagnetic interference cancellation system, cancellation method, and electronic musical instrument. The multi-speaker electromagnetic interference cancellation system includes: at least two speakers; a target element; the at least two speakers are configured such that, upon input of an electrical drive signal, the total magnetic flux change of the alternating magnetic fields generated by each speaker at the target element cancels each other out, and the sound emission phases of each speaker are the same. This invention eliminates electromagnetic interference by configuring at least two speakers to cancel out the total magnetic flux of the alternating magnetic fields generated at the target element, while maintaining the same sound emission phases of each speaker to ensure normal sound pressure superposition output.

Description

Technical Field

[0001] This invention belongs to the field of musical instruments, specifically relating to a multi-speaker electromagnetic interference cancellation system, cancellation method, and electronic musical instrument. Background Technology

[0002] In electroacoustic equipment (such as electronic musical instruments, smart speakers, and conference systems), loudspeakers are often integrated in close proximity with sensitive components like pickups, microphones, or magnetic sensors. However, when a loudspeaker is in operation, the alternating current flowing through its voice coil not only drives the diaphragm to vibrate and produce sound, but also radiates an alternating magnetic field as a current carrier. Target components are typically extremely sensitive to changes in magnetic fields and readily pick up interference signals from the alternating magnetic field radiated by the loudspeaker.

[0003] When the target component, such as an electric guitar pickup, picks up the interference signal and amplifies it to drive the speaker again, a strong positive feedback electromagnetic coupling loop is formed between the speaker, the target component, and the amplification circuit. This can cause a piercing self-excited howl or severe distortion of the magnetic sensor output signal. This problem poses a significant challenge to the structural design of electroacoustic devices with built-in speakers (especially electronic musical instruments such as electric guitars), making it difficult for the speaker and the target component to coexist in close proximity.

[0004] To suppress this electromagnetic interference, traditional designs typically employ the following methods: First, separate the speaker from the target component, increasing the physical distance, but this sacrifices portability and a unified user experience; second, wrap the speaker with a heavy magnetic shield, which not only increases the weight and cost of the device but also has limited shielding effectiveness against low-frequency alternating magnetic fields; third, implement significant gain limiting or complex notch filtering measures in the signal processing or power amplifier circuits, which, while suppressing feedback to some extent, severely sacrifices the system's sound quality, dynamic range, and performance experience. Furthermore, in systems requiring multiple speakers to increase sound pressure level or improve sound field coverage, the alternating magnetic fields generated by multiple speakers will superimpose, leading to more complex interference. Existing technologies struggle to eliminate the combined electromagnetic interference to the target component while ensuring that the sound from each speaker is in phase (maintaining normal sound pressure output). Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a multi-speaker electromagnetic interference cancellation system, cancellation method, and electronic musical instrument. By configuring at least two speakers, the total magnetic flux of the alternating magnetic field generated at the target element cancels each other out to eliminate electromagnetic interference, while maintaining the same sound phase of each speaker to ensure normal superposition and output of sound pressure levels.

[0006] This invention provides a multi-speaker electromagnetic interference cancellation system, comprising: At least two speakers; Target component; The at least two loudspeakers are configured such that, upon input of an electric drive signal, the total change in magnetic flux of the alternating magnetic fields generated by each loudspeaker at the target element cancels each other out. Furthermore, the sound output phase of each speaker is the same.

[0007] Furthermore, the speaker is provided in two parts, which are arranged on both sides of the target element in a centrally symmetrical or left-right symmetrical manner.

[0008] Furthermore, the magnetic fields of the permanent magnets in the two loudspeakers are in opposite directions, the voice coil windings of the two loudspeakers are wound in opposite directions, and the two loudspeakers are configured to be driven by the same electric drive signal; Alternatively, the magnetic fields of the permanent magnets in the two loudspeakers are in opposite directions, the voice coil windings of the two loudspeakers are wound in the same direction, and the two loudspeakers are configured to be driven by electrical drive signals that are out of phase with each other.

[0009] Furthermore, the loudspeaker includes a sound-producing diaphragm and a driving assembly; The drive assembly includes a cooperating magnetic circuit system and a voice coil; The magnetic circuit system includes: Magnetic column; The permanent magnet is a ring magnet, which is sleeved on the outside of the magnetic guide post, and a magnetic gap is formed between the inner wall of the ring magnet and the outer wall of the magnetic guide post. A magnetic guide plate is disposed on the side of the annular magnet away from the sound-producing diaphragm and is connected to the end of the magnetic guide post; At least a portion of the voice coil winding is placed within the magnetic gap.

[0010] Furthermore, the voice coil includes a coil frame and a winding, the winding being wound on the coil frame, the coil frame being fixed to the sound-producing diaphragm, and at least a portion of the winding being placed in the magnetic gap.

[0011] Furthermore, the speaker is provided in two forms; It also includes a control unit, which is used to dynamically adjust the gain of one of the loudspeakers based on the residual component of the alternating magnetic field generated by each loudspeaker picked up by the target element, so as to suppress the residual component; The control unit is configured to perform the following operations in calibration mode: Output a reference signal, and simultaneously drive the first speaker with a first gain and the second speaker with a second gain; Acquire a feedback signal generated by the target element in response to the reference signal, the feedback signal characterizing the residual component of the alternating magnetic field generated by the first loudspeaker and the second loudspeaker at the target element; The following iteration is performed repeatedly at multiple preset sampling times: Calculate the current residual component based on the feedback signal; The gain adjustment is obtained by multiplying the current residual component by a fixed step size; The second gain is updated with the aforementioned gain adjustment amount, causing the residual component to approach zero.

[0012] Furthermore, the speaker is provided in two forms; It also includes a control unit, which is used to dynamically adjust the gain of one of the loudspeakers based on the residual component of the alternating magnetic field generated by each loudspeaker picked up by the target element, so as to suppress the residual component; The control unit is configured to perform the following operations in calibration mode: Output a reference signal to drive the first speaker with a first gain and drive the second speaker with an initial value of the second gain. Acquire a first feedback signal generated by the target element in response to the reference signal, the first feedback signal characterizing a first residual component at the target element; The second gain is adjusted to be the sum of the initial value of the second gain and a preset increment; Acquire a second feedback signal generated by the target element in response to the reference signal, the second feedback signal characterizing a second residual component at the target element after adjusting the second gain; Based on the first feedback signal, the second feedback signal, and the preset increment, calculate the estimated value of the system gain; In subsequent sampling periods, the current feedback signal generated by the target element is acquired, and the current feedback signal is normalized with the estimated value of the system gain to obtain the actual error estimate; The actual error estimate is subjected to proportional-integral control operation to obtain a gain adjustment amount, and the second gain is updated with the gain adjustment amount to make the residual component approach zero.

[0013] The present invention also provides a method for canceling electromagnetic interference from multiple loudspeakers, using the above-described multi-loudspeaker electromagnetic interference cancellation system; comprising the following steps: An electric drive signal is input to each of the loudspeakers, such that the total magnetic flux change of the alternating magnetic field generated by each loudspeaker at the target element cancels each other out, and the sound emission phase of each loudspeaker is the same.

[0014] The present invention also provides an electronic musical instrument, including the above-mentioned multi-speaker electromagnetic interference cancellation system, wherein the target element is a pickup, and the speaker and the pickup are integrated and mounted on the electronic musical instrument.

[0015] The beneficial effects of this invention are that the multi-speaker electromagnetic interference cancellation system provided by this invention, by setting at least two speakers and ensuring that the changes in the total magnetic flux of the alternating magnetic fields generated by each speaker cancel each other out at the target element, while maintaining the same sound phase, fundamentally cuts off the path for the positive feedback loop formed by magnetic field coupling between the speakers and the target element. While ensuring that the normal sound production performance of the system is not affected and that the sound pressure is superimposed in phase, it effectively suppresses the electromagnetic interference generated by the speakers on various target elements, allowing multiple speakers to be integrated and used closely with sensitive elements such as pickups and microphones, realizing the functional feasibility and stability of electroacoustic equipment with integrated speakers.

[0016] Furthermore, the spatial arrangement of at least two speakers within the system provides additional design freedom for optimizing the system's sound field coverage and directivity. Without altering the core configuration used to suppress electromagnetic interference in this embodiment (i.e., the total magnetic flux of the alternating magnetic fields of each speaker cancels out at the target element, and the sound emission phase is the same), optimizing the relative positions and layout of the speakers provides flexible design space for improving sound quality and acoustic performance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the electronic musical instrument in this invention; Figure 2 This is a schematic diagram of the speaker structure in this invention; Figure 3 This is a schematic diagram of the operation of the control unit in this invention.

[0018] In the diagram, 1-speaker; 11-diaphragm; 12-drive assembly; 121-magnetic circuit system; 1211-magnetic post; 1212-ring magnet; 1213-magnetic gap; 1214-magnetic plate; 1215-magnetic component; 122-voice coil; 1221-coil frame; 1222-winding; 2-pickup. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0021] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0022] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0024] like Figure 1-Figure 3 As shown, the present invention provides a multi-speaker electromagnetic interference cancellation system, comprising: At least two loudspeakers 1; loudspeakers 1 are used to convert electrical drive signals into sound output and are the sound source of the system. In the working state, the voice coil 122 of loudspeaker 1 is supplied with an electrical drive signal to generate an alternating current. On the one hand, under the action of the constant magnetic field of the magnetic circuit system 121, an Ampere force is generated to drive the sound-producing diaphragm 11 to vibrate and produce sound. On the other hand, the voice coil 122 itself also acts as an alternating current carrier to radiate an alternating magnetic field outward.

[0025] Target component; the target component is a component susceptible to electromagnetic interference, such as the pickup 2, magnetic sensor, or microphone in an electric guitar. The target component is used to pick up the desired acoustic or vibration signal, but it is also easily and sensitively picked up the alternating magnetic field radiated by the surrounding speaker 1.

[0026] The at least two loudspeakers 1 are configured such that, when an electric drive signal is input, the total magnetic flux change of the alternating magnetic field generated by each loudspeaker 1 at the target element cancels each other out. Since the magnetic flux vector sum of the alternating magnetic field generated by each loudspeaker 1 at the target element approaches zero, the target element will not be subject to electromagnetic interference. Taking the pickup 2 as an example, since the magnetic flux vector sum of the alternating magnetic field generated by each loudspeaker 1 at the pickup 2 approaches zero, the interference signal from the loudspeaker cannot be effectively picked up, thereby destroying the condition for forming a positive feedback coupling loop between the loudspeaker and the target element, and suppressing the generation of self-excited howling from the root.

[0027] The multi-speaker electromagnetic interference cancellation system provided in this embodiment, by setting at least two speakers 1 and ensuring that the alternating magnetic fields generated by each speaker 1 cancel each other out in terms of the total magnetic flux change at the target element, and simultaneously emit sound, fundamentally cuts off the path for the positive feedback loop formed by magnetic field coupling between the speakers and the target element. When the sound emission phases of each speaker are the same, it can also effectively suppress the electromagnetic interference generated by the speakers on various target elements while ensuring that the normal sound emission performance of the system is not affected and that the sound pressure is superimposed in phase. This allows multiple speakers to be integrated and used closely with sensitive elements such as pickups and microphones, realizing the functional feasibility and stability of electroacoustic equipment with built-in speakers.

[0028] Furthermore, the spatial arrangement of at least two speakers 1 within the system provides additional design freedom for optimizing the system's sound field coverage and directivity. Without altering the core configuration used to suppress electromagnetic interference in this embodiment (i.e., the total magnetic flux of the alternating magnetic fields of each speaker 1 cancels out at the target element, and the sound emission phase is the same), optimizing the relative positions and layout of the speakers 1 provides flexible design space for improving sound quality and acoustic performance.

[0029] It is important to note that there can be two, three, four, or more groups of loudspeakers 1, as long as the total magnetic flux change of the alternating magnetic fields generated by all loudspeakers 1 cancels each other out at the target element. The principle for setting them up is as follows: all loudspeakers 1 are divided into a first category with a first polarity and a second category with opposite polarities according to the polarity of the alternating magnetic fields they radiate outward. The sum of the alternating magnetic flux generated by the first category of loudspeakers 1 and the sum of the alternating magnetic flux generated by the second category of loudspeakers 1 are equal in magnitude and opposite in direction at the target element, thus canceling out the change in total magnetic flux.

[0030] In one embodiment, the sound emission phases of each speaker 1 are the same. That is, although the phase relationship of the alternating magnetic fields generated by each speaker 1 is configured to cancel each other out in space, the phase of the sound waves generated by the voice coils 122 driving the sound-producing diaphragms 11 to vibrate is consistent. This means that while suppressing electromagnetic interference, the sound pressure radiated by each speaker 1 does not weaken each other, but rather is superimposed in phase, ensuring that the system can output sound normally and efficiently, and even achieve a higher sound pressure level acoustic output. This in-phase sound emission configuration is particularly suitable for applications with high requirements for sound fidelity, dynamic range, and sound pressure output. It can avoid problems such as volume attenuation, low-frequency hollowness, or uneven sound field caused by the anti-phase cancellation of sound waves, ensuring that the device provides an excellent listening experience.

[0031] However, it should be noted that having the same sound phase is a preferred embodiment of the present invention, the purpose of which is to balance the elimination of electromagnetic interference with the optimization of acoustic output performance. In another embodiment, the sound phases of each speaker 1 are different, which is also within the scope of protection of the present invention. For example, in a scenario where two identical speakers 1 are placed at a distance, if an out-of-phase electrical drive signal is input to the two speakers 1, causing the sound phases of the two speakers to be opposite (i.e., the sound waves to be out of phase), the alternating magnetic fields generated can still cancel each other out at the target element, thereby effectively eliminating electromagnetic interference. Although this out-of-phase configuration may acoustically lead to mutual attenuation of sound pressure and a weakening of acoustic performance, it can still achieve the core technical effect of eliminating electromagnetic interference in certain special sound field design requirements (such as intentionally canceling the sound pressure at a specific location to achieve a quiet zone) or in scenarios where it is impossible to achieve the same sound phase due to limitations in the internal structure of the equipment.

[0032] In one embodiment, two speakers 1 are provided, and the two speakers 1 are arranged on both sides of the target element in a centrally symmetrical or left-right symmetrical manner.

[0033] Two loudspeakers 1 are arranged on either side of the target element in a centrally symmetrical or left-right symmetrical manner. This is one of the core spatial configurations for achieving the cancellation of alternating magnetic flux at the target element while maintaining the same sound phase for each loudspeaker 1.

[0034] Its working principle is as follows: When two loudspeakers 1 are input with appropriate electric drive signals, their internal voice coils 122 generate alternating magnetic fields and radiate outwards. Since the two loudspeakers 1 are symmetrically arranged on both sides of the target element, by properly configuring the magnetic field directions or the phase of the electric drive signals of the two loudspeakers 1, the alternating magnetic fields generated by the two loudspeakers 1 at the target element can be made to be opposite in direction. Simultaneously, the symmetrical arrangement ensures that the spatial distance between the two loudspeakers 1 and the target element is equal, and the attenuation characteristics of the magnetic field propagation are consistent. This results in the magnetic flux of the two alternating magnetic fields with opposite directions being equal at the target element, achieving complete cancellation of the total magnetic flux change. This prevents the target element (such as a pickup, microphone, or magnetic sensor) from effectively picking up interference signals from the loudspeakers, thereby disrupting the conditions for forming a positive feedback coupling loop between the loudspeakers and the target element. This fundamentally suppresses the generation of self-excited howling or avoids distortion of the target element's output signal due to electromagnetic interference.

[0035] At the same time, when inputting the electric drive signal, it is necessary to ensure that the voice coils 122 inside the two speakers 1 drive their respective sound-producing diaphragms 11 to vibrate in the same phase. In this way, although the alternating magnetic fields radiated by the two speakers 1 to the target element cancel each other out, the sound waves they emit are superimposed in phase in space, which will not weaken the sound pressure output of the system and ensure that the system produces sound normally and efficiently.

[0036] This symmetrical arrangement gives the system a natural balance in its spatial structure, which helps to maximize the magnetic flux cancellation effect, reduce the residual magnetic flux introduced by installation position deviation or inconsistent spatial distance, and has a reasonable structural layout and high reliability of self-excitation suppression.

[0037] In one embodiment, the magnetic field directions of the permanent magnets in the two loudspeakers 1 are opposite, the voice coils 122 of the two loudspeakers 1 are wound in opposite directions, and the two loudspeakers 1 are configured to be driven by the same electric drive signal.

[0038] The two speakers 1 are designated as the first speaker and the second speaker, respectively. The magnetic field direction of the permanent magnet in the first speaker is opposite to that in the second speaker, and the winding direction of the voice coil 122 in the first speaker is opposite to that in the second speaker. The same electrical drive signal is simultaneously input to both the first speaker and the second speaker.

[0039] This is the first configuration scheme of the present invention to achieve magnetic flux cancellation and identical sound phase. Its working principle is as follows: Since the voice coils 122 of the two speakers 1 are wound in opposite directions, when the same electrical drive signal is input, the instantaneous directions of the current flowing through the two voice coils 122 are opposite. According to the law of electromagnetic induction, the alternating magnetic fields generated by the two voice coils 122 are in opposite directions. Combined with the core configuration of the permanent magnet magnetic fields in the two speakers 1 having opposite directions, and the symmetrical spatial relationship between the two, the alternating magnetic fields generated by the two speakers 1 are opposite in direction and equal in magnitude at the target element, achieving mutual cancellation of the total magnetic flux change. This prevents the target element (such as a pickup, microphone, or magnetic sensor) from effectively picking up the interference signal from the speaker 1, thereby disrupting the conditions for forming a positive feedback coupling loop between the speaker 1 and the target element, fundamentally suppressing the generation of self-excited howling, or avoiding distortion of the target element's output signal due to electromagnetic interference.

[0040] Meanwhile, according to the left-hand rule of Ampere's force, in the two permanent magnets of the loudspeakers with opposite magnetic field directions, the voice coils 122 carrying currents in opposite directions experience Ampere forces in the same direction, thereby driving their respective diaphragms 11 to vibrate in the same direction, achieving the same sound phase. This means that while suppressing electromagnetic interference, the sound pressure radiated by the two loudspeakers 1 will not weaken each other, but will instead be superimposed in phase, ensuring the normal and efficient sound production performance of the system.

[0041] The advantage of this scheme is that there is no need to set up an inverting amplifier circuit or a differential output circuit on the circuit side. Only one electrical drive signal is needed to simultaneously meet the dual requirements of magnetic flux cancellation and in-phase sound generation. The circuit structure is simple and the system has high reliability.

[0042] In one embodiment, the magnetic fields of the permanent magnets in the two loudspeakers 1 are in opposite directions, the voice coils 122 of the two loudspeakers 1 are wound in the same direction, and the two loudspeakers 1 are configured to be driven by electrical drive signals that are out of phase with each other.

[0043] The two speakers 1 are the first speaker and the second speaker, respectively. The magnetic field direction of the permanent magnet in the first speaker is opposite to that of the permanent magnet in the second speaker, and the winding direction of the voice coil 122 of the first speaker is the same as that of the voice coil 122 of the second speaker. However, the electrical drive signals input to the two speakers 1 are out of phase with each other.

[0044] This is the second configuration scheme of the present invention to achieve magnetic flux cancellation and identical sound phase, achieving an equivalent technical effect to the first scheme. Its working principle is as follows: Since the voice coils 122 of the two speakers 1 have the same winding direction, when an inverse electric drive signal is input, the instantaneous directions of the currents flowing through the two voice coils 122 are opposite. According to the law of electromagnetic induction, the alternating magnetic fields generated by the two voice coils 122 are opposite in direction. Combined with the core configuration of the permanent magnet magnetic fields in the two speakers 1 having opposite directions, and the symmetrical spatial relationship between the two, the alternating magnetic fields generated by the two speakers 1 are opposite in direction and equal in magnitude at the target element, achieving mutual cancellation of the total magnetic flux change. This prevents the target element (such as a pickup, microphone, or magnetic sensor) from effectively picking up interference signals from the speakers, thereby disrupting the conditions for forming a positive feedback coupling loop between the speakers and the target element, fundamentally suppressing the generation of self-excited howling, or avoiding distortion of the target element's output signal due to electromagnetic interference.

[0045] Meanwhile, according to the left-hand rule of Ampere's force, in the two permanent magnets of the loudspeakers with opposite magnetic field directions, the voice coils 122 carrying currents in opposite directions experience Ampere forces in the same direction, thereby driving their respective diaphragms 11 to vibrate in the same direction, achieving the same sound phase. This means that while suppressing electromagnetic interference, the sound pressure radiated by the two loudspeakers 1 will not weaken each other, but will instead be superimposed in phase, ensuring the normal and efficient sound production performance of the system.

[0046] The advantage of this scheme is that the voice coils 122 of the two loudspeakers 1 are wound in the same direction, and the same winding process can be shared in terms of manufacturing, which helps to improve the winding consistency of the two voice coils 122 and reduce the impact of manufacturing tolerances on the magnetic flux cancellation accuracy. At the same time, the inverting electric drive signal can be provided by a differential amplifier circuit or a dual-channel inverting output controlled by an MCU, enabling flexible signal phase management on the circuit side. These two schemes are technically equivalent and can be flexibly selected according to actual manufacturing process conditions and circuit design requirements.

[0047] In one embodiment, the loudspeaker 1 includes a sound-producing diaphragm 11 and a driving assembly 12; The drive assembly 12 includes a magnetic circuit system 121 and a voice coil 122 that cooperate with each other; The magnetic circuit system 121 includes: Magnetic post 1211; The permanent magnet is a ring magnet 1212, which is sleeved on the outside of the magnetic guide post 1211. A magnetic gap 1213 is formed between the inner ring wall of the ring magnet 1212 and the outer wall of the magnetic guide post 1211. A magnetic guide plate 1214 is disposed on the side of the annular magnet 1212 away from the sound-producing diaphragm 11 and is connected to the end of the magnetic guide post 1211; At least a portion of the winding of the voice coil 122 is placed in the magnetic gap 1213.

[0048] This embodiment provides a specific implementation structure of the magnetic circuit system 121 in the loudspeaker 1. The magnetic post 1211, the ring magnet 1212, and the magnetic plate 1214 together form a closed magnetic circuit. The ring magnet 1212 provides a constant magnetic field, and the magnetic post 1211 and the magnetic plate 1214 guide the magnetic field to concentrate at the magnetic gap 1213. The magnetic gap 1213 is the working area of ​​the voice coil 122 winding. When an electrical drive signal is applied to the winding, the current-carrying conductor generates an Ampere force under the action of the constant magnetic field in the magnetic gap 1213, driving the voice coil 122 and the fixed diaphragm 11 to vibrate and produce sound. This structure efficiently concentrates the magnetic energy of the ring magnet 1212 in the magnetic gap 1213, providing a stable and uniform working magnetic field for the voice coil 122, which is beneficial for improving the electro-electric conversion efficiency and reducing distortion. Meanwhile, the magnetic plate 1214 is located on the side of the annular magnet 1212 away from the sound-producing diaphragm 11, and is connected to the end of the magnetic post 1211, serving the dual purpose of closing the magnetic circuit and providing fixed support.

[0049] It should be noted that each loudspeaker 1 has an independent drive component 12 and magnetic circuit system 121. The magnetic circuit system 121 of each loudspeaker 1 forms an independent magnetic circuit, and there is no magnetic circuit interference between them. This facilitates the independent assembly of each loudspeaker 1 and the independent configuration of the magnetic field direction of the permanent magnet, thereby achieving more precise mutual cancellation of alternating magnetic flux at the target element.

[0050] In one embodiment, the voice coil 122 includes a coil frame 1221 and a winding 1222, the winding 1222 being wound on the coil frame 1221, the coil frame 1221 being fixed to the sound-producing diaphragm 11, and at least a portion of the winding 1222 being placed in the magnetic gap 1213.

[0051] The coil frame 1221 serves as a supporting structure for the voice coil 122, with one end fixedly connected to the sound-producing diaphragm 11, transmitting the driving force generated by the winding 1222 to the sound-producing diaphragm 11. The winding 1222 is made of conductive material wound around the outer wall of the coil frame 1221, forming a multi-layered helical tubular structure. In operation, the winding 1222 is placed in the magnetic gap 1213 of the magnetic circuit system 121. When an electrical drive signal is applied to the winding 1222, the current-carrying conductor experiences an Ampere force within the constant magnetic field of the magnetic gap 1213. This force is transmitted through the coil frame 1221 to the sound-producing diaphragm 11, driving the diaphragm 11 to vibrate and produce sound. The fixed connection between the coil frame 1221 and the sound-producing diaphragm 11 can be achieved by bonding, snap-fitting, or integral molding, ensuring the rigidity and reliability of the driving force transmission path.

[0052] It should be noted that each speaker 1 has an independent voice coil 122 and coil frame 1221. The coil frame 1221 of each voice coil 122 is fixed on the sound-producing diaphragm 11 of its respective speaker 1, which facilitates the independent assembly of each speaker 1 and the independent configuration of the winding direction of the voice coil 122, thereby more accurately realizing the mutual cancellation of alternating magnetic flux at the target component (such as pickup, microphone or magnetic sensor) of each speaker 1.

[0053] In one embodiment, two speakers 1 are provided; It also includes a control unit, which is used to dynamically adjust the gain of one of the loudspeakers 1 according to the residual component of the alternating magnetic field generated by each loudspeaker 1 picked up by the target element, so as to suppress the residual component; The control unit is configured to perform the following operations in calibration mode: Output a reference signal, and simultaneously drive the first speaker 1 with a first gain and drive the second speaker 1 with a second gain; Acquire a feedback signal generated by the target element in response to the reference signal, the feedback signal characterizing the residual component of the alternating magnetic field generated by the first loudspeaker 1 and the second loudspeaker 1 at the target element; The following iteration is performed repeatedly at multiple preset sampling times: Calculate the current residual component based on the feedback signal; The gain adjustment is obtained by multiplying the current residual component by a fixed step size; The second gain is updated with the aforementioned gain adjustment amount, causing the residual component to approach zero.

[0054] This embodiment is a preferred embodiment that introduces an active calibration function. In actual manufacturing, due to the unavoidable manufacturing tolerances in the magnetic circuit systems and voice coils 122 of the two speakers 1, coupled with assembly errors in the installation position, the alternating magnetic fields generated by the two speakers 1 are difficult to completely cancel at the target component, and a residual component will always remain. If this residual component is large enough, it may cause electromagnetic interference that distorts the output signal of the target component. Taking the pickup 2 as an example, the residual component may still form a positive feedback loop with the subsequent circuit through the target component, causing self-excited howling. This embodiment sets up a control unit to enter calibration mode when the system is powered on or at a specific time, and adaptively adjusts the drive gain of the two speakers 1 to compensate for the inconsistencies caused by manufacturing and assembly errors.

[0055] The control unit works as follows: In calibration mode, the control unit outputs a reference signal, such as a test signal in the ultrasonic frequency band, which is inaudible to the human ear and does not affect the user experience. This reference signal simultaneously drives both the first speaker 1 and the second speaker 1. However, due to the difference in the actual parameters of the two speakers 1, the target element will still pick up a weak feedback signal, which reflects the magnitude of the current residual component. The control unit calculates the current residual component at each sampling time iteratively and updates the second gain according to the fixed-step gradient descent method: each time, the residual component is multiplied by a preset fixed step size (a small constant), and the resulting product is added to the second gain as a gain adjustment. Since there is a definite gradient relationship between the residual component and the direction of the second gain adjustment, after several iterations, the residual component will converge exponentially to a level close to zero. The value of the fixed step size must meet the convergence condition, that is, the product of the step size and the system gain must be between 0 and 2. In practice, a sufficiently small step size can be used to ensure a stable convergence process. This control scheme requires minimal computing resources, does not require prior knowledge of system gain and other parameters, and is easy to implement in embedded MCUs, providing a reliable guarantee for the multi-speaker electromagnetic interference cancellation system to maintain low electromagnetic interference performance in practical use.

[0056] In one specific implementation of this embodiment, taking two speakers 1 as an example: the control unit uses a fixed-step gradient descent method for gain adjustment. The following parameters are defined: A Gain of the first speaker ( GainA This value can be set to a fixed value during the calibration process; B Gain of the second speaker ( GainB ), which is the variable to be adjusted during the calibration process; D The relative value of the current residual component, characterized by the feedback signal generated by the target element in response to the reference signal, is obtained by measurement; s System gain is an unknown constant coefficient determined by factors such as magnetic signal space loss, target component conversion efficiency, and internal circuit gain. s >0; m Fixed step size, which is a preset small positive constant, must satisfy... m s <2 to ensure convergence; E： error, E = A - B .

[0057] The relative value of the residual component picked up by the target element D The relationship between the gain of each speaker and the following is satisfied: D=s· (AB) .

[0058] The calibration process is as follows: Initialization: Settings B For initial values ​​(such as) B =0), keep A Set to a preset fixed gain; Iterative update: At each sampling time, perform the following update operation: Measurement D=s·(AB) renew B←B+μ·D Repeat this step until the residual component D approaches zero (or reaches the preset number of iterations / convergence threshold).

[0059] Explanation of the principle: Error after update E′=A-(B+μ·D)=AB-μ·s·(AB)=(1-μ·s·E Because 0 < μs <2, error E The system converges to zero exponentially. The step size μ must be chosen to be small enough to guarantee any possible system gain. s Lower convergence, m The actual value can be determined by experience or set through system debugging.

[0060] This specific implementation method fully utilizes the relative values ​​of the residual components obtained from the target element. D As a feedback quantity, there is no need to identify the system gain in advance. s The iterative process involves only multiplication and addition operations, with minimal resource consumption, making it suitable for execution in low-cost embedded MCUs. It can automatically balance the gain during power-on calibration, effectively compensating for inconsistencies caused by manufacturing tolerances and assembly errors, and ensuring that the total alternating magnetic flux change at the target component is suppressed to the maximum extent under normal operating conditions.

[0061] In one embodiment, two speakers 1 are provided; It also includes a control unit, which is used to dynamically adjust the gain of one of the loudspeakers 1 according to the residual component of the alternating magnetic field generated by each loudspeaker 1 picked up by the target element, so as to suppress the residual component; The control unit is configured to perform the following operations in calibration mode: Output a reference signal to drive the first speaker 1 with a first gain and drive the second speaker 1 with a second initial gain value; Acquire a first feedback signal generated by the target element in response to the reference signal, the first feedback signal characterizing a first residual component at the target element; The second gain is adjusted to be the sum of the initial value of the second gain and a preset increment; Acquire a second feedback signal generated by the target element in response to the reference signal, the second feedback signal characterizing a second residual component at the target element after adjusting the second gain; Based on the first feedback signal, the second feedback signal, and the preset increment, calculate the estimated value of the system gain; In subsequent sampling periods, the current feedback signal generated by the target element is acquired, and the current feedback signal is normalized with the estimated value of the system gain to obtain the actual error estimate; The actual error estimate is subjected to proportional-integral control operation to obtain a gain adjustment amount, and the second gain is updated with the gain adjustment amount to make the residual component approach zero.

[0062] This is another preferred embodiment of introducing active calibration function, employing a proportional-integral control method with initial estimation. Its core idea consists of two stages: the first stage involves actively applying a known gain disturbance and observing the system's response change, thereby deriving the system's gain parameters; the second stage uses the obtained system gain parameters to reconstruct the subsequently measured feedback signal, obtaining the true error, and then achieving rapid convergence and long-term stability through the proportional-integral controller.

[0063] In the first stage, the control unit is unaware of the overall signal attenuation factor from speaker 1 to the target component. This attenuation factor is determined by multiple factors, including the spatial propagation loss of the magnetic field, the conversion efficiency of the target component, and the internal circuit gain, and varies slightly from device to device due to manufacturing tolerances. To obtain this unknown parameter, the control unit first records the residual signal magnitude at the current gain setting, then actively fine-tunes the gain of one of the speakers 1 by a known small amount, and measures the change in the residual signal again. The difference between the two residual signals is entirely caused by this known gain fine-tuning; therefore, by dividing the difference between the two measurements by the known fine-tuning amount, the system's attenuation factor can be accurately estimated. The entire process requires only two measurements and one active fine-tuning, and is completely transparent to the user.

[0064] In the second stage, the control unit uses the estimated system attenuation factor to restore the feedback signal measured by the target element to the true gain deviation between the two speakers 1. Since the feedback signal is a reduced version of the true deviation after system attenuation, directly adjusting based on the feedback signal easily underestimates the magnitude of the deviation, leading to a slow response. However, the normalized value provides an estimate of the true deviation, which the control unit can then use a proportional-integral (PI) control strategy for fast and precise gain adjustment. The proportional control part responds instantly according to the current deviation magnitude, adjusting larger amounts when the deviation is large and smaller amounts when the deviation is small; the integral control part accumulates historical deviations and continuously compensates for long-standing small residuals, eliminating steady-state error. The combination of these two approaches allows the gain of the second speaker 1 to quickly approach the optimal equilibrium point, with the residual component converging to near-zero levels in a very short time and remaining stable over a long period. Compared to the fixed-step iterative method, this embodiment, because the system parameters are identified in advance, provides a clear direction and scale for the adjustment process, resulting in faster convergence and higher accuracy.

[0065] In one specific implementation of this embodiment, the control unit employs a proportional-integral control method with initial estimation for gain adjustment. For ease of description, the following parameters are defined: In one specific implementation of this embodiment, the control unit employs a proportional-integral control method with initial estimation for gain adjustment. For ease of description, the following parameters are defined: A The gain of the first speaker can be set to a fixed value during calibration. B The gain of the second speaker is the variable to be adjusted during calibration. D The relative value of the current residual component, characterized by the feedback signal generated by the target element in response to the reference signal, is obtained by measurement. D=s·(AB) ; s System gain is an unknown coefficient determined by factors such as magnetic signal space loss, target component conversion efficiency, and internal circuit gain. s >0, for a single device s It is relatively constant, but may vary slightly with external parameters such as temperature and usage environment; d The preset increment is a known small quantity, for example... d =0.1, used to actively perturb the second gain to estimate the system gain; System gain s The estimated value was obtained from the calculation in the first stage; Ê Actual error estimation Ê=D / , representing the true deviation E=AB The estimated value; Kp : Proportionality coefficient, which is a positive constant, for example Kp =1; Ki The integral coefficient is a positive constant, for example... Ki =0.1; I : The integral accumulation term, with an initial value of 0; T Sampling period, for example T =0.1 seconds; m Fixed step size, which is a preset small positive constant, must satisfy... m s <2 to ensure convergence.

[0066] The calibration process is carried out in two stages, with the following steps: Output a reference signal to drive a first speaker with a first gain and a second speaker with a second initial gain; acquire a first feedback signal generated by the target element in response to the reference signal, the first feedback signal characterizing a first residual component at the target element; Relative value of the first residual component: D 0 =s·(AB 0 ) This step establishes the initial error state under the current gain configuration. At this point, the first speaker is operating at a fixed gain. A Run, the second speaker at initial value B 0 operation, due to manufacturing tolerances and assembly errors of the two sets of speakers, A and B 0 are not equal, therefore there is a residual alternating magnetic flux at the target element, the relative magnitude of which is measured as D 0. D 0 represents the true deviation. E= AB 0 by system gain s The reaction after attenuation.

[0067] The control unit adjusts the second gain to the sum of the initial value of the second gain and a preset increment. Specifically, it adjusts the second gain from... B 0 is adjusted to: B 1 =B 0 +d The second feedback signal generated by the target element in response to the same reference signal is obtained again and denoted as the relative value of the second residual component: D 1 =s·(AB 1 ) This step involves actively applying a known gain perturbation. d Observe the changes in the system response. d This is a known small quantity preset by the control unit, and its value must balance the requirements of estimation accuracy and not causing audible noise. Because the second gain is actively changed... d The residual component at the target element changes accordingly, from D 0 becomes D 1. The difference between the two measurements is entirely due to the known gain perturbation. d This provides a basis for subsequently inferring the unknown system gain s.

[0068] Based on the first feedback signal, the second feedback signal, and the preset increment, an estimated value of the system gain is calculated. This is derived from the difference between the two measurements: D 0 -D 1 =s·(AB 0 )-s·(AB 0 -δ)=sδ The estimated value of the system gain can be obtained:

[0069] System gain *s* is a bridging parameter connecting the drive gain deviation and the feedback signal from the target component. It comprehensively reflects factors such as the spatial loss of the magnetic signal propagating from the two sets of speakers to the target component, the conversion efficiency of the target component in converting magnetic flux into an electrical signal, and the gain of the internal signal chain. Due to differences in manufacturing tolerances, assembly precision, and component parameters, each device... s The specific values ​​vary. Through two active measurements and a known increment, the control unit automatically identifies the estimated value of s without relying on any preset parameters. . The accuracy of the signal directly affects the convergence performance of subsequent PI control. d The larger the value, the higher the estimated signal-to-noise ratio, but an excessively large value... d A brief, audible noise may occur during the calibration process, therefore d A smaller, compromised amount is usually chosen.

[0070] In subsequent sampling periods, the current feedback signal generated by the target component is acquired, and the current feedback signal is normalized using the estimated system gain to obtain an actual error estimate. In each sampling period, the control unit acquires the current feedback signal.D ,calculate: Ê=D /

[0071] because D=s·(AB) When the estimate is accurate ≈ s Sometimes, Ê ≈ AB = E The significance of normalization lies in the feedback signal. D Is it the system gain s A scaled-down version after significant attenuation, if directly based on D Gain adjustment is performed, but the adjustment range is significantly insufficient due to attenuation, resulting in slow convergence. Divide by The true gain bias estimate was then recovered. Ê This ensures that the adjustment amount of subsequent PI control is proportional to the actual deviation, eliminates the influence of the attenuation factor, and guarantees that the adjustment strength and direction match the actual situation.

[0072] The actual error estimate is subjected to proportional-integral control operation to obtain a gain adjustment amount, and the second gain is updated with the gain adjustment amount to make the residual component approach zero.

[0073] Design a PI controller with the following continuous-domain expression: B(t)=Kp·Ê(t)+Ki·∫ 0 t Ê(τ)dτ in Kp、Ki For positive numbers (e.g.) Kp =1, Ki =0.1). This PI controller consists of a proportional term. Kp·Ê(t) and integral terms Ki·∫ 0 t Ê(τ)dτ It consists of two parts. The proportional term responds instantly to the magnitude of the current error, adjusting larger increments for larger errors and smaller increments for smaller errors, ensuring rapid adjustment. The integral term accumulates all historical errors since calibration began. Even if the current error is very small, the integral term will continue to compensate for long-standing minor residual errors, eliminating steady-state errors that cannot be avoided by proportional adjustment alone.

[0074] Discretization is implemented as follows: Initialize the integral term I =0, sampling period T (like T =0.1).

[0075] For each sampling period, perform the following operations: Measure the current feedback signal D ,calculateÊ=D / ; Update points accumulation items: I←I+Ê·T Update the second gain: B←B+μ·D Here, μ is a fixed step size, which has the same meaning as the step size in Algorithm 1, and is a preset small positive number. Since s is fixed and accurately estimated, the controller can make AB quickly approach zero.

[0076] The above steps are repeated until the residual components converge below a preset threshold or the preset number of iterations is reached, at which point the calibration is complete. Afterward, the control unit exits calibration mode and drives the two sets of speakers into normal operation with the calibrated gain configuration.

[0077] Compared to the fixed-step gradient descent method, this specific implementation method, because it pre-identifies the system gain s, is equivalent to having the direction and scale of error adjustment clearly defined before adjustment, resulting in faster convergence. Simultaneously, the integral action in the PI controller eliminates steady-state error, achieving higher precision flux cancellation. Furthermore, minor drifts in the system gain s caused by factors such as temperature changes and environmental variations can be automatically re-identified and compensated for during the next power-on calibration, ensuring the speaker maintains excellent low electromagnetic interference performance throughout long-term use.

[0078] The present invention also provides a method for canceling electromagnetic interference from multiple loudspeakers, using the above-described multi-loudspeaker electromagnetic interference cancellation system; comprising the following steps: An electric drive signal is input to each of the loudspeakers 1, such that the total magnetic flux change of the alternating magnetic field generated by each loudspeaker 1 at the target element cancels each other out, and the sound emission phase of each loudspeaker 1 is the same.

[0079] Using the above methods, the multi-speaker electromagnetic interference cancellation system can eliminate electromagnetic interference to target components to the greatest extent possible while ensuring sound pressure superposition and high sound efficiency, thus achieving close-range integration and stable operation of speakers and sensitive components such as pickups.

[0080] This invention also provides an electronic musical instrument, including the aforementioned multi-speaker electromagnetic interference cancellation system. The target element is a pickup 2, and the loudspeaker 1 and the pickup 2 are integrated and mounted on the electronic musical instrument. This electronic musical instrument integrates the multi-speaker electromagnetic interference cancellation system and the pickup 2 into the same body, such as an electric guitar, electric bass, or other electro-acoustic instrument with a pickup. The pickup 2 is used to pick up the string vibration signal through electromagnetic induction, and each loudspeaker 1 is used to convert the audio signal after signal processing and power amplification into sound output. Because the system uses the aforementioned configuration of at least two loudspeakers 1, the total magnetic flux change at the pickup 2 of the alternating magnetic field generated by each loudspeaker 1 cancels each other out. The pickup 2 cannot effectively pick up the interference signal from the loudspeaker, thereby cutting off the positive feedback self-excitation loop between the loudspeaker, pickup, signal processing circuit, and loudspeaker. Each speaker 1 and pickup 2 can coexist closely within the instrument body, eliminating the need for additional significant gain limiting or notch filtering measures in the signal processing or power amplifier circuits to suppress self-oscillation, thus ensuring a superior playing experience. At the same time, it achieves the autonomous sound generation function of the built-in speakers, allowing for playing and monitoring without the need for external speakers.

[0081] In one embodiment, the loudspeakers 1 and the pickups 2 are arranged symmetrically on the left and right or centrally within the instrument body. Specifically, when two loudspeakers 1 are provided, they are arranged symmetrically on both sides of the pickup 2 with the pickup 2 as the center. Since the alternating magnetic field generated by each loudspeaker 1 is distributed symmetrically in space, placing the pickup 2 in a balanced position of this symmetrical distribution can maximize the magnetic flux cancellation effect, further reduce the residual magnetic flux introduced by the installation position deviation, and ensure the reliability of self-excitation suppression.

[0082] The above description is merely an embodiment and does not constitute any limitation on the present invention. Any person skilled in the art can make many possible variations, modifications, or alterations to the technical solutions of the present invention without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A multi-speaker electromagnetic interference cancellation system, characterized in that, include: At least two speakers (1); Target component; The at least two loudspeakers (1) are configured such that, when an electric drive signal is input, the total change in magnetic flux of the alternating magnetic field generated by each loudspeaker (1) at the target element cancels each other out.

2. The multi-speaker electromagnetic interference cancellation system according to claim 1, characterized in that, The sound output phase of each loudspeaker (1) is the same.

3. The multi-speaker electromagnetic interference cancellation system according to claim 1, characterized in that, Two speakers (1) are provided, and the two speakers (1) are arranged on both sides of the target element in a centrally symmetrical or left-right symmetrical manner.

4. The multi-speaker electromagnetic interference cancellation system according to claim 2, characterized in that, The magnetic fields of the permanent magnets in the two loudspeakers (1) are in opposite directions, the voice coils (122) of the two loudspeakers (1) are wound in opposite directions, and the two loudspeakers (1) are configured to be driven by the same electric drive signal; Alternatively, the magnetic fields of the permanent magnets in the two loudspeakers (1) are in opposite directions, the voice coils (122) of the two loudspeakers (1) are wound in the same direction, and the two loudspeakers (1) are configured to be driven by electrical drive signals that are out of phase with each other.

5. The multi-speaker electromagnetic interference cancellation system according to claim 1, characterized in that, The loudspeaker (1) includes a sound-producing diaphragm (11) and a driving assembly (12). The drive assembly (12) includes a magnetic circuit system (121) and a voice coil (122) that cooperate with each other. The magnetic circuit system (121) includes: Magnetic post (1211); The permanent magnet is a ring magnet (1212) which is sleeved on the outside of the magnetic post (1211). A magnetic gap (1213) is formed between the inner wall of the ring magnet (1212) and the outer wall of the magnetic post (1211). A magnetic guide plate (1214) is disposed on the side of the annular magnet (1212) away from the sound-producing diaphragm (11) and is connected to the end of the magnetic guide post (1211); At least a portion of the winding of the voice coil (122) is placed in the magnetic gap (1213).

6. The multi-speaker electromagnetic interference cancellation system according to claim 5, characterized in that, The voice coil (122) includes a coil frame (1221) and a winding (1222), the winding (1222) being wound on the coil frame (1221), the coil frame (1221) being fixed on the sound-producing diaphragm (11), and at least a portion of the winding (1222) being placed in the magnetic gap (1213).

7. The multi-speaker electromagnetic interference cancellation system according to any one of claims 1-6, characterized in that, Two speakers (1) are provided; It also includes a control unit, which is used to dynamically adjust the gain of one of the loudspeakers (1) based on the residual component of the alternating magnetic field generated by each loudspeaker (1) picked up by the target element, so as to suppress the residual component; The control unit is configured to perform the following operations in calibration mode: Output a reference signal, and simultaneously drive the first speaker (1) with a first gain and drive the second speaker (1) with a second gain. Obtain the feedback signal generated by the target element in response to the reference signal, the feedback signal characterizing the residual component of the alternating magnetic field generated by the first loudspeaker (1) and the second loudspeaker (1) at the target element; The following iteration is performed repeatedly at multiple preset sampling times: Calculate the current residual component based on the feedback signal; The gain adjustment is obtained by multiplying the current residual component by a fixed step size; The second gain is updated with the aforementioned gain adjustment amount, causing the residual component to approach zero.

8. The multi-speaker electromagnetic interference cancellation system according to any one of claims 1-6, characterized in that, Two speakers (1) are provided; It also includes a control unit, which is used to dynamically adjust the gain of one of the loudspeakers (1) based on the residual component of the alternating magnetic field generated by each loudspeaker (1) picked up by the target element, so as to suppress the residual component; The control unit is configured to perform the following operations in calibration mode: Output a reference signal to drive the first speaker (1) with a first gain and drive the second speaker (1) with a second initial gain value. Acquire a first feedback signal generated by the target element in response to the reference signal, the first feedback signal characterizing a first residual component at the target element; The second gain is adjusted to be the sum of the initial value of the second gain and a preset increment; Acquire a second feedback signal generated by the target element in response to the reference signal, the second feedback signal characterizing a second residual component at the target element after adjusting the second gain; Based on the first feedback signal, the second feedback signal, and the preset increment, calculate the estimated value of the system gain; In subsequent sampling periods, the current feedback signal generated by the target element is acquired, and the current feedback signal is normalized with the estimated value of the system gain to obtain the actual error estimate; The actual error estimate is subjected to proportional-integral control operation to obtain a gain adjustment amount, and the second gain is updated with the gain adjustment amount to make the residual component approach zero.

9. A method for eliminating electromagnetic interference from multiple loudspeakers, characterized in that, Using the multi-speaker electromagnetic interference cancellation system as described in any one of claims 1-8; comprising the following steps: An electric drive signal is input to each of the loudspeakers (1) so that the total magnetic flux change of the alternating magnetic field generated by each loudspeaker (1) at the target element cancels each other out, and the sound emission phase of each loudspeaker (1) is the same.

10. An electronic musical instrument, characterized in that, The system includes a multi-speaker electromagnetic interference cancellation system as described in any one of claims 1-8, wherein the target element is a pickup (2), and the speaker (1) and the pickup (2) are integrated and mounted on the electronic musical instrument.

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