Noise-canceling headphones

Abstract

An embodiment of the present invention discloses a noise-canceling earphone, and the present application relates to the technical field of telecommunication call auxiliary devices. It includes a housing and a noise-canceling module. The housing is of a cavity structure, and a first cavity that is connected is formed between the housing and the ear; the noise-canceling module is located in the first cavity, and the noise-canceling module includes a sound-electricity transducer device and a sound impedance control unit. The sound impedance control unit is connected to the sound-electricity transducer device so that the equivalent sound impedance of the sound-electricity transducer device is a preset equivalent sound impedance. The embodiment of the present application achieves the effect of reducing the noise in a preset frequency band in the earphone without the need for an additional microphone to collect external noise or noise in the cavity.

Description

Technical Field

[0001] The present invention relates to the technical field of telecommunication call auxiliary devices, and particularly to a noise-canceling earphone. Background Art

[0002] In recent years, earphones have become common necessities in people's lives. During the use of earphones, noise is inevitably generated, which affects the use effect of people. Noise-canceling earphones are increasingly widely accepted by the public. Noise-canceling earphones usually need to add an additional microphone to collect external noise or cavity noise. The noise-canceling technologies commonly used for the collected noise are divided into active noise-canceling technology (ANC) and passive noise-canceling technology (PNC). Active noise-canceling technology needs to add an additional microphone to collect external noise or cavity noise for controlling the vibration of the sound source, so that the amplitude of the sound source is the same as that of the noise, and the phase is just opposite, so that the noise can be canceled to achieve noise reduction. For example, tools such as electronic filters are used to actively cancel the noise of the earphone. Passive noise-canceling technology absorbs noise at the noise source, during the noise propagation process, or at the human ear to achieve noise reduction. However, since the frequency range of the noise in the earphone is 20 Hz - 20 KHz, only using active noise-canceling technology mainly reduces the medium and low frequency noise with a frequency range of 50 Hz - 2 KHz, and the active noise-canceling technology has a poor noise reduction effect on the medium and high frequency noise in the noise. In existing noise-canceling earphones, a sound insulation structure is usually used to passively cancel the medium and high frequency noise in the noise. However, due to the existence of some resonances in the noise-canceling earphone, the noise reduction effect of some frequency bands is poor.

[0003] In view of this, it is necessary to provide a noise-canceling earphone to solve the above defects. Summary of the Invention

[0004] The present invention provides a noise-canceling earphone, aiming to solve problems such as the poor noise reduction effect of existing noise-canceling earphones on medium and high frequency noise.

[0005] To solve the above technical problems, the present invention proposes a noise-canceling earphone, which includes a housing and a noise-canceling module. Among them, the housing is a cavity structure, and a first cavity that is connected is formed between the housing and the ear; the noise-canceling module is located in the first cavity, and the noise-canceling module includes a sound-electricity transducer and a sound impedance control unit. The sound impedance control unit is connected to the sound-electricity transducer so that the equivalent sound impedance of the sound-electricity transducer is a preset equivalent sound impedance.

[0006] In a further technical solution, the sound impedance control unit is a resistance impedance device or a resistance impedance circuit with a preset resistance impedance value. The sound impedance control unit is connected to the positive and negative electrodes of the sound-electricity transducer so that the equivalent sound impedance of the sound-electricity transducer is a preset equivalent sound impedance.

[0007] In a further technical solution, the acoustic-electric transducer device is a first moving coil loudspeaker or a piezoelectric device, and the piezoelectric material in the piezoelectric device is piezoelectric ceramic or piezoelectric film.

[0008] In a further technical solution, the equivalent acoustic impedance Z on the diaphragm surface of the first moving coil loudspeaker sp1 is determined by the following formula:

[0009]

[0010] where Z m is the equivalent force impedance of the first moving coil loudspeaker, S d is the effective radiation area of the diaphragm of the first moving coil loudspeaker, Bl is the power conversion coefficient of the first moving coil loudspeaker, Z e is the impedance of the noise reduction unit, v is the vibration velocity of the diaphragm of the first moving coil loudspeaker, Z ab is the acoustic impedance on the back of the diaphragm of the first moving coil loudspeaker, U e is the driving voltage of the first moving coil loudspeaker.

[0011] In a further technical solution, the equivalent acoustic impedance Z of the piezoelectric device in is determined by the following formula:

[0012] Z in = Z m * T m + Z e * T e

[0013] where Z m is the mechanical impedance of the piezoelectric device, Z e is the impedance of the impedance device or the impedance circuit connected to the piezoelectric device, T m is the first transduction factor, T e is the second transduction factor.

[0014] In a further technical solution, the housing includes a cover body for mounting the acoustic-electric transducer device, the noise-canceling earphone further includes a sound output part, the sound output part is mounted on the cover body, and the sound output part cooperates with the cover body to form the first cavity.

[0015] In a further technical solution, the housing further includes a first housing, the first housing is a cavity structure with an opening, the cover body is mounted on the opening of the first housing to form a second cavity; the noise-canceling earphone further includes a sound generating part, the sound generating part is mounted on the cover body and is located in the second cavity, and the sound generating part is used for sound reproduction or active noise cancellation.

[0016] In a further technical solution, the first moving coil loudspeaker is mounted on the cover body and is disposed at a position corresponding to the sound generating part.

[0017] In a further technical solution, the noise-canceling earphone further includes a second housing, which is disposed on one side of the first housing and is mounted on the cover body. A third cavity is formed between the second housing and the cover body, and the first moving coil loudspeaker is disposed at a position corresponding to the third cavity and is mounted on the cover body.

[0018] In a further technical solution, the piezoelectric device is mounted on the cover body and is disposed at a position corresponding to the sound generating part.

[0019] Compared with the prior art, the noise-canceling earphone provided by the present invention is provided with a noise-canceling module in a first cavity formed between the housing and the ear. The noise-canceling module includes a sound-electricity transducer and a sound impedance control unit connected to the sound-electricity transducer. The equivalent sound impedance of the sound-electricity transducer is controlled by the sound impedance control unit to be a preset equivalent sound impedance. For example, when the preset equivalent sound impedance tends to zero, the sound-electricity transducer can absorb the noise in a preset frequency band in the first cavity at the ear, so as to realize the noise-canceling function of the noise-canceling earphone without adding an additional microphone to collect external noise or noise in the first cavity, thereby improving the user experience. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a cross-sectional view of an embodiment of the noise-canceling earphone of the present invention;

[0022] Figure 2 For Figure 1 The equivalent circuit diagram of the noise-canceling unit of the noise-canceling earphone shown;

[0023] Figure 3 For Figure 1 The equivalent circuit diagram of the first moving coil loudspeaker of the noise-canceling earphone shown;

[0024] Figure 4 It is a cross-sectional view of another embodiment of the noise-canceling earphone of the present invention;

[0025] Figure 5 It is a cross-sectional view of yet another embodiment of the noise-canceling earphone of the present invention;

[0026] Figure 6 For Figure 5Schematic diagram of the structure of the noise reduction unit of the noise-canceling headphone shown

[0027] Figure 7 is Figure 5 Equivalent circuit diagram of the noise reduction unit of the noise-canceling headphone shown Specific embodiments

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than 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 efforts shall fall within the protection scope of the present invention.

[0029] The directional terms mentioned in the present invention, such as "upper", "lower", "front", "rear", "left", "right", "inner", "outer", "side", etc., are only references to the directions in the attached drawings. Therefore, the directional terms used are for explaining and understanding the present invention, rather than for limiting the present invention. In addition, in the drawings, structures that are similar or the same are denoted by the same reference numerals.

[0030] An embodiment of the present invention provides a noise-canceling headphone 100, as shown in Figure 1 、 Figure 4 and Figure 5 shown, which includes a housing and a noise reduction module 5. Among them, the housing is a cavity structure, and a first cavity 7 is formed between the housing and the ear 9; the noise reduction module 5 is located in the first cavity 7, and the noise reduction module 5 includes a sound-electricity transducer and a sound impedance control unit. The sound impedance control unit is connected to the sound-electricity transducer so that the equivalent sound impedance of the sound-electricity transducer is a preset equivalent sound impedance.

[0031] Compared with the prior art, in the noise-canceling headphone 100 provided by the present invention, a noise reduction module is arranged in the connected first cavity formed between the housing and the ear 9. The noise reduction module includes a sound-electricity transducer and a sound impedance control unit 51 connected to the sound-electricity transducer. The equivalent sound impedance of the sound-electricity transducer is controlled by the sound impedance control unit 51 to be a preset equivalent sound impedance. For example, when the preset equivalent sound impedance tends to zero, the sound-electricity transducer can absorb the noise in the preset frequency band in the first cavity at the ear, so as to achieve the noise reduction function of the noise-canceling headphone without adding an additional microphone to collect external noise or noise in the first cavity, thereby improving the user experience.

[0032] In some embodiments, such as Figure 2 and Figure 6As shown, the acoustic impedance control unit 51 is an impedance device or impedance circuit with a preset impedance value. The acoustic impedance control unit 51 is connected to the positive and negative electrodes of the acoustic-electric transducer device so that the equivalent acoustic impedance of the acoustic-electric transducer device is the preset equivalent acoustic impedance. In this embodiment, the impedance device or impedance circuit can be a Foster circuit or device composed of resistors, capacitors, and inductors, or some non-Foster circuits or devices implemented by active circuits. Since the impedance of the impedance device or impedance circuit is adjustable, by adjusting the external impedance value equivalent to the impedance device or impedance circuit to the preset impedance value, the size of the equivalent acoustic impedance of the acoustic-electric transducer device can be adjusted. The adjustment method is simple and easy to operate. When the equivalent acoustic impedance of the acoustic-electric transducer device is adjusted to match the preset equivalent acoustic impedance of the noise in the first cavity 7 within a preset frequency band, the noise in the first cavity 7 can be absorbed to achieve the noise reduction effect.

[0033] In some embodiments, such as Figures 1 to 4 As shown, the acoustic-electric transducer device is the first moving coil loudspeaker 52. Taking the first moving coil loudspeaker 52 as the acoustic-electric transducer device, the first moving coil loudspeaker 52 absorbs the noise in the first cavity 7 and converts it into electrical energy to dissipate, so as to achieve the noise reduction effect of the noise-canceling earphone. Based on the relatively low production cost of the first moving coil loudspeaker 52, the production cost of the noise-canceling earphone can be reduced as a whole.

[0034] In some embodiments, the equivalent circuit diagram of the first moving coil loudspeaker 52 connected with an impedance device or impedance circuit is as shown in Figure 3 As shown, where Z m is the equivalent mechanical impedance of the first moving coil loudspeaker 52, S d is the effective radiation area of the diaphragm of the first moving coil loudspeaker 52, Bl is the electro-mechanical coupling coefficient of the first moving coil loudspeaker 52, Z e is the impedance of the noise reduction module. Since the first moving coil loudspeaker 52 itself has impedance, when the acoustic impedance control unit is an impedance device, Z e is the impedance of the first moving coil loudspeaker 52 and the impedance device. When the acoustic impedance control unit is an impedance circuit, Z e is the impedance of the first moving coil loudspeaker 52 and the impedance circuit, v is the vibration velocity of the diaphragm of the first moving coil loudspeaker, Z ab is the acoustic impedance on the back of the diaphragm of the first moving coil loudspeaker 52, U e is the driving voltage of the first moving coil loudspeaker 52, p f and p b are the sound pressures on the front and back of the first moving coil loudspeaker 52 respectively. Since the structure and principle of the first moving coil loudspeaker 52 are well known to those skilled in the art, they will not be elaborated here. In this embodiment, the equivalent acoustic impedance Z sp1Determined by the following formula:

[0035]

[0036] If the driving voltage U applied to the first moving coil loudspeaker 52 e is equal to 0, the equivalent acoustic impedance Z on the diaphragm surface of the first moving coil loudspeaker 52 sp1 is:

[0037]

[0038] When determining the magnitude of the preset equivalent acoustic impedance according to the frequency of the noise in the relevant frequency band in the first cavity 7, and then determining the preset impedance value, by adjusting the impedance Z e of the first moving coil loudspeaker 52 and the impedance device or impedance circuit connected to the first moving coil loudspeaker 52 to be the preset impedance value, the equivalent acoustic impedance Z sp1 on the diaphragm surface of the first moving coil loudspeaker 52 can be adjusted to be the preset equivalent acoustic impedance, so that the noise in the relevant frequency band located in the first cavity 7 is converted into electrical energy by the first moving coil loudspeaker 52 for consumption, thereby achieving the purpose of reducing the noise in the first cavity 7 and realizing the effect of passive noise reduction. In particular, when using an active circuit to form a non-Foster circuit or device, for example, the non-Foster device is a current inverse load converter (INC) or a voltage inverse load converter (VNC), since the non-Foster circuit or device can be equivalent to a negative impedance, the frequency width of the noise that can be adjusted can be further expanded.

[0039] In this embodiment, as Figure 1 , Figure 4 and Figure 5 shown, the housing includes a first housing 1 and a cover 2, and the noise-canceling earphone 100 further includes a sound generating part 3 and a sound output part 4. Among them, the first housing 1 is a cavity structure with an opening; the cover 2 is installed at the opening on the first housing 1 to form a second cavity 6; the sound generating part 3 is installed in the second cavity 6, and the sound generating part 3 is used for sound reproduction or active noise reduction; the sound output part 4 is installed on the side of the cover 2 away from the first housing 1, and the sound output part 4 cooperates with the cover 2 to form a first cavity 7 for sound output; the acoustic-electric transducer is installed on the cover 2, and the acoustic impedance control unit 51 is connected to the acoustic-electric transducer so that the equivalent acoustic impedance of the acoustic-electric transducer is the preset equivalent acoustic impedance, thereby reducing the noise level in the first cavity 7, where the preset equivalent acoustic impedance is the magnitude of the equivalent acoustic impedance when the noise in the relevant frequency band absorbed by the acoustic-electric transducer is completely consumed, for example, the preset equivalent acoustic impedance is zero.

[0040] In some embodiments, the noise-canceling headphone 100 can be a head-mounted headphone or an in-ear headphone. In this embodiment, the noise-canceling headphone 100 is a head-mounted headphone, and the sound generating part 3 is a second moving coil speaker. The coil of the second moving coil speaker drives the diaphragm to generate sound under the drive of the signal current to perform sound reproduction or achieve active noise cancellation. Since the technology of achieving sound reproduction or active noise cancellation through a moving coil speaker is a commonly used technology in the art, its specific structure and principle are well-known to those skilled in the art and will not be elaborated here. The sound output part 4 is an ear tip, and the ear tip is installed on the cover body 2 through a buckle. When the user wears the noise-canceling headphone 100, the user's ear 9 is close to the ear tip, and the ear tip and the cover body 2 form a first cavity 7. Since external noise will reach the inside of the first cavity 7 through various acoustic paths, the noise mainly perceived by the user's ear 9 is the noise inside the first cavity 7. The electroacoustic transducer adjusts the equivalent acoustic impedance of the electroacoustic transducer to a preset equivalent acoustic impedance through the connected acoustic impedance control unit 51, thereby reducing the noise level inside the first cavity 7.

[0041] In some embodiments, such as Figure 1 , Figure 4 and Figure 5 shown, the cover body 2 is provided with a mounting bracket 21. The mounting bracket 21 and the cover body 2 are of an integral structure. The mounting bracket 21 is arranged on the side facing the first housing 1. The end of the second moving coil speaker is installed on the mounting bracket 21, for example, fixed and installed by means of glue bonding. Based on the function of the mounting bracket 21, a gap is formed between the second moving coil speaker and the cover body 2. Based on the design of this structure, the second moving coil speaker is arranged in the second cavity 6 formed by the first housing 1 and the cover body 2, improving the safety of the second moving coil speaker and making the side of the cover body 2 where the sound output part 4 is provided flat, enhancing the aesthetic appearance of the device.

[0042] In some embodiments, such as Figure 1 , Figure 4 and Figure 5 shown, the noise-canceling headphone 100 is provided with a first opening 11 and a second opening 22. The first opening 11 is arranged on the first housing 1, and the second opening 22 is arranged on the cover body 2. The first opening 11 and the second opening 22 facilitate the inflow and outflow of air in the second cavity 6, balancing the internal pressure of the noise-canceling headphone 100, so that the built-in second moving coil speaker vibrates more smoothly.

[0043] In one embodiment, such as Figure 1As shown, the first moving coil speaker 52 is installed on the cover body 2 and is located at a position corresponding to the second moving coil speaker. The second opening 22 is located at the end of the first moving coil speaker 52 and is provided on the cover body 2 clamped between the mounting brackets 21. Since there is a gap between the second moving coil speaker and the cover body 2, and there is also a gap between the second moving coil speaker and the first moving coil speaker 52, the second opening 22 cooperates with the first opening to balance the internal pressure of the noise-canceling earphone 100, and at the same time, it is convenient for the sound of the second moving coil speaker to propagate into the gap between the second moving coil speaker and the first moving coil speaker 52. A third opening 23 is provided on the cover body 2 corresponding to the first moving coil speaker 52, and the end of the first moving coil speaker 52 is installed on the cover body 2 at the edge of the third opening 23. For example, it can be fixedly installed by means of glue bonding. The third opening 23 serves as the sound inlet hole of the first moving coil speaker 52 so that noise can propagate from the third opening 23 to the diaphragm of the first moving coil speaker 52. Based on the design of this structure, the first moving coil speaker 52 is installed on the cover body 2 close to the first cavity 7, which is convenient for absorbing the noise in the first cavity 7 and improving the noise reduction effect.

[0044] In another embodiment, as Figure 4 shown, the noise-canceling earphone 100 further includes a second housing 8. The second housing 8 is provided on one side of the first housing 1 and is installed on the cover body 2. A third cavity 10 is formed between the second housing 8 and the cover body 2. The first moving coil speaker 52 is located at a position corresponding to the third cavity 10 and is installed on the cover body 2. A third opening 23 is provided on the cover body 2 corresponding to the first moving coil speaker 52. The third opening 23 serves as a sound inlet hole to absorb noise to the diaphragm of the first moving coil speaker 52. Based on the design of this structure, the third cavity 10 serves as the rear cavity of the first moving coil speaker 52 itself. By adjusting the volume of the rear cavity of the first moving coil speaker 52 itself, the flexibility of adjusting the noise reduction parameters of the first moving coil speaker 52 is further increased.

[0045] In yet another embodiment, as Figures 5 to 7As shown, the acoustic-electric transducer device is a piezoelectric device 53. The piezoelectric device 53 is disposed at a position corresponding to the second moving coil speaker and mounted on the cover 2. The second opening 22 is provided on the cover 2 and located at the end of the piezoelectric device 53. The piezoelectric device 53 includes a substrate 54 and a piezoelectric material 55 attached to the substrate 54. In this embodiment, the piezoelectric material 55 is a piezoelectric ceramic. Since the piezoelectric ceramic has a high electromechanical coupling coefficient and its manufacturing process is simple, the production cost can be reduced. The piezoelectric material 55 can also be a piezoelectric thin film. Based on the characteristics of good formability and flexibility of the piezoelectric thin film and the simple processing technology, the production cost can also be reduced. In this embodiment, both the piezoelectric ceramic and the piezoelectric thin film are in a sheet structure, which can further reduce the size of the noise-canceling earphone 100 and improve the compactness of the structure. The positive and negative electrodes of the piezoelectric material 55 are connected to the acoustic impedance control unit 51, and the acoustic impedance control unit 51 is used to adjust the magnitude of the equivalent acoustic impedance of the piezoelectric device 53. Since the piezoelectric material 55 in the piezoelectric device 53 generates a voltage U due to the existence of deformation e is:

[0046]

[0047] where d 33 is the piezoelectric constant of the piezoelectric material 55, and x is the displacement of the substrate 54 generating deformation.

[0048] The equivalent capacitance C of the piezoelectric material 55 a is:

[0049]

[0050] where ε0 is the vacuum permittivity, ε r is the permittivity of the piezoelectric material 55, A is the area of the piezoelectric material 55, d is the thickness of the piezoelectric material 55, and the reaction force F e received by the piezoelectric material 55 is:

[0051]

[0052] When the sound pressure of the noise acts on both sides of the substrate 54 of the piezoelectric device 53, the sound pressure and the reaction force F e of the piezoelectric material 55 together constitute the acting force F t received by the substrate 54, then the acting force F t received by the substrate 54 is:

[0053]

[0054] where Z m is the equivalent mechanical impedance of the piezoelectric device 53, The derivative of the displacement of the substrate 54 with respect to time. The mechanical effect converted from the sound pressure received by the piezoelectric device 53, and then based on the direct piezoelectric effect of the piezoelectric device 53, the mechanical effect of the noise absorbed by the piezoelectric device 53 is converted into an electrical effect.

[0055] In some embodiments, such as the present embodiment, the equivalent acoustic impedance Z of the piezoelectric device 53 connected to an impedance device or an impedance circuit in is determined by the following formula:

[0056] Z in =Z m *T m +Z e *T e

[0057] wherein, Z m is the equivalent mechanical impedance of the piezoelectric device 53, Z e is the impedance of the impedance device or impedance circuit connected to the piezoelectric device 53. The impedance Z e can be a negative impedance to further expand the frequency width of the noise that can be adjusted. T m is the first transduction factor, T e is the second transduction factor. When adjusting the impedance Z e of the impedance device or impedance circuit connected to the piezoelectric device 53 to a preset impedance value, the surface of the piezoelectric device 53 can have a specific equivalent acoustic impedance for the noise in a preset frequency band, and then the noise in the first cavity 7 is consumed to achieve the noise reduction effect of the noise-canceling headphone 100 for the noise in the preset frequency band in the first cavity 7.

[0058] The noise-canceling headphone 100 provided by the present invention is provided with a noise reduction module in a first cavity formed between the housing and the ear. The noise reduction module includes an acoustic-electric transducer device and an acoustic impedance control unit connected to the acoustic-electric transducer device. By controlling the equivalent acoustic impedance of the acoustic-electric transducer device to a preset equivalent acoustic impedance, for example, when the preset equivalent acoustic impedance tends to zero, the acoustic-electric transducer device can absorb the noise in a preset frequency band in the first cavity at the ear, so as to achieve the noise reduction function of the noise-canceling headphone without adding an additional microphone to collect external noise or noise in the first cavity, and improve the user experience.

[0059] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A noise-canceling headphone, characterized in that, Comprising: A housing and a noise reduction module, wherein, The housing is of a cavity structure, and a first cavity that is connected is formed between the housing and the ear; The noise reduction module is located in the first cavity. The noise reduction module includes an acoustic-electric transducer device and an acoustic impedance control unit. The acoustic impedance control unit is connected to the acoustic-electric transducer device so that the equivalent acoustic impedance of the acoustic-electric transducer device is a preset equivalent acoustic impedance; The acoustic impedance control unit is an impedance device or an impedance circuit with a preset impedance value. The acoustic impedance control unit is connected to the positive and negative electrodes of the acoustic-electric transducer device so that the equivalent acoustic impedance of the acoustic-electric transducer device is a preset equivalent acoustic impedance; The acoustic-electric transducer device is a first moving coil loudspeaker or a piezoelectric device. The piezoelectric material in the piezoelectric device is piezoelectric ceramic or piezoelectric film; Wherein, by adjusting the magnitude of the impedance of the first moving coil loudspeaker and the impedance device or impedance circuit connected to the first moving coil loudspeaker to be the preset impedance value, the magnitude of the equivalent acoustic impedance on the diaphragm surface of the first moving coil loudspeaker is adjusted to be the preset equivalent acoustic impedance.

2. The noise-canceling earphone according to claim 1, wherein: The equivalent acoustic impedance Z on the diaphragm surface of the first moving coil loudspeaker sp1 is determined by the following formula: Among them, Z m is the equivalent impedance of the first moving coil loudspeaker, S d is the effective radiation area of the diaphragm of the first moving coil loudspeaker, Bl is the power conversion coefficient of the first moving coil loudspeaker, Z e is the impedance of the noise reduction module, v is the vibration velocity of the diaphragm of the first moving coil loudspeaker, Z ab is the acoustic impedance on the back of the diaphragm of the first moving coil loudspeaker, U e is the driving voltage of the first moving coil loudspeaker.

3. The noise-canceling earphone according to claim 1, wherein The equivalent acoustic impedance Z of the piezoelectric device in is determined by the following formula: Z in = Z m * T m + Z e * T e where Z m is the equivalent mechanical impedance of the piezoelectric device, and Z e is the impedance of the impedance device or the impedance circuit connected to the piezoelectric device, T m is the first transduction factor, and T e is the second transduction factor.

4. The noise-canceling earphone according to claim 1, wherein The housing includes a cover body for installing the acoustic-electric transducer device. The noise reduction earphone further includes a sound output part. The sound output part is installed on the cover body. The sound output part and the cover body cooperate to form the first cavity.

5. The noise reduction earphone according to claim 4, wherein, The housing further includes a first housing. The first housing is of a cavity structure with an opening. The cover body is installed at the opening on the first housing to form a second cavity; The noise reduction earphone further includes a sound generating part. The sound generating part is installed on the cover body and is located in the second cavity. The sound generating part is used for sound reproduction or active noise reduction.

6. The noise-canceling earphone according to claim 5, wherein: The first moving coil loudspeaker is installed on the cover body and is arranged at a position corresponding to the sound generating part.

7. The noise-canceling earphone according to claim 5, wherein: The noise reduction earphone further has a second housing. The second housing is arranged on one side of the first housing and is installed on the cover body. A third cavity is formed between the second housing and the cover body. The first moving coil loudspeaker is arranged at a position corresponding to the third cavity and is installed on the cover body.

8. The noise-canceling earphone according to claim 5, wherein, The piezoelectric device is installed on the cover body and is arranged at a position corresponding to the sound generating part.

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