Active noise reduction method, device and headphone calibration method

Abstract

The present invention provides an active noise reduction method, device and headphone calibration method, the method comprising: superimposing and mixing the signal to be played by the loudspeaker with the signal output by the feedforward filter and then sending it to the crosstalk cancellation filter; superimposing and mixing the signal output by the crosstalk cancellation filter with the signal output by the feedforward path and then sending it to the feedforward filter; the feedforward filter processes the mixed signal to obtain a signal with a phase opposite to the ambient noise in the ear, plays it through the loudspeaker, and cancels the noise in the human ear canal. Through the crosstalk cancellation filter and the difference signal analysis and processing steps, it can be ensured that the signal transmitted to the feedforward filter in the feedforward path is pure, thereby solving the crosstalk problem from the loudspeaker to the feedforward microphone and the feedforward noise reduction path caused by poor isolation or severe sound leakage.

Description

Technical Field

[0001] The technical field of the present invention belongs to the field of noise reduction, and is applied to headphones with active noise reduction function, and in particular relates to an active noise reduction method, device and headphone calibration method. Background Art

[0002] In the field of active noise reduction headphones, headphones are usually equipped with two noise reduction channels: feedforward and feedback. The feedforward noise reduction channel includes components such as a feedforward microphone, an analog-to-digital converter (ADC), a feedforward filter, and an adaptive algorithm. Its working principle is to play a reverse sound signal through a speaker (SPK) to achieve noise cancellation.

[0003] However, in actual applications, in order to ensure the noise reduction effect and avoid the howling problem, the feedforward microphone needs to be isolated from the speaker to prevent the feedforward microphone from receiving crosstalk from the speaker. However, during the production process, due to differences in operations and processes, some products may have poor isolation between the feedforward microphone and the speaker, resulting in crosstalk, which will not only reduce the production yield, but may also affect the noise reduction effect and user experience, and even pose a risk of hearing damage. In addition, after long-term use of the headset, the sealing state of the microphone cavity and the speaker cavity may change, which may also cause howling and poor noise reduction effects. Summary of the invention

[0004] The object of the present invention is to provide an active noise reduction method, device and headphone calibration method to solve the crosstalk problem from the speaker to the feedforward microphone and the feedforward noise reduction path caused by poor isolation or severe sound leakage.

[0005] According to a first aspect of the present invention, an active noise reduction method is provided, the steps of the active noise reduction method comprising:

[0006] The signal to be played by the loudspeaker is superimposed and mixed with the signal output by the feedforward filter and then sent to the crosstalk elimination filter;

[0007] The signal output by the crosstalk cancellation filter is superimposed and mixed with the signal output by the feedforward path, and then sent to the feedforward filter;

[0008] The feedforward filter processes the mixed signal to obtain a signal with a phase opposite to the ambient noise in the ear, and plays it through a speaker to cancel out the noise in the human ear canal.

[0009] Optionally, in the active noise reduction method, the signal output by the crosstalk cancellation filter is a signal with a phase opposite to that of the leakage signal;

[0010] The signal output by the feedforward path is an environmental noise signal containing a leakage signal;

[0011] After the signal output by the crosstalk cancellation filter is superimposed and mixed with the signal output by the feedforward path, the mixed signal obtained is a pure external environmental noise signal without leakage signal.

[0012] Optionally, in the active noise reduction method, after superimposing and mixing the signal to be played by the loudspeaker with the signal output by the feedforward filter, the mixed signal is sent to the loudspeaker;

[0013] And the mixed signal sent to the crosstalk cancellation filter is consistent with the mixed signal sent to the speaker.

[0014] According to a second aspect of the present invention, an active noise reduction device is provided, the active noise reduction device comprising:

[0015] Signal acquisition module, used to collect pure environmental noise outside the ear;

[0016] A signal mixing unit, used for superimposing and mixing different signals;

[0017] A crosstalk elimination filter, used for receiving the output from the signal mixing unit, and after processing, outputting a signal with a phase opposite to the leakage signal in the speaker cavity;

[0018] A feedforward filter, used for receiving the pure ambient noise outside the ear collected by the signal collection module, and processing it to generate a signal with a phase opposite to that of the noise inside the ear;

[0019] The loudspeaker is used to play the mixed signal processed by the signal mixing module to cancel out noise in the human ear canal.

[0020] According to a third aspect of the present invention, there is provided a headphone calibration method using the active noise reduction method described in the first aspect, wherein a test device initially sends an excitation signal, collects an audio signal Y1 obtained by superimposing and mixing the signal played by the speaker and the signal output by the feedforward filter, and an audio signal Y2 output by the feedforward path;

[0021] The leakage transfer function T1 is calculated using Y1 and Y2 in the test equipment, and whether the earphone needs calibration is determined based on the leakage transfer function T1.

[0022] Optionally, if the value of the leakage transfer function T1 exceeds a preset range, the earphone needs to be calibrated. In this case, the calibration parameters of the crosstalk cancellation filter are calculated using the leakage transfer function T1 and written into the firmware of the earphone.

[0023] Optionally, in the headphone calibration method, the test device further includes sending an excitation signal again, collecting an audio signal Y3 obtained by superimposing and mixing the signal played by the speaker at this time with the signal output by the feedforward filter, and an audio signal Y4 obtained by superimposing and mixing the signal output by the crosstalk cancellation filter with the signal output by the feedforward path;

[0024] The leakage transfer function T2 is calculated using Y3 and Y4 in the test equipment, and whether the calibration result is correct is determined based on the leakage transfer function T2.

[0025] Optionally, if the value of the leakage transfer function T2 is within a preset range, the calibration is successful; if the value of the leakage transfer function T2 exceeds the preset range, the calibration is restarted.

[0026] Optionally, in the headphone calibration method, before the test device sends the excitation signal for the first time, the method further includes setting the headphone to enter a calibration mode and muting all audio outputs except for a test signal playback path.

[0027] Optionally, in the headphone calibration method, the leakage transfer function T1 is a transfer function that has not been filtered by the crosstalk cancellation filter, and is used to determine whether the headphone needs to be calibrated, and to calculate the calibration parameters of the crosstalk cancellation filter according to the leakage transfer function T1 to calibrate the headphone;

[0028] The leakage transfer function T2 is a transfer function after being filtered by the crosstalk elimination filter, and is used to determine whether the calibration result meets the requirements and is correct.

[0029] Compared with the prior art, the present invention has at least the following technical effects:

[0030] By adding a crosstalk elimination filter and a difference signal analysis path in the feedforward noise reduction path, the signal that needs to be played by the speaker is superimposed and mixed with the signal output by the feedforward filter, and then sent to the crosstalk elimination filter for processing to obtain a signal that is opposite to the leakage signal in the speaker cavity. Then, the reverse signal is superimposed and mixed with the ambient noise signal with the leakage signal in the feedforward path to obtain a pure ambient noise signal outside the ear that does not contain a leakage signal. Through the crosstalk elimination filter and the difference signal analysis processing steps, the crosstalk from the speaker to the feedforward microphone and the feedforward noise reduction path caused by poor isolation or severe sound leakage can be eliminated, ensuring that the signal sent to the feedforward filter in the feedforward path is pure and does not contain external ambient noise signals interfered by the sound emitted by the speaker.

[0031] Furthermore, in the production line test calibration, by testing the leakage transfer function T1 from the speaker to the feedforward filter, the leakage signal between the speaker and the feedforward filter can be accurately measured and calculated. Based on the measurement results of the leakage transfer function T1, the parameters of the crosstalk elimination filter can be calculated and optimized to ensure that the crosstalk elimination filter can accurately generate a reverse signal with a phase opposite to the leakage signal, thereby improving the noise reduction effect. Through the leakage transfer function T2, the accuracy of the calibration results can be verified to ensure that the performance of the noise reduction system achieves the expected effect. This headphone calibration method can ensure the performance of the noise reduction system, improve sound quality, enhance user experience, and reduce long-term maintenance costs, while improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a simplified schematic diagram of the transmission of acoustic and electrical signals of a conventional earphone in one embodiment of the present invention;

[0033] Figure 2 is a flow chart of an active noise reduction method in one embodiment of the present invention;

[0034] Figure 3 A partial schematic diagram of a feed-forward path using an active noise reduction method in one embodiment of the present invention;

[0035] Figure 4 FIG. 4 is a flow chart of a headphone calibration method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following will be described in more detail with reference to a schematic diagram of an active noise reduction method, device and headphone calibration method of the present invention, wherein preferred embodiments of the present invention are shown, and it should be understood that those skilled in the art may modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art, and not as a limitation of the present invention.

[0037] For the sake of clarity, not all features of the actual embodiments are described. In the following description, well-known functions and structures are not described in detail because they would clutter the invention with unnecessary detail. It should be recognized that in the development of any actual embodiment, a large number of implementation details must be made to achieve the developer's specific goals, such as changing from one embodiment to another according to the limitations of the relevant system or the relevant business. In addition, it should be recognized that such development work may be complex and time-consuming, but it is just a routine task for those skilled in the art.

[0038] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are in very simplified form and are not in exact proportions, and are only used to facilitate and clearly assist in illustrating the purpose of the embodiments of the present invention.

[0039] Embodiment 1

[0040] like Figure 1 As shown, only the part involving the feedforward path signal is shown. Usually, when the earphones are worn, the earphones in good condition only contain the audio flow direction pointed by the solid arrow in the figure; Figure 1 The direction of the dotted arrow ① indicates the leakage path between the speaker cavity of the headphone and the feedforward microphone, which is usually caused by a sealing problem between the back cavity of the headphone speaker and the microphone cavity.

[0041] Based on this, Figure 2 As shown, in one embodiment of the present invention, an active noise reduction method is proposed, comprising the following steps:

[0042] Step S1, superimposing and mixing the signal to be played by the loudspeaker and the signal output by the feedforward filter and sending them to the crosstalk cancellation filter;

[0043] Step S2, superimposing and mixing the signal output by the crosstalk cancellation filter and the signal output by the feedforward path, and then sending them to the feedforward filter;

[0044] Step S3, the feedforward filter processes the mixed signal to obtain a signal with a phase opposite to the ambient noise in the ear, plays it through a speaker, and cancels out the noise in the human ear canal.

[0045] It should be noted that Figure 3 The position marked by the dotted line box is the crosstalk elimination filter and the difference signal analysis path added in the feedforward noise reduction path. By adding the crosstalk elimination filter and the difference signal analysis processing steps, it can ensure that the signal sent to the feedforward filter in the feedforward path is pure, thereby solving the crosstalk problem from the speaker to the feedforward microphone and the feedforward noise reduction path caused by poor isolation or severe sound leakage.

[0046] Specifically, for the above step S1, the signal that needs to be played by the speaker is superimposed and mixed with the signal output by the feedforward filter, and then converted by a digital-to-analog converter and sent to the speaker. At the same time, the superimposed and mixed signal is also sent to the crosstalk elimination filter. The process of sending the superimposed and mixed signal to the crosstalk elimination filter is recorded as node 1. The signal transmitted by node 1 is a signal consistent with all signals to be passed through the speaker, including an audio output signal and a noise reduction signal of the feedforward path. Among them, the signal that needs to be played by the speaker is an audio output signal, including a feedback signal in the feedback filter in the feedback noise reduction path, a downlink call, a music ringtone signal, and other audio downlink signals. The audio downlink signal includes an audio playback signal, a communication audio signal, a system audio signal, and an auxiliary audio signal. The signal output by the feedforward filter is a noise reduction signal of the feedforward path, including an environmental noise signal and an inverted signal (anti-noise signal). The crosstalk elimination filter processes the superimposed and mixed signal input, and obtains a reverse signal to the leakage signal in the speaker cavity through processing. The reverse signal is a signal with an opposite phase to the leakage signal in the speaker cavity.

[0047] For step S2, the signal output by the crosstalk elimination filter is superimposed and mixed with the signal output by the feedforward path, and then sent to the feedforward filter. It should be noted that the signal output by the feedforward path needs to be converted into a digital signal by an analog-to-digital converter. Specifically, the process of the output signal of the feedforward path is recorded as node 2. At this time, the signal output by node 2 is an environmental noise signal containing a leakage signal. The reverse signal of the leakage signal obtained in step S1 is superimposed and mixed with the environmental noise signal with a leakage signal output by node 1, and then sent to the feedforward filter. The process is recorded as node 3. At this time, a pure external environmental noise signal without a leakage signal can be obtained through node 3 to eliminate the influence of the leakage signal.

[0048] For step S3, the feedforward filter processes the mixed signal (pure ambient noise outside the ear) to obtain a signal with a phase opposite to the ambient noise outside the ear, plays it through a speaker (SPK), and cancels out noise in the human ear canal.

[0049] Specifically, in the process of processing the pure ambient noise outside the ear to achieve noise cancellation, the feedforward filter firstly sends the pure ambient noise outside the ear obtained through node 3 to the feedforward filter for processing. The feedforward filter is a filter based on finite impulse response (FIR), which can effectively compensate for the linear damage suffered by the signal during transmission. In this process, the feedforward filter analyzes the pure ambient noise signal outside the ear and generates a signal with the same amplitude but opposite phase as the pure ambient noise signal outside the ear. Therefore, the feedforward filter generates a signal reverse to the ambient noise inside the ear. The purpose is to cancel the ambient noise signal inside the ear. The generated reverse signal is played through a speaker. This speaker can be a speaker in an earphone or earplug, which plays the reverse signal into the human ear canal. When the reverse signal meets the ambient noise inside the ear in the human ear canal, the two will interfere, thereby achieving noise cancellation. If the amplitude and phase of the reverse signal are properly controlled, they can effectively cancel each other out and reduce the noise received by the human ear. Through the above steps, the feedforward filter can effectively reduce the noise received by the human ear and improve the auditory comfort and sound quality clarity.

[0050] In summary, by eliminating the leakage signal in the speaker cavity, the crosstalk cancellation filter can not only significantly improve the effect of the active noise reduction system, but also reduce the distortion of the sound quality and provide clearer and purer audio output. It can effectively reduce or eliminate the noise in the ear, improve the clarity and quality of audio playback, thereby achieving effective noise reduction and better sound quality in a noisy environment, and enhancing the user's auditory experience.

[0051] Embodiment 2

[0052] In this embodiment, an active noise reduction device is provided, the device comprising:

[0053] The signal acquisition module is used to collect pure environmental noise outside the ear.

[0054] The signal mixing unit is used to superimpose and mix different signals. For example, the signal to be played by the loudspeaker is superimposed and mixed with the signal output by the feedforward filter, and the signal output by the crosstalk elimination filter is superimposed and mixed with the signal output by the feedforward path.

[0055] The crosstalk elimination filter is used to eliminate the crosstalk (leakage signal) generated by the loudspeaker playing signal. The signal that needs to be played by the loudspeaker is superimposed and mixed with the signal output by the feedforward filter using the signal mixing unit. The crosstalk elimination filter receives the output from the signal mixing unit and, after processing, outputs a signal with a phase opposite to the leakage signal in the loudspeaker cavity.

[0056] The feedforward filter is used to receive the pure ambient noise outside the ear collected by the signal collection module, and process it to generate a signal with a phase opposite to that of the noise inside the ear. The output signal of the crosstalk cancellation filter is superimposed and mixed with the signal output by the feedforward path by using the signal mixing unit. The feedforward filter receives the output from the signal mixing unit, and processes the mixed signal in the feedforward filter, thereby obtaining a signal with a phase opposite to that of the ambient noise inside the ear.

[0057] The loudspeaker is used to play the mixed signal processed by the signal mixing module to cancel out noise in the human ear canal.

[0058] In summary, the device can achieve the function of active noise reduction through the coordinated work of the above modules, that is, by generating a signal with a phase opposite to the ambient noise, the noise is offset and the auditory experience is improved.

[0059] Embodiment 3

[0060] like Figure 4 As shown, this embodiment proposes a headphone calibration method using the active noise reduction method described in Example 1, the test device initially sends an excitation signal, collects an audio signal Y1 obtained by superimposing and mixing the signal played by the speaker and the signal output by the feedforward filter, and an audio signal Y2 output by the feedforward path, and saves Y1 and Y2 to the test device; uses Y1 and Y2 in the test device to calculate the leakage transfer function T1, and determines whether the headphone needs to be calibrated based on the leakage transfer function T1.

[0061] Furthermore, if the value of the leakage transfer function T1 exceeds a preset range, the earphone needs to be calibrated. At this time, the calibration parameters of the crosstalk cancellation filter are calculated using the leakage transfer function T1 and written into the firmware of the earphone.

[0062] Specifically, the step of judging whether calibration is required based on the leaked transfer function T1 includes: setting the headset to enter calibration mode and muting all audio outputs except the test signal playback path; after the test device sends the excitation signal for the first time, the headset collects the audio signal Y1 of node 1 and the audio signal Y2 of node 2, and saves Y1 and Y2 to the test device. The test device is used to calculate the leaked transfer function T1=Y2 / Y1, and the transfer function T1 can help determine whether the headset needs calibration.

[0063] Furthermore, if the value of the leakage transfer function T1 exceeds a preset range, the headset needs to be calibrated. At this time, the calibration parameters of the crosstalk elimination filter are calculated using the leakage transfer function T1 and written into the firmware of the headset. Specifically, if calibration is required, the test equipment uses the transfer function T1 to perform a crosstalk elimination filter fitting calculation; after the calculation is completed, the parameters of the crosstalk elimination filter are obtained, and the parameters of the crosstalk elimination filter will be used to eliminate crosstalk, and then the parameters of the crosstalk elimination filter are burned into the firmware of the headset.

[0064] It should be noted that after using the headphones for a long time, users can calibrate and adjust them through the mobile phone APP. In a relatively quiet environment, users can test by wearing them normally or manually blocking the sound outlet to ensure that there is no external interference during the test. In order to ensure the accuracy of the test and avoid other sounds interfering with the test signal, in calibration mode, all other audio outputs will be muted except for the signal used for testing.

[0065] In addition, in the headphone calibration method, the audio signal Y1 obtained by the node 1 is an audio signal that is not filtered by the crosstalk elimination filter after the signal to be played by the speaker is superimposed and mixed with the signal output by the feedforward filter, that is, the sound signal normally played by the headphone, such as the signal transmitted by node 1 in the first embodiment includes the audio output signal and the noise reduction signal of the feedforward path. The audio signal Y2 of the node 2 is the audio signal output by the feedforward path after conversion by the analog-to-digital converter, that is, the ambient noise signal with a leakage signal.

[0066] Furthermore, if it is determined that the headphones need to be calibrated, the test device sends an excitation signal again, collects the audio signal Y3 obtained by superimposing and mixing the signal played by the speaker at this time with the signal output by the feedforward filter, and collects the audio signal Y4 obtained by superimposing and mixing the signal output by the crosstalk elimination filter with the signal output by the feedforward path, saves Y3 and Y4 in the test device, and uses Y3 and Y4 in the test device to calculate the leakage transfer function T2, wherein the leakage transfer function T2 = Y4 / Y3, and then determines whether the calibration result is correct based on the leakage transfer function T2.

[0067] Furthermore, if the value of the leakage transfer function T2 is within a preset range, the calibration is successful; if the value of the leakage transfer function T2 exceeds the preset range, the calibration is restarted until the crosstalk problem of the earphone is successfully solved.

[0068] It should be noted that, in the headphone calibration method, the audio signal Y3 of node 1 is an audio signal obtained by superimposing and mixing the signal to be played by the speaker and the signal output by the feedforward filter after being filtered by the crosstalk elimination filter; the audio signal Y4 of node 3 is an audio signal obtained by superimposing and mixing the signal output by the crosstalk elimination filter and the signal output by the feedforward path after being filtered by the crosstalk elimination filter.

[0069] In addition, in the headphone calibration method, the leakage transfer function T1 is a transfer function that has not been filtered by the crosstalk elimination filter, and is used to determine whether the headphone needs to be calibrated, and the calibration parameters of the crosstalk elimination filter are calculated according to the leakage transfer function T1 to calibrate the headphone. The leakage transfer function T2 is a transfer function that has been filtered by the crosstalk elimination filter, and is used to determine whether the calibration result meets the requirements and is correct. Through the above calibration method, it can be ensured that each headphone is accurately calibrated before leaving the factory to provide the best sound quality and minimum crosstalk, thereby improving product quality and enhancing user experience.

[0070] In summary, by adding a crosstalk elimination filter and a difference signal analysis path in the feedforward noise reduction path, the signal that needs to be played by the speaker is superimposed and mixed with the signal output by the feedforward filter, and then sent to the crosstalk elimination filter for processing to obtain a signal that is opposite to the leakage signal in the speaker cavity. Then, the reverse signal is superimposed and mixed with the ambient noise signal with the leakage signal in the feedforward path to obtain a pure ambient noise signal outside the ear that does not contain a leakage signal. Through the crosstalk elimination filter and the difference signal analysis processing steps, the crosstalk from the speaker to the feedforward microphone and the feedforward noise reduction path caused by poor isolation or severe sound leakage can be eliminated, ensuring that the signal sent to the feedforward filter in the feedforward path is pure and does not contain external ambient noise signals interfered by the sound emitted by the speaker.

[0071] Furthermore, in the production line test calibration, by testing the leakage transfer function T1 from the speaker to the feedforward filter, the leakage signal between the speaker and the feedforward filter can be accurately measured and calculated. Based on the measurement results of the leakage transfer function T1, the parameters of the crosstalk elimination filter can be calculated and optimized to ensure that the crosstalk elimination filter can accurately generate a reverse signal with a phase opposite to the leakage signal, thereby improving the noise reduction effect. Through the leakage transfer function T2, the accuracy of the calibration results can be verified to ensure that the performance of the noise reduction system achieves the expected effect. This headphone calibration method can ensure the performance of the noise reduction system, improve sound quality, enhance user experience, and reduce long-term maintenance costs, while improving production efficiency.

[0072] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any technician in the relevant technical field, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, which does not depart from the content of the technical solution of the present invention and still falls within the protection scope of the present invention.

Claims

1. An active noise reduction method, characterized in that: include: The signal to be played by the loudspeaker is superimposed and mixed with the signal output by the feedforward filter and then sent to the crosstalk elimination filter; The signal output by the crosstalk cancellation filter is superimposed and mixed with the signal output by the feedforward path, and then sent to the feedforward filter; The feedforward filter processes the mixed signal to obtain a signal with a phase opposite to the ambient noise in the ear, and plays it through a speaker to cancel out the noise in the human ear canal.

2. The active noise reduction method according to claim 1, characterized in that: The signal output by the crosstalk cancellation filter is a signal with a phase opposite to that of the leakage signal; The signal output by the feedforward path is an environmental noise signal containing a leakage signal; After the signal output by the crosstalk cancellation filter is superimposed and mixed with the signal output by the feedforward path, the mixed signal obtained is a pure external environmental noise signal without leakage signal.

3. The active noise reduction method according to claim 1, characterized in that: After superimposing and mixing the signal to be played by the loudspeaker with the signal output by the feedforward filter, the mixed signal is sent to the loudspeaker; And the mixed signal sent to the crosstalk cancellation filter is consistent with the mixed signal sent to the speaker.

4. An active noise reduction device, characterized in that: The active noise reduction device comprises: Signal acquisition module, used to collect pure environmental noise outside the ear; A signal mixing unit, used for superimposing and mixing different signals; A crosstalk elimination filter, used for receiving the output from the signal mixing unit, and after processing, outputting a signal with a phase opposite to the leakage signal in the speaker cavity; A feedforward filter, used for receiving the pure ambient noise outside the ear collected by the signal collection module, and processing it to generate a signal with a phase opposite to that of the noise inside the ear; The loudspeaker is used to play the mixed signal processed by the signal mixing module to cancel out noise in the human ear canal.

5. A method for calibrating a headphone using the active noise reduction method according to any one of claims 1 to 3, characterized in that: The test device sends an excitation signal for the first time, collects an audio signal Y1 obtained by superimposing and mixing the signal played by the speaker and the signal output by the feedforward filter, and an audio signal Y2 output by the feedforward path; The leakage transfer function T1 is calculated using Y1 and Y2 in the test equipment, and whether the earphone needs calibration is determined based on the leakage transfer function T1.

6. The headphone calibration method according to claim 5, characterized in that: If the value of the leakage transfer function T1 exceeds a preset range, the earphone needs to be calibrated. At this time, the calibration parameters of the crosstalk cancellation filter are calculated using the leakage transfer function T1 and written into the firmware of the earphone.

7. The headphone calibration method according to claim 6, characterized in that: The test device also sends an excitation signal again, collects an audio signal Y3 obtained by superimposing and mixing the signal played by the speaker at this time with the signal output by the feedforward filter, and obtains an audio signal Y4 obtained by superimposing and mixing the signal output by the crosstalk elimination filter with the signal output by the feedforward path; The leakage transfer function T2 is calculated using Y3 and Y4 in the test equipment, and whether the calibration result is correct is determined based on the leakage transfer function T2.

8. The headphone calibration method according to claim 7, characterized in that: If the value of the leakage transfer function T2 is within the preset range, the calibration is successful; if the value of the leakage transfer function T2 is beyond the preset range, the calibration is restarted.

9. The headphone calibration method according to claim 5, characterized in that: Before the test device sends the excitation signal for the first time, the headset is also set to enter a calibration mode to mute all audio outputs except the test signal playing path.

10. The headphone calibration method according to claim 8, characterized in that: The leakage transfer function T1 is a transfer function that has not been filtered by the crosstalk cancellation filter, and is used to determine whether the earphone needs to be calibrated, and to calculate the calibration parameters of the crosstalk cancellation filter according to the leakage transfer function T1 to calibrate the earphone; The leakage transfer function T2 is a transfer function after being filtered by the crosstalk elimination filter, and is used to determine whether the calibration result meets the requirements and is correct.

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