Active noise reduction device

Abstract

The invention provides active noise reduction equipment, and belongs to the technical field of noise control. The active noise reduction device comprises a tympanic membrane monitoring module used for monitoring vibration characteristics of a tympanic membrane, a secondary source loudspeaker used for emitting noise reduction sound waves and a control module. The control module determines noise characteristics of the residual noise based on the vibration characteristics of the tympanic membrane, determines an updated feedback noise reduction strategy based on the noise characteristics of the residual noise, and is used for controlling the secondary source loudspeaker to continuously emit noise reduction sound waves based on the updated feedback noise reduction strategy. Due to the fact that the noise feature of the residual noise determined based on the vibration feature of the tympanic membrane directly represents the noise feature sensed by the user, the influence of the ear canal feature of the user on the residual noise does not need to be considered, and a better feedback noise reduction control effect can be guaranteed while the complexity of a noise reduction processing algorithm is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of noise control technology, and in particular to an active noise reduction device. BACKGROUND

[0002] Active noise reduction devices such as active noise reduction earphones, active noise reduction hearing protectors, etc. use an error microphone (i.e., a sound pickup) to collect residual noise (residual noise is noise after phase cancellation of noise waves and environmental noise), and update a noise reduction strategy according to characteristics of the residual noise. The error microphone is arranged on the body of the active noise reduction device. Due to the wearing manner and the structure of the device body, the error microphone can only be arranged at the entrance of the ear canal. Since the sound field at the entrance of the ear canal is not consistent with the sound field at the eardrum of the human ear, and the length and curvature characteristics of the ear canal of different users are different, the residual noise at the entrance of the ear canal cannot be used to estimate the residual noise at the eardrum of different users based on the same acoustic transfer function, which limits the noise reduction performance of the active noise reduction earphone.

[0003] To further improve the noise reduction performance of the active noise reduction earphone, a virtual microphone technology and a multi-error microphone technology are proposed in the related art. The virtual microphone technology assumes that a virtual error microphone is arranged at the eardrum. After obtaining the real residual noise collected by the real error microphone at the entrance of the ear canal, the estimated residual noise at the eardrum is obtained based on the real residual noise and the residual noise transfer function. The multi-error microphone technology arranges error microphones at different positions of the entrance of the ear canal, realizes multi-point sound field characteristic measurement through the multiple error microphones, and estimates the estimated residual noise at the eardrum by using a sound wave propagation model. The estimated residual noise at the eardrum obtained by the foregoing two technologies through the model estimation method may not correctly restore the residual noise at the eardrum. SUMMARY

[0004] The embodiments of the present disclosure provide an active noise reduction device. The active noise reduction device comprises a eardrum monitoring module for monitoring vibration characteristics of a eardrum, a secondary source loudspeaker for emitting noise reduction sound waves, and a control module. The control module determines noise characteristics of residual noise based on the vibration characteristics of the eardrum, determines an updated feedback noise reduction strategy based on the noise characteristics of the residual noise, and controls the secondary source loudspeaker to continue emitting the noise reduction sound waves based on the updated feedback noise reduction strategy.

[0005] Since the noise characteristics of the residual noise determined based on the vibration characteristics of the eardrum directly represent the noise characteristics perceived by the user, the influence of the ear canal characteristics of the user on the residual noise does not need to be considered, the complexity of the noise reduction processing algorithm is reduced, and better feedback noise reduction control effect can be ensured.

[0006] In some optional implementations, the active noise cancellation device further includes a reference microphone for monitoring the noise characteristics of ambient noise; the control module determines an updated feedback noise cancellation strategy based on the noise characteristics of residual noise and ambient noise. By using a reference microphone, determining the feedback noise cancellation strategy based on the ambient noise characteristics and residual noise characteristics monitored by the reference microphone allows the feedback control strategy to conform to the changing characteristics of ambient noise, thereby achieving better noise cancellation control.

[0007] In some optional implementations, the control module first calculates the filtered characteristics of the ambient noise based on the noise characteristics of the ambient noise and the path model of the secondary path; then, it determines the feedback strategy adjustment amount based on the filtered characteristics and the noise characteristics of the residual noise; finally, it determines an updated feedback noise reduction strategy based on the feedback strategy adjustment amount and the current feedback noise reduction strategy. Considering the impact of the secondary path path model on ambient noise when formulating the feedback control strategy allows the feedback noise reduction control strategy to better reflect changes in equipment characteristics and ambient noise.

[0008] In some optional implementations, the noise reduction control strategy also includes a pre-determined feedforward control strategy. The control module first calculates a feedback noise reduction signal based on the updated feedback noise reduction strategy and the noise characteristics of the residual noise, and then calculates a feedforward noise reduction signal based on the noise characteristics of the ambient noise and the feedforward control strategy. Subsequently, the control module generates a noise reduction signal based on the feedback noise reduction signal and the feedforward noise reduction signal, and controls the secondary source speaker to continue emitting noise reduction waves based on the noise reduction signal. Using both the feedforward noise reduction strategy and the feedback noise reduction strategy simultaneously can achieve a better final noise reduction effect and improve the user experience.

[0009] In some alternative implementations, the secondary source speaker is also used to play the target sound; the control module determines the noise characteristics of the residual noise based on the vibration characteristics of the tympanic membrane and the sound characteristics of the target sound.

[0010] In some optional implementations, the tympanic membrane monitoring module includes: a light emitter for emitting a monitoring laser to the tympanic membrane; a light receiver for receiving reflected laser light formed by the reflection of the monitoring laser by the tympanic membrane; and a vibration analysis submodule for performing data analysis based on the monitoring laser and the corresponding reflected laser light to determine the vibration characteristics of the tympanic membrane. Using optical recognition methods to determine the vibration characteristics of the tympanic membrane eliminates the need to apply an acoustic load to the tympanic membrane, avoiding the reduced user experience caused by adding an acoustic load to the tympanic membrane.

[0011] In some optional implementations, the monitoring laser is a frequency-modulated laser signal; the vibration analysis submodule performs Doppler frequency shift analysis on the monitoring laser and the reflected laser to determine the vibration characteristics of the tympanic membrane.

[0012] In some optional implementations, the tympanic membrane monitoring module further includes an adjustment controller for adjusting the irradiation position of the monitoring laser emitted by the light emitter. The vibration analysis submodule is further used to analyze the monitoring laser from different irradiation directions and the corresponding reflected laser light to determine the maximum range of motion on the tympanic membrane surface, and to control the adjustment controller to adjust the irradiation position of the light emitter so that subsequent monitoring lasers always irradiate the maximum range of motion. By monitoring the tympanic membrane in the maximum range of motion, the obtained tympanic membrane vibration characteristics are more obvious, thus making the obtained residual noise characteristics more accurate.

[0013] In some optional implementations, the tympanic membrane monitoring module further includes: an otoscope coupler, including an optical guide channel for realizing the propagation of laser signals and a sound transmission channel for realizing the transmission of noise-reduced waves emitted by a secondary source speaker; one end of the optical guide channel is connected to or opposite to both the optical transmitter and the optical receiver; the sound transmission channel is connected to or opposite to the secondary source speaker.

[0014] In some alternative implementations, the active noise reduction device further includes a reflector with a microprism structure; the reflector is used to reflect the monitoring laser and / or the reflected laser. By setting up a reflector to increase light reflection, the laser signal transmission efficiency can be improved, which is more conducive to processing the optical signal to obtain the tympanic membrane vibration characteristics. Attached Figure Description

[0015] Figure 1 A structural framework diagram of the active noise cancellation device provided in the embodiments of this disclosure;

[0016] Figure 2 The flowchart illustrates noise control using feedforward and feedback control strategies.

[0017] Figure 3 This is a schematic diagram of the structure of the tympanic membrane monitoring module in some embodiments of this disclosure;

[0018] Figure 4 This is a frequency domain noise reduction result diagram of the active noise reduction device provided in the embodiments of this disclosure;

[0019] Figure 5 This is a time-domain noise reduction result diagram of the active noise reduction device provided in the embodiments of this disclosure;

[0020] Among them: 100-Active noise reduction device, 110-Tympanic membrane monitoring module, 111-Light transmitter, 112-Light receiver, 113-Vibration analysis submodule, 114-Otoscopic coupler, 115-Adjustment controller, 120-Control module, 130-Secondary source speaker, 140-Reference microphone. Detailed Implementation

[0021] The term "and / or" used in this article describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. The symbol " / " in this article indicates that the related objects are in an "or" relationship; for example, A / B means A or B.

[0022] The terms "first" and "second," etc., used in the specification and claims herein are used to distinguish different objects, not to describe a specific order of objects. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same properties in the description of embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such processes, methods, systems, products, or apparatus.

[0023] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is being described as an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being better or more advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.

[0024] This application provides an active noise cancellation device that formulates a noise cancellation control strategy by directly monitoring the vibration of the tympanic membrane, and achieves active noise cancellation based on the noise cancellation control strategy.

[0025] Figure 1 This is a structural framework diagram of the active noise cancellation device provided in an embodiment of this disclosure. Figure 1 As shown, the active noise cancellation device 100 provided in this embodiment includes a tympanic membrane monitoring module 110, a control module 120, and a secondary source speaker 130. In some applications, the tympanic membrane monitoring module 110, the secondary source speaker 130, and the control module 120 can be integrated and installed on the device body of the active noise cancellation device 100 to form an integrated structure. In other applications, the tympanic membrane monitoring module 110 and the secondary source speaker 130 can be installed on the device body of the active noise cancellation device 100, while the control module 120 is set independently of the device body of the active noise cancellation device 100 (e.g., set in a terminal device).

[0026] The tympanic membrane monitoring module 110 is used to monitor the vibration characteristics of the tympanic membrane. The monitored vibration characteristics include vibration frequency, vibration phase, and vibration intensity (which can also be described as the amplitude at the monitoring location). In specific implementations, the tympanic membrane monitoring module 110 can monitor the vibration characteristics of the tympanic membrane using either a non-contact or contact detection method. To facilitate the use of the active noise cancellation device 100, a non-contact monitoring method is preferred in specific implementations. The tympanic membrane monitoring module 110 used in the specific embodiment will be analyzed later; here, it is only necessary to confirm that the tympanic membrane monitoring module 110 can achieve tympanic membrane vibration monitoring.

[0027] The secondary source loudspeaker 130 is a loudspeaker used to emit noise-reducing waves. The term "secondary source" here refers to a source relative to ambient noise (that is, the ambient noise source is treated as the primary sound source). In specific implementations, the secondary source loudspeaker 130 can be a balanced armature loudspeaker, a moving coil loudspeaker, or a planar loudspeaker; this application does not impose any limitations.

[0028] In active noise cancellation control, the ideal control objective is for the secondary source speaker 130 to emit a noise-canceling wave with the same frequency and amplitude as the ambient noise but opposite phase. This would cause the noise-canceling wave and the ambient noise to interfere and cancel each other out at the eardrum, thus preventing the ambient noise from being perceived by the eardrum. However, in reality, due to inaccurate monitoring of ambient noise characteristics and inaccurate estimation of the acoustic transmission characteristics of the ear canal, residual noise may still remain after the noise-canceling wave emitted by the secondary source speaker 130 interferes and cancels out the ambient noise at the eardrum. This residual noise is collected by the eardrum, forming corresponding vibrations that allow the ear to perceive ambient noise of a certain intensity.

[0029] In this embodiment of the disclosure, the tympanic membrane monitoring module 110 monitors the vibration characteristics of the tympanic membrane. The goal is to identify the tympanic membrane vibration caused by residual noise, thereby determining the noise characteristics of the residual noise and using it for the formulation of subsequent noise reduction strategies.

[0030] The control module 120 is responsible for data processing and noise reduction strategy formulation. Specifically, the control module 120 has the following functions: (1) analyzing the vibration characteristics of the tympanic membrane to determine the noise characteristics of the residual noise; (2) formulating an updated feedback noise reduction strategy based on the noise characteristics of the residual noise; and (3) controlling the secondary source speaker 130 to continue emitting noise-reduced waves based on the updated feedback noise reduction strategy. In specific applications, the control module 120 can be integrated into a digital signal processing (DSP) chip and some chips used for analog signal processing.

[0031] It should be noted that here the secondary source speaker 130 is controlled to continue emitting noise-reduced waves based on the updated feedback noise reduction strategy, rather than solely based on the feedback control strategy. In specific applications, noise reduction control signals may be generated based on both feedforward and feedback noise reduction strategies, and then used to control the secondary source speaker 130 to emit noise-reduced waves.

[0032] As analyzed above, the active noise cancellation device 100 provided in this embodiment directly determines the noise characteristics of residual noise based on the vibration characteristics of the tympanic membrane, and then formulates a feedback noise cancellation strategy. Since the tympanic membrane is the organ through which the human ear perceives sound, determining the noise characteristics of residual noise based on the vibration characteristics of the tympanic membrane is direct and eliminates the need to consider issues such as the varying acoustic transfer functions caused by the structure of the ear canal, as required by setting error microphones. In other words, by determining the noise characteristics of residual noise based on the vibration characteristics of the tympanic membrane, and then formulating a feedback noise cancellation strategy based on these characteristics, there is no need to consider the influence parameters of intermediate uncertainties. This reduces the complexity of the noise cancellation algorithm while improving the noise cancellation effect.

[0033] In real-world environments, ambient noise can vary randomly. Feedback noise reduction strategies based solely on the noise characteristics of residual noise fail to account for these variations, resulting in ineffective noise reduction in practical applications. To address this issue, the active noise cancellation device 100, in addition to the tympanic membrane monitoring module 110, secondary source speaker 130, and control module 120, may also include a reference microphone 140. The reference microphone 140 is a microphone located on the outside of the device body, used to monitor ambient noise and capture its characteristics. Essentially, the reference microphone 140 is a microphone. In specific applications, a microphone manufactured using MEMS technology is preferred as the reference microphone 140 to reduce the weight and size of the active noise cancellation device 100.

[0034] When the reference microphone 140 is used to monitor the noise characteristics of the ambient noise, the controller can determine an updated feedback noise reduction strategy based on the noise characteristics of the residual noise and the ambient noise. According to the foregoing analysis, the feedback noise reduction strategy takes into account the impact of changes in the ambient noise characteristics on the feedback noise reduction strategy, which can improve the noise reduction effect of the feedback noise reduction strategy.

[0035] The following describes how, in practical applications, an updated feedback noise reduction control strategy is determined based on the noise characteristics of residual noise and ambient noise. In some embodiments, the noise reduction filter coefficients in the feedback control strategy adopt C... b Indicated. The noise reduction filter coefficients at time n-1 use C. b (n-1) represents the noise reduction filter coefficient at time n, which uses C. b(n) represents the input. In specific implementation, the feedback control strategy can be updated based on the least mean square algorithm, where C represents the input. b (n)=C b (n-1)+μx'(n)e(n-1). Where μ is the step size factor, x'(n) is the filtered characteristic of the environmental noise, calculated based on the noise characteristics of the environmental noise and the path model of the secondary path. The path model of the secondary path is a model characterizing the mathematical transfer characteristics of the actual physical system from the feedback filter output signal, the sound signal generated by the secondary source speaker 130, to the detection of the reference noise, and e(n-1) is the noise characteristic of the residual noise at time n-1. In the feedback control strategy, the noise reduction filtering coefficients adopt C... b In the case of [the given information], the feedback control signal C generated based on the feedback control strategy [is described]. b (n)e(n).

[0036] To further improve the noise reduction effect, in addition to setting a feedback noise reduction strategy, a feedforward noise reduction strategy will also be set in the specific embodiment.

[0037] In some embodiments, the feedforward control strategy is predetermined, that is, it uses feedforward noise reduction filter coefficients with fixed coefficients. Specifically, the feedforward noise reduction filter coefficient C... f = -P(z) / S(z), where P(z) is the acoustic transfer function between the reference microphone and the eardrum of the headphone system, also known as the true primary channel, and S(z) is the acoustic transfer function between the secondary source speaker and the eardrum of the headphone system, also known as the true secondary channel. The feedforward noise reduction filter coefficients use C... f In the given case, the feedforward control signal generated based on the feedforward control strategy is C. f x(n+1). Correspondingly, the noise reduction signal obtained by combining the feedforward control signal and the feedback control signal for controlling the secondary source speaker 130 is y(n+1)=C f x(n+1)+C b (n+1)e(n). By combining feedforward control and feedback control, stable noise suppression can be achieved under varying environmental noise conditions.

[0038] Figure 2 The flowchart illustrates noise control using both feedforward and feedback control strategies. For ease of representation of data transmission relationships, time markers for various signals are not distinguished in the diagram. Following the arrows, ambient noise x is transmitted through the primary channel (i.e., the ear canal) to the tympanic membrane and becomes d. Ambient noise x is simultaneously input to the feedforward controller (deploying the feedforward control strategy) to generate the feedforward control signal C. fx; Simultaneously, the environmental noise signal, after being processed into x' by the secondary path model, is synchronized with the noise feature e of the residual noise from the previous moment to adjust the feedback control strategy in the feedback controller. The noise feature e, after being adjusted and updated by the feedback controller, generates the feedback control signal C. b e. Then Cx and C b The integrated signal e controls the secondary source speaker 130 to generate a noise-reduced wave y. The noise-reduced wave y is transmitted to the eardrum and converted into a noise-reduced wave y'. The noise-reduced wave d cancels out the ambient noise d to form residual noise e.

[0039] In some embodiments, the active noise cancellation device 100 is an active noise cancellation headphone or other device that needs to play music and voice. Correspondingly, the aforementioned secondary source speaker 130, in addition to playing noise-canceling waves, also simultaneously plays the target sound (i.e., the aforementioned music sound, voice, etc.). In a specific implementation, after generating a feedback control signal, the active noise cancellation device 100 integrates the feedback control signal and the audio signal to form a final drive signal controlling the secondary source speaker 130 to emit sound, and uses the drive signal to control the secondary source speaker 130 to emit sound. The sound and noise emitted by the secondary source speaker 130 are simultaneously collected at the eardrum, causing the eardrum vibration characteristics to fuse with the residual noise and the vibration characteristics of the played target sound. To obtain the noise characteristics of the residual noise, it is necessary to remove the target sound vibration characteristic component from the eardrum vibration characteristics. The target sound's sound characteristic component can be determined by the source and volume of the target sound. Accordingly, after aligning the eardrum vibration characteristics and the target sound's sound characteristics (i.e., determining the real-time sound that causes eardrum vibration), the control module 120 subtracts the target sound's sound characteristics from the eardrum vibration characteristics to obtain the eardrum vibration characteristics.

[0040] The above describes the overall structure and method of active noise cancellation in the active noise cancellation device 100. The following describes how the tympanic membrane monitoring module 110 monitors the vibration characteristics of the tympanic membrane. Figure 3 This is a schematic diagram of the structure of the tympanic membrane monitoring module 110 in some embodiments of this disclosure. For example... Figure 3 As shown, the tympanic membrane monitoring module 110 may include a light transmitter 111, a light receiver 112, and a vibration analysis submodule 113. Both the light transmitter 111 and the light receiver 112 are mounted on the device body, and after the user wears the active noise cancellation device 100, both the light transmitter 111 and the light receiver 112 are located inside the user's ear canal. The vibration analysis submodule 113 is a submodule for data processing; it can be integrated into the aforementioned DSP chip or located in a dedicated chip.

[0041] like Figure 3As shown, the light emitter 111 emits a monitoring laser towards the tympanic membrane. After the monitoring laser shines on and is reflected by the tympanic membrane, it is received by the light receiver 112. Upon receiving the reflected laser from the tympanic membrane, the light receiver 112 performs analog-to-digital conversion on the reflected laser to generate a digitized reflected laser. The digitized reflected laser is sent to the vibration analysis submodule 113. The automatic analysis submodule performs data analysis based on the signal characteristics of the monitoring laser and the reflected laser, determining the positional characteristics of the tympanic membrane monitoring points at multiple time points. Then, based on the positional characteristics of the tympanic membrane monitoring points at multiple time points, it determines the vibration characteristics of the tympanic membrane, namely its vibration frequency, vibration phase, and vibration intensity.

[0042] In a specific embodiment, the laser signal emitted by the optical emitter 111 is a low-power, safe signal that will not damage the tympanic membrane. For example, in one application, the optical emitter 111 is a 650nm wavelength laser diode with a power of less than 1mW and a spot diameter of less than 0.5mm. In practical applications, the laser signal emitted by the optical emitter 111 can be a single-frequency continuous laser, a linearly modulated laser pulse, a coherent beam, a structured spot, or a speckle pattern. Correspondingly, the automatic analysis submodule can use the corresponding Doppler frequency shift analysis method, interference intensity analysis method, or regional pixel displacement image method to determine the relative position of the monitoring points at each time point, thereby determining the vibration characteristics of the tympanic membrane. In practical applications, to ensure that the obtained tympanic membrane vibration characteristics are usable, it is necessary to ensure that the resolution of signal processing based on the automatic analysis submodule meets the corresponding standard. In a specific application, it is necessary to ensure that the resolution of the tympanic membrane vibration velocity reaches 0.01μm / s.

[0043] See further Figure 3 In some embodiments, the tympanic membrane controller further includes an adjustment controller 115. The adjustment controller 115 is used to adjust the irradiation direction of the monitoring laser emitted by the light emitter 111, so that the monitoring laser irradiates the target position in the tympanic membrane perpendicularly. Specifically, the target position is the area of ​​maximum activity in the tympanic membrane. Because the umbilicus region on the tympanic membrane surface is the area of ​​maximum amplitude, the umbilicus region of the tympanic membrane is highly likely to be identified as the area of ​​maximum activity. Specifically, the adjustment controller 115 can adjust the irradiation direction of the light emitter 111 multiple times, so that the vibration analysis submodule 113 obtains multiple combinations of monitoring laser and reflected laser. After obtaining the combinations of monitoring laser and reflected laser, the vibration analysis submodule 113 analyzes the corresponding combinations to determine the activity level of the vibration area corresponding to the corresponding combination, thereby determining the area of ​​maximum activity on the tympanic membrane surface. Subsequently, the adjustment controller 115 controls the light emitter 111 to irradiate the area of ​​maximum activity for subsequent tympanic membrane vibration characteristic monitoring. Because the monitoring laser irradiates the area of ​​maximum activity of the tympanic membrane almost perpendicularly, the vibration amplitude at the monitoring point in the tympanic membrane vibration characteristics is relatively large, making the monitoring and identification of the tympanic membrane vibration characteristics more accurate.

[0044] In some embodiments, the tympanic membrane monitoring module 110 may also include an otoscope coupler 114. The otoscope coupler 114 includes a light guide channel for transmitting laser signals and a sound transmission channel for transmitting noise-reduced waves emitted by the secondary source speaker 130. One end of the light guide channel is connected to or opposite to both the light transmitter 111 and the light receiver 112, and the sound transmission channel is connected to or opposite to the secondary source speaker 130. The otoscope coupler 114 extends to a certain depth into the ear canal, overcoming the problem that the emitted signal cannot reach the tympanic membrane or the reflected signal cannot return to the light receiver 112 due to ear canal curvature. Furthermore, the sound transmission channel in the headphone coupler can achieve directional propagation of the noise-reduced waves, avoiding sound wave delay or interference.

[0045] Furthermore, the active noise cancellation device 100 in some embodiments of this disclosure also includes a reflector. The reflector may be a microprism structure with a size of approximately 1 mm × 1 mm. The reflector is disposed in the inner wall of the ear canal to emit the monitoring laser and the reflected laser, thereby improving the propagation efficiency of the laser in the ear canal and thus improving the accuracy of monitoring the vibration characteristics of the tympanic membrane.

[0046] In a specific application, an active noise-canceling headphone is designed according to the structure of the active noise-canceling device 100 mentioned above, and the aforementioned headphone is tested. Figure 4 The diagram illustrates the frequency domain noise reduction results using both the active noise cancellation device and the active noise cancellation device employing an error microphone, as described in this disclosure. The green line represents the frequency domain noise reduction characteristics of the active noise cancellation device 100, the orange line represents the frequency noise reduction characteristics of the active noise cancellation device 100 employing an error microphone, and the blue line represents the frequency domain noise reduction characteristics after disabling active noise cancellation (i.e., using passive noise cancellation). Figure 4 It is known that in the critical low-frequency band of 50Hz to 800Hz, the noise reduction depth and bandwidth of the active noise reduction device 100 provided in this embodiment are significantly better than those of the noise reduction depth and bandwidth using traditional error microphone signals. Figure 5The diagram illustrates the time-domain noise reduction results of noise reduction control using the active noise cancellation device of this disclosure and the active noise cancellation device using an error microphone. Similarly, the green line represents the time-domain noise reduction characteristics of the active noise cancellation device 100 of this disclosure, the orange line represents the time-domain noise reduction characteristics of the active noise cancellation device 100 using an error microphone, and the blue line represents the time-domain noise reduction characteristics after disabling active noise cancellation. After noise cancellation is enabled, the residual noise amplitude obtained using the active noise cancellation device 100 of this disclosure is much smaller than the residual noise amplitude of the traditional error microphone scheme, and the residual noise amplitude is closer to zero. This intuitively shows that the present invention can more effectively cancel primary noise, achieving a more thorough and stable noise suppression effect in the time domain. In contrast, the noise reduction performance of the active noise cancellation device using an error microphone is limited by the transfer function mismatch between the error microphone and the diaphragm, resulting in unstable noise reduction effects and insufficient noise reduction at some frequency points.

[0047] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above description is only a specific embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. An active noise cancellation device, characterized in that, include: Tympanic membrane monitoring module, used to monitor the vibration characteristics of the tympanic membrane; A secondary source loudspeaker is used to emit a noise-reducing wave; the noise-reducing wave is used to achieve interference cancellation of environmental noise at the tympanic membrane. The control module is used to determine the noise characteristics of residual noise based on the vibration characteristics of the tympanic membrane, determine an updated feedback noise reduction strategy based on the noise characteristics of the residual noise, and control the secondary source speaker to continue emitting noise-reduced waves based on the updated feedback noise reduction strategy.

2. The active noise cancellation device according to claim 1, characterized in that, Also includes: Reference microphone, used to monitor the noise characteristics of ambient noise; The control module determines an updated feedback noise reduction strategy based on the noise characteristics of the residual noise and the noise characteristics of the ambient noise.

3. The active noise cancellation device according to claim 2, characterized in that, The control module determines an updated feedback noise reduction strategy based on the noise characteristics of the residual noise and the noise characteristics of the ambient noise, including: The filtered characteristics of the environmental noise are calculated based on the noise characteristics of the environmental noise and the path model of the secondary path. The adjustment amount of the feedback strategy is determined based on the noise characteristics of the filtered features and the residual noise. The updated feedback noise reduction strategy is determined based on the adjustment amount of the feedback strategy and the current feedback noise reduction strategy.

4. The active noise cancellation device according to claim 2, characterized in that, Noise reduction control strategies also include pre-determined feedforward control strategies; The updated feedback noise reduction strategy is used to control the secondary source speaker to continue emitting noise-reduced waves, including: The feedback denoising signal is calculated based on the updated feedback denoising strategy and the noise characteristics of the residual noise; The feedforward noise reduction signal is calculated based on the noise characteristics of the environmental noise and the feedforward control strategy; A noise reduction signal is generated based on the feedback noise reduction signal and the feedforward noise reduction signal, and the secondary source speaker is controlled to continue emitting noise reduction waves based on the noise reduction signal.

5. The active noise cancellation device according to any one of claims 1-4, characterized in that, The secondary source speaker is also used to play the target sound; The control module determines the noise characteristics of the residual noise based on the vibration characteristics of the tympanic membrane and the acoustic characteristics of the target sound.

6. The active noise cancellation device according to any one of claims 1-4, characterized in that, The tympanic membrane monitoring module includes: A light emitter is used to emit a monitoring laser towards the tympanic membrane; A light receiver is used to receive reflected laser light generated by the tympanic membrane reflecting the monitoring laser light. The vibration analysis submodule is used to perform data analysis based on the monitoring laser and the corresponding reflected laser to determine the vibration characteristics of the tympanic membrane.

7. The active noise cancellation device according to claim 6, characterized in that, The monitoring laser is a frequency-modulated laser signal; The vibration analysis submodule performs Doppler frequency shift analysis on the monitoring laser and the reflected laser to determine the vibration characteristics of the tympanic membrane.

8. The active noise cancellation device according to claim 6, characterized in that, The tympanic membrane monitoring module also includes: An adjustment controller is used to adjust the irradiation position of the monitoring laser emitted by the light emitter; The vibration analysis submodule is also used to analyze the monitoring laser and the corresponding reflected laser based on different irradiation directions, determine the maximum range of motion area on the tympanic membrane surface, and control the adjustment controller to adjust the irradiation position of the light emitter so that the subsequent monitoring laser always irradiates the maximum range of motion area.

9. The active noise cancellation device according to claim 6, characterized in that, The tympanic membrane monitoring module also includes: The otoscope coupler includes an optical guide channel for propagating laser signals and an acoustic transmission channel for transmitting noise-reduced waves emitted by a secondary source loudspeaker. One end of the optical guide channel is connected to both the optical transmitter and the optical receiver, or they are positioned opposite to each other. The sound transmission channel is connected to or positioned opposite the secondary source speaker.

10. The active noise cancellation device according to claim 6, characterized in that, Also includes: A reflector with a microprism structure; the reflector is used to reflect the monitoring laser and / or the reflected laser.

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