Low-frequency active noise reduction device and method

Abstract

The invention discloses a low-frequency active noise reduction device and method, and relates to the technical field of noise control. The low-frequency active noise reduction device comprises a low-frequency noise sensing unit, a self-adaptive control processing unit and a reverse sound source emission unit, the low-frequency noise sensing unit comprises a reference microphone, and the reference microphone is arranged at a noise source and used for collecting a reference signal of the noise source; the self-adaptive control processing unit is electrically connected with the low-frequency noise sensing unit and is used for receiving a signal acquired by the reference microphone and generating an anti-phase control signal; and the reverse sound source emission unit is electrically connected with the self-adaptive control processing unit and is used for receiving the reverse phase control signal and emitting reverse sound waves. Based on the technical scheme disclosed by the invention, 100-500Hz characteristic low-frequency noise can be precisely and efficiently inhibited remarkably, long-term stable operation under extreme mine working conditions can be realized, comprehensive and reliable occupational health protection can be provided for operators, and the field operation efficiency can be improved.

Description

Technical Field

[0001] This invention relates to the field of noise control technology, specifically to a low-frequency active noise reduction device and method. Background Technology

[0002] Pneumatic rock drills, as crucial excavation equipment in mine tunneling, generate significant low-frequency noise during operation by breaking rocks with high-intensity impact. This noise primarily concentrates in the 100-500Hz frequency range. This type of noise has long wavelengths, strong penetrating power, and long propagation distances, making it difficult to effectively attenuate using conventional methods. Prolonged exposure to this environment can lead to hearing damage for operators, as well as fatigue, difficulty concentrating, and a range of other physiological and psychological problems, posing a serious occupational health hazard.

[0003] Currently, noise control for rock drills primarily employs passive noise reduction techniques, such as installing soundproof enclosures, using sound-absorbing materials, and wearing protective earplugs. These methods are generally effective for mid-to-high frequency noise, but their suppression effect on low-frequency sound waves (100-500Hz) is limited. Furthermore, traditional passive noise reduction techniques require increasing the thickness or weight of materials to improve low-frequency sound insulation performance, which conflicts with engineering requirements such as equipment portability and ease of operation, making it difficult to achieve a balance.

[0004] In related technologies, noise reduction can also be achieved through active noise control (ANC) technology. However, due to the special working environment of rock drills and the strong impact and time-varying nature of the noise they generate, existing general-purpose ANC systems are difficult to adapt to their special spectral characteristics and dynamic response. This has resulted in a lack of active noise reduction devices on the market that can be tightly integrated with the rock drill body and can work reliably for a long time under harsh working conditions. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a low-frequency active noise reduction device and method to solve the technical problems in the prior art where the noise environment in mining operations is harsh, noise reduction devices are difficult to work reliably for a long time, which is detrimental to the occupational health of personnel and affects work efficiency.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a low-frequency active noise cancellation device, comprising: A low-frequency noise sensing unit includes a reference microphone, which is located at the noise source and is used to acquire a reference signal from the noise source. An adaptive control processing unit, electrically connected to the low-frequency noise sensing unit, is used to receive the signal collected by the reference microphone and generate an inverse control signal; and The reverse sound source emitting unit is electrically connected to the adaptive control processing unit and is used to receive the reverse control signal and emit reverse sound waves.

[0007] In some embodiments, the low-frequency noise sensing unit further includes: An error microphone is positioned near the operator's ear and electrically connected to the adaptive control processing unit. It is used to collect residual sound pressure in the area and feed back the error signal to the adaptive control processing unit. The adaptive control processing unit is configured to generate an inverse control signal based on the signals collected by the reference microphone and the error microphone, and form a closed-loop feedback control loop with the error microphone.

[0008] In some embodiments, the adaptive control processing unit includes a digital signal processor configured to process the received signal using a Filtered-X LMS algorithm to control the output of an acoustic signal that cancels out the ambient sound signal.

[0009] In some embodiments, the adaptive processing unit further includes: A preamplifier, electrically connected to the low-frequency noise sensing unit, is used to receive analog signals and amplify and perform preliminary filtering; and An analog-to-digital converter module, which is electrically connected to the preamplifier and the digital signal processor, is used to receive analog signals and perform analog-to-digital conversion.

[0010] In some embodiments, the adaptive processing unit further includes: A filter, electrically connected to the digital signal processor, is used to receive the control signal and update the filter coefficients to output an inverted control signal; A digital-to-analog converter module, electrically connected to the filter, is used to receive the filter signal and perform digital-to-analog conversion; and A power amplifier is electrically connected to the digital-to-analog converter module and the reverse sound source emitting unit, respectively, and is used to drive the reverse sound source emitting unit to emit reverse sound waves.

[0011] In some embodiments, the adaptive control processing unit includes a bandpass filter circuit, which is used to filter the acquired signal in the 100-500Hz frequency band.

[0012] In some embodiments, the low-frequency active noise reduction device further includes an attachment mounting structure unit, which is connected to the low-frequency noise sensing unit, the adaptive control processing unit and the reverse sound source emitting unit respectively, and is connected to the noise source using a quick-release structure, and a vibration damping structure is provided between it and the noise source.

[0013] In some embodiments, the reverse sound source emitting unit includes a plurality of low-frequency loudspeakers arranged in an array, the plurality of low-frequency loudspeakers being mounted on a noise source via an angle-adjustable bracket.

[0014] In some embodiments, the adaptive control processing unit further includes a wireless communication module, which is connected to an external mobile terminal for remote parameter configuration and status monitoring.

[0015] Secondly, the present invention also provides a low-frequency active noise reduction method, which, when using the aforementioned low-frequency active noise reduction device, includes the following steps: S1. Real-time acquisition of reference signals from noise sources and residual sound pressure signals in the operator's area; S2. Generate an inverting control signal based on the reference signal and the residual sound pressure signal; S3. Based on the inverse control signal, emit a reverse sound wave; S4. Repeat steps S2-S3 above until the emitted reverse sound wave can cancel the noise in the target frequency band in the working environment, and continue to emit the effective reverse sound wave.

[0016] Compared with the prior art, the present invention provides a low-frequency active noise reduction device and method, which collects reference signals of noise sources through a low-frequency noise sensing unit, receives the reference signals through an adaptive control processing unit, generates corresponding inverse control signals, and emits corresponding inverse sound waves through an inverse sound source emitting unit, so as to superimpose them with the original noise in the working environment to form an interference attenuation region, thereby achieving the purpose of active noise reduction.

[0017] In this way, the application bottleneck of general active noise reduction technology can be overcome, and the characteristic low-frequency noise of 100-500Hz can be significantly suppressed with precision and efficiency. It effectively solves the problems of weak control and easy generation of standing waves in this frequency band by traditional passive noise reduction methods. It can operate stably for a long time under extreme mining conditions and can form a synergistic noise reduction system with existing passive protection measures to provide comprehensive and reliable occupational health protection for operators. It also helps to improve on-site operation efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of a low-frequency active noise reduction device in one embodiment of the present invention; Figure 2 This is a schematic diagram of the composition of the adaptive control processing unit in one embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the reverse sound source emitting unit in one embodiment of the present invention; Figure 4 This is a schematic diagram of the attachment and mounting structure unit in one embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of a low-frequency noise sensing unit in one embodiment of the present invention; Figure 6 This is a flowchart illustrating a low-frequency active noise reduction method in one embodiment of the present invention; Figure 7 This is a schematic diagram illustrating the principle of a low-frequency active noise reduction method in one embodiment of the present invention.

[0019] Explanation of reference numerals in the attached diagram: 100, Noise source; 200, External mobile terminal; 10, Low-frequency noise sensing unit; 11, Reference microphone; 12, Error microphone; 20, Adaptive control processing unit; 21, Preamplifier; 22, Analog-to-digital converter module; 23, Digital signal processor; 24, Filter; 25, Digital-to-analog converter module; 26, Power amplifier; 27, Memory; 28, Wireless communication module; 30, Reverse sound source transmitting unit; 31, Low-frequency speaker; 32, Speaker mounting panel; 33, Fixed base; 34, Adjustable bracket; 341, Fastening knob; 40, Attachment mounting structure unit; 41, Connecting harness; 42, Silicone shock-absorbing pad; 43, Snap-on quick-release base; 50, Power supply module. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0021] To address the aforementioned technical problems, this invention provides a low-frequency active noise reduction device and method. This not only overcomes the application bottleneck of general active noise reduction technology, but also achieves significant suppression of characteristic low-frequency noise in the 100-500Hz range with precision and efficiency, effectively solving the problems of weak control and easy induction of standing waves in this frequency band by traditional passive noise reduction methods. Furthermore, it can operate stably for a long time under extreme mining conditions and can form a synergistic noise reduction system with existing passive protection measures to provide comprehensive and reliable occupational health protection for operators, and also helps to improve on-site operation efficiency.

[0022] Please see Figure 1 , Figure 1 This is a schematic diagram of the overall structure of a low-frequency active noise reduction device in one embodiment of the present invention. The low-frequency active noise reduction device can be applied in a mining operation environment, or it can be applied in other noise environments as needed to achieve active noise reduction.

[0023] For ease of understanding, this embodiment will use a pneumatic rock drill used in mining as the example to illustrate the specific structure of the low-frequency active noise reduction device.

[0024] Please see Figure 1The low-frequency active noise reduction device may include a low-frequency noise sensing unit 10, an adaptive control processing unit 20, a reverse sound source emission unit 30, and an attachment mounting structure unit 40.

[0025] The low-frequency noise sensing unit 10 can collect noise signals; the adaptive control processing unit 20 can be electrically connected to the low-frequency noise sensing unit 10, and can receive noise signals and generate corresponding anti-phase control signals; the reverse sound source emitting unit 30 can be electrically connected to the adaptive control processing unit 20, and can receive anti-phase control signals and emit reverse sound waves; and the attachment mounting structure unit 40 can fix the low-frequency noise sensing unit 10, the adaptive control processing unit 20 and the reverse sound source emitting unit 30 on the pneumatic rock drill.

[0026] In one embodiment, the low-frequency noise sensing unit 10 may include a reference microphone 11 disposed near the noise source 100. The reference microphone 11 can acquire a reference signal from the noise source 100, which, after being processed by the bandpass filter circuit on the adaptive control processing unit 20 and in conjunction with the adaptive control algorithm, generates an inverse control signal to drive the inverse sound source emitting unit 30 to emit a sound wave that is out of phase with the original noise. This inverse sound wave can be superimposed on the original noise in the operator area to form an interference attenuation region.

[0027] In another embodiment, the low-frequency noise sensing unit 10 may further include an error microphone 12 disposed in the operator's ear area. The error microphone 12 can monitor the residual sound pressure in the operator's area and feed back the error signal to the adaptive control processing unit 20, and can form a closed-loop control structure with the adaptive control processing unit 20 to achieve low-frequency noise suppression in the 100-500Hz frequency band.

[0028] In practical applications, the reference microphone 11 can be mounted on the surface of the rock drill body near the noise source 100 via the attachment mounting structure unit 40, facilitating the acquisition of the original airborne sound signal uncontaminated by solid vibrations of the machine body; while the error microphone 12 is positioned near the operator's ear and can be used to monitor the residual noise signal after noise reduction. Simultaneously, the diaphragm surfaces of both microphones can be covered with a microporous dustproof film, ensuring the authenticity and reliability of the input signal even in high-dust environments like mines. In one embodiment, please refer to Figure 2The aforementioned adaptive control processing unit 20 includes a preamplifier 21, an analog-to-digital converter (ADC) 22, and a digital signal processor (DSP) 23. The preamplifier 21 is electrically connected to the aforementioned low-frequency noise sensing unit 10 and can be used to receive analog signals, amplify them, and perform preliminary filtering. The ADC 22 is electrically connected to the preamplifier 21 and can be used to receive analog signals and perform analog-to-digital conversion. The DSP 23 is electrically connected to the ADC 22 and can process the received digital signals and generate corresponding control signals.

[0029] Based on this, the adaptive control processing unit 20 may further include a filter 24, a digital-to-analog converter (DAC) module 25, a power amplifier 26, and a memory 27. The filter 24 can be electrically connected to the digital signal processor 23, and can be used to receive control signals and update the filter coefficients to output an inverted control signal; the DAC module 25 can be electrically connected to the filter 24, and can be used to receive the signal from the filter 24 and perform digital-to-analog conversion; the power amplifier 26 can be electrically connected to both the DAC module 25 and the reverse sound source emitting unit 30, and can be used to drive the reverse sound source emitting unit 30 to emit reverse sound waves.

[0030] Based on the above settings, the internal signal flow of the adaptive control processing unit 20 can be as follows: the analog signals of the reference microphone 11 and the error microphone 12 are amplified and pre-filtered by the preamplifier 21, and then input into the analog-to-digital converter (ADC) 22, and processed by the digital signal processor 23 in the digital domain.

[0031] During processing, the digital signal processor 23 first calls the digital bandpass filter module and extracts the components in the 100-500 Hz frequency band, and then uses the quadratic path estimation stored in the memory 27. The Filtered-X LMS algorithm is executed to update the coefficients of filter 24 in real time. The inverted control signal output from the updated filter 24 is output through the digital-to-analog converter (DAC) module 25 and then driven by the power amplifier 26 to drive the speaker array, thereby forming an inverted signal that interferes with the original noise in the operator's ear area. At the same time, the signal from the error microphone 12 can be fed back to the digital signal processor 23 to form a closed-loop control structure.

[0032] It should be noted that the output of the low-frequency noise sensing unit 10 can be a weak analog signal at the millivolt level. After preliminary amplification by the preamplifier 21, the signal level can be increased to a range suitable for sampling by the analog-to-digital conversion module 22, thereby ensuring the signal-to-noise ratio and accuracy of the subsequent digitization process.

[0033] Meanwhile, the digital signal processor 23 employs an adaptive noise control algorithm, including but not limited to Filtered-X LMS, to control the output sound signal to cancel out the ambient sound signal. In practical applications, the output sound signal can be iterated based on the ambient sound signal, the error noise signal, the convergence step size in the target noise reduction algorithm parameters, and the weighting coefficients of the filter 24, until the output sound signal can cancel out the ambient sound signal.

[0034] The iterative formula for the Filtered-X LMS algorithm is as follows:

[0035]

[0036]

[0037] In the formula, These are the 24 weighting coefficients of the filter. To converge the step size, The error noise signal collected by error microphone 12 For the target noise signal, The acoustic signal is the control output after the nth iteration. The reference signal is collected by the reference microphone 11. Reference signal Estimated secondary path The filtered signal.

[0038] When the preset iteration termination condition is met, the coefficient update of filter 24 is stopped, and the output of filter 24 at this time is used as a control signal to obtain the corresponding target cancellation noise signal. The reverse sound source emission unit 30 can emit a corresponding reverse sound wave according to the target cancellation noise signal to cancel the noise in the target frequency band in the working environment of the rock drill.

[0039] It should be noted that the above iteration termination condition can be that the number of iterations reaches or exceeds a preset threshold, for example, when the number of iterations is greater than the preset number, the iteration stops; the iteration termination condition can also be other conditions, such as the error signal converging to below the threshold or the rate of change of the filter coefficient 24 being lower than the preset value, etc., and there is no specific limitation on this.

[0040] In one embodiment, the adaptive control processing unit 20 may also integrate a wireless communication module 28 (such as Bluetooth BT 5.0 or a Wi-Fi module), which allows engineers to access the system from a safe distance via an external mobile terminal 200 (such as a mobile phone or tablet).

[0041] With wireless connectivity, engineers can perform real-time remote parameter configuration and / or status monitoring. Monitored parameters include, but are not limited to, key status parameters such as noise reduction depth, filter 24 coefficient convergence status, battery level, and system operating temperature. Remote dynamic configuration includes, but is not limited to, core parameters such as the algorithm step size factor μ, bandpass filter 24 center frequency and bandwidth, and active noise cancellation (ANC) function switch. This allows engineers to complete equipment debugging and diagnostics without on-site contact, greatly improving system maintainability and intelligence.

[0042] In one embodiment, please refer to Figure 3 The aforementioned reverse sound source emitting unit 30 may include a plurality of low-frequency loudspeakers 31 arranged in an array, a loudspeaker mounting panel 32, and a fixed base 33. Each low-frequency loudspeaker 31 may be fixed on the loudspeaker mounting panel 32, which may be connected to the fixed base 33 via an adjustable bracket 34, and the adjustable bracket 34 may be provided with a fastening knob 341 for adjustment. Thus, by tightening or loosening the fastening knob 341, the loudspeaker array can be driven to adjust its pitch angle within a specified angular range (e.g., ±15°), thereby optimizing its sound field directivity.

[0043] In one embodiment, please refer to Figure 4-5 The aforementioned attachment and installation structure unit 40 includes a connecting harness 41 between each functional unit and a snap-on quick-install base 43.

[0044] Specifically, all connecting harnesses 41 between the functional units in the low-frequency active noise reduction device are preferably made of flexible wear-resistant sheathed cables, and can be uniformly customized or wrapped in protective conduits or cable trays made of ABS and flame-retardant rubber composite materials.

[0045] Based on this, each functional unit can be equipped with a protective shell made of ABS and flame-retardant rubber composite material. The protective shell provides impact resistance, dust protection, and flame retardant protection for the internal precision electronic components. This protective shell and the main body of the device can be installed together on the rock drill body via a snap-on quick-release base 43, and its internal cavity can be filled with vibration-damping and sound-absorbing materials (such as polyurethane foam) as needed. At the same time, a vibration-damping structure, such as a silicone vibration damping pad 42, can be set between the snap-on quick-release base 43 and the rock drill body to achieve high adaptability to the mining environment.

[0046] Meanwhile, the low-frequency active noise reduction device also includes a power supply module 50, which can be installed on the rock drill in the manner described above. Specifically, the power supply module 50 can be a replaceable lithium battery pack, and it preferably has short-circuit protection and power indication functions to ensure that it can provide an independent and safe power supply for the system. Understandably, the attachment installation structure unit 40 adopts a snap-on quick-installation base 43 to enable the rapid and stable installation of each functional unit on the pneumatic rock drill, and can provide dustproof, shockproof and impact-resistant protection for each functional unit.

[0047] It should be noted that, in this embodiment, to ensure the compatibility of the low-frequency active noise cancellation device with the pneumatic rock drill, a comprehensive dustproof and vibration-resistant design is implemented to ensure the reliability and durability of the low-frequency active noise cancellation device in high-dust and high-vibration environments. The dustproof design is achieved by covering the diaphragm surfaces of the reference microphone 11 and the error microphone 12 with a microporous dustproof film, while the vibration-resistant design is achieved by using a composite vibration-damping structure combining a silicone shock-absorbing pad 42 and a snap-on quick-release base 43 in the attachment mounting unit.

[0048] In practical applications, both the reference microphone 11 and the error microphone 12 can be connected to the rock drill through the corresponding snap-on quick-release base 43 and silicone shock-absorbing pad 42, thereby effectively isolating the high-frequency vibration transmitted by the rock drill body and preventing sensor signal distortion.

[0049] Meanwhile, the protective shell of the adaptive control processing unit 20 can be filled with vibration damping and sound absorption materials (such as polyurethane foam) to provide buffer for the internal precision circuits such as DSP, ADC / DAC. The protective shell itself is directly fixed to the area of ​​the rock drill body with relatively small vibration through the snap-on quick-release base 43, which can realize a dual anti-vibration strategy of "rigid fixation and flexible buffer".

[0050] Furthermore, the reverse sound source emission unit 30 can be installed via an adjustable bracket 34 with a fastening knob 341, ensuring that the speaker array will not shift or loosen under strong vibration, thus maintaining the stability of the sound field directivity. All connecting harnesses 41 are uniformly customized as flexible, abrasion-resistant sheathed cables, reducing cable swaying, wear, and loosening of connectors caused by vibration.

[0051] Please see Figure 6 This invention also provides a low-frequency active noise cancellation method, which uses the above-mentioned low-frequency active noise cancellation device and includes the following steps: S1. Real-time acquisition of the reference signal of noise source 100 and the residual sound pressure signal of the operator's area; S2. Generate an inverting control signal based on the above reference signal and residual sound pressure signal; S3. Based on the above-mentioned phase-reversing control signal, a reverse sound wave is emitted; S4. Repeat steps S2-S3 above until the emitted reverse sound wave can cancel the noise in the target frequency band in the working environment, and continue to emit the effective reverse sound wave.

[0052] For details, please refer to Figure 7In step S1, the reference microphone 11 can collect the reference signal of the noise source 100. After bandpass filtering and algorithm processing by the adaptive control processing unit 20, an inverse control signal is generated to drive the inverse sound source emission unit 30 to emit a sound wave that is opposite in phase to the original noise. The inverse sound wave can be superimposed with the original noise in the operator area to form an interference attenuation zone.

[0053] Error microphone 12 can monitor residual sound pressure in the operator area and feed back the error signal to adaptive control processing unit 20. It can also form a closed-loop control structure with adaptive control processing unit 20 to achieve low-frequency noise suppression in the 100-500 Hz frequency band.

[0054] Based on this, in step S2, the analog signals from the reference microphone 11 and the error microphone 12 are amplified and pre-filtered by the preamplifier 21, and then input into the analog-to-digital converter (ADC) 22, and processed by the digital signal processor 23 in the digital domain.

[0055] During processing, the digital signal processor 23 first calls the digital bandpass filter module and extracts the components in the 100-500 Hz frequency band, and then uses the quadratic path estimation stored in the memory 27. The Filtered-X LMS algorithm is executed to update the coefficients of filter 24 in real time. The inverted control signal output from the updated filter 24 is output through the digital-to-analog converter (DAC) module 25 and then driven by the power amplifier 26 to drive the speaker array, thereby forming an inverted signal that interferes with the original noise in the operator's ear area. At the same time, the signal from the error microphone 12 can be fed back to the digital signal processor 23 to form a closed-loop control structure.

[0056] During this process, the digital signal processor 23 runs an adaptive noise control algorithm, including but not limited to Filtered-X LMS, to control the output sound signal to cancel out the ambient sound signal. Specifically, the digital signal processor 23 can iterate the output sound signal according to the ambient sound signal, the error noise signal, the convergence step size in the target noise reduction algorithm parameters, and the weight coefficients of the filter 24, until the output sound signal can cancel out the ambient sound signal, thus achieving step S3 described above.

[0057] When the preset iteration termination condition is met, the coefficient update of filter 24 is stopped, and the output of filter 24 at this time is used as a control signal to obtain the corresponding target cancellation noise signal. The reverse sound source emission unit 30 can emit a corresponding reverse sound wave according to the target cancellation noise signal to cancel the noise in the target frequency band in the working environment of the rock drill, that is, to realize the above step S4.

[0058] By using the above methods, the application bottleneck of general active noise reduction technology can be overcome, and the characteristic low-frequency noise of 100-500Hz can be significantly suppressed with precision and efficiency. This effectively solves the problems of weak control and easy generation of standing waves in this frequency band by traditional passive noise reduction methods. It can operate stably for a long time under extreme mining conditions and can form a synergistic noise reduction system with existing passive protection measures to provide comprehensive and reliable occupational health protection for operators. It also helps to improve on-site operation efficiency.

[0059] In the description of this application, it should be noted that the terms "upper" and "lower," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0060] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0061] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A low-frequency active noise reduction device, characterized in that, include: A low-frequency noise sensing unit includes a reference microphone, which is located at the noise source and is used to acquire a reference signal from the noise source. An adaptive control processing unit, electrically connected to the low-frequency noise sensing unit, is used to receive the signal collected by the reference microphone and generate an inverse control signal. as well as The reverse sound source emitting unit is electrically connected to the adaptive control processing unit and is used to receive the reverse control signal and emit reverse sound waves.

2. The low-frequency active noise reduction device according to claim 1, characterized in that, The low-frequency noise sensing unit further includes: An error microphone is positioned near the operator's ear and electrically connected to the adaptive control processing unit. It is used to collect residual sound pressure in the area and feed back the error signal to the adaptive control processing unit. The adaptive control processing unit is configured to generate an inverse control signal based on the signals collected by the reference microphone and the error microphone, and form a closed-loop feedback control loop with the error microphone.

3. The low-frequency active noise reduction device according to claim 1, characterized in that, The adaptive control processing unit includes a digital signal processor configured to process the received signal using the Filtered-X LMS algorithm to control the output of an acoustic signal that cancels out the ambient sound signal.

4. The low-frequency active noise reduction device according to claim 3, characterized in that, The adaptive processing unit further includes: A preamplifier, electrically connected to the low-frequency noise sensing unit, is used to receive analog signals and amplify and perform preliminary filtering; and An analog-to-digital converter module, which is electrically connected to the preamplifier and the digital signal processor, is used to receive analog signals and perform analog-to-digital conversion.

5. The low-frequency active noise reduction device according to claim 3, characterized in that, The adaptive processing unit further includes: A filter, electrically connected to the digital signal processor, is used to receive the control signal and update the filter coefficients to output an inverted control signal; A digital-to-analog converter module, electrically connected to the filter, is used to receive the filter signal and perform digital-to-analog conversion; and A power amplifier is electrically connected to the digital-to-analog converter module and the reverse sound source emitting unit, respectively, and is used to drive the reverse sound source emitting unit to emit reverse sound waves.

6. The low-frequency active noise reduction device according to claim 1, characterized in that, The adaptive control processing unit includes a bandpass filter circuit, which is used to filter the acquired signal in the 100-500Hz frequency band.

7. The low-frequency active noise reduction device according to claim 1, characterized in that, The low-frequency active noise reduction device also includes an attachment mounting structure unit, which is connected to the low-frequency noise sensing unit, the adaptive control processing unit and the reverse sound source emitting unit respectively, and is connected to the noise source using a quick-release structure, and a vibration damping structure is provided between it and the noise source.

8. The low-frequency active noise reduction device according to claim 1, characterized in that, The reverse sound source emitting unit includes multiple low-frequency loudspeakers arranged in an array, which are mounted on the noise source via angle-adjustable brackets.

9. The low-frequency active noise reduction device according to claim 1, characterized in that, The adaptive control processing unit also includes a wireless communication module, which is connected to an external mobile terminal for remote parameter configuration and status monitoring.

10. A low-frequency active noise reduction method, characterized in that, The application of the low-frequency active noise cancellation device as described in any one of claims 1-9 includes the following steps: S1. Real-time acquisition of reference signals from noise sources and residual sound pressure signals in the operator's area; S2. Generate an inverting control signal based on the reference signal and the residual sound pressure signal; S3. Based on the inverse control signal, emit a reverse sound wave; S4. Repeat steps S2-S3 above until the emitted reverse sound wave can cancel the noise in the target frequency band in the working environment, and continue to emit the effective reverse sound wave.

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