368 results about "Noise control" patented technology

The invention provides a video content enhancement method for a low-illumination environment, and the method comprises the steps: achieving the data preprocessing based on an original low-illumination video frame sequence through frame synchronization, color space conversion and local brightness analysis, generating a noise sensitivity thermodynamic diagram through multi-feature unsupervised learning, and constructing a noise perception gating mechanism through the combination of affine transformation. Dynamic modulation of the characteristic channel is realized; in the multi-scale network structure, a channel attention module is used for carrying out layer-by-layer self-adaptive adjustment on a noise sensitive area; a basic illumination image and an edge enhancement image are generated through double-branch decoding, and then weighted fusion is carried out in combination with a noise thermodynamic diagram, so that brightness balance and detail enhancement are realized; a noise smoothing regular term is introduced during end-to-end training, so that the network achieves dynamic balance between an enhancement effect and noise control.

The invention discloses a track noise control method and system based on active acoustic control, and the method comprises the steps: collecting a track noise signal through a sensor array, and processing the signal through Fourier transform to obtain a spectrum distribution characteristic; judging the type of a noise source according to the spectral distribution characteristics, if the spectral distribution shows high-frequency dominance, determining the noise as wheel-rail contact noise, and if the spectral distribution shows low-frequency dominance, determining the noise as rail vibration noise, and obtaining a noise source contribution proportion; according to the noise source contribution proportion, a dynamically adjusted control signal is obtained; acquiring noise source coupling information which changes in real time from the dynamically adjusted control signal, and determining a fused noise source model; according to the fused noise source model, a least square method is adopted to optimize a control strategy, and an optimized control instruction sequence is obtained; and according to the optimized control instruction sequence, acquiring matching data of the current operation density and speed, and if the effect does not reach the standard, iteratively updating the model to obtain final control output.

The invention provides a motor vibration noise control method and system based on modal resonance frequency prediction, and belongs to the field of motor control. The method comprises the following steps: acquiring each order of intrinsic mode frequency of the permanent magnet motor; a cost function parameter, a current constraint condition and a control target are set, and a model prediction control method is adopted to drive an inverter to operate, specifically, the current operation state quantity of the permanent magnet motor is collected; predicting a state response in a future finite time domain based on the operation state quantity; constructing a value function, and evaluating and optimizing a state change result; and selecting an optimal voltage vector, generating a pulse signal to drive an inverter to execute, obtaining a motor high-frequency electromagnetic force wave distribution condition, comparing the motor high-frequency electromagnetic force wave distribution condition with the intrinsic mode frequency of the permanent magnet motor, and optimizing an optimal voltage vector selection logic. The problems that harmonic waves are concentrated and resonance is easily caused by a fixed switching frequency modulation method in the prior art, and a passive suppression method is high in cost and poor in flexibility are solved.

The invention provides an impedance combined type broadband silencer based on a sound wave black hole gradient structure and a design method, and belongs to the technical field of noise control and environmental protection engineering, the whole impedance combined type broadband silencer is of an axisymmetric cylindrical structure, and the impedance combined type broadband silencer is composed of an inlet and outlet channel and a middle-section expanding type acoustic processing area; the expanded acoustic processing area comprises an inlet and outlet side expansion cavity, a composite impedance gradient perforation section and a porous sound absorption material layer. According to the sound wave black hole type multi-stage perforated ring structure, the sound wave black hole type multi-stage perforated ring structure composed of an axial uniform-parameter perforated ring belt and a radial gradient perforated ring belt is sequentially constructed in the silencer, so that the thickness of a perforated ring and the aperture and the perforation rate of the perforated ring belt are arranged on a propagation path according to a parameter gradient rule; porous materials are filled among the annular bands to form a gradient impedance composite dissipation system, so that sound waves are sequentially subjected to focusing and dissipation caused by geometric gradual shrinkage and viscosity and heat dissipation of porous media in the propagation process, and low-frequency enhanced absorption and wide-frequency-band continuous sound absorption are achieved.

The invention discloses a college dormitory noise multi-dimensional evaluation method based on psychoacoustic and sound field simulation, and belongs to the field of building environment and noise control. The objective of the invention is to solve the problem that an existing dormitory noise evaluation method is single in index and neglects subjective perception and spatial distribution heterogeneity. The method comprises the following steps: acquiring physical data and original audio of dormitory noise through multi-point synchronous acquisition; calculating loudness, sharpness, roughness, fluctuation intensity and comprehensive psychoacoustic annoyance (PA) by using a psychoacoustic model, and scientifically quantifying subjective interference of noise; meanwhile, sound field simulation is carried out based on the accurately established three-dimensional dormitory model, a sound pressure level distribution cloud picture is generated, and a standing wave phenomenon and a sound energy accumulation area are visually revealed; and finally, generating a targeted noise reduction optimization strategy by integrating subjective and objective and spatial analysis results. According to the method, full-chain diagnosis of physical characteristics-subjective perception-spatial distribution of dormitory noise is realized, and a scientific basis is provided for accurate and efficient noise treatment.

An electronic device is provided. The electronic device includes a slidable housing including a first housing and a second housing, a first substrate included in the first housing and including a processor, a second substrate included in the second housing, a flexible printed circuit board (FPCB) which includes a ground line, electrically connects the first substrate and the second substrate to each other, and has a shape changed according to the movement of the slidable housing, and a matching circuit electrically connecting the first substrate and at least a portion of the ground line of the FPCB, and changing impedance under the control of the at least one processor according to the shape of the FPCB.

The present application relates to pipeline system damping and noise reduction technical field, provide a kind of active noise cancellation pressure relief valve, comprising: valve body, with the liquid inlet cavity and pressure relief cavity being communicated are formed;Bypass pipe, with liquid inlet cavity is communicated;Piezoelectric actuator and pressure relief component, pressure relief component includes adjusting piece, pressure relief elastic piece and pressure relief valve core, pressure relief valve core and pressure relief elastic piece are set in pressure relief cavity, adjusting piece is movably arranged on valve body, piezoelectric actuator is arranged on adjusting piece, pressure relief elastic piece is pressed between piezoelectric actuator and pressure relief valve core;Piezoelectric actuator is configured to drive pressure relief elastic piece, to eliminate the transient noise caused by pulsating pressure when pressure relief valve core moves.The active noise cancellation pressure relief valve provided by the present application introduces active noise cancellation technology into the active noise cancellation pressure relief valve pulsating noise control by arranging piezoelectric actuator, can be adjusted by pressure relief elastic piece The force exerted on the pressure relief valve core can eliminate the transient noise caused by pulsating pressure when the pressure relief valve core moves.

The invention discloses a voiceprint monitoring method and system integrating bird recognition and noise traceability, and the method comprises the following steps: a position optimization deployment stage: collecting environment parameters of a destination, and carrying out the evaluation of a plurality of candidate positions through a scoring model based on the environment parameters, selecting the candidate position with the highest score as the final deployment position of the microphone array; in the voiceprint data acquisition stage, at the final deployment position, a solar-powered microphone array is used for acquiring mixed sound signals in the environment; a voiceprint analysis processing stage: carrying out parallel processing on the mixed sound signal, the parallel processing process comprising: a bird recognition processing sub-stage: extracting voiceprint features of bird buzzing from the mixed sound signal, and inputting the voiceprint features to a deep learning classification model integrated with a feature enhancement module, and outputting an identification result containing the bird species and the calibrated confidence. According to the invention, high-precision bird monitoring can be realized, and meanwhile, precise noise control can be synchronously carried out based on bird monitoring equipment.

The invention relates to the technical field of head-up display optimization, in particular to an operation noise control method and device for a vehicle-mounted head-up display, and the method comprises the steps: carrying out the bench noise and vibration testing of a target vehicle-mounted head-up display, so as to collect the body operation noise and vibration data in a bench state; the body operation noise and vibration data in the rack state are compared with a preset threshold value, and under the condition that the body operation noise and vibration data in the rack state are larger than the preset threshold value, motor or vibration isolation optimization is conducted on the target vehicle-mounted head-up display; and under the condition that the body operation noise and the vibration data in the rack state are smaller than a preset threshold value, performing a whole vehicle vibration test on the target vehicle-mounted head-up display to collect vibration data in the whole vehicle state, and optimizing the target vehicle-mounted head-up display according to the vibration data in the whole vehicle state. Therefore, noise generated in the self-checking process of the HUD assembly is effectively reduced, and the sound quality of the whole vehicle is improved.

The invention relates to the technical field of wind power plant optimization, and discloses a wind power plant noise control and power optimization method and device, and the method comprises the steps: obtaining the multi-source noise data of a wind power plant, constructing a multi-source noise feature database, and constructing a noise propagation theoretical model; determining a plurality of monitoring points in the wind power plant based on the noise propagation theoretical model, and collecting actual multi-source noise data and fan operation data of the plurality of monitoring points in real time; on the basis of actual multi-source noise data and fan operation data, a multi-objective optimization function fusing constraint conditions is constructed by taking minimization of dispatching instruction difference, fan operation load and noise superscale as objectives; and solving the multi-objective optimization function to generate an optimal power distribution scheme of the fan under the noise constraint. According to the invention, intelligent monitoring and intelligent control can be carried out on the noise of the wind power plant near the residential area, so that the noise influence of the wind power plant on the nearby residential area is reduced, and the contradiction between the residential area and the wind power plant is solved.

The invention relates to the technical field of power management, in particular to an LDO (low dropout regulator) circuit with a wide input voltage range, which comprises a pre-voltage-stabilizing module, a band-gap reference module, an error amplification module, a voltage-stabilizing control module and a power tube, the pre-voltage-stabilizing module is used for preprocessing a wide-range input voltage into a stable low power supply voltage; the band-gap reference module is used for converting the low power supply voltage into a reference voltage; the error amplification module is used for amplifying the difference value between the reference voltage and the feedback voltage of the output circuit into a high-gain and low-noise control signal; the control signal drives the power tube after being compensated and buffered by the voltage stabilization control module, and the power tube converts the wide input voltage into an LDO output signal. Only one LDO main body circuit is adopted, the wide input voltage range can be achieved, high input voltage can be adapted, low input voltage can also be adapted, the use number of components of an LDO chip is reduced, and the occupied area of the chip is greatly reduced.

The invention relates to a multi-channel acoustic black hole sound absorption structure and a silencing device, belongs to the technical field of noise control, and solves the defects of a current acoustic black hole sound absorption structure. The multi-channel acoustic black hole sound absorption structure comprises a shell, one side of the shell is open, and the open side of the shell is used for receiving incident sound waves; partition plates are arranged in the shell to divide the space in the shell into a plurality of sound absorption channels, a plurality of rib plates are arranged in each sound absorption channel, the outer ends of the rib plates are fixed to the inner side face of the shell, the rib plates are arranged perpendicular to the incidence direction of sound waves, the rib plates are arranged at intervals in the incidence direction of the sound waves, and the rib plates are arranged at intervals in the incidence direction of the sound waves. The widths of the multiple rib plates are gradually increased, the inner ends of the multiple rib plates are distributed in a set power law function mode, the inner ends of the multiple rib plates are attached to the outer side face of the perforated plate and fixedly connected with the perforated plate, and the sound absorption structure can better achieve ultra-wideband sound absorption.

The invention discloses a needle-punched glass fiber aerogel sound-absorbing plate which comprises the following components: 30-50% of a silicon dioxide aerogel precursor, 20-40% of a needle-punched glass fiber felt, 1-3% of a silane coupling agent, 0.5-1% of a dispersing agent, 0.2-0.5% of a defoaming agent, 3-8% of reinforced fibers and 2-5% of a binder. Through needled glass fiber mat reinforcement, silane interface modification and normal-pressure drying processes, collaborative optimization of high strength (compressive strength is greater than 0.64 MPa), high sound absorption performance (sound absorption coefficient is greater than 0.8) and low heat conductivity coefficient (0.018) of the material is realized. The preparation process is simple, the cost is low, and the material is suitable for noise treatment in the fields of buildings, automobiles, aerospace and the like and has remarkable economic benefits and environmental benefits.

Apparatus and methods are described including using a sensor to monitor a sleeping subject and generate a signal in response to the monitoring. A noise control device is controlled in response to the signal.

A method for controlling noise of a vehicle, comprising: when a state of charge of a battery is greater than a preset state of charge, acquiring a vehicle speed, a gear position, an electronic handbrake state, and an automatic parking state of a current vehicle; on the basis of the vehicle speed, the gear position, the electronic handbrake state, and the automatic parking state, determining whether to activate a noise control mode of the vehicle; when activating the noise control mode, on the basis of the vehicle speed, obtaining a first engine power of the vehicle; and, on the basis of the first engine power, controlling noise of the vehicle. The present invention also relates to an apparatus for controlling noise of a vehicle, a device for generation of noise control, and a storage medium.

This application discloses a toilet noise control method, control device, and toilet, relating to the field of toilet control technology. The method includes the following steps: in response to a noise signal, calculating a noise level coefficient based on the current state data of the toilet; obtaining the noise level action amplitude of the toilet based on the noise level coefficient and the initial action amplitude of the toilet; and in response to a control signal, executing a toilet action corresponding to the control signal based on the noise level action amplitude of the toilet. The beneficial effects of this application are: by calculating the noise level coefficient based on the current state data of the toilet, the noise level changes with the toilet's usage state, lid-open state, etc., thereby executing actions of different amplitudes in different toilet states, resulting in a higher cleaning effect when the toilet is used for extended periods, achieving a balance between cleaning effectiveness and noise reduction.

The application discloses a kind of based on multi-scale control technology's unmanned system cooperation privacy protection method, belong to unmanned system safety cooperation control field.This method solves the ill-conditioned numerical problem in the cooperative control of unmanned system with fast-slow coupling characteristics, and the state privacy leakage problem caused by communication eavesdropping.Scheme includes: establishing system dynamic model;Design the differential privacy leader-following multi-scale cooperative controller containing attenuation noise;Obtain the standard singular perturbation form of error system through matrix transformation;Based on multi-scale control theory, solve the state control gain that guarantees mean square consistency;Determine the noise control gain and privacy parameter in combination with probability theory and matrix spectral theory.The present application avoids the ill-conditioned numerical problem, and the controller is robust, while achieving accurate cooperative control, provides verifiable differential privacy protection for the initial state of the system, significantly improves the safety and reliability of unmanned system in the hostile environment.

This application discloses a method, device, medium, and product for active control of aerodynamic noise in the target area during tiltrotor transition flight, relating to the field of noise control. The method includes: during tilt transition conditions, constructing a target noise control area within a set region based on flight mission and environmental requirements, discretizing it into multiple spatial observation points and assigning weights; parameterizing the controllable aerodynamic loads on the blades to obtain control load variables, establishing the relationship between the control load variables and the acoustic response of the target noise control area, determining unknowns, and establishing a global acoustic optimization objective function; using the DDQN algorithm as a solver, optimizing the global acoustic optimization objective function under the premise of satisfying actuator physical constraints to obtain the optimal control law, performing feedforward execution and feedback correction to achieve active control of aerodynamic noise in the target area. This application can solve the main shortcomings and derived problems caused by focusing on single-point noise control.

The application discloses a novel light-weight pressure-resistant multifunctional metamaterial pipeline silencer system, which comprises an expansion section, a base section and a transition section; the two ends of the expansion section are connected with the base section through the transition section, and the inner diameter of the expansion section is larger than the outer diameter of the base section; the expansion section comprises at least one annular metamaterial base ring, the metamaterial base ring comprises a plurality of anisotropic super-structure shell units connected in sequence along the ring direction, and each anisotropic super-structure shell unit comprises a rigid support framework and a flexible support material; the rigid support framework is provided with holes, and the flexible support material is filled in the holes of the rigid support framework and between two adjacent rigid support frameworks. The application relates to the field of pipeline noise control and can effectively solve the problem of how to realize the integrated design of a pipeline system low-frequency broadband silencer system under the conditions of high pressure resistance and small size, thereby providing a solution with good application prospect for the design of pipeline systems widely used in the fields of aviation and navigation engineering and mechanical engineering.

The invention relates to a wing-shaped structure hydrodynamic noise control device with a heated internal wall surface and a porous medium coated outside, and belongs to the field of ship vibration noise control. The device comprises a wing-shaped structure trailing edge, a heat insulation layer, a heat preservation layer, a first electric heating piece, a first temperature sensor, a second temperature sensor, a second electric heating piece, a third temperature sensor, a fourth temperature sensor, a first outer covering porous medium, a second outer covering porous medium, a third outer covering porous medium, an electric heating piece controller and a first fixing bolt. A second fixing bolt, a third fixing bolt and a fourth fixing bolt. According to the characteristic that the control effect of wall surface heating and the porous medium is mainly influenced by viscosity, a combined control device of internal wall surface heating and outer coating of the porous medium is provided, and hydrodynamic noise generated by flow separation of the trailing edge of the airfoil structure can be remarkably reduced.

The invention relates to the technical field of railway vehicles, and provides a sound absorption device and a railway vehicle. In the sound absorption device, a surrounding plate structure and a flexible film in sealed connection form a closed cavity, at least one through hole is formed in the flexible film, hollow pipes and the through holes are arranged in a one-to-one correspondence mode, one ends of the hollow pipes are inserted into the corresponding through holes, and the other ends of the hollow pipes penetrate through a sound absorption structure and extend to an interval space between the sound absorption structure and a cavity bottom. And a coupling resonance sound absorption system of the flexible film, the hollow pipe, the interval space and the closed cavity is formed. According to the sound absorption device, the sound resistance and the sound quality are improved through the hollow pipe, the resonance frequency is made to move to the low frequency in cooperation with dual coupling resonance of the flexible film and the hollow pipe and dual coupling resonance of the hollow pipe and the cavity, and low-and-medium-frequency noise of 100-500 Hz is efficiently absorbed; the two types of coupling resonance cooperate to broaden the sound absorption frequency band, and the sound absorption structure is attached to the flexible film to enhance the sound energy dissipation efficiency. Efficient low-frequency sound absorption can be achieved without increasing the size, the requirements for light weight and thinness of railway vehicles are met, and the noise control effect is improved.

The application discloses an air conditioner and relates to the technical field of air conditioners. The air conditioner comprises a high-pressure pressure sensor configured to detect the exhaust pressure of a compressor; and a controller configured to periodically acquire the exhaust pressure of the compressor and the change rate thereof when the air conditioner operates in a reverse defrosting mode; determine whether the exhaust pressure reaches a first threshold P1 and the change rate reaches a first set value; if yes, control the compressor to operate at a reduced frequency and the frequency reduction amplitude is △H1; if no, when the exhaust pressure reaches a second threshold P2 and the change rate reaches a second set value, control the compressor to operate at a reduced frequency and the frequency reduction amplitude is △H2; wherein P1>P2 and △H1>△H2. By setting two different frequency reduction nodes and combining real-time judgment of the change rate of the exhaust pressure, a dynamic and conditional hierarchical frequency reduction control strategy is constructed, so that the dual optimization of defrosting efficiency and noise control is simultaneously realized under the premise of ensuring the defrosting effect.

The utility model discloses a noise control device for a clean room purification air conditioner, which belongs to the technical field of purification air conditioners and comprises an air outlet, a connecting seat is fixedly connected to the outer wall of the air outlet, mounting components are arranged on two sides of the air outlet, an adjusting component is arranged in the air outlet, and each mounting component comprises a first mounting plate. The bottom end of the first mounting plate is fixedly connected with a second spring; according to the air conditioner, the second spring is arranged in the air conditioner, through the design, vibration of the air outlet can be blocked through the second spring and the damping rod in the using process of the air conditioner, and therefore noise caused by vibration of the air outlet is reduced, and the noise is prevented from influencing workers in a clean room; and meanwhile, in the mounting process, the threaded plate can be separated from the lead screw, so that the height of the air outlet can be quickly adjusted, and mounting of the air outlet is facilitated.

The application relates to the technical field of motor noise reduction, in particular to a motor noise reduction method for a portable fan. The handheld fan is internally provided with a driving motor. The method comprises the following steps: obtaining motor noise generated by the portable fan during operation; the motor noise comprises mechanical vibration noise, electromagnetic noise and aerodynamic noise of the driving motor; when the signal strength of the motor noise is greater than a preset strength threshold, generating a noise control instruction based on the motor noise; generating and emitting noise reduction signals for the mechanical vibration noise, the electromagnetic noise and the aerodynamic noise based on the noise control instruction, so as to perform destructive interference on the motor noise. The motor operation noise level is reduced through active noise reduction and accurate processing of the fan motor noise.

The utility model relates to air conditioning system, specifically provide a refrigerant's silencer and air conditioning system, to solve the refrigerant of existing in air conditioning system operation easy to produce high frequency noise and difficult to effectively restrain, and the existing noise reduction scheme still has the problem of significant deficiency in high frequency noise control, safety, system performance and compactness of structure etc. For this purpose, a refrigerant's silencer of the utility model includes tubular shell, and the refrigerant can flow inside the tubular shell, and the tubular shell includes first stage cavity, second stage cavity and third stage cavity connected in turn, the diameter of first stage cavity is greater than the diameter of second stage cavity, and the diameter of second stage cavity is greater than the diameter of third stage cavity. By setting the diameter of three tubular structures from big to small in turn decreases, can effectively change the refrigerant flow state under the premise of not significantly increasing system resistance, realizes the graded attenuation and disturbance suppression of different frequency band noise especially high frequency noise.

This application discloses a multimodal rain-sensing wiper system for vehicles, comprising: a multimodal sensing module that collects first sensing data characterizing the state of rainwater on the glass surface and second sensing data characterizing the motion state of raindrops in the air; an intelligent control module that fuses the two types of data to generate a fused rainfall feature value and generates a wiping mode command accordingly; and a low-noise execution module composed of vibration-damping composite material and a buffer device that executes the wiping action and suppresses noise. This application solves the problem of low recognition accuracy of a single sensor by fusing optical and radar sensing data from different sources, achieving accurate determination of rainfall intensity; simultaneously, it utilizes the damping properties of the composite material and the buffer device to reduce noise from both the vibration source and the transmission path. Compared with existing technologies, this application improves rainfall detection accuracy and controls operating noise at a low level, significantly improving driving safety and comfort.

The invention discloses a quick positioning and mounting tool for a large partitioned acoustic shield, and relates to the technical field of noise control equipment mounting. The device comprises a supporting platform, a supporting frame and positioning blocks, the supporting frame is fixedly installed on the supporting platform and extends upwards, the supporting frame is provided with a movable platform, a worker can assemble the device on the movable platform, and the multiple positioning blocks are installed on the supporting platform and the supporting frame correspondingly. The spatial layout of the multiple positioning blocks is consistent with the spatial layout of the sound insulation cover, the sound insulation cover is formed by connecting the multiple sound insulation plates, the positioning blocks are used for abutting against the sound insulation plates, so that positioning of the sound insulation plates is achieved, and accurate abutting positioning of all the sound insulation plates is achieved through the positioning blocks consistent with the sound insulation cover in spatial layout. According to the sound insulation cover installation device, the traditional manual visual and manual measurement modes are replaced, accumulated errors in the installation process are greatly reduced, the installation stress is reduced, the installation efficiency of the sound insulation cover is improved, and the splicing sealing performance and the installation precision of all the sound insulation plates are guaranteed.

The offshore pile driving device comprises a pile hammer, a mounting frame, a lifting mechanism and a noise reduction mechanism, a lifting driving mechanism is mounted on the mounting frame and connected to a lifting disc, and the lifting disc is arranged on the outer side of the pile hammer in a sleeving mode; the lifting driving mechanism can drive the lifting disc to slide relative to the mounting frame in the length extending direction of the pile hammer. The noise reduction mechanism comprises a noise reduction cylinder, and the lifting disc can drive the noise reduction cylinder to move in the length extension direction of the pile hammer so as to adjust the depth of the working face, stretching into the noise reduction cylinder, of the pile hammer. The noise reduction cylinder of the noise reduction mechanism accurately covers a piling impact area through flexible lifting, and the noise control requirements under different piling depths are met; meanwhile, the surrounding sleeve structure of the noise reduction cylinder of the noise reduction mechanism directly acts on the periphery of a noise source, and the noise blocking efficiency is remarkably improved.

This invention discloses a reconstituted bamboo sound barrier and its manufacturing method, relating to the field of sound barrier technology. Specifically, it is a reconstituted bamboo sound barrier comprising spaced, inclined columns, with standard modular screen bodies fixed between the columns by clamping angle steel. The screen body uses a reconstituted bamboo main screen body as the core sound-absorbing body, combined with reconstituted bamboo panels, reconstituted bamboo cavities, reinforcing frames, and other components. The reconstituted bamboo panels have 0.3mm-1.0mm micro-perforations, forming an auxiliary sound-absorbing structure with the sealed reconstituted bamboo cavities, enhancing the sound absorption effect of the reconstituted bamboo main screen body. The diffusion texture of the reconstituted bamboo main screen body disperses reflected sound waves, improving the uniformity of the sound field, allowing more sound energy to "penetrate" into the sound-absorbing material and be consumed. The manufacturing process involves bamboo bundle pretreatment, shaping, and assembly, resulting in a product with low cost, light weight, good durability, environmental friendliness, and excellent acoustic performance, suitable for noise control on highways, railways, and other road sections.

This invention discloses a low-frequency noise reduction and sound insulation device for industrial applications, belonging to the field of noise control technology. The device includes an outer soundproof cover, an inner composite sound-absorbing structure, and an active noise control system. The outer soundproof cover is constructed of high-density board. The inner composite sound-absorbing structure is located on the inner wall of the outer soundproof cover and includes an acoustic metamaterial layer and a micro-perforated plate layer, which are spaced apart to form a first resonant cavity. The active noise control system includes: an error microphone embedded in the inner wall of the outer soundproof cover; a controller electrically connected to the error microphone; and a secondary sound source electrically connected to the controller and installed on the inner wall of the outer soundproof cover. This invention achieves broadband passive sound absorption through the composite structure of acoustic metamaterial and micro-perforated plate, providing a high signal-to-noise ratio environment for the active control system. Furthermore, the active control system based on the FxLMS algorithm precisely cancels residual low-frequency line spectra, achieving efficient and stable low-frequency noise reduction.