Railway line side airwave active noise reduction system

Abstract

The invention relates to a railway line side airwave active noise reduction system which comprises a multi-mode sensing module, a control module and an execution module which are deployed on two transverse sides of a noise reduction area line. The multi-mode sensing module comprises a microphone array and a laser velocimeter and is used for collecting noise signals and train speed signals and sending the noise signals and the train speed signals to the control module. The control module receives the noise signal and the train speed signal, obtains a self-adaptive anti-phase sound wave signal through calculation processing, converts the self-adaptive anti-phase sound wave signal into driving information and sends the driving information to the execution module; the execution module comprises airwave generating devices which are arranged in an array mode, and after the driving information is received, airwaves are sent out according to the power indication of the driving information. According to the invention, air waves with the same frequency and opposite phase as train noise are actively emitted, opposite consumption of low-frequency noise energy is realized, the problem that a traditional sound barrier is poor in low-frequency noise reduction effect is solved, frequency tracking and adjustment are realized, and accurate matching of opposite-phase sound waves and noise frequencies is ensured.

Description

Technical Field

[0001] This invention relates to the field of railway noise control technology, specifically to an active noise reduction system for air waves on the railway line side. Background Technology

[0002] Noise control in high-speed railway operation mainly relies on engineering measures such as sound barriers. The noise reduction principle is based on the propagation characteristics of sound waves. By setting up physical barriers between the railway line and sensitive areas, noise is reflected, absorbed, and blocked, and a significant sound shadow zone is formed behind the barrier, thereby effectively reducing the noise level.

[0003] However, traditional sound barrier measures have limitations, especially in reducing noise from tall buildings on both sides of the railway line, and their construction and maintenance costs are relatively high. Traditional sound barriers have weak penetration and poor noise reduction effect on low-frequency noise (50-500Hz) dominated by trains, and since train aerodynamic noise accounts for more than 60%, traditional sound barriers are insufficient to cope with it. In addition, the Doppler effect generated by the high-speed movement of trains causes the noise frequency to change dynamically, and traditional sound barrier devices cannot track the frequency changes in real time to implement targeted measures.

[0004] Therefore, it is necessary to propose new measures to overcome the above-mentioned shortcomings. Summary of the Invention

[0005] The purpose of this invention is to provide an active noise reduction system for air waves on the railway line side, so as to solve the problem of limited noise reduction effect of existing sound barrier measures.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] An active noise reduction system for air waves on the side of a railway line is provided. The system includes a multimodal sensing module, a control module, and an execution module, which are deployed on both sides of the line in the noise reduction zone.

[0008] The multimodal sensing module includes a microphone array and a laser velocimeter, used to collect noise signals and train speed signals and send them to the control module;

[0009] The control module receives noise signals and train speed signals, processes them to obtain adaptive anti-phase acoustic wave signals, converts them into drive information, and sends them to the execution module.

[0010] The execution module includes an array of air wave generators. After receiving the drive information, it emits air waves according to the power indication of the drive information.

[0011] Furthermore, the control module receives noise signals and train speed signals, and processes them to obtain adaptive anti-phase acoustic wave information, including:

[0012] Preprocess the noise signal;

[0013] The noise frequency shift is calculated based on the train speed, and the noise signal is frequency-shifted.

[0014] The FxLMS algorithm is used to generate adaptive antiphase acoustic signals based on filters.

[0015] Furthermore, the noise signal is preprocessed, including:

[0016] The noise signal x(n) is bandpass filtered from 20 to 2000 Hz to remove environmental noise;

[0017] The time-frequency characteristics of the noise signal are extracted by short-time Fourier transform to obtain the noise frequency distribution.

[0018] Furthermore, based on the train speed, the noise frequency shift is calculated, and the noise signal is frequency-shifted, including:

[0019] Δf = f0 (v / (v_sound±v));

[0020] in:

[0021] Δf is the noise frequency shift;

[0022] f0 is the original noise frequency in the noise frequency distribution;

[0023] v represents the train speed;

[0024] v_sound is the speed of sound;

[0025] The noise signal x(n) is frequency shifted to restore the original noise frequency f0, and the frequency error after compensation is ≤ ±1Hz.

[0026] Furthermore, the FxLMS algorithm is used to generate adaptive anti-phase acoustic signals based on filters, including:

[0027] y(n) = w(n) * x(n);

[0028] in:

[0029] y(n) is an adaptive anti-phase acoustic signal;

[0030] w(n) are the filter coefficients.

[0031] Furthermore, the control module allocates the operating power of each air wave generator according to its position weight, including:

[0032] α_i = e^(-(d_i - d0) / σ);

[0033] in:

[0034] α_i is the weight function;

[0035] d_i is the distance between the i-th air wave generator and the current position of the train;

[0036] d0 is the optimal effective distance;

[0037] σ is the attenuation coefficient.

[0038] Furthermore, the adaptive anti-phase acoustic wave signal is converted into driving information, including:

[0039] The driving information is the operating power information of the air wave generator;

[0040] Calculate the sound pressure level of the antiphase sound wave;

[0041] Correlate the acoustic power and sound pressure level of axial flow fans;

[0042] Calculate the input power of the variable frequency motor.

[0043] Furthermore, the system also includes an energy supply module, comprising a solar panel, a lithium battery energy storage module, and a piezoelectric stacked train motion energy recovery device deployed under the rails. The solar panel and the piezoelectric stacked train motion energy recovery device generate electrical energy, which is stored in the lithium battery energy storage module and supplies energy to the entire system.

[0044] Furthermore, the system also includes a startup module, comprising a power-on magnet sensor and a power-off magnet sensor, which are deployed on both sides of the longitudinal direction of the noise reduction zone line, respectively, to detect trains entering or leaving the noise reduction zone and to start and stop the system.

[0045] Furthermore, steel columns are installed on both sides of the line in the noise reduction zone, and sound-absorbing and sound-insulating baffles are arranged from top to bottom between adjacent steel columns in the longitudinal direction. Multiple air wave generating devices are deployed in a longitudinal arrangement between two adjacent sound-absorbing and sound-insulating baffles.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] This invention provides an active airwave noise reduction system for railway lines. By actively emitting airwaves that are in the same frequency but out of phase with train noise, it achieves the opposite dissipation of low-frequency noise energy, solving the problem of poor low-frequency noise reduction effect of traditional sound barriers. Furthermore, by integrating acoustic and speed sensor data, it achieves real-time compensation for the Doppler effect, with extremely low frequency tracking error. It can adapt to dynamic noise changes within the train speed range of 0-400 km / h, enabling frequency tracking and adjustment to ensure precise matching between the out-of-phase sound wave and the noise frequency. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0049] Figure 1 This is a system structure diagram provided in an embodiment of the present invention.

[0050] The diagram is labeled as follows:

[0051] 1-Power-on magnetic steel sensor, 2-Piezoelectric stacked train motion energy recovery device, 3-Steel column, 4-Sound-absorbing and sound-insulating baffle, 5-Air wave generator, 6-Steel rail, 7-Installation foundation, 8-Power-off magnetic steel sensor. Detailed Implementation

[0052] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0053] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing this invention 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 invention.

[0054] It should be noted that similar labels and letters indicate similar items; therefore, once an item is defined in one embodiment, it does not need to be further defined and explained in subsequent embodiments.

[0055] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0056] It should also be noted that although the order of steps is mentioned in the method description, in some cases, steps may be performed in a different order than that described here, and this should not be interpreted as a restriction on the order of steps.

[0057] In a specific implementation, the direction of the railway line is defined as longitudinal, and the direction perpendicular to it is defined as transverse. Figure 1 In this context, the left side is defined as front, and the right side is defined as back.

[0058] This invention provides an active noise reduction system for air waves on the side of railway lines. Unlike the working principle of traditional sound barriers, this system can actively emit air waves that are in the same frequency but out of phase as train noise, thereby achieving the opposite dissipation of low-frequency noise energy. Furthermore, it can achieve frequency tracking and adjustment, allowing the out-of-phase sound waves to be precisely matched with the noise frequency.

[0059] Specifically, the system of the present invention includes a multimodal sensing module, a control module, an execution module, a power supply module, and a startup module, which are deployed on both sides of the line in the noise reduction zone.

[0060] 1. Multimodal sensing module:

[0061] The multimodal sensing module includes a microphone array and a laser speedometer, which are used to collect noise signals and train speed signals and send them to the control module. The noise signals and train speed signals are collected synchronously.

[0062] A multimodal sensing module is deployed every 50 meters along the railway line. Each module contains 8-16 MEMS microphone arrays (sampling frequency 48kHz, satisfying the Nyquist sampling theorem) and one laser velocimeter (laser Doppler velocimeter, speed range 0-400km / h, accuracy ±1km / h). The microphone arrays are arranged linearly (5-10cm spacing), and the laser velocimeter is installed 1.5 meters above the center of the microphone arrays. The output signals from the microphone arrays, laser velocimeter, and sensors are connected to the control module via shielded cables.

[0063] 2. Control Module:

[0064] The control module receives noise signals and train speed signals, processes them to obtain adaptive anti-phase acoustic signals, converts them into drive information, and sends them to the execution module.

[0065] The control module adopts an FPGA+DSP heterogeneous architecture, integrating bandpass filtering (20-2000Hz), short-time Fourier transform, and FxLMS adaptive filtering algorithm modules. The control module communicates with the multimodal sensing module via RS485 bus (115200bps baud rate) and with the execution module via CAN bus (500kbps transmission rate), with processing latency controlled within 5ms.

[0066] First, the control module, based on a speed feedback-based Doppler effect real-time compensation algorithm, processes the received noise signal and train speed signal to obtain adaptive anti-phase acoustic wave information. This addresses the dynamic changes in noise frequency caused by train movement, enabling coordinated sensing and real-time compensation of speed and noise. The specific process is as follows:

[0067] ① Preprocess the noise signal, with a processing time ≤ 0.05ms. Specifically:

[0068] The noise signal x(n) is subjected to a 20-2000Hz bandpass filter to remove environmental noise, such as wind noise and birdsong, with a noise reduction of ≥15dB.

[0069] The time-frequency features of the noise signal are extracted by short-time Fourier transform (frame length 512 points, overlap rate 50%) to obtain the noise frequency distribution.

[0070] ② Doppler effect compensation, processing time ≤ 0.03ms:

[0071] The noise frequency shift is calculated based on the train speed, and the noise signal is frequency-shifted. Specifically:

[0072] Δf = f0(v / (v_sound±v));

[0073] in:

[0074] Δf is the noise frequency shift;

[0075] f0 is the original noise frequency in the noise frequency distribution;

[0076] v represents the train speed;

[0077] v_sound is the speed of sound, with a value of 340m / s. A "-" is used when the train is approaching and a "+" is used when it is moving away.

[0078] The noise signal x(n) is frequency-shifted to restore the original noise frequency f0. After compensation, the frequency error is ≤ .

[0079] ③ Adaptive anti-phase acoustic wave generation, processing time ≤ 0.02ms:

[0080] The FxLMS algorithm is used to generate an adaptive anti-phase acoustic signal based on a filter (filter order 1024). Specifically:

[0081] y(n) = w(n) * x(n);

[0082] in:

[0083] y(n) is an adaptive anti-phase acoustic signal;

[0084] w(n) are the filter coefficients.

[0085] Coefficient update: w(n+1) = w(n) + 2μe(n) x(n), step size factor μ takes the value of 0.001-0.01 (dynamically adjusted, taking the smaller value after convergence to ensure steady state error ≤ ±0.5dB).

[0086] Then, the control module converts the adaptive anti-phase acoustic wave information into driving information. The specific process is as follows:

[0087] The driving information is the operating power information of the air wave generator;

[0088] Step 1: Calculate the sound pressure level of the antiphase sound wave.

[0089] Based on the time-domain amplitude A(n) of the antiphase acoustic signal y(n), and combined with the theory of air acoustics, the target sound pressure level SPL_target is calculated as follows: SPL_target = 20lg(A(n) / A_ref), where A_ref is the reference sound pressure (20μPa, the threshold of human hearing), and must satisfy SPL_target = SPL_noise - ΔSPL (SPL_noise is the noise sound pressure level after compensation, and ΔSPL is the target noise reduction amount, which is taken as 10-15dB).

[0090] Step 2: Correlation between sound power and sound pressure level of axial flow fan.

[0091] By fitting the acoustic characteristics of the wind turbine through experiments, a relationship model between sound power W and sound pressure level SPL was established: SPL = 10lg(W / W_ref) + K, where W_ref is the reference sound power (10^-12 W), and K is a correction coefficient (determined by the wind turbine structure and installation environment, and its value is [not specified]). (Determined through calibration experiments), the target acoustic power is then derived. .

[0092] Step 3: Calculation of the input power of the variable frequency motor. Considering the fan efficiency η_fan (axial fan efficiency is taken as 0.75-0.85) and the motor efficiency η_motor (variable frequency motor efficiency is taken as 0.88-0.92), the motor input power... At the same time, a power correction factor β (affected by air density and wind speed, with a value of 0.95-1.05) is introduced, resulting in a final operating power. (α_i is the position weight coefficient calculated in step 6).

[0093] ④ Distributed collaborative control, processing time ≤ 0.05ms:

[0094] As the train passes, the control module allocates the operating power of each air wave generator according to its position weight, including:

[0095] α_i = e^(-(d_i - d0) / σ);

[0096] in:

[0097] α_i is the weight function;

[0098] d_i is the distance between the i-th air wave generator and the current position of the train;

[0099] d0 is the optimal effective distance, which is 10-15 meters.

[0100] σ is the attenuation coefficient, with a value of 5-8 meters.

[0101] After weight allocation, the output power error of each device is ≤ .

[0102] 3. Execution Module:

[0103] The execution module includes an array of air wave generators 5. After receiving the drive information, it emits air waves according to the power indication of the drive information, with a response time of ≤0.05ms.

[0104] like Figure 1 Steel columns 3 are installed on both sides of the line in the noise reduction zone. The bottom of the steel columns 3 has an installation base 7. The vertically adjacent steel columns 3 are provided with sound-absorbing and sound-insulating baffles 4 arranged from top to bottom. Multiple air wave generating devices 5 are arranged vertically between two vertically adjacent sound-absorbing and sound-insulating baffles 4.

[0105] Each air wave generator has 5 covers. In the corner area, noise reduction is achieved across the entire line side. The air wave generator 5 includes one axial flow fan (1-1.5 meters in diameter, made of non-metallic materials, preferably fiberglass or engineering plastics), one variable frequency motor (0.5-1.5kW power, speed range 0-3000rpm), and one PWM drive module. The axial flow fan outlet is equipped with a guide shroud (angle adjustable range 0-90°). The variable frequency motor is connected to the control module via a CAN bus to receive power signals.

[0106] Specifically, the control module generates a PWM drive signal (frequency 10-20kHz) and sends it to the variable frequency motor via the CAN bus. The variable frequency motor adjusts its speed (0-3000rpm) and phase according to the PWM signal, driving the axial flow fan to generate 0-500Hz air waves. The phase difference between the air waves and noise waves is controlled within 180°±5°.

[0107] 4. Power supply module:

[0108] The power supply module includes a solar panel (200-300W), a lithium battery energy storage module (100Ah, cycle life ≥2000 times), and a piezoelectric stacked train motion energy recovery device 2 deployed under the rail 6 (compatible with a 25kV high-voltage power supply system). The solar panel and the piezoelectric stacked train motion energy recovery device generate electrical energy, which is stored in the lithium battery energy storage module and then supplied to the entire system through a DC-DC converter (output voltage 24V, ripple ≤5%), forming an energy self-sufficient system.

[0109] 5. Startup module:

[0110] Based on the requirements of the noise-sensitive point range and the speed of trains at different speeds, the system introduces a start-up magnetic sensor 1 and a stop-down magnetic sensor 8, which are deployed on the longitudinal front and rear sides of the noise reduction zone line, respectively, to detect the train entering and leaving the noise reduction zone, start and stop the system, and precisely control the rotation speed of the air wave generator 5 to reduce ineffective energy consumption. Existing active noise reduction systems mostly rely on external power supply, which has high energy consumption and no energy recovery mechanism.

[0111] Additionally, electronic tag readers can be deployed. Before the train enters the noise reduction zone, the powered-on magnetic sensor 1 monitors wheel signals in real time and uses radio frequency identification (RFID) technology to identify vehicle information. When two or more consecutive wheel pulses of a train at the corresponding speed are detected, the system determines that a valid train has arrived and triggers the ground antenna to transmit microwaves via the signal from the powered-on magnetic sensor 1, thus activating the system. Similarly, when the train leaves the noise reduction zone, the system is shut down via the powered-off magnetic sensor 8.

[0112] The system of the present invention has the following technical advantages:

[0113] 1. Significant low-frequency noise reduction effect: By actively emitting 0-500Hz air waves to consume energy in the opposite direction to the low-frequency noise of the train, the noise reduction in the 50-500Hz frequency band is ≥10dB, which is more than 3 times better than the noise reduction effect of traditional sound barriers, thus solving the problem of railway aerodynamic noise control.

[0114] 2. Fast dynamic response: Integrates acoustic and velocity sensor data to achieve real-time compensation for the Doppler effect, with frequency tracking error ≤ It can adapt to the dynamic changes in noise within the train speed range of 0-400km / h, and has a wider range of applicable scenarios compared to existing fixed-frequency active noise reduction devices (which cannot track frequency changes).

[0115] 3. Low energy consumption and energy self-sufficiency: It integrates 200-300W solar panels and a piezoelectric energy recovery interface for train movement. The average energy consumption of a 100-meter line section is ≤80W. It can switch on and off autonomously and store solar energy. The proportion of solar power supply is ≥60%, and the dependence on the power grid is reduced.

[0116] 4. Wide coverage and strong coordination: Adopting a distributed control strategy, each air wave generator covers a ±45° angle area, forming a linear array with a spacing of 10-20 meters. Multi-device coordination is achieved through position weight allocation, and noise reduction can be achieved across a 100-meter line segment, improving coverage efficiency by 5-8 times compared to a single device.

[0117] 5. High environmental adaptability and reliability: Based on predictions of rain, snow, strong wind environments and long-term reliability, the microphone array signal-to-noise ratio decreases by ≤3dB, and the axial flow fan speed fluctuation is ≤±2%, meeting the long-term operation requirements of complex outdoor railway environments and reducing maintenance costs by more than 30%.

[0118] In other embodiments, when the laser Doppler velocimeter is affected by severe weather (such as heavy rain, dense fog, visibility <50 meters), it can be replaced with a millimeter-wave radar (operating frequency band 24 GHz, speed measurement range 0-400 km / h, accuracy...). Alternatively, a BeiDou positioning module (with positioning accuracy of 1 meter, calculating speed based on real-time train location) can be used. This solution is more suitable for rainy and foggy areas (such as railways in hilly southern regions) and high-altitude open railways (such as the Qinghai-Tibet Railway).

[0119] In other embodiments, if the FPGA+DSP heterogeneous architecture is too expensive, it can be replaced with an industrial-grade ARM chip (such as an STM32H743 with a main frequency of 480MHz) + a dedicated noise reduction chip. This solution is more suitable for ordinary passenger dedicated lines with limited budgets (such as intercity railways with a speed of 250km / h).

[0120] In other embodiments, in the absence of sunlight (such as long tunnels, >1000 meters in length), solar panels can be omitted and replaced with a power supply module from the overhead contact line inside the tunnel (compatible with 10kV high voltage, stepped down to 24V via an isolation transformer). This solution is more suitable for tunnel complex sections (such as railways in the southwestern mountainous areas).

[0121] In other embodiments, the lithium battery energy storage module can be replaced with a low-temperature lithium battery (operating temperature -40~60℃, capacity retention ≥70%@-30℃), and the fan guide cover can be made of cold-resistant rubber (temperature resistance -50℃); this solution is more suitable for high-altitude and cold regions (such as the Northeast Railway).

[0122] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. An active noise reduction system for air waves on the side of railway lines, characterized in that: The system includes a multimodal sensing module, a control module, and an execution module, which are deployed on both sides of the line in the noise reduction zone. The multimodal sensing module includes a microphone array and a laser velocimeter, used to collect noise signals and train speed signals and send them to the control module; The control module receives noise signals and train speed signals, processes them to obtain adaptive anti-phase acoustic wave signals, converts them into drive information, and sends them to the execution module. The execution module includes an array of air wave generators. After receiving the drive information, it emits air waves according to the power indication of the drive information.

2. The active noise reduction system for air waves on the railway line side according to claim 1, characterized in that: The control module receives noise signals and train speed signals, processes them to obtain adaptive anti-phase acoustic wave information, including: Preprocess the noise signal; The noise frequency shift is calculated based on the train speed, and the noise signal is frequency-shifted. The FxLMS algorithm is used to generate adaptive antiphase acoustic signals based on filters.

3. The active noise reduction system for air waves on the railway line side according to claim 2, characterized in that: Preprocessing of noise signals includes: The noise signal x(n) is bandpass filtered from 20 to 2000 Hz to remove environmental noise; The time-frequency characteristics of the noise signal are extracted by short-time Fourier transform to obtain the noise frequency distribution.

4. The active noise reduction system for air waves on the railway line side according to claim 3, characterized in that: The noise frequency shift is calculated based on the train speed, and the noise signal is frequency-shifted, including: Δf = f0(v / (v_sound±v)); in: Δf is the noise frequency shift; f0 is the original noise frequency in the noise frequency distribution; v represents the train speed; v_sound is the speed of sound; The noise signal x(n) is frequency shifted to restore the original noise frequency f0, and the frequency error after compensation is ≤ ±1Hz.

5. The active noise reduction system for air waves on the railway line side according to claim 4, characterized in that: The FxLMS algorithm is used to generate adaptive anti-phase acoustic signals based on filters, including: y(n) = w(n) * x(n); in: y(n) is an adaptive anti-phase acoustic signal; w(n) are the filter coefficients.

6. The active noise reduction system for air waves on the railway line side according to claim 5, characterized in that: The control module allocates the operating power of each air wave generator according to its position weight, including: α_i = e^(-(d_i - d0) / σ); in: α_i is the weight function; d_i is the distance between the i-th air wave generator and the current position of the train; d0 is the optimal effective distance; σ is the attenuation coefficient.

7. The active noise reduction system for air waves on the railway line side according to claim 6, characterized in that: The adaptive anti-phase acoustic signal is converted into driving information, including: The driving information is the operating power information of the air wave generator; Calculate the sound pressure level of the antiphase sound wave; Correlate the acoustic power and sound pressure level of axial flow fans; Calculate the input power of the variable frequency motor.

8. The active noise reduction system for air waves on the railway line side according to claim 7, characterized in that: The system also includes an energy supply module, comprising a solar panel, a lithium battery energy storage module, and a piezoelectric stacked train motion energy recovery device deployed under the rails. The solar panel and the piezoelectric stacked train motion energy recovery device generate electrical energy, which is stored in the lithium battery energy storage module and supplies energy to the entire system.

9. The active noise reduction system for air waves on the railway line side according to claim 8, characterized in that: The system also includes a startup module, comprising a power-on magnet sensor and a power-off magnet sensor, which are deployed on both sides of the longitudinal direction of the noise reduction zone line to detect trains entering or leaving the noise reduction zone and to start and stop the system.

10. The active noise reduction system for air waves on the railway line side according to claim 9, characterized in that: The noise reduction zone has steel columns on both sides of the horizontal line, and sound-absorbing and sound-insulating baffles arranged from top to bottom are installed between the vertically adjacent steel columns. Multiple air wave generating devices are arranged vertically between two vertically adjacent sound-absorbing and sound-insulating baffles.

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