An optimized installation method and system for an active controlled noise barrier
By installing an active noise reduction module at the top of the sound barrier and utilizing the principle of anti-acoustic interference, the problem of insufficient attenuation of low-frequency noise by traditional sound barriers is solved, achieving a more effective noise reduction effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- RES INST OF HIGHWAY MINIST OF TRANSPORT
- Filing Date
- 2023-05-06
- Publication Date
- 2026-07-07
AI Technical Summary
Traditional passive noise reduction measures have limited effectiveness in reducing low-frequency noise, and the limited geometric dimensions result in insufficient attenuation of low-frequency noise.
An active noise reduction barrier is adopted. By setting an active noise reduction module at the top of the sound barrier, the speaker emits reflected sound to reduce the diffracted sound source, forming a sound shadow zone and an interference zone. The speaker, microphone and host are combined to perform signal processing to achieve superimposed noise reduction.
It improves the overall noise reduction performance of the sound barrier, especially the attenuation effect on low-frequency noise, and overcomes the shortcomings of traditional sound barriers.
Smart Images
Figure CN116543738B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of noise control technology, and particularly to an optimized installation method and system for an active noise barrier. Background Technology
[0002] With the rapid development of highway transportation, residents along the routes have suffered greatly from noise pollution. Currently, there are three common noise reduction measures for highway traffic noise: noise reduction at the source, noise reduction during propagation, and noise reduction at the receiving point. All of these are passive noise reduction methods.
[0003] Traditional noise reduction measures include the use of sound barriers, a simple, practical, and effective method for controlling traffic noise. A sound barrier is a specially designed acoustic barrier placed between a noise source and a receiving point. It is typically designed for a specific sound source and a specific protected location (or area). Sound barriers are mainly used for noise reduction on highways, expressways, elevated roads, and other noise sources. They are divided into purely sound-insulating reflective sound barriers and composite sound barriers that combine sound absorption and sound insulation; the latter is a relatively more effective sound insulation method. Sound barriers are wall-like structures erected beside railways and highways to reduce the impact of traffic noise on nearby residents. Sound barriers are also called noise walls. Inserting a facility between a sound source and a receiver to significantly attenuate sound wave propagation, thereby reducing the noise impact in a certain area where the receiver is located, is called a sound barrier. Sound barriers are categorized into traffic noise barriers, equipment noise attenuation barriers, and industrial plant boundary barriers. Highways and expressways are where various types of sound barriers are most commonly used. However, its limited geometric dimensions determine its insufficient ability to attenuate low-frequency sound. Compared with traditional passive noise reduction measures, its noise reduction effect on low-frequency noise is limited. Low-frequency noise is closer to the resonant frequency of some human organs and is more harmful to the human body. Summary of the Invention
[0004] To address the aforementioned shortcomings, this invention provides an optimized installation method and system for an active noise barrier, aiming to overcome the limitations of traditional passive noise reduction measures in reducing low-frequency noise and the insufficient attenuation capacity of low-frequency noise due to limited geometric dimensions, thereby improving the overall noise reduction performance of the sound barrier.
[0005] This invention proposes an optimized installation method for an active noise barrier, wherein the active noise barrier includes an active noise reduction module and a sound barrier, comprising the following steps:
[0006] The sound barrier blocks the propagation path of the noise field, forming a sound shadow zone. The noise field is a primary sound field. The primary sound field will gather at the top of the sound barrier to form a new diffracted sound source.
[0007] The active noise reduction module is installed at the top of the sound barrier to emit reflected sound to reduce the diffracted sound emitted by the diffracted sound source, and to expand the area of the sound shadow zone and form an interference zone.
[0008] The expanded sound shadow area is superimposed with the formed interference area to form a noise reduction area after the noise reduction effect is superimposed.
[0009] Furthermore, the reflected sound is a sound with the same spectrum as the diffracted sound but opposite in phase.
[0010] Furthermore, the method also includes:
[0011] The sound barrier initially reduces the primary sound field.
[0012] The primary sound field is further reduced by the active noise reduction module.
[0013] Furthermore, the active noise reduction module comprises three parts: a loudspeaker, a microphone, and a host; the microphone collects the diffracted sound signal and outputs it to the host; the host receives the diffracted sound signal collected by the microphone, processes and calculates it to obtain the reflected sound signal, and then outputs the reflected sound signal to the loudspeaker; the loudspeaker receives the reflected sound signal output by the host and emits the reflected sound, and since the loudspeaker is used as a sound source, the loudspeaker is called a secondary sound source.
[0014] Furthermore, the factors affecting noise reduction of the active module include the layout of the secondary sound source and the layout of the error sensor. The spatial optimization of the active module is achieved by finding a better layout of the secondary sound source and a better layout of the error sensor.
[0015] Furthermore, the secondary sound source and the error sensor are installed according to a preferred secondary sound source layout and a preferred error sensor layout, and the deviation of the installation position is controlled by controlling the error sensor.
[0016] Furthermore, the step of finding a better secondary sound source layout and a better error sensor layout includes:
[0017] Determine the positions of multiple sets of alternative error sensors and microphones;
[0018] Simulate the primary sound field;
[0019] Each of the alternative error sensors and the microphone measures the primary sound field data;
[0020] Each of the alternative secondary sound sources emits sound, and each of the alternative error sensors and the microphone measures the secondary sound field data;
[0021] Import the primary sound field data and the secondary sound field data into the program for calculating layout optimization to obtain a better secondary sound source layout and a better error sensor layout.
[0022] Furthermore, under simulation conditions and real-world conditions, electroacoustic devices are installed according to a preferred secondary sound source layout and a preferred error sensor layout to obtain simulated noise reduction and experimental noise reduction, respectively. The accuracy of the preferred secondary sound source layout and preferred error sensor layout obtained under simulation conditions is verified by comparing the simulated noise reduction and the experimental noise reduction. The electroacoustic devices include the secondary sound source and the error sensor.
[0023] To address the aforementioned technical problems, the present invention also provides an optimized installation system for an active noise reduction barrier, wherein the active noise reduction barrier includes an active noise reduction module and a sound barrier.
[0024] The active noise reduction module includes a speaker unit, a sound transmission unit, and a computing and processing unit.
[0025] The sound transmission unit is used to collect the diffracted sound signal and output it to the computing and processing unit; the computing and processing unit is used to receive the diffracted sound signal collected by the sound transmission unit, process and calculate it to obtain the reflected sound signal, and then output the reflected sound signal to the speaker unit; the speaker unit is used to receive the reflected sound signal output by the computing and processing unit and emit the reflected sound.
[0026] Furthermore, an optimized installation system for an active noise reduction barrier is provided, characterized in that the sound barrier is used to block the propagation path of the primary sound field; and the active noise reduction module is used to reduce the primary sound field after it has been attenuated by the sound barrier.
[0027] This invention provides an optimized installation method and system for an active noise barrier, which solves the shortcomings of traditional passive noise reduction measures, such as limited noise reduction effect on low-frequency noise and insufficient low-frequency noise attenuation capability due to limited geometric dimensions, thereby improving the overall noise reduction performance of the sound barrier. Attached Figure Description
[0028] Figure 1 This is a schematic diagram illustrating the working principle of an optimized installation method for an active noise barrier provided in an embodiment of the present invention.
[0029] Figure 2 This is a schematic diagram of the active noise reduction module of an optimized installation system for an active control noise reduction barrier provided in an embodiment of the present invention. Detailed Implementation
[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0031] Example 1
[0032] Reference Figure 1 To address the aforementioned technical problems, this invention provides an optimized installation method for an active noise reduction barrier. The active noise reduction barrier includes an active noise reduction module 102 and a sound barrier 103. The original sound barrier 103 forms a sound shadow zone 104 by blocking the propagation path of the noise sound field, and the noise sound field generated by the noise source 101 is a primary sound field 108. The primary sound field 108 converges at the top of the sound barrier 103 to form a new diffracted sound source. The active noise reduction module 102 is installed at the top of the sound barrier 103, emitting reflected sound to reduce the diffracted sound 105 emitted by the diffracted sound source, and expanding the area of the sound shadow zone 104 to form an interference zone 106. The expanded sound shadow zone 104 can be called an extension zone 107, and its superposition with the formed interference zone 106 constitutes the noise reduction area after the noise reduction effect is superimposed. The present invention provides an optimized installation method for an active noise barrier, which overcomes the shortcomings of traditional passive noise reduction measures, such as limited noise reduction effect on low-frequency noise and insufficient low-frequency noise attenuation capability due to limited geometric dimensions, thereby improving the overall noise reduction performance of the sound barrier.
[0033] All sounds consist of a certain frequency spectrum. If we can find a sound whose frequency spectrum is exactly the same as the noise 201 to be eliminated, but with the exact opposite phase (180° out of phase), which is the reflected sound 202, then the reflected sound 202 can completely cancel out the noise 201, thus achieving noise cancellation state 203. This is the principle of interference cancellation, which can be referenced. Figure 2 Active noise reduction technology utilizes this principle to analyze the propagation characteristics of the sound source and the coherence of sound waves. It cancels out the anti-noise emitted by the loudspeaker with the actual noise, thereby achieving the purpose of noise reduction.
[0034] This invention employs active noise reduction technology to modify existing highway sound barriers. An active noise reduction module is installed atop the original sound barrier, and the module's speakers emit anti-noise signals to suppress highway noise. Furthermore, the active noise reduction module can be continuously powered by lighting electricity.
[0035] An active noise barrier mainly consists of two parts: an active noise reduction module and a sound barrier. The active noise reduction module is installed on top of the sound barrier. The dimensions of the active noise reduction module are 160mm*80mm*100mm (can be adjusted to be smaller according to the design).
[0036] Active noise cancellation technology is an electroacoustic control technique based on the principle of sound wave superposition. It utilizes a digital signal processor to generate a sound signal with the opposite phase and the same amplitude as the noise source signal, thus canceling it out and achieving noise reduction. It is particularly effective at reducing low-frequency noise. With the ever-increasing processing speed of digital signal processors, active noise cancellation technology has developed rapidly and is now widely used in fields such as active silencing in pipelines, active noise-canceling headphones, aircraft, and automobiles. Because the control area is concentrated in these applications, the noise reduction effect of active noise cancellation technology is significant.
[0037] With the rapid development of highway transportation, residents along the routes suffer greatly from noise pollution. Currently, the most common noise reduction measures for highway traffic noise are threefold: noise reduction at the source, noise reduction during propagation, and noise reduction at the receiving point—all passive noise reduction methods. Sound barriers are a simple, practical, and effective measure for controlling traffic noise. However, their limited geometric dimensions limit their ability to attenuate low-frequency sound. Active sound barriers are a new type of sound barrier that combines active noise control technology. They compensate for the aforementioned shortcomings of sound barriers by actively interfering with diffracted low-frequency sound, thus actively controlling noise through active noise reduction technology.
[0038] Active noise reduction for traffic noise involves installing active noise reduction nodes on both sides of the highway. The nodes collect traffic noise through microphones, process the collected noise through a computing unit, and then emit sound with the same amplitude but opposite phase through a loudspeaker to cancel out the traffic noise, thereby reducing traffic noise.
[0039] Traditional sound barriers are a simple, practical, and effective measure for controlling traffic noise. However, their limited geometric dimensions limit their ability to attenuate low-frequency sound. Active sound barriers are a new type of sound barrier that incorporates active noise control technology. They compensate for the aforementioned shortcomings of traditional sound barriers by actively interfering with diffracted low-frequency sound. An active sound barrier is essentially a traditional sound barrier with active noise reduction modules installed as an auxiliary component, featuring a multi-channel distributed adaptive active sound control system.
[0040] Active noise reduction technology is a method of actively controlling noise. It generally involves artificially creating and controlling a secondary sound source, ensuring that the sound emitted by this secondary source has the same amplitude but is out of phase with the noise radiated by the original noise source (primary source), thus achieving noise reduction. Active control can be effective, generating additional attenuation on top of barrier insertion attenuation; active control is stable and effective when the distance between the sound pressure cancellation points at the upper edge of the barrier is less than half the wavelength; the closer the secondary source is to the primary source, the better the active control effect.
[0041] An active noise cancellation module mainly consists of three parts: a loudspeaker, a microphone, and a main unit. Each active noise cancellation module is composed of three main parts: a loudspeaker, a microphone, and a main unit. Details of each module are as follows:
[0042] Speaker: The active noise cancellation module uses a high-performance outdoor speaker, which must have good frequency response characteristics, as well as high temperature resistance and waterproof performance.
[0043] Microphone: The active noise reduction module uses a high-performance waterproof microphone with an operating frequency range of 20Hz to 20000Hz.
[0044] Main unit: The main unit of the active noise cancellation module consists of an ARM+DSP architecture board. The main unit processes the sound signal collected by the microphone, analyzes the distribution pattern and propagation characteristics of the sound field, calculates the anti-noise, and then inputs the anti-noise signal to the speaker for output.
[0045] The effective height design of a sound barrier is crucial. According to sound barrier noise reduction theory, when sound waves are incident on a sound barrier, diffraction, transmission, reflection, and absorption occur, creating a low-level sound shadow zone within a certain distance behind the barrier, thus achieving noise reduction. To reduce noise from sensitive targets, the targets must be within the sound shadow zone of the sound barrier, and the size of the sound shadow zone is directly related to the height of the sound barrier. Therefore, implementing active noise reduction measures will correspondingly increase the effective height of the sound barrier.
[0046] Active noise reduction modules artificially generate secondary sound waves, which control and cancel out the original noise through interference cancellation. The degree of noise reduction depends entirely on the amplitude relationship between the two. Its physical basis mainly includes sound field coherence theory and JMC theory.
[0047] The algorithm implementation path is as follows: Assume that s, n0, and n1 are stationary random processes with zero mean, and that s is uncorrelated with n0 and n1. The output y = n2 of the adaptive filter is the filtered signal of the noise n1. Then the output of the entire system is: z = dy = s + n0 - y. Squaring both sides, we get: z2 = s2 + (n0 - y)2 + 2s(n0 - y).
[0048] Taking the expected value from both sides: E[z2]=E[s2]+E[(n0-y)2]+2E[s(n0-y)2],E[z2]=E[s2]+E[(n0-y)2],where E[s2] represents the power of the signal.
[0049] As can be seen from the above formula, in order to make the system output z as close as possible to the signal s, E[(n0-y)2] must be minimized.
[0050] As shown in the formula, zs = n0 - y. In an ideal situation, y = n0, then z = s; the noise in the output signal z is completely canceled, leaving only the useful signal s. Therefore, the key to active noise reduction lies in the adaptive filter. Adaptive algorithms are used to change the filter parameters and structure according to changes in the environment. Commonly used adaptive algorithms include: Recursive Least Squares (RLS), Least Mean Square (LMS), and Root Square Adaptive Filtering (QR_RLS).
[0051] For active noise control, it mainly consists of: primary source and sound field characteristics; secondary source layout; error sensor layout; control algorithm and hardware; and microphone / loudspeaker characteristics.
[0052] Among them, the primary source and sound field characteristics, namely the traffic noise of the bridge section, are objective factors that have the greatest impact on the noise reduction effect; the layout of the secondary sound source and the layout of the error sensor are electroacoustic device layout issues that have a significant impact on the noise reduction effect; the active control algorithm, hardware, and microphone / speaker characteristics have the least impact.
[0053] Generally speaking, objective factors are uncontrollable, so we optimize the active module here.
[0054] The optimization process includes:
[0055] Multiple candidate error sensors and microphone positions are determined; the primary sound field is simulated; each candidate error sensor and microphone measures the primary sound field data; each candidate secondary sound source emits sound, and each candidate error sensor and microphone measures the secondary sound field data; the primary and secondary sound field data are imported into a layout optimization program to obtain a better secondary sound source layout and a better error sensor layout; under simulation and real-world conditions, electroacoustic devices are installed according to the better secondary sound source layout and the better error sensor layout to obtain simulated noise reduction and experimental noise reduction, respectively; the accuracy of the better secondary sound source layout and the better error sensor layout obtained under simulation conditions is verified by comparing the simulated noise reduction and the experimental noise reduction.
[0056] The constraints for active modules include:
[0057] To maximize noise reduction: In practice, the output of the error sensor (i.e., the sound pressure at a limited location) is used as the monitoring quantity, usually in one of the following forms: sound energy, average sound potential energy, active sound intensity, etc. In order to adapt to the human auditory perception of noise, sound quality evaluation parameters have also been used as evaluation quantities in recent years.
[0058] Minimize the number of electroacoustic devices: reduce system cost to the greatest extent possible and increase system stability and reliability.
[0059] Restrictions on the installation location of electroacoustic devices: They must be installed away from areas with high human activity, equipment installation, and other sensitive locations that may affect safety.
[0060] Limitations of secondary sound source output power: Exceeding the rated power will cause nonlinear response of the speaker, and prolonged operation will cause damage to the device; in order to maintain the sound field balance in all parts of the space after noise reduction, the output power of different secondary speakers should avoid excessive fluctuations as much as possible.
[0061] During system implementation, the installation position of electroacoustic devices inevitably deviates from the design position. This perturbation can be divided into systematic deviation and random error. Therefore, it is necessary to control the error sensor. The residual sound pressure at the error sensor is: p r =p p +Zq; Control cost function, residual sum of squares of sound pressure is: The optimal secondary sound source intensity under this control objective is: q = -(Z H Z) -1 Z H p p Noise reduction at the error sensor:
[0062] The modules employ a distributed control serial connection. To accommodate a two-layer VW (Vehicle Warp Drive) installation mode, two types of active modules are designed: Type A and Type B. Type A is installed in the lower section, and Type B is installed in the upper section. Type A has a 7-core serial connection, while Type B has a 9-core serial connection. A main unit is installed every 30-50 meters.
[0063] Example 2
[0064] To address the aforementioned technical problems, embodiments of the present invention provide an optimized installation system for an active noise reduction barrier, wherein the active noise reduction barrier includes the active noise reduction module and the sound barrier;
[0065] The active module includes a speaker unit, a sound transmission unit, and a computing and processing unit.
[0066] The sound transmission unit is used to collect the diffracted sound signal and output it to the computing and processing unit; the computing and processing unit is used to receive the diffracted sound signal collected by the sound transmission unit, process and calculate it to obtain the reflected sound signal, and then output the reflected sound signal to the speaker unit; the speaker unit is used to receive the reflected sound signal output by the computing and processing unit and emit the reflected sound; the sound barrier is used to block the propagation path of the primary sound field; the active module is used to reduce the primary sound field after attenuation by the sound barrier.
[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. An optimized installation method for an active noise barrier, characterized in that, The active noise reduction barrier includes an active noise reduction module and a sound barrier, and includes the following steps: The sound barrier blocks the propagation path of the noise field, forming a sound shadow zone. The noise field is a primary sound field. The primary sound field will gather at the top of the sound barrier to form a new diffracted sound source. The active noise reduction module is installed at the top of the sound barrier to emit reflected sound to reduce the diffracted sound emitted by the diffracted sound source, and to expand the area of the sound shadow zone and form an interference zone. The expanded sound shadow area is superimposed with the formed interference area to form a noise reduction area after the noise reduction effect is superimposed; The noise reduction influencing factors of the active noise reduction module include the layout of the secondary sound source and the layout of the error sensor. The space optimization of the active noise reduction module is achieved by finding the optimal layout of the secondary sound source and the optimal layout of the error sensor. The active noise reduction module comprises three parts: a speaker, a microphone, and a main unit; The steps for determining the optimal secondary sound source layout and the optimal error sensor layout include: Determine the positions of multiple sets of alternative error sensors and microphones; Simulate the primary sound field; Each of the alternative error sensors and the microphone measures the primary sound field data; Each of the alternative secondary sound sources emits sound, and each of the alternative error sensors and the microphone measures the secondary sound field data; Import the primary sound field data and the secondary sound field data into the program for calculating layout optimization to obtain a better secondary sound source layout and a better error sensor layout. The secondary sound source and the error sensor are installed according to the preferred secondary sound source layout and the preferred error sensor layout, and the deviation of the installation position is controlled by controlling the error sensor. The constraints of active noise reduction modules include: maximizing noise reduction effect, minimizing the number of electroacoustic devices, limiting the installation location of electroacoustic devices, and limiting the output power of secondary sound sources. The modules are connected in a distributed control series manner. In order to adapt to the two-layer VW installation mode, two types of active modules are designed, namely Type A and Type B. Type A is installed in the lower section and Type B is installed in the upper section. Type A series connection has 7 cores, and Type B series connection has 9 cores.
2. The optimized installation method for an active noise barrier according to claim 1, characterized in that, The reflected sound is a sound with the same spectrum as the diffracted sound but opposite in phase.
3. The optimized installation method for an active noise barrier according to claim 1, characterized in that, Also includes: The sound barrier initially reduces the primary sound field. The primary sound field is further reduced by the active noise reduction module.
4. The optimized installation method for an active noise barrier according to claim 1, characterized in that, The microphone collects the diffracted sound signal and outputs it to the host; the host receives the diffracted sound signal collected by the microphone, processes and calculates it to obtain the reflected sound signal, and then outputs the reflected sound signal to the loudspeaker; the loudspeaker receives the reflected sound signal output by the host and emits the reflected sound, and the loudspeaker is used as the sound source, then the loudspeaker is called the secondary sound source.
5. The optimized installation method for an active noise barrier according to claim 4, characterized in that, Under simulated and real-world conditions, electroacoustic devices are installed according to a preferred secondary sound source layout and a preferred error sensor layout to obtain simulated noise reduction and experimental noise reduction, respectively. The accuracy of the preferred secondary sound source layout and preferred error sensor layout obtained under the simulated conditions is verified by comparing the simulated noise reduction and the experimental noise reduction. The electroacoustic devices include the secondary sound source and the error sensor.
6. An optimized installation system for an active noise barrier, characterized in that, The active noise reduction barrier includes an active noise reduction module and a sound barrier. The active noise reduction module includes a speaker unit, a sound transmission unit, and a computing and processing unit. The sound transmission unit is used to collect the diffracted sound signal and output it to the calculation and processing unit; the calculation and processing unit is used to receive the diffracted sound signal collected by the sound transmission unit, process and calculate it to obtain the reflected sound signal, and then output the reflected sound signal to the speaker unit. The speaker unit is used to receive the reflected sound signal output by the computing and processing unit and to emit the reflected sound; By using sound reflection to reduce diffracted sound and expanding the area of the sound shadow zone formed by the sound barrier blocking the noise sound field to form an interference zone, the expanded sound shadow zone and the formed interference zone are superimposed to form a noise reduction area after the noise reduction effect is superimposed. The noise reduction influencing factors of the active noise reduction module include the layout of the secondary sound source and the layout of the error sensor. The space optimization of the active noise reduction module is achieved by finding the optimal layout of the secondary sound source and the optimal layout of the error sensor. The steps for determining the optimal secondary sound source layout and the optimal error sensor layout include: Determine the positions of multiple sets of candidate error sensors and sound transmission units; Simulates a primary sound field; Each of the alternative error sensors and the sound transmission unit measures the primary sound field data; Each of the alternative secondary sound sources emits sound, and each of the alternative error sensors and the sound transmission unit measures the secondary sound field data; Import the primary sound field data and the secondary sound field data into the program for calculating layout optimization to obtain a better secondary sound source layout and a better error sensor layout. The secondary sound source and the error sensor are installed according to the preferred secondary sound source layout and the preferred error sensor layout, and the deviation of the installation position is controlled by controlling the error sensor. The constraints of active noise reduction modules include: maximizing noise reduction effect, minimizing the number of electroacoustic devices, limiting the installation location of electroacoustic devices, and limiting the output power of secondary sound sources. The modules are connected in a distributed control series manner. In order to adapt to the two-layer VW installation mode, two types of active modules are designed, namely Type A and Type B. Type A is installed in the lower section and Type B is installed in the upper section. Type A series connection has 7 cores, and Type B series connection has 9 cores.
7. The optimized installation system for an active noise barrier as described in claim 6, characterized in that, The sound barrier is used to block the propagation path of the primary sound field; the active noise reduction module is used to reduce the primary sound field after it has been attenuated by the sound barrier.