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Recent Applications of Active and Passive Noise Control

A topical collection in Applied Sciences (ISSN 2076-3417). This collection belongs to the section "Acoustics and Vibrations".

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Editors


E-Mail Website
Collection Editor
School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore
Interests: active noise control; adaptive signal processing; psycho-acoustical signal processing; spatial/3D audio processing
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Collection Editor
Department of Electrical, Electronic and Information Engineering, Faculty of Engineering Science, Kansai University, Osaka 564-8680, Japan
Interests: audio and acoustic signal processing; active noise control; sound reproduction
Special Issues, Collections and Topics in MDPI journals

Topical Collection Information

Dear Colleagues,

Active and Passive Noise Control (ANPC) has been successfully applied to many commercial applications, such as the use of noise-cancelling headsets in airplanes, hearing aids, noise control for head rests, vacuum cleaners, and noise-quietening car seats in automobiles. In larger-scale systems, this technology has been used in ventilation ducts, cooker hoods, data server racks, and free field noise control systems for the interior parts of propeller planes, trains, and luxury yachts. In recent years, we have also witnessed growing research interest in controlling noise entering residential buildings through open windows. With the advancement of low-cost, fast-computation hardware, which can take on more complex, multi-channel, adaptive, signal-processing algorithms, coupled with reliable sensors and actuators, we are expecting to see more innovative products that harness the power of ANPC to make quieter devices and machinery. However, there are still several research and development issues under investigation. In this Topical Collection, we aim to solicit the latest research findings, approaches, and applications of ANPC to better mitigate acoustic noise in a more efficient manner.

Prof. Woon-Seng Gan
Prof. Yoshinobu Kajikawa
Collection Editors

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Keywords

active noise control algorithms; sensor and actuator placement; virtual sensing and noise control; secondary path modeling; new applications of active and passive noise control; multiple-channel active noise control system; psychoacoustic techniques applied to active noise control; applying machine learning techniques for active noise control; integration of active noise control subsystems; hybrid approach to noise mitigation; new techniques in active noise control; acoustical modeling and simulation; commercial applications or industry deployments; experimentation studies

Published Papers (15 papers)

2023

Jump to: 2021, 2020, 2019

23 pages, 7803 KiB  
Article
Strategies for Reducing Booming Noise Generated by the Tailgate of an Electric Sport Utility Vehicle
by Dongju Kim, Sangmin Jeon, Jeonga Lee, Kyoungtaek Kwak, Manhee Cho, Horyul Lee, Minsik Kim and Jintai Chung
Appl. Sci. 2023, 13(24), 13134; https://doi.org/10.3390/app132413134 - 10 Dec 2023
Viewed by 1017
Abstract
This article investigates the source of booming noise emanating from the tailgate of an electric sport utility vehicle (SUV), along with proposed strategies to mitigate it. This annoying low-frequency booming noise, which significantly impacts interior sound quality, is less perceptible in conventional internal [...] Read more.
This article investigates the source of booming noise emanating from the tailgate of an electric sport utility vehicle (SUV), along with proposed strategies to mitigate it. This annoying low-frequency booming noise, which significantly impacts interior sound quality, is less perceptible in conventional internal combustion engine vehicles. However, this noise is more readily detected in electric SUVs, highlighting the necessity for focused measures to reduce it. This study involved the measurement of booming noises during on-road vehicle tests to pinpoint their origins. Additionally, ODSs were extracted from the tailgate vibration signals to gain insight into its dynamic behavior. Modal tests were conducted on the tailgate to determine its dynamic characteristics and compared with driving test results to reveal the mechanism responsible for tailgate-induced booming noise. It was established that such noise is primarily due to the tailgate modes, resulting from a combination of rigid body motion in the fore-aft direction and deformation in the central section of the panel. An analytical model of the tailgate was developed using commercial finite-element analysis software to propose measures for reducing booming noise. Experimental findings validated this model’s accuracy. Structural enhancements were implemented to enhance the panel stiffness and improve the connection between the vehicle and tailgate via bushings to reduce the booming noise resulting from tailgate motion. Under random force inputs, the analytical results demonstrated a 13.8% reduction in maximum deformation in the tailgate model in the improved structural configuration with increased panel stiffness. This study identifies the mechanism generating booming noise, establishes a practical and simple dynamic model, and proposes improvement measures aimed at reducing the booming noise. Full article
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2021

Jump to: 2023, 2020, 2019

15 pages, 5363 KiB  
Article
Development and Validation of a Masking System for Mitigation of Low-Frequency Audible Noise from Electrical Substations
by Rogerio Regazzi, Brunno Cunha, Hugo Villela de Miranda, Juan José Gómez Acosta, Carlos Roberto Hall Barbosa, Mauricio Nogueira Frota, João Vitor Souza and Carlos Augusto Machado Gomes
Appl. Sci. 2021, 11(17), 7771; https://doi.org/10.3390/app11177771 - 24 Aug 2021
Cited by 1 | Viewed by 1486
Abstract
Low-frequency audible noise generated by the magnetostriction effect inherent to the operation of power transformers has become a major drawback, especially in cases where the electrical substation is located in urban areas subject to strict environmental regulations that impose noise limits, differing for [...] Read more.
Low-frequency audible noise generated by the magnetostriction effect inherent to the operation of power transformers has become a major drawback, especially in cases where the electrical substation is located in urban areas subject to strict environmental regulations that impose noise limits, differing for day and night periods. Such regulations apply a +5 dB penalty if a tonal component of noise is present, which is clearly the case of magnetostriction noise, typically concentrated at twice the industrial frequency (50 Hz or 60 Hz, depending on the country). The strategy used to eliminate the tonal characteristics, therefore contributing to establish compliance with the applicable regulation and to alleviate the discomfort it causes to the human ear, consisted in superimposing to the substation noise a masking sound synthesized from “sounds of nature” with suitable intensities, to flatten the noise spectrum while enhancing the soundscape. The masking system (heavy-duty speakers powered by a microprocessor platform) was validated at an already judicialized urban scenario. Measurement results confirmed that the masking solution was capable of flattening the tonal frequencies, whose beneficial effect yielded the cancellation of the public civil action filed by the neighbors. The proposed solution is ready to be replicated in other scenarios. Full article
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20 pages, 4733 KiB  
Article
Improved Power Normalized Cepstrum Coefficient Based on Wavelet Packet Decomposition for Trunk Borer Detection in Harsh Acoustic Environment
by Huanyu Zhou, Ziqi He, Liping Sun, Dongyan Zhang, Hongwei Zhou and Xiaodong Li
Appl. Sci. 2021, 11(5), 2236; https://doi.org/10.3390/app11052236 - 03 Mar 2021
Cited by 7 | Viewed by 1830
Abstract
The sound-detection method of trunk borer is a very promising method in the field of forestry prevention and control of trunk borers. However, the detection accuracy of commonly used algorithms often decreases sharply in the case of noise reverberation interference. In practical applications, [...] Read more.
The sound-detection method of trunk borer is a very promising method in the field of forestry prevention and control of trunk borers. However, the detection accuracy of commonly used algorithms often decreases sharply in the case of noise reverberation interference. In practical applications, the sound monitoring of trunk borers often takes place in a harsh acoustic environment. To solve this problem, we intend to introduce methods which are effective in other related acoustic fields. Unfortunately, most of the methods are not suitable for acoustic detection of trunk borers and perform extremely poorly. After trying various methods, we found that Power-Normalized Cepstral Coefficients (PNCC) performed well in some cases, while it did not in others. This is due to the difference between speech and trunk borer sound. Therefore, an improved anti-noise PNCC based on wavelet package is proposed. The dmey wavlet system always obtains the best performance. We collected the audio of the following five dry borer pests for testing. They are red palm weevil, mountain pine beetle, red necked longicorn, Asian longhorn beetle and citrus longhorn beetle. In the experimental part, we used genetic algorithm-support vector machine (GA-SVM) as a classifier to compare Mel Cepstral Coefficients (MFCC), which are the most common methods in the field of audio detection of trunk borer, PNCC and improved PNCC in a variety of noise environments. The results showed that, compared with other methods, the newly proposed method can often achieve better results. The above experiments take the audio clips made of clear pest sound mixed noise. In order to further verify the effectiveness of the method, we designed another experiment with a harsh outdoor acoustic environment. We found that the proposed method achieved 88% accuracy and the traditional PNCC achieved 78% accuracy. However, the Mel cepstrum coefficient completely lost its ability to distinguish. In sum, the proposed PNCC based on wavelet packet decomposition can be used as a detection method for trunk borer in the harsh acoustic environment. This method has many advantages, including simple extraction and strong robustness to noise. Combined with cheap audio acquisition equipment, this method can effectively improve the early warning ability of forestry borer pests. Full article
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2020

Jump to: 2023, 2021, 2019

24 pages, 5436 KiB  
Article
Modified Filtered-X Hierarchical LMS Algorithm with Sequential Partial Updates for Active Noise Control
by Pedro Ramos Lorente, Raúl Martín Ferrer, Fernando Arranz Martínez and Guillermo Palacios-Navarro
Appl. Sci. 2021, 11(1), 344; https://doi.org/10.3390/app11010344 - 31 Dec 2020
Cited by 4 | Viewed by 1942
Abstract
In the field of active noise control (ANC), a popular method is the modified filtered-x LMS algorithm. However, it has two drawbacks: its computational complexity higher than that of the conventional FxLMS, and its convergence rate that could still be improved. Therefore, we [...] Read more.
In the field of active noise control (ANC), a popular method is the modified filtered-x LMS algorithm. However, it has two drawbacks: its computational complexity higher than that of the conventional FxLMS, and its convergence rate that could still be improved. Therefore, we propose an adaptive strategy which aims at speeding up the convergence rate of an ANC system dealing with periodic disturbances. This algorithm consists in combining the organization of the filter weights in a hierarchy of subfilters of shorter length and their sequential partial updates (PU). Our contribution is threefold: (1) we provide the theoretical basis of the existence of a frequency-dependent parameter, called gain in step-size. (2) The theoretical upper bound of the step-size is compared with the limit obtained from simulations. (3) Additional experiments show that this strategy results in a fast algorithm with a computational complexity close to that of the conventional FxLMS. Full article
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12 pages, 7831 KiB  
Article
A Basic Study on Sound Control System for Ultra-Compact Electric Vehicle by Using Masking
by Taro Kato, Hiroya Nakayama, Hideaki Kato and Takayoshi Narita
Appl. Sci. 2020, 10(10), 3412; https://doi.org/10.3390/app10103412 - 15 May 2020
Cited by 3 | Viewed by 1820
Abstract
In this study, we conducted a quantitative evaluation of the comfort of the interior of an electric vehicle (EV) using the brain wave appearance rate, which is part of the human biologic information that the initial stage of the proposed active noise control [...] Read more.
In this study, we conducted a quantitative evaluation of the comfort of the interior of an electric vehicle (EV) using the brain wave appearance rate, which is part of the human biologic information that the initial stage of the proposed active noise control (ANC) system for ultra-compact EVs reveals. EVs have become easy-to-use mobility solutions and have been researched and actively developed focusing on using music characteristics. We performed fundamental testing of music including 1/f fluctuation for the evaluation of ride comfort based on the relationship between the participant’s heart rate and tempo of music using a driving simulator. The results suggest that if a passenger listened to music including a 1/f fluctuation, then he/she could relax. Thus, it was concluded that if we could pre-grasp the passenger’s biologic information of the heart rate and beats per minute for masking, then the comfort in the interior space could be improved even when using a driving simulator. Full article
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12 pages, 325 KiB  
Article
A Supervised Speech Enhancement Approach with Residual Noise Control for Voice Communication
by Andong Li, Renhua Peng, Chengshi Zheng and Xiaodong Li
Appl. Sci. 2020, 10(8), 2894; https://doi.org/10.3390/app10082894 - 22 Apr 2020
Cited by 7 | Viewed by 2999
Abstract
For voice communication, it is important to extract the speech from its noisy version without introducing unnaturally artificial noise. By studying the subband mean-squared error (MSE) of the speech for unsupervised speech enhancement approaches and revealing its relationship with the existing loss function [...] Read more.
For voice communication, it is important to extract the speech from its noisy version without introducing unnaturally artificial noise. By studying the subband mean-squared error (MSE) of the speech for unsupervised speech enhancement approaches and revealing its relationship with the existing loss function for supervised approaches, this paper derives a generalized loss function that takes residual noise control into account with a supervised approach. Our generalized loss function contains the well-known MSE loss function and many other often-used loss functions as special cases. Compared with traditional loss functions, our generalized loss function is more flexible to make a good trade-off between speech distortion and noise reduction. This is because a group of well-studied noise shaping schemes can be introduced to control residual noise for practical applications. Objective and subjective test results verify the importance of residual noise control for the supervised speech enhancement approach. Full article
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13 pages, 2285 KiB  
Article
A Unified Speech Enhancement System Based on Neural Beamforming With Parabolic Reflector
by Tao Zhang, Yanzhang Geng, Jianhong Sun, Chen Jiao and Biyun Ding
Appl. Sci. 2020, 10(7), 2218; https://doi.org/10.3390/app10072218 - 25 Mar 2020
Cited by 5 | Viewed by 2399
Abstract
This paper presents a unified speech enhancement system to remove both background noise and interfering speech in serious noise environments by jointly utilizing the parabolic reflector model and neural beamformer. First, the amplification property of paraboloid is discussed, which significantly improves the Signal-to-Noise [...] Read more.
This paper presents a unified speech enhancement system to remove both background noise and interfering speech in serious noise environments by jointly utilizing the parabolic reflector model and neural beamformer. First, the amplification property of paraboloid is discussed, which significantly improves the Signal-to-Noise Ratio (SNR) of a desired signal. Therefore, an appropriate paraboloid channel is analyzed and designed through the boundary element method. On the other hand, a time-frequency masking approach and a mask-based beamforming approach are discussed and incorporated in an enhancement system. It is worth noticing that signals provided by the paraboloid and the beamformer are exactly complementary. Finally, these signals are employed in a learning-based fusion framework to further improve the system performance in low SNR environments. Experiments demonstrate that our system is effective and robust in five different noisy conditions (speech interfered with factory, pink, destroyer engine, volvo, and babble noise), as well as in different noise levels. Compared with the original noisy speech, significant average objective metrics improvements are about Δ STOI = 0.28, Δ PESQ = 1.31, Δ fwSegSNR = 11.9. Full article
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25 pages, 15196 KiB  
Article
Research on Ride Comfort and Driving Safety under Hybrid Damping Extension Control for Suspension Systems
by Guoqing Geng, Yi Yu, Liqin Sun and Hao Li
Appl. Sci. 2020, 10(4), 1442; https://doi.org/10.3390/app10041442 - 20 Feb 2020
Cited by 5 | Viewed by 3026
Abstract
This paper is concerned with the conflicting performances of ride comfort and driving safety for semi-active suspension systems. To alleviate this conflict, a novel hybrid damping extension control (HDEC) method is proposed. This method adopts various control methods and the weights of each [...] Read more.
This paper is concerned with the conflicting performances of ride comfort and driving safety for semi-active suspension systems. To alleviate this conflict, a novel hybrid damping extension control (HDEC) method is proposed. This method adopts various control methods and the weights of each method are determined by extension theory. Firstly, body acceleration and tire dynamic transformation are selected to evaluate ride comfort and driving safety performance for the semi-active suspension system and their frequency responses of passive suspension, sky-hook control, ground hook control, and S-GH (sky-ground hook) control are analyzed based on a two degree-of-freedom (2-DOF) model. Secondly, extension theory is introduced and the extension control system, which contains three modes and corresponding control algorithms, is established. In addition, the low-frequency excitation and high-frequency excitation simulations are designed to determine the parameters of the extension control system. Finally, ve-DYNA vehicle suspension model simulation is applied to prove the feasibility and effectiveness of the extension control. The simulation results show that, based on the suspension state, extension control can improve the performance of ride comfort and driving safety. Full article
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2019

Jump to: 2023, 2021, 2020

7 pages, 1500 KiB  
Article
Dual-Zone Active Noise Control Algorithm
by Ran Wang, Xiaolin Wang, Jingwei Liu and Jun Yang
Appl. Sci. 2020, 10(1), 4; https://doi.org/10.3390/app10010004 - 18 Dec 2019
Cited by 4 | Viewed by 2334
Abstract
When active noise control (ANC) is applied to acquire a ‘quiet zone’, it may produce an increase in the sound power outside the quiet zone and a change in the primary sound field, which are undesirable in anti-detection and personal audio. To obtain [...] Read more.
When active noise control (ANC) is applied to acquire a ‘quiet zone’, it may produce an increase in the sound power outside the quiet zone and a change in the primary sound field, which are undesirable in anti-detection and personal audio. To obtain a large noise reduction in the control zone and a small increase of sound power outside the control zone, three wideband ANC algorithms are proposed based on the acoustic contrast control (ACC), least-squares (LS), and least-squares with acoustic contrast control (SFR-ACC) algorithms. With a loudspeaker array as the secondary source, dual-zone ANC with directivity, which realizes noise reduction in one zone without changing the sound power in the other zone, is achieved. Compared with the traditional LS algorithm, the three algorithms proposed in this paper can not only realize that the sound power outside the control zone is increased by less than 1 dB, but also reduce the noise in the control zone by more than 10 dB, which provides a new solution to multi-zone ANC research. Full article
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10 pages, 3365 KiB  
Article
Voltage-Controlled Synthetic Inductors for Resonant Piezoelectric Shunt Damping: A Comparative Analysis
by Marian Vatavu, Vasile Nastasescu, Flaviu Turcu and Ioan Burda
Appl. Sci. 2019, 9(22), 4777; https://doi.org/10.3390/app9224777 - 08 Nov 2019
Cited by 15 | Viewed by 3091
Abstract
In this paper, the design, simulations, and experimental results related to new analog circuits for voltage controlled synthetic inductors (VCSI) are presented. The new circuits based on a generalized impedance converter (GIC) are proposed for adaptive resonant piezoelectric shunt damping. The VCSIs are [...] Read more.
In this paper, the design, simulations, and experimental results related to new analog circuits for voltage controlled synthetic inductors (VCSI) are presented. The new circuits based on a generalized impedance converter (GIC) are proposed for adaptive resonant piezoelectric shunt damping. The VCSIs are implemented using (1) an analog multiplier and (2) an operational transconductance amplifier (OTA) as voltage-controlled resistor. The simulation and experimental results for the new proposed VCSIs are presented and a comparative analysis follows. The proposed VCSIs work in a stable manner in parallel with negative impedance converters (NIC) to enhance structural damping in resonant piezoelectric resistive-inductive shunt applications. The behavior of the synthetic inductor is identical to a real inductor only in a specific frequency range and this situation can explain the reported spreading performance in the literature for resonant piezoelectric shunt damping. The simulation results are validated by a group of experimental investigations that confirm the improved stability and linearity of the new circuits proposed as VCSIs. Experimental results show that the VCSI based on an analog multiplier have an enhanced linearity in comparison with the OTA version in a limited voltage control range. Full article
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15 pages, 391 KiB  
Brief Report
Multichannel Active Noise Control Based on Filtered-x Affine Projection-Like and LMS Algorithms with Switching Filter Selection
by Ángel A. Vázquez, Eduardo Pichardo, Juan G. Avalos, Giovanny Sánchez, Hugo M. Martínez, Juan C. Sánchez and Héctor M. Pérez
Appl. Sci. 2019, 9(21), 4669; https://doi.org/10.3390/app9214669 - 01 Nov 2019
Cited by 7 | Viewed by 2680
Abstract
Affine projection (AP) algorithms have been demonstrated to have faster convergence speeds than the conventional least mean square (LMS) algorithms. However, LMS algorithms exhibit smaller steady-state mean square errors (MSEs) when compared with affine projection (AP) algorithms. Recently, several authors have proposed alternative [...] Read more.
Affine projection (AP) algorithms have been demonstrated to have faster convergence speeds than the conventional least mean square (LMS) algorithms. However, LMS algorithms exhibit smaller steady-state mean square errors (MSEs) when compared with affine projection (AP) algorithms. Recently, several authors have proposed alternative methods based on convex combinations to improve the steady-state MSE of AP algorithms, even with the increased computational cost from the simultaneous use of two filters. In this paper, we present an alternative method based on an affine projection-like (APL-I) algorithm and least mean square (LMS) algorithm to solve the ANC under stationary Gaussian noise environments. In particular, we propose a switching filter selection criteria to improve the steady-state MSE without increasing the computational cost when compared with existing models. Here, we validate the proposed strategy in a single and a multichannel system, with and without automatically adjusting the scaling factor of the APL-I algorithm. The results demonstrate that the proposed scheme exploits the best features of each filter (APL-I and LMS) to guarantee rapid convergence with a low steady-state MSE. Additionally, the proposed approach demands a low computational burden compared with existing convex combination approaches, which will potentially lead to the development of real-time ANC applications. Full article
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20 pages, 666 KiB  
Article
Chatter Mitigation in Milling Process Using Discrete Time Sliding Mode Control with Type 2-Fuzzy Logic System
by Satyam Paul and Ruben Morales-Menendez
Appl. Sci. 2019, 9(20), 4380; https://doi.org/10.3390/app9204380 - 16 Oct 2019
Cited by 5 | Viewed by 3700
Abstract
In order to achieve a high-quality machining process with superior productivity, it is very important to tackle the phenomenon of chatter in an effective manner. The problems like tool wear and improper surface finish affect the milling process and are caused by self-induced [...] Read more.
In order to achieve a high-quality machining process with superior productivity, it is very important to tackle the phenomenon of chatter in an effective manner. The problems like tool wear and improper surface finish affect the milling process and are caused by self-induced vibration termed as chatter. A strategy to control chatter vibration actively in the milling process is presented. The mathematical modeling of the process is carried out initially. In this paper, an innovative technique of discrete time sliding mode control (DSMC) is blended with the type-2 fuzzy logic system. The proposed active controller results in a significantly high mitigation of vibration. The DSMC is linked to the time-varying gain which is an innovative approach to mitigate chattering. The theorem is laid down which validates that the system states are bounded in the case of DSMC-type-2 fuzzy. Stability analysis is carried out using Lyapunov candidate. The nonlinearities linked with the cutting forces and damper friction are handled effectively by using the type-2 fuzzy logic system. The performance of the DSMC-type-2 fuzzy concept is compared with the discrete time PID (D-PID) and discrete time sliding mode control for validating the effectiveness of the controller. The better performance of DSMC-type-2 fuzzy over D-PID and DSMC-T1 fuzzy in the minimization of milling chatter are validated by a numerical analysis approach. Full article
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12 pages, 1267 KiB  
Article
Directional Active Noise Control with a Local Minimax Error Criterion
by Kexun Chi, Ming Wu, Rong Han, Chen Gong and Jun Yang
Appl. Sci. 2019, 9(19), 4065; https://doi.org/10.3390/app9194065 - 29 Sep 2019
Cited by 2 | Viewed by 2006
Abstract
The traditional mean squared error (MSE) criterion can be formulated as a quadratic function of a vector of control filter coefficients, and it is easy to obtain optimal control filter coefficients. Although the MSE criterion can lead to noise reductions in the control [...] Read more.
The traditional mean squared error (MSE) criterion can be formulated as a quadratic function of a vector of control filter coefficients, and it is easy to obtain optimal control filter coefficients. Although the MSE criterion can lead to noise reductions in the control area, an unpredictable directional residual sound field is generated. In this paper, we propose a method for multi-channel active harmonic noise control with a local minimax error criterion based on the Nelder–Mead algorithm, which leads to reductions at all error positions and greater reductions at controllable positions. Directional noise reduction experiments of two areas are presented for two different error criteria at discrete locations in an anechoic chamber. Compared with a system employing the traditional MSE criterion, the results show that an active noise control system with the proposed criterion can achieve extra reductions at specified locations and overall noise reductions at the same time. The present research offers some important insights into directional control. Full article
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17 pages, 3152 KiB  
Article
Active Control of Sound Transmission through Orthogonally Rib Stiffened Double-Panel Structure: Mechanism Analysis
by Xiyue Ma, Kean Chen and Jian Xu
Appl. Sci. 2019, 9(16), 3286; https://doi.org/10.3390/app9163286 - 10 Aug 2019
Cited by 8 | Viewed by 2192
Abstract
Physical mechanisms of active control of sound transmission through orthogonally two ribs stiffened double-panel structure are investigated. This is the continued work of the single rib stiffened case. For the orthogonally two ribs stiffened case, four different cluster mode groups can be coupled [...] Read more.
Physical mechanisms of active control of sound transmission through orthogonally two ribs stiffened double-panel structure are investigated. This is the continued work of the single rib stiffened case. For the orthogonally two ribs stiffened case, four different cluster mode groups can be coupled with each other, due to the interlaced coupling effects of the horizontal and vertical ribs. One cavity mode can couple with and transmit sound energy to any type of base plate mode of the radiating ribbed plate. Consequently, the main differences of the control mechanism, when compared with the single ribbed case, lie in two aspects. One is that a novel mechanism appears. That is, suppressing and rearranging the cavity modes simultaneously achieves the suppression of the base plate modes. The other is that rearrangement of the cavity modes to rearrange the base plate modes for achieving sound radiation cancellation almost does not appear. The reason is that all types of cavity mode can couple with any one of the base plate modes due to the coupling effects of the two ribs. There is only a need to rearrange several important cavity modes to achieve suppressing the base plate mode of the radiating ribbed plate. Full article
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11 pages, 3459 KiB  
Article
A Four-Stage Method for Active Control with Online Feedback Path Modelling Using Control Signal
by Somanath Pradhan, Xiaojun Qiu and Jinchen Ji
Appl. Sci. 2019, 9(15), 2973; https://doi.org/10.3390/app9152973 - 25 Jul 2019
Viewed by 2501
Abstract
The presence of control signal feedback to the reference microphone in feedforward active control systems deteriorates the control performance. A four-stage method is proposed in this paper to carry out online feedback path modelling with the control signal. It consists of controller initialization, [...] Read more.
The presence of control signal feedback to the reference microphone in feedforward active control systems deteriorates the control performance. A four-stage method is proposed in this paper to carry out online feedback path modelling with the control signal. It consists of controller initialization, feedback path modelling using decorrelation filters, active control operation, and feedback path change detection for maintaining the control operation. In contrast to the existing auxiliary noise injection method, the proposed method uses five switches and three thresholds to control and maintain the system stability by avoiding the interference between control operation and feedback path modelling, and adaptive decorrelation filters are used to increase the feedback path modelling performance. Simulation results reveal that the proposed method is capable of tracking feedback path changes without injecting any auxiliary noise and maintaining the noise reduction performance and stability of the system. Full article
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