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"Noise control."
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Noise-controlling casings
\"Noise-Controlling Casings offers a range of feasible noise-controlling strategies for different kinds of devices generating excessive noise. Depending on the required performance and the availability of energy sources, three solution categories are presented: passive (no external energy is needed, but performance is limited), semi-active (little energy is needed, but performance achieves higher values) and active (best performance, but an external energy source is needed). Two very important benefits of these proposed solutions are global noise reduction (in an entire enclosure or the surrounding space) and compact technology (contrary to other active noise control solutions requiring a large number of secondary sources and distributed sensors). Many of the solutions presented are original approaches by the authors, their own developed concepts and new elements and designs that have gained recognition in prestigious journals. The book provides a theoretical background to the research, looking at system configurations, mathematical modelling, signal processing implementation and numerical analysis. The proposed ideas can be applied to any devices provided they have casings of thin walls or they can be enclosed by casings of thin walls. Applications include industrial devices, household appliances, vehicle or aircraft cabins and more. This book will be of interest to professionals and students in the fields of acoustics, vibration, signal processing, control, automotive and aircraft engineering.\"--Publisher marketing.
Book
Bio-inspired evolutionary computing approach for distributed active noise control problem
In this study, a distributed active noise control (DANC) system for spatial noise control in a network of acoustic sensor nodes based on the behavioural traits of felines is presented. An unified strategy based on incremental co-operative learning and cat swarm intelligence is proposed for noise mitigation in spatial region. The hybrid nature of the proposed incremental cat swarm optimisation (ICSO) algorithm provides efficient noise control without prior estimation of multiple secondary paths. In the developed ICSO-based DANC scheme, the individual sensor nodes communicate the intermediate solutions using incremental mode of cooperation to attain overall global noise mitigation over the distributed network. The performance of the proposed ICSO based DANC scheme is validated for tonal, broadband and practical air conditioner noise control test scenarios. Evaluation results show that the proposed system achieves faster convergence with computational efficiency of over 36% and ∼2–9 dB improvement in noise cancellation for different noise cases and acoustic environments over genetic algorithm and particle swarm optimisation based DANC counterparts.
Journal Article
Sound-politics in São Paulo
\"Cardoso presents Sound-Politics in São Paulo as the first book-length treatment on controversies surrounding noise control in Latin America\"-- Provided by publisher.
Book
A Hybrid Active Noise Control System for the Attenuation of Road Noise Inside a Vehicle Cabin
This paper proposed a local active control method for the reduction of road noise inside a vehicle cabin. A multichannel simplified hybrid active noise control (sHANC) system was first developed and applied to the rear left seat of a large sport utility vehicle (SUV). The attenuation capability of the sHANC system was investigated through simulations, using reference signals provided by accelerometers on the suspensions and bodywork of the vehicle and microphones on the floor of cabin, respectively. It was shown that compared to the traditional feedforward system, the sHANC system using either vibrational or acoustical reference signals can produce a significant suppression of the narrowband peak noise between 75 and 80 Hz, but the system lost the control capability in a range of 100–500 Hz when the acoustic signals were used as references. To reduce the practical implementation costs while maintaining excellent reduction performance, a modified simplified hybrid ANC (msHANC) system was further proposed, in which combined vibrational and acoustical signals were used as reference signals. The off-line analyses showed that four reference accelerometers can be substituted by ten microphones without compromising attenuation performance, with 3.7 dBA overall noise reduction being achieved. The effect of delays on the reduction performance of msHANC system was also investigated. The result showed that the msHANC system was more sensitive to the delays compared to the sHANC system if using only vibrational reference signals.
Journal Article
Diffusion Filtered-x Inverse Tangent Generalized Maximum Correntropy Criterion with Reduced Complexity for Distributed Active Noise Control
Active noise control (ANC) techniques are an alternative for employing passive noise reduction methods in real-world systems. Designing an ANC model across a network of dispersed acoustic sensor nodes with reduced complexity is a challenging task. Active noise mitigation in the existence of impulsive noise is an important issue in a dispersed scenario. A robust diffusion filtered-x inverse tangent generalized maximum correntropy criterion technique for distributed active noise control (DF-xIGDANC) is built to mitigate impulsive noise. Further the proposed DF-xIGDANC is modified as improved DF-xIGDANC (IDF-xIGDANC) technique to reduce the computational complexity. In the inverse tangent technique, the saturation qualities of error non-linearities are combined with the similarity index of generalized maximum correntropy criterion. The proposed method has been examined for active noise cancellation in a dispersed scenario using chaotic and real noise inputs. The effectiveness of noise cancellation can be seen by a 2–3 dB improvement in average noise reduction over existing methods.
Journal Article
Adaptive Filtered-x Least Mean Square Algorithm to Improve the Performance of Multi-Channel Noise Control Systems
This paper proposes an optimized control filter (OCF) based on the Filtered-x Least Mean Square (FxLMS) algorithm for multi-channel active noise control (ANC) systems. The proposed OCF-McFxLMS algorithm delivers three key contributions. Firstly, even in difficult noise situations such as White Gaussian, Brownian, and pink noise, it greatly reduces error, reaching nearly zero mean squared error (MSE) values across all Microphone (Mic) channels. Secondly, it improves computational efficiency by drastically reducing execution time from 58.17 s in the standard McFxLMS algorithm to just 0.0436 s under White Gaussian noise, enabling real-time noise control without compromising accuracy. Finally, the OCF-McFxLMS demonstrates robust noise attenuation, achieving signal-to-noise ratio (SNR) values of 137.41 dB under White Gaussian noise and over 100 dB for Brownian and pink noise, consistently outperforming traditional approaches. These contributions collectively establish the OCF-McFxLMS algorithm as an efficient and effective solution for real-time ANC systems, delivering superior noise reduction and computational speed performance across diverse noise environments.
Journal Article
A-weighted convex combination step-size based active impulsive noise control for construction vehicle noise reduction
Construction vehicles generate significant cabin noise, which includes both consistent and impulsive noise from engines and components. The noise imposes hearing loss threats to the operators during long operation hours. Active reduction is required for efficient impulsive noise minimization. Traditional approaches such as the filtered-x least mean square (FxLMS) algorithm, often prove inadequate in effectively controlling these impulsive noises, due to non-Gaussian characteristics. Robust algorithms for active impulsive noise control (AINC) systems are required for applications to construction equipment. The convex combined step-size (CCSS) based variable step-size (VSS) along with integrating the normalized least mean square (NLMS) into a modified FxLMS (MFxLMS) with an adaptive step-size update algorithm is used for reduction of the vehicle interior noise. The A-weighted filtering enhanced the noise reduction efficiency by incorporating human auditory characteristics. This filtering also minimized unnecessary control loadings at low frequency noise components. The performance of the proposed algorithm was evaluated through experiments conducted using a portion of the actual excavator cabin. The results demonstrated robust and excellent noise reduction performance against unexpected impulsive sounds.
Journal Article
Active noise control of a supersonic underexpanded planar jet guided by resolvent analysis
This study is dedicated to achieving efficient active noise control in a supersonic underexpanded planar jet, utilizing control parameters informed by resolvent analysis. The baseline supersonic underexpanded jet exhibits complex wave structures and substantial high-amplitude noise radiations. To perform the active control, unsteady blowing and suction are applied along the nozzle inner wall close to the exit. Employing both standard and acoustic resolvent analyses, a suitable frequency and spanwise wavenumber range for the blowing and suction is identified. Within this range, the control forcing can be significantly amplified in the near field, effectively altering the original sound-producing energetic structure while minimizing far-field amplification to prevent excessive noise. A series of large-eddy simulations are further conducted to validate the control efficiency, demonstrating an over 10 dB reduction in upstream-propagated screech noise. It is identified that the present unsteady control proves more effective than steady control at the same momentum coefficient. The controlled jet flow indicates that the shock structures become more stable, and the stronger the streamwise amplification of the forcing, the more likely it is to modify the mean flow characteristics, which is beneficial for reducing far-field noise radiation. Spectral proper orthogonal decomposition analysis of the controlled flow confirms that the control redistributes energy to higher forcing frequencies and suppresses large-scale antisymmetric and symmetric modes related to screech and its harmonics. The findings of this study highlight the potential of resolvent-guided control techniques in reducing noise in supersonic underexpanded jets and provide a detailed understanding of the inherent mechanisms for effective noise reduction through active control strategies.
Journal Article