Special Issue "Active and Passive Noise Control"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Acoustics and Vibrations".

Deadline for manuscript submissions: 28 February 2019

Special Issue Editors

Guest Editor
Prof. Woon Seng Gan

School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore
Website | E-Mail
Guest Editor
Prof. Yoshinobu Kajikawa

Department of Electrical, Electronic and Information Engineering, Faculty of Engineering Science, Kansai University, Japan
Website | E-Mail
Interests: Audio and acoustic signal processing, Active noise control, Spatial audio, Acoustic transducer design

Special Issue Information

Dear Coleagues,

Active and Passive Noise control (ANPC) has been successfully applied to many commercial applications, such as the noise cancelling headsets used in airplane, hearing aids, noise control for head rests, vacuum cleaners, and noise-quietening car seats in automobiles; and also in bigger scale systems, such as, ventilation ducts, cooker hoods and data server racks, and free field noise control systems for the interior of propeller planes, trains, and luxury yachts, etc. In recent years, we are also witnessing growing research interest in controlling noise coming into the 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, and 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 machineries. However, there are still several research and development issues under investigation. In this special issue, we aim to solicit the latest research findings, new approaches and applications of ANPC to better mitigate acoustical noise in a more efficient manner and approach.

Prof. Woon Seng Gan
Prof. Yoshinobu Kajikawa
Guest Editors

Manuscript Submission Information

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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 Channels 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)

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Research

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Open AccessArticle Suppression of the Hydrodynamic Noise Induced by the Horseshoe Vortex through Mechanical Vortex Generators
Appl. Sci. 2019, 9(4), 737; https://doi.org/10.3390/app9040737
Received: 26 January 2019 / Revised: 14 February 2019 / Accepted: 18 February 2019 / Published: 20 February 2019
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Abstract
The hydrodynamic noise from the horseshoe vortex can greatly destroy the acoustic stealth of underwater vehicles at low frequency. We investigated the flow-induced noise suppression mechanism by mechanical vortex generators (VGs) on a SUBOFF model. Based on the numerical simulation, we calculated the [...] Read more.
The hydrodynamic noise from the horseshoe vortex can greatly destroy the acoustic stealth of underwater vehicles at low frequency. We investigated the flow-induced noise suppression mechanism by mechanical vortex generators (VGs) on a SUBOFF model. Based on the numerical simulation, we calculated the flow field and the sound field of the three shapes of mechanical VGs: triangular, semi-circular, and trapezoidal. The triangular VGs with an angle of 30° to the flow direction achieved a better noise reduction. The optimum noise suppression is 8.93 dB, when the distance from the triangular VGs to the sail hull’s leading edge is 0.1c, where c is the chord length. The noise reduction mechanism is such that the mechanical VGs can destroy the formation of the horseshoe vortex at the origin and produce counter-rotation vortices to weaken its intensity. We created two steel models according to the simulation, and the experimental measurement was carried out in a gravity water tunnel. The measured results showed that the formation of the horseshoe vortex could be effectively inhibited by the triangular VGs. The results in our study can provide a new method for hydrodynamic noise suppression by flow control. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle Quantification of Active Structural Path for Vibration Reduction Control of Plate Structure under Sinusoidal Excitation
Appl. Sci. 2019, 9(4), 711; https://doi.org/10.3390/app9040711
Received: 21 January 2019 / Revised: 12 February 2019 / Accepted: 13 February 2019 / Published: 18 February 2019
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Abstract
The engines of electric and hybrid vehicles cause vibration and noise with complex frequency spectra. This tendency is observed especially for mid-frequency components. Therefore, there are limitations in achieving vibration attenuation using only structural changes, which is the conventional isolation method. A smart [...] Read more.
The engines of electric and hybrid vehicles cause vibration and noise with complex frequency spectra. This tendency is observed especially for mid-frequency components. Therefore, there are limitations in achieving vibration attenuation using only structural changes, which is the conventional isolation method. A smart structure-based active engine mounting system is a core technology that can continuously improve the noise, vibration, and harshness performance under various operating conditions by continuously controlling the dynamic characteristics of the mount. It can replace the existing mount technology which supports the engine by realizing both static and dynamic stiffness. This study focuses on vibration reduction for a typical mid-frequency excitation. Based on a source–path–receiver structure, a mathematical model for a 3D plate structure with three active paths is proposed. The amplitude and phase of the actuator were calculated for the reduction of given vibrations on the basis of the model. When controlling with the proposed method, it was necessary to perform a large amount of computation and to newly define the modeling according to the structural change. To solve this inconvenience, the NLMS (normalized least mean squares) algorithm was applied, and the results were compared. It is shown that the application of the NLMS algorithm to perform the overall vibration reduction is more effective than the previous method. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle Development of Multi-Staged Adaptive Filtering Algorithm for Periodic Structure-Based Active Vibration Control System
Appl. Sci. 2019, 9(3), 611; https://doi.org/10.3390/app9030611
Received: 27 January 2019 / Revised: 7 February 2019 / Accepted: 9 February 2019 / Published: 12 February 2019
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Abstract
A digital adaptive filtering system is applied to various fields such as current disturbance, noise cancellation, and active vibration and noise control. The least mean squares (LMS) algorithm is widely adopted, owing to its simplicity and low computational burden. A limitation of the [...] Read more.
A digital adaptive filtering system is applied to various fields such as current disturbance, noise cancellation, and active vibration and noise control. The least mean squares (LMS) algorithm is widely adopted, owing to its simplicity and low computational burden. A limitation of the LMS algorithm with fixed step size is the trade-off between convergence speed and stability. Several studies have tried to overcome this limitation by varying the step size according to filter input and error; however, the related algorithms with variable step size have not been suitable for signals with complex frequency spectra. As the error decreases, the quality of the output signal deteriorates due to the increase in the higher-order components, depending on the characteristics of the algorithm. Therefore, a novel adaptive filtering algorithm was proposed to overcome these drawbacks. It increased the stability of the system by decreasing the step size using an exponential function. In addition, the error was reduced through normalization using the power of the input signal in the initial state, and the misadjustments in the system were adjusted properly by introducing an energy autocorrelation function of instantaneous error. Furthermore, a novel multi-staged adaptive LMS (MSA-LMS) algorithm was introduced and applied to active periodic structures. The proposed algorithm was validated by simulation and observed to be superior to the conventional LMS algorithms. The results of this study can be applied to active control systems for the reduction of vibration and noise signals with complex spectra in next-generation powertrains, such as hybrid and electric vehicles. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle Exploiting the Underdetermined System in Multichannel Active Noise Control for Open Windows
Appl. Sci. 2019, 9(3), 390; https://doi.org/10.3390/app9030390
Received: 18 November 2018 / Revised: 11 January 2019 / Accepted: 16 January 2019 / Published: 23 January 2019
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Abstract
Active noise control (ANC) is a re-emerging technique to mitigate noise pollution. To reduce the noise power in large spaces, multiple channels are usually required, which complicates the implementation of ANC systems. In this paper, we separate the multichannel ANC problem into two [...] Read more.
Active noise control (ANC) is a re-emerging technique to mitigate noise pollution. To reduce the noise power in large spaces, multiple channels are usually required, which complicates the implementation of ANC systems. In this paper, we separate the multichannel ANC problem into two subproblems, where the subproblem of computing the control filter is usually an underdetermined problem. Therefore, we could leverage the underdetermined system to simplify the ANC system without degrading the noise reduction performance. For a single incidence, we compare the conventional fully-coupled (pseudoinverse) multichannel control with the colocated (diagonal) control method and find that they can achieve equivalent performance, but the colocated control method is less computationally intensive. Furthermore, the underdetermined system presents an opportunity to control noise from multiple incidences with one common fixed filter. Both the full-rank and the overdetermined optimal control filters are realized. The performance of these control methods was analyzed numerically with the Finite Element Method (FEM) and the results validate the feasibility of the full-rank and overdetermined optimal control methods, where the latter could even offer more robust performance in more complex noise scenarios. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle The Generation Mechanism of the Flow-Induced Noise from a Sail Hull on the Scaled Submarine Model
Appl. Sci. 2019, 9(1), 106; https://doi.org/10.3390/app9010106
Received: 22 November 2018 / Revised: 24 December 2018 / Accepted: 24 December 2018 / Published: 29 December 2018
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Abstract
Flow-induced noise from the sail hull, which is induced by the horseshoe vortex, the boundary layer separation and the tail vortex shedding, is a significant problem for the underwater vehicles, while has not been adequately studied. We have performed simulations and experiments to [...] Read more.
Flow-induced noise from the sail hull, which is induced by the horseshoe vortex, the boundary layer separation and the tail vortex shedding, is a significant problem for the underwater vehicles, while has not been adequately studied. We have performed simulations and experiments to reveal the noise generation mechanism from these flows using the scaled sail hull with part of a submarine body. The large eddy simulation and the wavenumber–frequency spectrum are adopted for simulations. The frequency ranges from 10 Hz to 2000 Hz. The simulation results show that the flow-induced noise with the frequency less than 500 Hz is mainly generated by the horseshoe vortex; the flow-induced noise because of the tail vortex shedding is mainly within the frequency of shedding vortex, which is 595 Hz in the study; the flow-induced noise caused by the boundary layer separation lies in the whole frequency range. Moreover, we have conducted the experiments in a gravity water tunnel, and the experimental results are in good accordance with the simulation results. The results can lay the foundation for the design of flow control devices to suppress and reduce the flow-induced noise from the sail hull. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle A Multi-Tone Sound Absorber Based on an Array of Shunted Loudspeakers
Appl. Sci. 2018, 8(12), 2484; https://doi.org/10.3390/app8122484
Received: 1 November 2018 / Revised: 23 November 2018 / Accepted: 23 November 2018 / Published: 4 December 2018
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Abstract
It has been demonstrated that a single shunted loudspeaker can be used as an effective low frequency sound absorber in a duct, but many shunted loudspeakers have to be used in practice for noise reduction or reverberation control in rooms, thus it is [...] Read more.
It has been demonstrated that a single shunted loudspeaker can be used as an effective low frequency sound absorber in a duct, but many shunted loudspeakers have to be used in practice for noise reduction or reverberation control in rooms, thus it is necessary to understand the performance of an array of shunted loudspeakers. In this paper, a model for the parallel shunted loudspeaker array for multi-tone sound absorption is proposed based on a modal solution, and then the acoustic properties of a shunted loudspeaker array under normal incidence are investigated using both the modal solution and the finite element method. It was found that each shunted loudspeaker can work almost independently where each unit resonates. Based on the interaction analysis, multi-tone absorbers in low frequency can be achieved by designing multiple shunted loudspeakers with different shunt circuits respectively. The simulation and experimental results show that the normal incidence sound absorption coefficient of the designed absorber has four absorption peaks with values of 0.42, 0.58, 0.80, and 0.84 around 100 Hz, 200 Hz, 300 Hz, and 400 Hz respectively. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle Frequency-Domain Filtered-x LMS Algorithms for Active Noise Control: A Review and New Insights
Appl. Sci. 2018, 8(11), 2313; https://doi.org/10.3390/app8112313
Received: 23 October 2018 / Revised: 14 November 2018 / Accepted: 16 November 2018 / Published: 20 November 2018
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Abstract
This paper presents a comprehensive overview of the frequency-domain filtered-x least mean-square (FxLMS) algorithms for active noise control (ANC). The direct use of frequency-domain adaptive filters for ANC results in two kinds of delays, i.e., delay in the signal path and delay in [...] Read more.
This paper presents a comprehensive overview of the frequency-domain filtered-x least mean-square (FxLMS) algorithms for active noise control (ANC). The direct use of frequency-domain adaptive filters for ANC results in two kinds of delays, i.e., delay in the signal path and delay in the weight adaptation. The effects of the two kinds of delays on the convergence behavior and stability of the adaptive algorithms are analyzed in this paper. The first delay can violate the so-called causality constraint, which is a major concern for broadband ANC, and the second delay can reduce the upper bound of the step size. The modified filter-x scheme has been employed to remove the delay in the weight adaptation, and several delayless filtering approaches have been presented to remove the delay in the signal path. However, state-of-the-art frequency-domain FxLMS algorithms only remove one kind of delay, and some of these algorithms have a very high peak complexity and hence are impractical for real-time systems. This paper thus proposes a new delayless frequency-domain ANC algorithm that completely removes the two kinds of delays and has a low complexity. The performance advantages and limitations of each algorithm are discussed based on an extensive evaluation, and the complexities are evaluated in terms of both the peak and average complexities. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle Multichannel Feedforward Active Noise Control System with Optimal Reference Microphone SelectorBased on Time Difference of Arrival
Appl. Sci. 2018, 8(11), 2291; https://doi.org/10.3390/app8112291
Received: 27 October 2018 / Revised: 12 November 2018 / Accepted: 13 November 2018 / Published: 19 November 2018
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Abstract
In this paper, we propose a multichannel active noise control (ANC) system with an optimal reference microphone selector based on the time difference of arrival (TDOA). A multichannel feedforward ANC system using upstream reference signals can reduce various noises such as broadband noise [...] Read more.
In this paper, we propose a multichannel active noise control (ANC) system with an optimal reference microphone selector based on the time difference of arrival (TDOA). A multichannel feedforward ANC system using upstream reference signals can reduce various noises such as broadband noise by arranging reference microphones close to noise sources. However, the noise reduction performance of an ANC system degrades when the noise environment changes, such as the arrival direction. This is because some reference microphones do not satisfy the causality constraint that the unwanted noise propagates to the control point faster than the anti-noise used to cancel the unwanted noise. To solve this problem, we propose a multichannel ANC system with an optimal reference microphone selector. This selector chooses the reference microphones that satisfy the causality constraint based on the TDOA. Some experimental results demonstrate that the proposed system can choose the optimal reference microphones and effectively reduce unwanted acoustic noise. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle Impact and Control of Reflected Noise from an Overpass Bottom
Appl. Sci. 2018, 8(10), 1908; https://doi.org/10.3390/app8101908
Received: 17 September 2018 / Revised: 10 October 2018 / Accepted: 12 October 2018 / Published: 14 October 2018
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Abstract
This study examines the effects of noise reflected from the overpass bottom under various conditions using onsite measurements and model simulation. Reflected noise from the overpass bottom may be as high as 8 dB(A). Bottom materials (steel and reinforced concrete (RC)) have no [...] Read more.
This study examines the effects of noise reflected from the overpass bottom under various conditions using onsite measurements and model simulation. Reflected noise from the overpass bottom may be as high as 8 dB(A). Bottom materials (steel and reinforced concrete (RC)) have no discernible effect on the reflected noise level. As the height of an overpass increases, the level of reflected noise decreases. When an overpass is parallel to the noise source (i.e., the freeway), the size of the area impacted by reflected noise increases. As the sound absorption rating of the material installed at the overpass bottom increased, the level of reflected noise decreased. A sound absorbing material with a sound absorption rate of at least 0.60 is recommended to reduce reflected noise level. When the distance between the overpass side and a receiver exceeded 30 m, the level of reflected noise level reduced significantly. Therefore, if the distance between a residential area and overpass could be increased to create a buffer zone coupled with the installation of sound absorbing material at the overpass bottom, the impact of reflected noise on nearby residents can be reduced. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle Noise-Canceling Office Chair with Multiple Reference Microphones
Appl. Sci. 2018, 8(9), 1702; https://doi.org/10.3390/app8091702
Received: 31 August 2018 / Revised: 14 September 2018 / Accepted: 16 September 2018 / Published: 19 September 2018
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Abstract
Office employees are exposed to acoustic noise, especially in an open office environment. Passive or active headsets sufficiently reduce the level of noise, but their long-time wear is uncomfortable. The paper presents an active headrest system built into a chair. Feedforward control is [...] Read more.
Office employees are exposed to acoustic noise, especially in an open office environment. Passive or active headsets sufficiently reduce the level of noise, but their long-time wear is uncomfortable. The paper presents an active headrest system built into a chair. Feedforward control is utilized with multiple reference microphones, and flexible gooseneck microphones serve as error sensors. The reference sensors surround the chair, allowing the suppression of sound waves arriving from any direction. The concept of multiple reference control has been tested by extensive experiments showing that multiple reference signals help to increase the suppression in normal rooms where reverberation occurs, even if only one noise source is present. The preliminary experiments are completed by a series of simulations aiming to explore the zones of quiet at the user’s ears. The paper introduces the construction details of the noise-canceling chair: The two loudspeakers are controlled by the signals of two error microphones and four reference signals. The controller is based on the normalized filtered error least mean squared algorithm, implemented on an Analog Devices ADSP-21262 signal processor-based hardware. Experimental results are reported that show the efficient suppression of tonal, as well as broadband disturbances. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle A New Method for Active Cancellation of Engine Order Noise in a Passenger Car
Appl. Sci. 2018, 8(8), 1394; https://doi.org/10.3390/app8081394
Received: 8 June 2018 / Revised: 3 August 2018 / Accepted: 14 August 2018 / Published: 17 August 2018
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Abstract
This paper presents a novel active noise cancellation (ANC) method to reduce the engine noise inside the cabin of a car. During the last three decades, many methods have been developed for the active control of a quasi-stationary narrowband sinusoidal signal. However, since [...] Read more.
This paper presents a novel active noise cancellation (ANC) method to reduce the engine noise inside the cabin of a car. During the last three decades, many methods have been developed for the active control of a quasi-stationary narrowband sinusoidal signal. However, since the interior noise signal is non-stationary with a fast frequency variation when the car accelerates rapidly, these methods cannot stably reduce the interior noise. The proposed method can reduce the interior noise stably even if the speed of the car is changed quickly. The method uses an adaptive filter with an optimal weight vector for the active control of such an engine noise. The method of determining the optimal weight vector of an adaptive filter is demonstrated. In order to validate the advantages of the proposed method, a conventional method and the proposed method are simulated with three synthesized signals. Finally, the proposed method is applied to the cancellation of booming noise in a sport utility vehicle. We demonstrate that the performance of the ANC system with the proposed algorithm is excellent for the attenuation of engine noise inside the cabin of a car. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle Development and Evaluation of Light-Weight Active Noise Cancellation Earphones
Appl. Sci. 2018, 8(7), 1178; https://doi.org/10.3390/app8071178
Received: 26 May 2018 / Revised: 12 July 2018 / Accepted: 17 July 2018 / Published: 19 July 2018
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Abstract
This paper presents the development of active noise control (ANC) for light-weight earphones, and proposes using music or natural sound to estimate the critical secondary path model instead of extra random noise. Three types of light-weight ANC earphones including in-ear, earbud, and clip [...] Read more.
This paper presents the development of active noise control (ANC) for light-weight earphones, and proposes using music or natural sound to estimate the critical secondary path model instead of extra random noise. Three types of light-weight ANC earphones including in-ear, earbud, and clip phones are developed. Real-time experiments are conducted to evaluate their performance using the built-in microphone inside KEMAR’s ear and to compare with commercially-available ANC headphones and earphones. Experimental results show that the developed light-weight ANC earphones achieve higher noise reduction than the commercial ANC headphones and earphones, and the in-ear ANC earphone has the best noise reduction performance. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle Modified LMS Strategies Using Internal Model Control for Active Noise and Vibration Control Systems
Appl. Sci. 2018, 8(6), 1007; https://doi.org/10.3390/app8061007
Received: 26 April 2018 / Revised: 14 June 2018 / Accepted: 19 June 2018 / Published: 20 June 2018
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Abstract
Traditional adaptive filtering algorithms are non-recursive systems that cannot use a time-variant reference input in real time and are not appropriate for control signals with uncertainties and unanticipated conditions. The main purpose of this research is to design novel adaptive digital filtering algorithms [...] Read more.
Traditional adaptive filtering algorithms are non-recursive systems that cannot use a time-variant reference input in real time and are not appropriate for control signals with uncertainties and unanticipated conditions. The main purpose of this research is to design novel adaptive digital filtering algorithms based on internal model control (IMC). The new methods consist of a process model for the target plant so as to estimate its dynamic behavior for active vibration and noise attenuation schemes in order to improve the stability, robustness, and tracking performance. On the basis of on the existing least mean squares, the methods are combined with an internal model controller, or the whole adaptive filtering system could become a feedback control system structure based on IMC. The performances were validated in numerical simulations with various conditions that could have happened in realistic applications, and the results were compared with the original algorithms. This study shows that the active noise and vibration systems that are applied to vehicles, mechanical systems, and other targets are enhanced through improving the performance of conventional adaptive filtering algorithms and by using internal model control effectively. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Open AccessArticle Acoustic Improvement of Stator–Rotor Interaction with Nonuniform Trailing Edge Blowing
Appl. Sci. 2018, 8(6), 994; https://doi.org/10.3390/app8060994
Received: 16 May 2018 / Revised: 4 June 2018 / Accepted: 16 June 2018 / Published: 19 June 2018
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Abstract
The results of unsteady-flow simulations and experiments are discussed to investigate active noise-reduction effects on the stator–rotor interaction in a single-stage low-speed compressor with nonuniform trailing edge blowing. It is found that for the investigated type of stator–rotor interaction noise, nonuniform trailing edge [...] Read more.
The results of unsteady-flow simulations and experiments are discussed to investigate active noise-reduction effects on the stator–rotor interaction in a single-stage low-speed compressor with nonuniform trailing edge blowing. It is found that for the investigated type of stator–rotor interaction noise, nonuniform trailing edge blowing has beneficial noise-reducing effects. The overall aim is to demonstrate that nonuniform trailing edge blowing can compensate momentum loss and reduce the axial thrust on rotor blades. The results illustrate how nonuniform trailing edge blowing influences the sound pressure level of the blade-passing frequencies and results in active noise reduction effects. The study was conducted using a trailing edge blowing system, a four-hole dynamic flow-field measurement system, and phase lock technology. The results obtained show that nonuniform trailing edge blowing leads to substantial noise-reduction effects, lowering sound levels by more than 10 dB with about 5‰ of inlet mass flow. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Other

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Open AccessBrief Report A Time-Efficient Method for Determining an Optimal Scaling Factor and the Encoder Resolution in the Multichannel FXECAP-L Algorithm with Evolving Order for Active Noise Control
Appl. Sci. 2019, 9(3), 560; https://doi.org/10.3390/app9030560
Received: 5 December 2018 / Revised: 22 January 2019 / Accepted: 1 February 2019 / Published: 8 February 2019
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Abstract
Affine projection (AP) algorithms have demonstrated faster convergence speed than conventional least mean square (LMS) algorithms, thus providing an attractive solution in the active noise control (ANC) field. However, the AP algorithms demand high computational cost, restricting their practical use in real-time ANC [...] Read more.
Affine projection (AP) algorithms have demonstrated faster convergence speed than conventional least mean square (LMS) algorithms, thus providing an attractive solution in the active noise control (ANC) field. However, the AP algorithms demand high computational cost, restricting their practical use in real-time ANC applications. Recently, a multichannel filtered-x error-coded affine projection-like (FXECAP-L) algorithm with evolving order has been proposed to reduce the computational burden by maintaining the convergence speed of AP algorithms. In order to obtain an efficient and robust FXECAP-L algorithm with evolving order, the scaling factor and encoder resolution need to be adjusted manually, which is a time-consuming and costly effort that must be carried out by expert designers. To reduce these costs and efforts, we introduce, for the first time, a strategy for automatic adjustment of the scaling factor and encoder resolution that benefits the rapid development of practical ANC applications. To demonstrate its practical use, we applied the proposed strategy for controlling the noise in an acoustic duct. The practical results demonstrate the automatic adjustment of the FXECAP-L algorithm which maintains high convergence speed at the expense of a small compromise in terms of processing time. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

The type of paper: Article
Tentative title: Development and Evaluation of Light-weight Active Noise Cancellation Earphones
Author: Cheng-Yuan Chang(張政元)
Affiliation:
Professor, EE Dept., Chung Yuan Christian University, Jhongli 320, Taiwan
Abstract:This paper presents the development of active noise control (ANC) for light-weight earphones, and proposes using music or natural sound to estimate the critical secondary path model instead of extra random noise. Three types of light-weight ANC earphones including in-ear, earbud, and clip phones are developed. Real-time experiments are conducted to evaluate their performance using the built-in microphone inside KEMAR’s ear and compare with commercial-available ANC headphones and earphone. Experimental results show the developed light-weight ANC earphones achieve higher noise reduction than the commercial ANC headphones and earphone, and the in-ear ANC earphone has the best noise reduction performance.

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