Active Noise Control Method Research Articles

The Study of Active Noise Control Method for Moving Target in Noisy Space

For the noise problem of moving target in noisy space, This work is dedicated to developing a novel and promising solution based on the moving target tracking technology and the active noise control (ANC) technology. The development process began with the simplified sound field interaction model, the “auto position tracking near head space ANC” strategy has been proposed from the modelling study. Furthermore, the primary experimental system that consists of the acoustic positioning and tracking subsystem for tracking the control point and the ANC subsystem for generating the anti-noise signal is presented, with the emphasis on the development of the improved TDC-FXLMS ANC algorithm. Finally, the performance of the auto-position tracking near head space ANC device is evaluated by carrying out the primary experiments on an experimental evaluation system.

726 遅延駆動パラメトリックアレイスピーカによる三次元広域能動騒音制御

This paper presents a global active noise control method for three-dimensional acoustic field that compensates these disadvantages. Parametric Array Loudspeaker (PAL) in which multiple ultrasonic transducers are placed concentrically is introduced as the control sound source. Driving the ultrasonic transducers with proper time delays, the control sound source produces the wavefront similar to the noise away from the noise source. Superposing the control sound on the original noise sound, and suppressing the sound pressure at the error sensor, sound pressure is suppressed over a wide area around the error sensor. Compared with the case of using a ordinary speaker as the control sources, the validity of the proposed method is clarified.

Broadband active noise control with transfer path equalization.

Active systems for noise reduction are typically of interest for applications in which low-frequency noise is a main source of disturbance and only limited amounts of installation space and payload are available. When applying active noise control methods in small aircraft cabin area such as the crew rest compartment of a long range jet, the transfer path between sensor and actuator is strongly influenced by room acoustics and transducer behavior, thereby affecting control in a frequency selective manner, especially when using filtered reference algorithms. In this study, a concept for transfer path equalization in a feedback-control approach with virtual microphones and the feedback filtered-reference least mean squares algorithm are evaluated. The implementation and influence of the prediction-error filter based equalizer on broadband active noise control are analyzed in simulation as well as in experiments in an acoustic mock-up. The use of the equalizer improves broadband attenuation (f < 350 Hz) by 3–4 dB with a total attenuation of 20 dB at the error sensor.

ACTIVE NOISE CONTROL USING NEURAL SYSTEM

The principle of active noise control (ANC) is to produce a secondary acoustic noise which has the same magnitude as the unwanted primary noise but with opposite phase. The sum of these two signals reduces acoustic noise in the noise control area. In this paper we present a new ANC method using neural system. Moreover a new method for compensating the saturation of the power applifier is also introduced. The performance of the proposed method is compared to that of traditional methods. Simulation results are provided for illustration.

Nonlinear ANC using a NPVSS-NLMS algorithm and online modelling of an acoustic linear feedback path

Acoustic feedback and background noise variation can degrade the performance of an active noise control (ANC) system. In this paper, nonlinear ANC using a non-parametric VSS-NLMS (or NPVSS-NLMS) algorithm and online feedback path modeling is proposed, whereby the conventional linear ANC with online acoustic feedback-path modeling is further extended to nonlinear Volterra ANC with a linear acoustic feedback path. In particular, the step-size of the NPVSS-NLMS algorithm is controlled to reduce the effect of background noise variation in the ANC system. Simulation results demonstrate that the proposed approach yields better nonlinear ANC performance compared with the conventional nonlinear ANC method.

Active noise cancellation of variable frequency narrow band noise using mixture of RLS and LMS algorithms

Due to the good tracking behaviour of the LMS adaptive filter in a noisy environment, the FX-LMS algorithm is proposed in the literature as a method of active noise control, ANC. But each of the LMS and RLS algorithms have their own advantages and disadvantages. In this paper, a new approach based on a mixture of the RLS and LMS algorithms, RLMS, is presented. The optimum weights of the mixture are derived and it is proved that the MMSE of the proposed system is reduced compared to those of the RLS and LMS algorithms. Then, the proposed RLMS algorithm is employed for active noise cancellation to form the FX-RLMS algorithm, in a duct. Experimental results show better performance of the RLMS algorithm compared to both the RLS and LMS algorithms of convergence and tracking behaviour in the system identification problem and noisy chirp tracking. The FX-RLMS algorithm shows better results in active noise cancellation compared to the FX-LMS algorithm.

Active noise control method to reduce free field noise from fixed and moving noise source using plural single-channel controllers

Active noise control method to reduce free field noise from fixed and moving noise source using plural single-channel controllers

Acoustic feedback neutralization in active noise control systems

This letter proposes a method for active noise control (ANC) systems with online acoustic feedback neutralization. The proposed method is a modified version of authors' previous work, and the objective here is to reduce the computational complexity. This is achieved by combining the role of feedback path modeling and neutralization filters. The computer simulations are carried out which demonstrate that the proposed method achieves better performance than the existing methods and at somewhat reduced computational cost.

DESIGN OF DECOUPLING ACTIVE NOISE CONTROL SYSTEMS

In this paper a simple method for multi-channel Active Noise Control (ANC) is introduced. The proposed structure is a combination of an adaptive FIR filter, based on the FXLMS algorithm, and the ALIGN algorithm resulting in a decoupled matrix for secondary path transfer function. This structure thus converts a multi-channel ANC system to decoupled systems which results in the reduction in computational load without affecting the convergence behavior of the FXLMS system.

Design of Active Noise Control System Using Phase Shift Network for a Hydraulic Surface Grinder

In the present research the feedforward method of Active Noise Control (ANC) using Phase Shift Network (PSN) has been proposed for reducing noise generated by a hydraulic Surface Grinder. The PSN was a simple network whose function was to change the phase of the input wave. A passive damping material was used to prepare a duct of 150 mm × 150 mm × 1960 mm for converting multidimensional random noise into a single dimension. The duct was also utilized for housing two speakers employed in the ANC system. The system when installed on the grinder resulted in a total noise reduction of 13.1 dB(A).

The integration of advanced active and passive structural noise control methods

This paper reports on an investigation into the feasibility of using active and passive means of vibration control in aerospace structures. In particular, attention is focused on controlling vibration transmission through light weight satellite structures at medium frequencies. The initial structure under test here is a 4.5-meter long satellite boom consisting of 10 identical bays with equilateral triangular cross sections. This structure is typical of those that might be used in space telescopes, space stations or synthetic aperture radar systems. Such a structure is typically used to support sensitive instruments in precise alignments spaced tens of metres apart. While a great deal of work has been done on this problem at low frequencies, relatively little has been achieved to date at medium frequencies (here taken to be between 150 Hz and 250 Hz). Nonetheless, this is of importance to new space missions. Using the techniques described here, an overall reduction in vibration transmission of 31.0 dB is achieved in an essentially undamped structure using passive means alone. The amounts of attenuation achievable for active control with one, two and three actuators are found to be 15.1 dB, 26.1 dB and 33.5 dB, respectively. With the combined passive control (using 10% geometric deviations) and active control (using three actuators) an overall reduction of 49.5 dB is achievable in practice.

LMI Design of Frequency Selective LMS Adaptive Filters and Its Application to Active Noise Control

Recently, a frequency selective adaptive filter design method for active noise control has been proposed based on the so-called least mean square algorithm. However, this method does not sufficiently exploit the degree of freedom of the step parameter of the recursive rule in the case where a priori information on an uncertain plant is available. This paper proposes a design method of the step parameter such that noise cancellation is guaranteed against the plant uncertainty. The design problem of the step parameter is reduced to an optimization problem involving linear matrix inequalities and is efficiently solvable. Experimental results are provided to illustrate the effectiveness of the proposed method.

Blind preprocessing method for multichannel feedforward active noise control

Blind preprocessing method for multichannel feedforward active noise control

The Boundary Surface Control Principle and Its Applications

In order to control a sound field using multiple sources and microphones, we must choose the optimum values of parameters such as the numbers of sources and microphones, the location of the sources and the microphones and the filter tap length. Because there is a huge number of possible combinations of these conditions, the boundary surface control principle can be useful as a basis of a design method of such a system. In this paper, a design method of sound field reproduction and active noise control based on the BSC principle are described and several example of its application are presented.

Passive and active interior noise control of box structures using the structural intensity method

This paper presents passive and active vibro-acoustic noise control methods for attenuating the interior noise level in box structures which can be an analogy of cabins of vehicle and aircraft. The structural intensity (SI) approach is adopted to identify the predominant vibration panels and interior noise sources for box structures. In the study, the finite element method is used to determine the structural vibration and structural intensity in the box surfaces. According to structural intensity vectors plot and structural intensity stream lines presentation, the possible effective control positions where the dampers may be attached and the active control forces may act to reduce vibration and interior noise, are identified. From the study, it can be demonstrated that the structural intensity approach and stream line presentation are possible methods for identifying the vibro-acoustic interior noise source and predominant panels which may be modified to reduce the interior noise level. The structural intensity methodology, passive and active noise control results can be extended to the further study of the vibration and interior noise control of actual cabins of vehicles and aircraft.

A preprocessing method for multichannel feedforward active noise control

A multichannel filtered-x least mean square (LMS) algorithm is an efficient feedforward algorithm in an active noise control (ANC) system, whose convergence rate is known to be limited by many factors, such as a secondary path model and the correlation between reference signals. In this paper, we introduce an adaptive blind preprocessing method for reducing the eigenvalue spread of the correlation matrix of reference signals, which is often ignored in a typical multichannel ANC algorithm. Two blind adaptive decorrelation algorithms are derived for different reference path models. Numerical experiments verify the robust performance of the proposed preprocessing methods, including reducing the mean square error and improving the convergence speed.

LMI design of frequency domain LMS filters for active noise control

Recently, a frequency-domain adaptive filter design method for active noise control has been proposed based on the so-called least mean square algorithm. However, this method does not sufficiently exploit the degree of freedom of the step parameter of the recursive rule in the case where a priori information on an uncertain plant is available. This paper proposes a design method of the step parameter such that noise cancellation is guaranteed against the plant uncertainty. The design problem of the step parameter is reduced to a semidefinite programming problem which is efficiently solvable. Experimental results are provided to illustrate the effectiveness of the proposed method.

Active noise control of flexible linkage mechanism with piezoelectric actuators

An active noise control method for flexible linkage mechanism systems with piezoelectric actuators and strain gauge sensors is studied. By employing a set of wave number transformations on the original equations of motion of the flexible linkage mechanisms, a new set of equations of motion is obtained, in which the unknown variables can describe the structural acoustic radiation level of the mechanism system directly. On the basis of the new equations, the active noise control of the flexible linkage mechanism system with piezoelectric actuators is discussed. Firstly, the optimal control forces are determined based on the optimal control theory. Secondly, the controller of the system that consists of the output feedback and the disturbance feed-forward control laws is presented. Simulations show that the method presented in this paper is valid.

환형 스마트 폼을 이용한 덕트 내부의 능동 소음 제어 및 상쇄 경로 최적화

This paper presents a method for active noise control (ANC) in a duct by using a ring-tyPe smart foam. The ring-type smart foam consists of an elastic porous material of lining shape and a PVDF film embedded In the material. The PVDF element acts as a secondary sound source to reduce the noise. Active noise control using a ring-type smart foam is only effective locally because of the way to excite radially. To enlarge the quiet zone, the duct Is lined with additional acoustic foam between the smart foam and the error microphone. When cancellation path ks optimized by the LMS/RLS algorithm, the computation power is reduced while control performance Is maintained. The filtered-x LMS algorithm is used to minimize the error signal.

Hybrid active and passive control of fan noise

This paper deals with the global reduction of axial flow fan noise in ducts in a building using a hybrid passive–active noise control method. The effectiveness of using an infra-red device as a reference signal source is also investigated. It is shown that using such a hybrid noise control system over an axial-flow fan reduces the overall sound pressure level by 5 dB(A) in the surrounding environment and global control of the blade passing frequency can also be achieved. This paper also shows that using an infra-red device as a reference signal source produces marginally better control as compared with using a microphone reference sensor. Moreover, long term stability is guaranteed and the possibility of acoustic feedback is eliminated.