THEORETICAL ANALYSIS OF SEMI-ACTIVE NOISE CONTROL

Akustika ◽  
2021 ◽  
pp. 152
Author(s):  
Thomas Kletschowski
Keyword(s):  
Active Control ◽  
Noise Control ◽  
Control Volume ◽  
Active Noise Control ◽  
Broadband Noise ◽  
Electrical Network ◽  
Single Input Single Output ◽  
Single Output ◽  
Active Noise ◽  
Single Input

significant reduction of disturbing noise can be achieved by passive, semi-active and fully active control approaches. Passive noise treatments such as dynamic vibration absorber are very robust and can be applied to obtain a broadband performance. Active noise control systems are designed to control harmonic or broadband noise. They are very effective, if the control volume is small as known from single-input/single-output systems used in active headphones. However, if distributed control is required, the control profit is not scalable, because the required multiple-input/multiple output systems must be adjusted to specific acoustic modes as known from the active control of propeller-aircraft interior noise. Semi-active control that is based on the principle of dissipation allows to combine several single-input/single-output systems without coupling. Thus semi-active approaches are capable to solve the problem of scalability. The present paper reports on a specific approach that is based on a dynamic absorber attached to a vibrating structure and coupled with a dissipating electrical network. The electrical components of this network can be adjusted to the mechanical impedance to realize dissipation. To focus on the performance principle, the theoretical investigations are presented in a dimensionless analysis.

Two Step Optimization of Transducer Locations in Single Input Single Output Tonal Global Active Noise Control in Enclosures

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
J. Ignacio Palacios ◽  
Jordi Romeu ◽  
Andreu Balastegui
Keyword(s):  
Control System ◽  
Active Control ◽  
Acoustic Field ◽  
Noise Control ◽  
Active Noise Control ◽  
Single Input Single Output ◽  
Secondary Sources ◽  
Single Output ◽  
Active Noise ◽  
Single Input

Global active control of sound can be achieved inside enclosures under low modal acoustic fields. However, the performance of the system depends largely on the localization of the elements of the control system. For a purely acoustic active control system in which secondary acoustic sources (loudspeakers) and pressure transducers (microphones) as error sensors are used, several optimization strategies have been proposed. These strategies usually rely on partial approximation to the problem, focusing on the study of number and localization of secondary sources without considering error transducers, or selecting the best positions of secondary sources and error transducers of an initial set of candidate locations for these elements. The strategy presented here for tonal global active noise control of steady states comprises two steps; the first is rather common for this sort of problem and its goal is to find the best locations for secondary sources and their strengths by minimizing the potential energy of the enclosure. The second step is the localization of the error transducer, which ensures the results of the first step. It is analytically demonstrated that for a single input single output system, the optimum location of error transducers is at a null pressure point of the optimally attenuated acoustic field. It is also shown that in a real case, the optimum position is that of a minimum of the optimally attenuated acoustic field. Finally, a numerical validation of this principle is carried out in a parallelipedic enclosure.

Adaptive Feedforward Active Noise Control in an Acoustic Duct

2001 ◽  
Author(s):  
A. R. Ohadi ◽  
E. Esmailzadeh ◽  
A. Alasty
Keyword(s):  
Noise Control ◽  
Active Noise Control ◽  
Superior Performance ◽  
Single Input Single Output ◽  
Single Output ◽  
Active Noise ◽  
Input Signals ◽  
Single Input ◽  
Simulation Results ◽  
Adaptive Feedforward

Abstract The single-reference/multi-output active noise control (ANC) of an accurate physical model of an acoustic duct system has been investigated. Computer model of a multi-channel ANC system with tonal and sweep sine input signals, and an adaptive feedforward algorithm that minimizes the generic cost function are developed. Results obtained for various single-input/single-output (SISO) configurations of ANC systems were compared. The dynamic response of a single-reference/multi-output ANC system, using Minimax and MEFXLMS algorithms, is studied and the effect of acoustical feedback neutralization in a multichannel ANC system is studied. Simulation results demonstrate that the multi-channel adaptive feedforward ANC system, using the Minimax algorithm, has a superior performance in comparison to the same system with MEFXLMS.

scholarly journals Design of Self-Tuning Minimum Effort Active Noise Control with Feedback Inclusion Architecture

2009 ◽  
Vol 28 (3) ◽  
pp. 205-215 ◽  
Author(s):  
R. K. Raja Ahmad ◽  
M. O. Tokhi
Keyword(s):  
Noise Control ◽  
Transfer Functions ◽  
Controller Design ◽  
Active Noise Control ◽  
The Self ◽  
Recursive Least Squares ◽  
Single Input Single Output ◽  
Single Output ◽  
Active Noise ◽  
Self Tuning

This paper presents the development of a self-tuning controller design of minimum effort active noise control (ANC) for feedforward single-input single-output (SISO) architecture which includes the feedback acoustic path in the controller formulation. The controller design law is derived for suitable self-tuning implementation and the self-tuning controller is evaluated in a realistically constructed ANC simulation environment. The self-tuning controller design involves a two-stage identification process where the controller is replaced by a switch. This switch is closed and opened in sequence generating two transfer functions which are then used in constructing the controller specified by a minimum effort control law. The implementation requires an estimate of the secondary path transfer function which can be identified either online or offline. The controller design and implementation are evaluated in terms of the level of cancellation at the observer through simulation studies for various values of modified effort weighting parameter in the range 0 ≤ γ ≤ 1. It was found that the optimal controller designed using this technique which is constrained only by the accuracy of the two models identified using recursive least squares algorithm, yields good cancellation level.

scholarly journals Multichannel Feedforward Active Noise Control System with Optimal Reference Microphone SelectorBased on Time Difference of Arrival

2018 ◽  
Vol 8 (11) ◽  
pp. 2291 ◽  
Author(s):  
Kenta Iwai ◽  
Satoru Hase ◽  
Yoshinobu Kajikawa
Keyword(s):  
Noise Control ◽  
Acoustic Noise ◽  
Control Point ◽  
Active Noise Control ◽  
Broadband Noise ◽  
Time Difference ◽  
Arrival Direction ◽  
Noise Sources ◽  
Time Difference Of Arrival ◽  
Active Noise

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.

Active Noise Control Using Multi-Layered Perceptron Neural Networks

1997 ◽  
Vol 16 (2) ◽  
pp. 109-144 ◽  
Author(s):  
M.O. Tokhi ◽  
R. Wood
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Network Architecture ◽  
Noise Control ◽  
Learning Algorithm ◽  
Free Field ◽  
Active Noise Control ◽  
Three Dimensional ◽  
Broadband Noise ◽  
Active Noise

This paper presents the development of a neuro-adaptive active noise control (ANC) system. Multi-layered perceptron neural networks with a backpropagation learning algorithm are considered in both the modelling and control contexts. The capabilities of the neural network in modelling dynamical systems are investigated. A feedforward ANC structure is considered for optimum cancellation of broadband noise in a three-dimensional propagation medium. An on-line adaptation and training mechanism allowing a neural network architecture to characterise the optimal controller within the ANC system is developed. The neuro-adaptive ANC algorithm thus developed is implemented within a free-field environment and simulation results verifying its performance are presented and discussed.

Application of a Least Squares Lattice Algorithm to Active Noise Control for an Automobile

1997 ◽  
Vol 119 (2) ◽  
pp. 318-320 ◽  
Author(s):  
Hisashi Sano ◽  
Shuichi Adachi ◽  
Hideki Kasuya
Keyword(s):  
Least Squares ◽  
Noise Control ◽  
Active Noise Control ◽  
Broadband Noise ◽  
Lms Algorithm ◽  
Least Mean Square ◽  
The Road ◽  
Active Noise ◽  
Alternative Approach ◽  
Lattice Algorithm

The purpose of this paper is to propose an alternative approach to active noise control (ANC) using the least squares lattice (LSL) algorithm. Typically, in ANC applications, the least-mean-square (LMS) algorithm has been used because of its simplicity. However, the LMS algorithm has the disadvantage of slow convergence speed in the case of broadband noise, such as the road noise present in the passenger compartment of automobiles traveling on rough road surfaces. In order to solve this problem, the LSL algorithm for ANC is considered. By computer simulation using actual car data, the LSL algorithm proves to be more effective than the LMS one.

Numerical Evaluation of the Performance of Active Noise Control Systems

1990 ◽  
Vol 112 (2) ◽  
pp. 230-236 ◽  
Author(s):  
C. G. Mollo ◽  
R. J. Bernhard
Keyword(s):  
Boundary Element ◽  
Control Systems ◽  
Noise Control ◽  
Noise Source ◽  
Numerical Technique ◽  
Active Noise Control ◽  
Boundary Element Methods ◽  
Single Input Single Output ◽  
Active Noise ◽  
Analytical Approaches

Most of the approaches to the prediction of the effectiveness of active noise control systems are analytical in nature. Analytical approaches are limited to active noise control systems where a solution to the governing acoustic wave equation is available. The objective of the investigation presented in this paper was to develop a generalized numerical technique for evaluating the optimal performance of active noise controllers. The numerical technique used as the basis of the numerical analysis is the indirect boundary element method (IBEM). Boundary element methods have been shown to be straightforward and accurate numerical methods for the prediction of the acoustic response of a system. The IBEM numerical procedures are used here to derive the active noise controllers for optimal control of enclosed harmonic sound fields where the noise source strengths or the enclosure boundary description may not be known. Detectors are introduced into the system to deduce the unknown noise source strengths. The performance prediction for a single input, single output system is presented. Analysis of the stability and observability of the active noise control system employing detectors is also presented.

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