Active noise control using noise source having adaptive resonant frequency tuning through variable panel loading

Abstract The purpose of this paper is to propose an experimental design methodology for global active noise control in an enclosed space. We aim to control the noise caused by an internal noise source. Since each enclosed space has different acoustic characteristics, it is difficult to design different controllers suitable for each enclosed space. So, we decided to design a controller that could be used universally. The basic concept is the collocation of noise source and control speakers to generate a sound field opposite in phase to the noise source in a free field. For implementation of the proposed method, we propose a configuration method of control speakers and error microphones, and an active noise control algorithm. Also, to confirm the applicability of the proposed method, we design a controller in an anechoic chamber, which represents a free field condition, and perform active noise control in other enclosed spaces with the controller designed for the anechoic chamber. The experimental results show that the solution calculated in the free field condition can be used in other enclosed spaces without any modifications.

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Experimental investigation on the potential of the Feedback Fx-LMS Active Noise Control technology for use in industrial generator sets

E3S Web of Conferences ◽

10.1051/e3sconf/202131208007 ◽

2021 ◽

Vol 312 ◽

pp. 08007

Author(s):

Marco Ciampolini ◽

Lorenzo Bosi ◽

Luca Romani ◽

Andrea Toniutti ◽

Matteo Giglioli ◽

...

Keyword(s):

Acoustic Waves ◽

Noise Control ◽

Noise Source ◽

Acoustic Noise ◽

Active Noise Control ◽

Lms Algorithm ◽

Destructive Interference ◽

Exhaust Pipe ◽

Least Mean Square ◽

Active Noise

Active Noise Control (ANC) has been considered a promising technology for the abatement of acoustic noise from the mid-20th century. Feedback and Feedforward ANC algorithms, based on the destructive interference principle applied to acoustic waves, have been developed for different applications, depending on the spectrum of the noise source. Feedback ANC algorithms make use of a single control microphone to measure an error signal which is then employed by an adaptive filter to estimate the noise source and generate an opposite-phase control signal. The Fx-LMS (Filtered-X Least Mean Square) algorithm is mostly adopted to update the filter. Feedback ANC systems have proven to be effective for the abatement of low-frequency quasi-steady noises; however, different challenges must be overcome to realize an effective and durable system for high-temperature application. This paper aims at experimentally assessing the feasibility of a Feedback Fx-LMS ANC system with off-line Secondary Path estimation to be used in mid-size diesel gensets for the reduction of the exhaust noise. Several solutions are proposed, including the mechanical design, the development of the Fx-LMS algorithm in the LabVIEW FPGA programming language, and the key features required to prevent parts from thermal damage and fouling. The developed prototype was implemented on a 50-kW diesel genset and tested in a semi-anechoic chamber. The noise abatement inside the exhaust pipe and at different measurement points around the machine was evaluated and discussed, showing good potential for improving the acoustic comfort of genset users.

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Numerical Evaluation of the Performance of Active Noise Control Systems

Journal of Vibration and Acoustics ◽

10.1115/1.2930117 ◽

1990 ◽

Vol 112 (2) ◽

pp. 230-236 ◽

Cited By ~ 11

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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Multichannel feedforward active noise control system combined with noise source separation by microphone arrays

Journal of Sound and Vibration ◽

10.1016/j.jsv.2019.04.016 ◽

2019 ◽

Vol 453 ◽

pp. 151-173 ◽

Cited By ~ 2

Author(s):

Kenta Iwai ◽

Satoshi Kinoshita ◽

Yoshinobu Kajikawa

Keyword(s):

Control System ◽

Noise Control ◽

Noise Source ◽

Source Separation ◽

Active Noise Control ◽

Microphone Arrays ◽

Active Noise

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Suitability of Active Noise Barriers for Construction Sites

Applied Sciences ◽

10.3390/app10186160 ◽

2020 ◽

Vol 10 (18) ◽

pp. 6160

Author(s):

Shahin Sohrabi ◽

Teresa Pàmies Gómez ◽

Jordi Romeu Garbí

Keyword(s):

Noise Control ◽

Noise Source ◽

Active Noise Control ◽

Target Area ◽

Construction Sites ◽

Noise Barriers ◽

Active Noise ◽

Noise Barrier ◽

Passive Noise ◽

Suitable Location

Barriers are increasingly used to protect the pedestrian and neighboring buildings from construction noise activities. This study aims to investigate the suitability of applying active noise control on barriers in a construction site to protect the street area and neighboring buildings. Transducers that are simulated in this work are close to the barrier, and their optimal positions are defined in such a way that the control system has the maximum performance at the neighboring areas close to the construction sites. To begin with, the suitable location of the control sources is found when the total squared pressure is minimized at the positions of noise receivers. The suitable location of the error sensors is, then, found when the control sources are fixed at the position of the previous step and the total squared pressure is minimized at the error sensors. The best location for the error sensors is defined when the maximum reduction is achieved in the target area. It is observed that suitable positions for the transducers depend on the location of target areas for noise control, the position of the noise source, and its operating frequency. In this investigation, a unique configuration is proposed for the transducers that achieves a comparable reduction both at the street area and the neighboring buildings, simultaneously. The results show that the active noise barrier with a height of 2.5 m can achieve an extra insertion loss in the street zone, varies from 9.3 to 16.4 dB (in comparison with passive noise barrier) when the distance of the noise source from the barrier changes in the range of 7 to 1 m, respectively. Those values are of the same order for the passive noise attenuation. Furthermore, similar results are achieved when attempting to cancel the shadow zone of a façade 15 m away from the barrier.

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A Boundary Element Approach to Optimization of Active Noise Control Sources on Three-Dimensional Structures

Journal of Vibration and Acoustics ◽

10.1115/1.2930196 ◽

1991 ◽

Vol 113 (3) ◽

pp. 387-394 ◽

Cited By ~ 24

Author(s):

K. A. Cunefare ◽

G. H. Koopmann

Keyword(s):

Boundary Element ◽

Noise Control ◽

Noise Source ◽

Active Noise Control ◽

Three Dimensional ◽

Control Technique ◽

Optimization Analysis ◽

Radiated Power ◽

Active Noise ◽

Control Source

This paper presents the theoretical development of an approach to active noise control (ANC) applicable to three-dimensional radiators. The active noise control technique, termed ANC Optimization Analysis, is based on minimizing the total radiated power by adding secondary acoustic sources on the primary noise source. ANC Optimization Analysis determines the optimum magnitude and phase at which to drive the secondary control sources in order to achieve the best possible reduction in the total radiated power from the noise source/control source combination. For example, ANC Optimization Analysis predicts a 20 dB reduction in the total power radiated from a sphere of radius α at a dimensionless wavenumber ka of 0.125, for a single control source representing 2.5 percent of the total area of the sphere. ANC Optimization Analysis is based on a boundary element formulation of the Helmholtz Integral Equation, and thus, the optimization analysis applies to a single frequency, while multiple frequencies can be treated through repeated analyses.

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