Hybrid Active and Passive Noise Control of Cavities

2011 ◽  
Vol 97 (5) ◽  
pp. 752-760 ◽  
Author(s):  
Lenin Babu ◽  
Chandramouli Padmanabhan
Keyword(s):  
Porous Material ◽  
Elastic Material ◽  
Sound Absorption ◽  
Noise Suppression ◽  
Noise Control ◽  
Active Noise Control ◽  
Elastic Materials ◽  
Active Noise ◽  
Absorption Performance ◽  
Passive Noise

In this paper a hybrid active noise control of a cavity with poro-elastic material has been investigated. It has been found that the noise reduction achieved with active noise control in the cavity without poro-elastic material is not significantly altered with the presence of poro-elastic materials. This is shown to be independent of the porous material and its thickness and is true both at lower and mid-frequency ranges. Further, it is seen that macro perforations do not alter the sound absorption performance of the poro-elastic material in the presence of active noise control. The results clearly indicate that one can choose a smaller thickness of the porous material when active noise control is used in a cavity for noise suppression.

Impedance Characteristics of Structural-Acoustic Control for Interior Noise Suppression

1997 ◽  
Author(s):  
V. Jayachandran ◽  
J. Q. Sun
Keyword(s):  
Sound Absorption ◽  
Noise Suppression ◽  
Noise Control ◽  
Active Noise Control ◽  
Interior Noise ◽  
Acoustic Medium ◽  
Main Stream ◽  
Active Noise ◽  
Acoustic Control ◽  
Structural Acoustic Control

Abstract There has been a growing interest in interior noise control problems for aircraft and automobiles in recent years. While active noise cancellation (ANC) and active structural acoustic control (ASAC) are two main stream technologies, much attention has also been paid to sound absorption by active or semi-active means. Sound absorption occurs when the impedance of an absorbing medium such as an active foam or trim panel matches the impedance of the acoustic medium. To develop such an active or semi-active system for sound absorption, one needs to be able to describe the acoustic impedance accurately at the structural-acoustic interface. This paper presents a particular solution approach for solving the inhomogeneous Helmholtz equation, which allows us to obtain an accurate representation of the impedance field near the boundary. Qualitative and quantitative analysis of the impedance of the acoustic medium before and after active noise control are presented along with numerical results. The study in this paper provides a better understanding of the physics of the problem and may be useful in designing absorption systems for interior noise suppression.

A Review of Active Noise Control Applications on Noise Barrier in Three-Dimensional/Open Space: Myths and Challenges

2019 ◽  
Vol 18 (04) ◽  
pp. 1930002 ◽  
Author(s):  
Hsiao Mun Lee ◽  
Zhaomeng Wang ◽  
Kian Meng Lim ◽  
Heow Pueh Lee
Keyword(s):  
Open Space ◽  
Noise Control ◽  
Active Noise Control ◽  
Three Dimensional ◽  
Construction Site ◽  
Noise Sources ◽  
Current State ◽  
Active Noise ◽  
Noise Barrier ◽  
Passive Noise

Active noise control (ANC), with counteracting sound in exact equal magnitude and opposite phase to the noise to be controlled, is often considered as a potential solution for solving complex noise problems. However, there are both myths and challenges in its implementations. In a crowded city like Singapore, many noise sources from construction site and subway track are located very close to the residential and commercial buildings. It was suggested by few researchers that by placing suitable control speakers at the construction site (working principle of ANC), the noise from the construction site could be prevented from propagating to the surrounding buildings. Similarly, for viaduct or subway track, by placing control speakers along the viaduct or track, the noise generated by the passing trains or vehicles could be reduced based on the principle of ANC technique. However, implementation of ANC technique on these noise issues is not easy as all of these noise control problems involve multiple noise sources with complex or transient frequency spectrum in large three-dimensional/open space. Therefore, the main intention of the present paper is to discuss the current state of the art of this topic as well as to examine the potential application and limitation of the ANC technique in mitigating unwanted noise, particularly in large three-dimensional/open space and with cooperation of passive noise barrier.

scholarly journals Adaptive Active Noise Suppression Using Multiple Model Switching Strategy

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Quanzhen Huang ◽  
Suxia Chen ◽  
Mingming Huang ◽  
Zhuangzhi Guo
Keyword(s):  
Control System ◽  
Control Algorithm ◽  
Noise Suppression ◽  
Noise Control ◽  
Active Noise Control ◽  
System Response ◽  
Multiple Model ◽  
Switching Strategy ◽  
Online Identification ◽  
Active Noise

Active noise suppression for applications where the system response varies with time is a difficult problem. The computation burden for the existing control algorithms with online identification is heavy and easy to cause control system instability. A new active noise control algorithm is proposed in this paper by employing multiple model switching strategy for secondary path varying. The computation is significantly reduced. Firstly, a noise control system modeling method is proposed for duct-like applications. Then a multiple model adaptive control algorithm is proposed with a new multiple model switching strategy based on filter-u least mean square (FULMS) algorithm. Finally, the proposed algorithm was implemented on Texas Instruments digital signal processor (DSP) TMS320F28335 and real time experiments were done to test the proposed algorithm and FULMS algorithm with online identification. Experimental verification tests show that the proposed algorithm is effective with good noise suppression performance.

Design and Implementation of Self-Tuning Regulators for Active Noise Control

1991 ◽  
Author(s):  
Rahmat Shoureshi ◽  
Yasuhiro Matsuyoshi
Keyword(s):  
High Frequency ◽  
Noise Control ◽  
Acoustic Noise ◽  
Active Noise Control ◽  
Frequency Noise ◽  
Control Methods ◽  
Active Noise ◽  
Self Tuning ◽  
Passive Noise ◽  
Industrial Societies

Abstract Acoustic noise has become an increasingly important problem, especially in industrial societies. The main reason being the increase in usage of machines in virtually all aspects of our lives, higher population densities, and concerns about the health consequences of exposure to acoustic noise. Passive noise control methods work well for relatively high frequency noise, but become progressively more expensive and less effective as one considers control of lower frequency noise. Development and implementation of an adaptive active noise controller is presented.

Vibration Measurements for Active Noise Control in a HVAC System with a Passive Absorber

2016 ◽  
Vol 248 ◽  
pp. 49-56
Author(s):  
Karol Szumski ◽  
Marek Pawelczyk
Keyword(s):  
Control System ◽  
Noise Control ◽  
Active Noise Control ◽  
Audio Signal ◽  
Passive Component ◽  
Frequency Range ◽  
Active System ◽  
Active Noise ◽  
Narrow Frequency Range ◽  
Passive Noise

A hybrid active-passive noise control system for a HVAC duct combines both a physicalnoise absorber and an active system. Due to the presence of the passive component, requirements forthe active system can be relaxed, removing the need for detecting and suppressing noise in the frequencyrange already covered by the passive elements. A typical noise measurement system adaptedto working in airflow usually uses a microphone with a housing designed to reduce the noise generateddue to local turbulent flow introduced by the housing itself. Alternatively, there are microphonesspecifically designed to work in the airflow.During work on the hybrid active-passive noise control system both a microphone designed forairflow and a microphone with special housing were tested. While these solutions can be used forresearch, both have issues making them impractical when designing a commercial product. This, alongwith the required narrow frequency range motivated the authors to consider vibration measurementsperformed by appropriately installed accelerometers. An audio signal is then synthesized using thosemeasurements and it is confronted with signals obtained at the same time with microphones.In the paper the proposed method is presented and validated with a laboratory HVAC installation ofa large cross-section and an originally designed passive absorber. Obtained results encourage further research.

scholarly journals Suitability of Active Noise Barriers for Construction Sites

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.

scholarly journals Integration of Bass Enhancement and Active Noise Control System in Automobile Cabin

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Liang Wang ◽  
Woon Seng Gan ◽  
Sen M. Kuo
Keyword(s):  
Control System ◽  
Noise Suppression ◽  
Noise Control ◽  
Active Noise Control ◽  
Low Frequency ◽  
Audio Signal ◽  
Digital Signal ◽  
Processing Technologies ◽  
Active Noise

With the advancement of digital signal processing technologies, consumers are more concerned with the quality of multimedia entertainment in automobiles. In order to meet this demand, an audio enhancement system is needed to improve bass reproduction and cancel engine noise in the cabins. This paper presents an integrated active noise control system that is based on frequency-sampling filters to track and extract the bass information from the audio signal, and a multifrequency active noise equalizer to tune the low-frequency engine harmonics to enhance the bass reproduction. In the noise cancellation mode, a maximum of 3 dB bass enhancement can be achieved with significant noise suppression, while higher bass enhancement can be achieved in the bass enhance mode. The results show that the proposed system is effective for solving both the bass audio reproduction and the noise control problems in automobile cabins.

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