Active reduction of an enclosed sound field

an experimental investigation by A. R. D. Curtis

Publisher: University of Sheffield, Dept. of Control Engineering in Sheffield

Written in English
Published: Downloads: 143
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Edition Notes

StatementA.R.D. Curtis, P.A. Nelson, S.J. Elliott.
SeriesResearch report / University of Sheffield. Department of Control Engineering -- no.381, Research report(University of Sheffield. Department of Control Engineering) -- no.381.
ContributionsNelson, P. A., Elliott, S. J.
ID Numbers
Open LibraryOL13964065M

Regarding the active control, results confirm that the best approach to avoid sound transmission consists of achieving a global control inside the enclosure, rather than look for a local cancellation at the aperture. Finally, the principle of active control of sound transmission is applied successfully to a real case of incoming aircraft noise.   Zero-spillover control of enclosed sound fields Zero-spillover control of enclosed sound fields Al-Bassyiouni, Moustafa ABSTRACT In designing a controller, one way to avoid energy spillover is to use what is called the zero spillover control scheme. Here, this scheme is studied for actively controlling sound fields inside an enclosure with a flexible boundary. Existing publications on diffraction and noise reduction by barrier inside an enclosed space can be divided into two broad categories: those that employ classical diffuse-field theory [1,2], and. Recently much research has focused on the control of enclosed sound fields, particularly in automobiles. Both Active Noise Control (ANC) and Active Structural Acoustic Control (ASAC) techniques are being applied to problems stemming from power train noise and road noise (noise due to the interaction of the tires with the surface of the road).

  The invention also concerns a device for active noise reduction in a local area in accordance with the introduction of claim 9. There is a known method of using an active noise reduction based on sound waves destructive interference in order thereby to reduce the energy in a sound field. Author: Scott D. Snyder Publisher: Springer Science & Business Media ISBN: Size: MB Format: PDF, ePub, Mobi View: Get Books. Active Noise Control Primer Active Noise Control by Scott D. Snyder, Active Noise Control Primer Books available in PDF, EPUB, Mobi Format. Download Active Noise Control Primer books, By providing all the basic knowledge needed to . The present research involved a numerical analysis of the influence of the rotational and translational flexibilities of sound-transmitting panel edges in a two-dimensional cavity-panel system on t. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): Current approaches for active noise control in large listening spaces require a high number of sensors to control the sound field within a given volume. This contribution presents a new approach based on the theory of acoustic wave propagation. It exploits the fact, that a distribution of sources and sensors on the.

When does active control work best? Active noise control works best for sound fields that are spatially simple. The classic example is low-frequency sound waves traveling through a duct, an essentially one-dimensional problem. The spatial character of a sound field depends on wavelength, and therefore on frequency. In this paper, a modified cost function is proposed in order to achieve the maximum noise attenuation using a set of secondary sources for a harmonically excited sound field. The modified cost func. aircraft manufacturers to seek cabin noise reduction by passive and Typically, the active noise control system is aimed to minimize a For the steady state, the potential energy of an enclosed sound field excited by the primary sources. a. p. and a set of secondary point. Noise control for mechanical and electrical system equipment and components is addressed. Vibration reduction techniques (inertia blocks, resilient support, and floating floors) are described. Control of duct system noise is important. Active noise cancellation is an alternative noise reduction technique for non-random noises.

Active reduction of an enclosed sound field by A. R. D. Curtis Download PDF EPUB FB2

The experimental sound field is enclosed by a 6m long duct constructed of high density chipboard with a cross section m by m. The duct was designed and built by Silcox6 for experiments in the active reduction of propagating sound and is modified in these experiments by sealing both ends with chipboard panels to enclose the sound field.

The simplest enclosed sound field, a duct with closed ends, is studied and it is experimentally demonstrated that strategies developed for the control of sound in ducts do not perform as well as a strategy developed for the control of sound in enclosed spaces. The enclosed sound field has the simple structure of standing wave composed of two propagating waves, an incident wave from Author: A.R.D.

Curtis, P.A. Nelson, S.J. Elliott. Active Control Of Enclosed Sound Fields In this chapter a third ‘general group’ of active noise control problems will be examined: that of controlling sound fields in enclosed spaces.

This group of problems includes many commonly encountered systems, such as automobile interiors, aircraft cabins, ship cabins and rooms in : Colin Hansen, Scott Snyder, Xiaojun Qiu, Laura Brooks, Danielle Moreau.

Three control strategies for the active reduction of an enclosed sound field are experimentally implemented and compared.

A strategy of energy minimization successfully reduces the sound field at both resonant and antiresonant frequencies, whereas strategies developed for the control of propagating sound in ducts do not perform by: Global noise reduction is the objective of many active noise control applications in small enclosures such as aircraft trol of a pure tone in a diffuse sound field.

10,11 It was found that minimising both the pressure and pressure gradient along Active Control of Enclosed Sound Fields Using Three-axis Energy Density Sensors:Cited by: 3.

Abstract. The total time averaged acoustic potential energy in a steady harmonic sound field can be expressed as a positive definite quadratic function of the complex strengths of a number of “secondary sources” of sound introduced into the enclosure. This work considers the use of secondary acoustic sources for the reduction of noise levels in harmonically excited enclosed sound fields.

This possibility is studied initially through the use of an analytical model of a single frequency `two-dimensional' rectangular, enclosed sound field of. A new method of controlling enclosed sound fields subjected to impulsive or broadband disturbances is presented based upon direct rate‐feedback control.

Results from this preliminary study suggest that if a pressure transducer is collocated with a volumetric source in an enclosed sound field and rate‐feedback control is employed, then the global properties of the sound field can be. An alternative approach to the control of enclosed sound fields subjected to impulsive or broadband disturbances is presented based upon direct rate‐feedback control.

Results from this preliminary study suggest that if a pressure transducer is collocated with a volumetric source in an enclosed sound field and rate‐feedback control is employed, then the global properties of the sound field.

Abstract An analysis is presented of the effectiveness with which active methods can be used for producing global reductions in the amplitude of the pressure fluctuations in a harmonically excited enclosed sound field.

The active control of low‐frequency random sound in enclosures is then addressed and the classical Wiener theory extended in order to deal with problems involving the minimization of multiple errors.

The active control of a one‐dimensional enclosed sound field is presented as a simple example. Journals & Books; Help Download full text in PDF Download. Share. Export. Advanced.

Journal of Sound and Vibration. VolumeIssue 1, 22 AugustPages The active minimization of harmonic enclosed sound fields, part II: A computer simulation. The most successful control strategy investigated in this thesis for dealing with high frequency enclosed sound fields is the cancellation of the pressure at a point close to the secondary loudspeaker i.e., the 'Sound pressure reducer'.

This is the subject of chapter 6. In addition, the noise field in the enclosed space is generated by the vibration of the boundary structure of the enclosure, therefore, the input matrices properties of the noise and control sound field are very similar and more controllable.

If there is no other primary source, this approach is the same, in principle, as the reduction of the noise. Computer programs which can be used to calculate the total acoustic potential energy in enclosures with various geometries and damping (assuming various primary source distributions and secondary source positions) are discussed.

Consideration is given to the use of these programs in cases where the frequency is low so that single doses can give rise to a resonant sound field and where the. Available from UMI in association with The British Library. Requires signed TDF.

This work considers the use of secondary acoustic sources for the reduction of noise levels in harmonically excited enclosed sound fields. This possibility is studied initially through the use of an analytical model of a single frequency "two-dimensional" rectangular, enclosed sound field of low modal density.

Abstract. This paper is Part II in a series of three papers on the active minimization of harmonic enclosed sound fields. In Part I it was shown that in order to achieve appreciable reductions in the total time averaged acoustic potential energy, E p, in an enclosed sound field of high modal density then the primary and secondary sources must be separated by less than one half wavelength, even.

The first deals with the active control of harmonic enclosed sound fields at low frequencies where the frequency response function is composed of distinct, well isolated modal resonances. In this frequency regime the sound field in the room is amenable to global control: for example, minimizing the total acoustic potential energy in the enclosure.

This work considers the use of secondary acoustic sources for the reduction of noise levels in harmonically excited enclosed sound fields. This possibility is studied initially through the use of an analytical model of a single frequency `two-dimensional' rectangular, enclosed sound field of low modal density.

Quadratic optimisation theory is used to predict the effectiveness of these active. Noise reduction and active noise control of high frequency narrow band dental drill noise the author of this book is refreshingly different.

in an enclosed sound field of high modal. The problem of active sound field reduction/reproduction in enclosed spaces has been widely studied because of its practical significance. In case that the incident sound is annoying this problem is studied mostly under the title of active sound control in the literature.

Active noise control - the reduction of noise by generating an acoustic signal that actively interferes with the noise - has become an active area of basic research and engineering applications.

The aim of this book is to present all of the basic knowledge one needs for assessing how useful active noise control will be for a given problem and then to provide some guidance for. An active structural–acoustic control system for a composite fuselage type structure is developed in this paper.

The focus of the active control system is the global reduction of the sound field in an enclosed acoustic cavity using structure-integrated sensors and actuators.

This book is a companion text to Active Control of Sound by P.A. Nelson and S.J. Elliott, also published by Academic Press. Three control strategies for the active reduction of an enclosed. Results show that the hybrid system provides 5 to 30 dB active performance in the frequency range Hz for tonal noise and dB active performance in the same frequency range for.

NOISE CONTROL Room Acoustics J. Lamancusa Penn State 12/1/ The Noise Reduction Coefficient (NRC) is an attempt to get a single number to quantify a material. It is the numerical average of the absorption coefficients in the, and Hz bands.

Design of an end-to-end active noise control system in a partially enclosed sound field, such as a bedroom with an openable window, by applying the latest machine learning techniques.

Introduction. This research aims to design an endto-end active noise control system in a partially enclosed. Active Damping of Enclosed Sound Fields Through Direct Rate Feedback Control,” J.

Acoust. Analysis, Testing, and Control of a Reverberant Sound Field within the Fuselage of a Business Jet,” J. Acoust. Lane, S. A.,Active Noise Control in Acoustic Enclosures Using a Constant Volume Velocity Source, Ph.D.

dissertation, Duke. the effectiveness of the proposed system in reduction of the acoustic potential energy in the kiosk. Keywords: Modal analysis, Global Reduction, Rectangular Enclosure 1.

INTRODUCTION Initial consideration of the active control of an enclosed sound field dates back to the work by Olson and May [1]. Because of advances in microprocessor technology. Various issues associated with active noise control in free-field conditions are addressed through a series of seven questions, and in fact I have used this approach to introduce my graduate class in acoustics to the concept of active noise control.

From the free-field problems the author moves to enclosed sound fields in chapter 5 and the. The content of the upcoming chapter is therefore oriented on (Kuo and Morgan in Active noise control systems—algorithms and DSP implementations, Wiley, Canada, ) and (Elliott in Signal processing for active noise control, Academic Press, London, )—two fundamental books about signal processing for ANC that are (without detailed.approaches have been established: active vibration control of a flexible sound-transmitting panel (control of the transmission paths through relatively weak structures using ASAC) [1]-[5] and active noise control of the enclosed sound field using acoustic sources [6]-[10].

Previous work generally employed potential energy [6]-[9] or squared.Get this from a library! Active Noise Control Primer. [Scott D Snyder] -- Active noise control - the reduction of noise by generating an acoustic signal that actively interferes with the noise - has become an active area of basic research and engineering applications.

The.