Geometry.Net - Science: Active Noise Control

WileyEurope :: Active Noise Control Systems: Algorithms And DSP Implementations
WileyEurope, active noise control Systems Algorithms andDSP Implementations by Sen M. Kuo, Dennis R. Morgan.
http://www.wileyeurope.com/cda/product/0,,0471134244|desc|2815,00.html
Welcome To Siemens
DETROIT, MI., October 21, 2002 Siemens VDO Automotive is taking active noise control(ANC) from the exhibit to the streets during 2002 Convergence scheduled
http://www.usa.siemens.com/press/PressReleases/PressReleases/VDO_021021b_REL.htm

Extractions: "We will have demonstration vehicles and interactive exhibits equipped with new product innovations and next-generation technology," said Siemens VDO Automotive Director of Central Technology Michael Gauthier. "We invite media and vehicle manufacturers to experience, first hand, the numerous possibilities and enhancements enabled by electronics, in applications traditionally of a mechanical nature." Such examples of electronic solutions replacing mechanical products include Siemens VDO Automotive's Active Noise Control (ANC). Particularly at low speeds, the sound level in a car is dominated by the noise created by the engine as it draws in fresh air. Siemens VDO Automotive is contributing to improved acoustic comfort and performance with its Active Noise Control (ANC) system for engines being presented at 2002 Convergence.
ACTIVE 99 Final Technical Program
Program of the 1999 international conference on active noise and vibration control.Category Science Technology active noise control Chris Fuller, Virginia Tech University, Blacksburg, VA, USA, p. 609 1100 14.02Investigation of active noise control in nondiffuse sound fields Jingnan Guo
http://members.aol.com/noisenewsi/a99_pgm.html
Experiment
active noise control Experiment. With this shareware, you can test andexperiment with a very simple active noise control system at home.
http://www.val.me.vt.edu/Experiment/experiments.html

Extractions: With this shareware, you can test and experiment with a very simple active noise control system at home. The purpose of this experiment is to demonstrate active noise control. The basic principle of active noise control is to cancel a sound wave (noise) by emitting a secondary opposite (out-of-phase) sound wave (control wave). The active noise control principle is illustrated in the figure below. In the real world, the implementation of active noise control is much more complex due to phase and spatial matching, efficient transducers, system identification, etc., as explained in the paper " Active Control of Sound and Vibration ," by C. R. Fuller and A. H. Flotow. The shareware that you can download, sends a single frequency wave (sine wave at 1000 Hz) to your right speaker. This sound wave represents the noise to be cancelled. By activating the control (pushing on the control button in the program), sound wave of equal amplitude and opposite phase is sent to the left speaker to cancel the noise. Note that for an effective demonstration, the two speakers should face each other and be close to one another (see picture above). If desired, the speakers can then be moved apart and the resulting effect on the sound cancellation observed. This share was tested using "Labtec LCS-800" speakers; the sound cancellation obtained was large and appreciable. Note that the control results depends highly on the quality of speakers used. Please make sure that the volume of each speaker is set to be identical. Also notice that this experiment is more impressive at medium-high volume (please be careful not to overdrive your speakers and ears!).
Quiet Aircraft Facts
active noise control. A new approach to noise reduction is the activenoise control effort. The primary principle of active noise
http://www.grc.nasa.gov/WWW/PAO/PAIS/fs03grc.htm

Extractions: Glenn Effort will Reduce Engine Noise The U.S. aviation industry is a significant contributor to the nation's economy, boasting annual sales in excess of $36 billion and providing nearly 1 million jobs. With the recent boom in air travel brought on by the global marketplace, the industry stands to gain an even greater share of the nation's and the world's economy. Continued competitiveness is important to the industry and to the U.S. economy. Quieter airplanes have a competitive advantage. Just as significant, aircraft noise continues to be a nuisance. Increases in air traffic and growth in populations that surround airports are resulting in a noise impact on a larger percentage of the community and a stronger desire to reduce the noise around airports. The figure to the right illustrates the noise annoyance "footprint" surrounding an airport and how that might be reduced so that airplane noise affects fewer people. Commercial technology necessary to significantly reduce the footprint is not yet available and may be 20 years away. In response to this, NASA is working to develop the required technologies by the year 2000. These technologies are being developed under the Advanced Subsonic Technology (AST) program, which was initiated in 1992 as a partnership between NASA, the U.S. aviation industry, and the Federal Aviation Administration. The goal of the AST program is to develop high-payoff technologies that enable a safe, highly productive global air transportation system. This system will include a new generation of aircraft and engines that are both environmentally compatible and economical.
ENGINEERING ANALYSIS INC. ACTIVE NOISE CONTROL
ENGINEERING ANALYSIS INC. active noise control. An adaptive filter designbased on fractional calculus was developed for active noise control.
http://www.mindspring.com/~eai/EAInoise.html
Active Shielding And Control Of Noise
To conclude, we very briefly discuss the numerical (finitedifference) frameworkfor active noise control that has, in fact, already been worked out, as well
http://epubs.siam.org/sam-bin/dbq/article/36758

Extractions: pp. 563-596 Abstract. In the paper, we construct a general solution to the aforementioned noise control problem. The apparatus used for deriving the general solution is closely connected to the concepts of generalized potentials and boundary projections of Calderon's type. For a given total wave field, the application of Calderon's projections allows us to definitively split its incoming and outgoing components with respect to a particular domain of interest, which may have arbitrary shape. Then the controls are designed so that they suppress the incoming component for the domain to be shielded or alternatively, the outgoing component for the domain, which is complementary to the one to be shielded. To demonstrate that the new noise control technique is appropriate, we thoroughly work out a two-dimensional model example that allows full analytical consideration. To conclude, we very briefly discuss the numerical (finite-difference) framework for active noise control that has, in fact, already been worked out, as well as some forthcoming extensions of the current work: optimization of the solution according to different criteria that would fit different practical requirements, applicability of the new technique to quasi-stationary problems, and active shielding in the case of the broad-band spectra of disturbances. In the future, the aforementioned finite-difference framework for active noise control is going to be used for analyzing complex configurations that originate from practical designs.
Campanella Associates (Acoustics Consultants) - Active Noise Control
Click Here to Return to Home Page active noise control or Cancellation (ANC). Otherwise,perform a new web search on the subject active noise control .
http://www.campanellaacoustics.com/anc.htm

Extractions: Active Noise Control or Cancellation (ANC) Many folks called us recently asking about the application of ANC to domestic and commercial noise control problems. The conventional wisdom seems to be that any noise situation is amenable to an ANC solution. This is false, just as is the notion that a computer is the solution to all of your calculation and bookkeeping problems or that computers reduce the consumption of paper. Consider that most general noise problems are 3-dimensional in nature, typically a noisy area where one or more persons move about. Some explanation is in order: ANC uses the principle of destructive interference where the noise sound wave is sensed with a microphone. This signal is amplified and fed to a loudspeaker which emits it precisely 180 degrees out of phase with the original wave. Cancellation is created at that point. In one-dimensional propagation as down a duct, the sound wave for all intents is "stopped" at that point since the sound from the loudspeaker also proceeds one-dimensionally down the duct, matching the original noise waves precisely along the way. In the case of two or three dimensional propagation into space or into a room, The noise may have been produced a distance away. The divergence of the loudspeaker sound does not match the pattern of the divergence of the noise field, so cancellation does not occur. It requires that the loudspeaker be precisely placed at the center of the source of noise, usually an impossible task.
WIT Press 1853125687
active noise control Information and Control Systems in Engineering and NatureG. ROSENHOUSE, TechnionIsrael Institute of Technology, Haifa, Israel ISBN 1
http://www.witpress.com/acatalog/5687.html
LORD MPD
Manufactures rubberto-metal products, including lord mounts, elastomeric bearings, engine isolators, Category Business Energy and Environment Products Control Rail/Metro, Recreational Marine, Truck, active noise control, Active StructuralControl, Active Vibration Isolators, Aerospace Accessory Mounts, Aircraft Interiors,
http://www.lordmpd.com/
Tech Topics
active noise control (Noise Cancellation). Thanks product. Some examplesof successful applications of active noise control are as follows
http://www.cavtocci.com/techtopics.htm

Extractions: Sound Barrier Screens Vibration Isolator Adjustment ... Do Your Ears Ring? Thanks to the publicity generated by vendors of Active Noise Control, many of our clients ask whether this new technology can be applied to their noise problems. In most cases, the answer is no . This is not because active cancellation doesn't work, but current technology can only address a limited range of problems. Most of the noise problems we work on are solved more effectively by "passive" noise control methods such as vibration isolation, enclosures, barriers, sound absorbing materials, etc. Active Noise Control is most likely to be used by a product manufacturer to solve a noise problem in a specific product. Some examples of successful applications of Active Noise Control are as follows: Noise cancellation headphones - available as a consumer product from several manufacturers. Priced from $150.00, these open air headphones provide significant attenuation of low frequency noise (below 700 Hz) but do not interfere with speech communication. Active exhaust mufflers - these have been applied to public transit busses in New York City. Several automobile companies are also experimenting with active mufflers as a way to control engine noise with less back pressure than a conventional muffler. The main benefit is more peak horsepower from the engine.
Launch Noise Attenuation
Active structural control using piezoelectrics and reaction mass actuators;Speakerbased interior active noise control and boundary control.
http://www.csaengineering.com/acoustic/launchattenuation.shtml

Extractions: As the loads transmitted to satellite structures are reduced through SoftRide systems, the effects of acoustic energy have become increasingly important. When launch vehicles travel at high speed through the atmosphere into space, the turbulent boundary layers on the fairing or shroud exterior lead to high interior sound levels within the shroud in the vicinity of the satellite being launched. Additional sound results during initial liftoff as ground effects tend to accentuate the contributions of rocket exhaust beneath the vehicle. The high sound pressure levels cause satellite components to vibrate, possibly resulting in damage to those components. To reduce acoustic loading on satellites, CSA has worked to develop a group of technologies known as QuietRide. The overall goal of this development is to present alternatives to the acoustic blankets traditionally used to reduce interior noise in launch vehicle payload shrouds. Using both passive and active approaches, CSA is aiming to provide improved performance with reduced weight. CSA is developing the following technologies to attack the very difficult problem of launch noise attenuation: Integral damping within composite structures Augmented passive dampers and absorbers for structural and acoustic control Active structural control using piezoelectrics and reaction mass actuators
Special Sessions
structural vibrations; Active control of sound radiation and transmission;active noise control in enclosures; Other applications of
http://fubini.swarthmore.edu/~bbard/sessions.html
Signal Processing And Control,SPCG
There is also an emphasis on realtime computation for estimation,speech processing and control. Research. active noise control.
http://www.isvr.soton.ac.uk/SPCG/INDEX.HTM

Extractions: TECHNOLOGY TRANSFER TO INDUSTRY The group specialises in digital signal processing and control for sound, vibration and biomedical applications. The signal processing research has developed from off-line computation of conventional spectral quantities, to advanced tools for the analysis of non-linear systems and non-stationary data. There is also an emphasis on real-time computation for estimation, speech processing and control. Acoustic noise can sometimes be reduced by introducing a secondary noise source, such as a loudspeaker, which is carefully controlled so that the sound field it produces interferes destructively with the original sound field. The group has been involved in research into such active noise control systems for some time, investigating both the basic physical limitations of active control and also the practical implementations of real-time controllers. These physical limitations generally restrict the frequency range of global active control systems to below a few hundred hertz. Above this frequency it may still be possible to cancel the sound in a zone around a listener's ear and the acoustic performance of such "local" control systems is the subject of continuing investigation.
Snecma Moteurs Snecma Services Turbomeca Techspace Aero Snecma
Engine aeroacoustic design, active technologies; Nacelle aeroacousticdesign, innovative acoustic treatment, active noise control;
http://www.snecma.com/en/group/research/cooperation/index.php

Extractions: A technology demonstration program in partnership with General Electric, to develop CFM56 follow-on versions by working on all major aspects of aero-engines. The primary objectives are to improve fuel consumption, efficiency, environmental friendliness, maintenance costs and reliability. These developments are then demonstrated on engines under actual conditions.
CARDI Home Page
below Hybrid active noise control for Automotive and Industrial Machinery.Due to active noise control Experimental Setup. A large body
http://egweb.mines.edu/cardi/
Usenet FAQs By Archive-name
Newsgroups (Part 3); activenoise-control-faq - active noise controlFAQ v1996-03-14; afs-faq - AFS distributed filesystem FAQ; ai-faq
http://www.faqs.org/faqs/by-archive-name.html
Www.faqs.org/ftp/usenet/news.answers/index
part3 List of Active Newsgroups (Part 3) news.lists,news.groups,news.announce.newgroups,news.answersactivenoise-control-faq active noise control FAQ v1996-03
http://www.faqs.org/ftp/usenet/news.answers/index

Extractions: Deutsche Babylon 5-FAQ de.rec.sf.babylon5.infos,de.rec.sf.babylon5.misc,de.answers,news.answers de-babylon5/mini-faq de.rec.mampf: Hinweise fuer Einsteiger de.rec.mampf,de.answers,news.answers de-mensa/info de.org.mensa FAQ, v1.95, (mod. 1999-05-10) de.org.mensa,de.answers,news.answers de-net-abuse/email-header-faq E-Mail-Header lesen und verstehen de.admin.net-abuse.mail,de.answers,news.answers de-net-abuse/falsche-email-adressen-faq Falsche E-Mail-Adressen - FAQ de.admin.net-abuse.mail,de.newusers.questions,de.answers,news.answers de-net-abuse/fremdcancel-faq Fremdcancel-FAQ de.admin.net-abuse.news,de.admin.net-abuse.announce,de.admin.news.misc,de.newusers.questions,de.soc.netzkultur,de.answers,news.answers de-net-abuse/mail-faq FAQ, Abkuerzungen: de.admin.net-abuse.mail de.admin.net-abuse.mail,de.answers,news.answers de-newsgroups/chartas Chartas der Newsgruppen in de.* de.etc.lists,de.answers,news.answers de-newsreaders/msinfaq MS Internet Newsclient FAQ de.etc.lists,de.answers,news.answers de-newusers/dana-manual Erlaeuterungen zur Einrichtung neuer Gruppen in de.* de.admin.infos,de.answers,news.answers de-newusers/einleitung
Airport Design Tutorial Page 6
NASA Research A new approach to noise reduction is the active noisecontrol effort. The primary principle of active noise control
http://virtualskies.arc.nasa.gov/design/tutorial/tutorial6.html
ACOUSTICAL ORGANIZATIONS - COMMERCIAL
Brüel Bertrand Johnson Acoustics Brüel Kjær Sound and Vibration MeasurementC37 Sound Systems Causal Systems PTY LTD - active noise control CE Martin
http://www.acoustics.org/org.com.html

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