Geometry.Net - Science: Active Noise Control

Acoustical Society Of America-Active Control Of Automobile Cabin
This method has been proven effective for high frequencies above 1000 Hz due to theirshort wavelengths, while active noise control techniques work better for
http://www.acoustics.org/press/136th/couche2.htm
Active Noise Control FAQ V1996-03-14 FAQ
This FAQ describes active noise control, a novel method for controllingunwanted sound and vibration. active noise control FAQ v199603-14.
http://www.non.com/news.answers/active-noise-control-faq.html

Extractions: Next: advertisers-blacklist Frequently Asked Questions: Active noise control SUMMARY: The FAQ you are now reading discusses active noise control, a novel way of using basic physics to control noise and/or vibration. What is an FAQ, you say? Well, the Internet supports thousands of "newsgroups" discussion forums covering every imaginable topic. An FAQ (Frequently Asked Questions list) is a summary written to answer specific questions that arise repeatedly in the newsgroups. This particular FAQ was written for the newsgroups news: alt.sci.physics.acoustics and news: comp.dsp comp.dsp 1994/12/22 revised list of applications (2.8) 1994/12/12 added new references 1994/10/04 expanded description of mechanisms; corrected typos 1994/06/14 initial release - - - - - - - - - - - - - - - - - - - - - - - The Active Noise Control FAQ is updated monthly; see the version date cited above. You have several options to obtain the latest version: * Usenet: the FAQ is posted monthly to these newsgroups: news: alt.sci.physics.acoustics
Principle Of Active Noise Control
vibrations. TechnoFirst industrial leader in active control of noiseand vibration. What's active noise control ? Definition. The
http://www.technofirst.com/us/antibruit_us.htm

Extractions: What's Active Noise Control ? Definition The principle of active sound control has been known for a long time, but its application to real situations is often difficult and raises numerous difficulties. It consists of canceling an undesirable noise by superposing an inverse noise, which results in the destructive interference of the pressure waves. Sound is driven by the propagation of a pressure wave. It is possible to cancel this wave by adding its opposite As you can see on the following animation, the resulting wave if very weak. External noise Analyze and signal processing Resulting wave How is it realized ? First of all, the creation of an opposite sound requires the use of at least one noise source (loud-speaker). Sensors (microphones) are also needed to gather information about the acoustic field. The characteristics of the sources and sensors are closely related to the application concerned. Finally, the heart of noise control is an electronic system (analog or digital), which generates the canceling noise which will interfere with the undesirable noise.
Hi-Fi Headset With Active Noise Control
LITE Audio Headphone with Active Noise Reduction system. Listento music in noisy environment ! (Train, Plane, Computer room, ).
http://www.technofirst.com/us/casq_lite_us.htm

Extractions: LITE: Audio Headphone with Active Noise Reduction system Listen to music in noisy environment (Train, Plane, Computer room,...) The LITE headphone benefits from the technology of professional NoiseMaster headsets. It provides an attenuation of external noise from 10 to 15 dB in the 20 to 1000 Hz frequency range. Audio input : jack 3.5 mm. Battery : 9 Volts. Box weight : 80 g. Power cable length : 1 m. Headphone sold without CD player ref. : tf-1060 Performances and characteristics
Analog Feedback Active Noise Control
Analog Feedback active noise control. 0) Introduction to single channelfeedback noise control. The system consists of a microphone
http://ourworld.compuserve.com/homepages/discoveryengineering/fanc1.htm

Extractions: Analog Feedback Active Noise Control Introduction to single channel feedback noise control The system consists of a microphone sensor, a loudspeaker actuator, and an equalizer to correct for the delay from the speaker to the microphone and for the transfer function of the speaker itself. The microphone is usually placed close to the speaker. The system transfer function is increasingly difficult to equalize as the mic moves away from the speaker (the phase change goes from gradual over the bandwidth of interest to very rapid). A disturbance input at the sensor (low frequency acoustic noise) can be attenuated by the proper choice of equalization. The zone of silence around the sensor is approximately 1/10 th of the wavelength of the noise to be attenuated. see Sections 7.3, 7.4 and 7.7 from Active Control of Sound , Nelson and Elliott and Section 6.2 from Active Noise Control Systems , Kuo and Morgan Pick the problem For example, reduce a 100 Hz tone by at least 10 dB in the vicinity of an error microphone Assemble the HW needed Noise generator to measure the system transfer function - use an analyzer with a built in source, buy, or build your own
Courses.html
Developments in active barriers and active noise control. Design andcalculation by computers. Papers taught in other departments.
http://www.acoustics.auckland.ac.nz/Courses.html
Purdue University School Of Mechanical Engineering
psychological considerations; experimental techniques. active noise controlof highorder acoustical source in anechoic chamber. Applications
http://me.www.ecn.purdue.edu/ME/Research/Acoustics_and_Noise_Control

Extractions: Active Noise control of high-order acoustical source in anechoic chamber. Applications involve aircraft and automobile components and systems, household appliances, computers, buildings, and refrigerant compressors. Most acoustics and noise control research is conducted at the Ray W. Herrick Laboratories
[International Conference On Noise And Vibration Engineering] ISMA Related Ph.D.
K. HENRIOULLE, Distributed actuators and sensors for active noise control, 2001.Abstract. The first is the active control of engine noise in a car interior.
http://www.isma-isaac.be/publications/phd2001/khenrioulle_en.phtml
Applied Acoustics - Education - Courses - ANC - Course PM
active noise control 2002/2003. Welcome to the course page of Active NoiseControl. First Test of Fan active noise control (ANC) Completed.
http://cthta4.ta.chalmers.se/documents/edu/anc/
Siemens Automotive: News Release
And Eliminating The Negative Is A Sound Engineering Solution At Siemens VDOAutomotive Siemens VDO Automotive Develops active noise control For Engines
http://media.siemensauto.com/mediacenter2/queries/releasefull.phtml?prjob_num=13
Thayer Faculty - Laura Ray
coauthored over 40 refereed articles and conference publications on robust control,nonlinear estimation and control, active noise control, and applications
http://engineering.dartmouth.edu/thayer/faculty/lauraray.html

Extractions: In complex systems, underlying dynamics governing processes can be poorly known or must be modeled empirically. For example, friction behavior, which is important in motion control, is nonlinear, contains hysteresis, and varies based on lubrication, temperature, humidity, loading, and numerous other factors. Professor Ray's research develops non-model-based methods of estimating process models. Such estimation methods have been demonstrated in motion control systems for applications ranging from semiconductor manufacturing and inspection to precise positioning of read-write heads in disk drives. These methods have also been used for tire force estimation in order to improve the tire design and optimization process. One might envision a vehicle of the future in which tire force estimation methods are employed to provide exquisite control of the forces at the road-tire interface, in order to vastly improve vehicle stability and traction. National Public Radio
Headsets, Inc. Noise Reduction Headsets For Aviation
Noise reduction modules for headsets. Factory installation.Category Shopping Recreation Aviation Pilot Shops Our active noise control system gives superior performance and installsinto most headsets. Read what others have to say about our products.
http://www.headsetsinc.com/
Kenneth A. Cunefare (Acoustics And Dynamics)
A Boundary Element Approach to Optimization of active noise control Sources on ThreeDimensionalStructures. Journal of Vibration and Acoustics113(3), 387-394.
http://www.me.gatech.edu/me/publicat/brochures/rb/Cunefare.html

Extractions: After obtaining his bachelor's degree in 1982, Dr. Cunefare worked for Exxon Corporation for more than five years in a number of gas and oil production and transportation assignments in Texas and Wyoming. He then returned to the academic fold to obtain his master's and doctoral degrees. Dr. Cunefare became a member of the Woodruff School faculty in 1990, though he did not arrive on campus until 1991. Following his graduation from Penn State, Dr. Cunefare spent a research year at the Technical University of Berlin in the Institute for Technical Acoustics, as the Acoustical Society of America's F. V. Hunt Postdoctoral Fellow. Dr. Cunefare arrived in Berlin in time to witness firsthand the economic and political union of the two Germanys. Research Dr. Cunefare's research has been directed toward controlling and tailoring the sound produced by engineered structures, such as from transformers, motors, and in aircraft and automobile interiors. He has investigated the means to better model the acoustic radiation from such structures, and how sound and vibration propagate through these structures. He has developed design optimization methods to permit tailoring of the acoustic characteristics of structures by integrating commercially available modeling codes. This optimization might be used, for example, to design and reduce interior noise levels within aircraft cabins by optimally distributing the mass and stiffness of the material in the fuselage. Dr. Cunefare has also investigated how active control might be used to tailor acoustic responses. In active control, secondary powered actuators are used to suppress or cancel the sound produced by some other source, such as from an engine exhaust.
Sound Internet Resources
active noise control FAQ This FAQ for active noise control, provides history, basics,and answers to many questions on cancelling noise in acoustics, persented
http://www.eeglossary.com/sound.htm

Extractions: ... home ... Our favorite links for this topic area. Enjoy, fellow researchers! Questions, comments, new links? Email eewindow@aol.com other great electronics sites ee toolbox site sound digital signal processing and its relationship to sound or audio is the subject of this keyword. (Note: The Electronic Engineers Toolbox provides an alternative set of featured links for this word at http://www.eg3.org/sound.htm Featured Links: Active Noise Control FAQ This FAQ for active noise control, provides history, basics, and answers to many questions on cancelling noise in acoustics, persented ina non-mathematical setting. It includes many analogies to help those who aren't very familiar with DSP or acoustic physics. http://users.erols.com/ruckman/ancfaq.htm The Servo16 module is perfectly designed for analog measurement and control applications requiring high accuracy and channel density. This module employs sixteen, simultaneous sampling, 100 kHz, 16 bit A/Ds and sixteen, simultaneous update, 100 kHz, 16 bit D/As for an unprecedented analog I/O density. Applications include vibration measurement/control, SONAR and industrial process control to name just a few.
SOA Staff
Summary of Qualifications More than 15 years of experience in research and systemsdevelopment of signal processing, active noise control, and acoustics.
http://www.arl.psu.edu/areas/soa/staff.html
Medical Physics Keywords 125I Brachytherapy 125I Source 137Cs
active matrix detector. active matrix flatpanel imager. active matrix readout.active noise control. adaptive portal CT. adaptive sampling. additive noise.
http://www.medphys.org/keywords.asp

Extractions: Medical Physics Keywords 125I brachytherapy 125I source 137Cs irradiator 32P Source wire 3D algorithms 3D and MIP image artifacts 3D conformal radiotherapy 3D contrast-enhanced 3D dose distribution 3D dosimetry 3D imaging 3D reconstruction 3-D reconstruction of marker positions 3D treatment planning 3-D ultrasonography 3-D ultrasound 3D vascular reconstruction 3-dimensional 3-dimensional treatment planning 3-dimensional treatment planning system 72 MeV protons AAPM TG-43 and TG-60 dose calculation formalism abnormal readings absolute dosimetry absorbed dose absorption spectra abutment regions accelerator accelerator neutron source accelerator output fluctuation accelerator spectra accelerator-based Boron Neutron Capture Therapy (ABNCT) acceptance test acceptance testing accuracy accuracy evaluation acrylic cone acting portion activation active matrix detector active matrix flat-panel imager active matrix readout active noise control adaptive portal CT adaptive sampling additive noise adjoint difference afterglow agarose agarose gel air cavity air-kerma strength aliasing alignment alpha-particle emitters AMFPI amorphous selenium amorphous silicon amorphous silicon array analytic model analytical approximation analytical fit analytical methods anatomical background anatomical models anger camera angiography angioplasty angular distribution anisotrophy function anistrophy anthropomorphic phantom antibodies aperiodic application accuracy apron aqueous gel area over perimeter rule area/perimeter ratio arterial input function artero-venous malformations arthritis
Noise Control- Illinois EPA - Bureau Of Land
While Illinois EPA does not have an active noise control program, regulations canbe viewed on the Internet at the Pollution Control Board's Environmental
http://www.epa.state.il.us/land/noise/

Extractions: All Illinois Gov't Noise Control While Illinois EPA does not have an active noise control program, regulations can be viewed on the Internet at the Pollution Control Board's Environmental Regulations page . Any law enforcement office can enforce these regulations. If you have a complaint about excessive noise, the following might help: Regulatory Information Links Land Menu
Wyle Laboratories :: Acoustic Research And Consulting - Acoustics Vibration Avia
acoustics,highway noise,military noise,environmental noise, community noise,industrial noise, effects of noise on humans, and active noise control.
http://www.wyleacoustics.com/

Extractions: The Wyle Acoustics Group provides a wide range of professional services concerned principally with acoustics, vibration, and their allied technologies, including services to the aviation industry. Since its inception in 1963, Wyle has completed thousands of projects in areas as diverse as aircraft noise, railroad and railyard noise, acoustical design of buildings, highway noise, sonic boom studies, research into the effects of noise on people, specialized noise and vibration studies, and active noise control. NASA Federal Aviation Administration Aerospace industry U.S. National Park Service
Journal Of Vibration And Acoustics
mechanical signatures; rotor dynamics; vibration control; passive and active damping;random vibration; acousic emission; active noise control; machinery noise
http://www.asme.org/pubs/journals/vibrate/
Technical Committee On Noise (TCN) Of The Acoustical Society Of America (ASA) -
Additionally, the engineering and structural committees sponsored severalsessions that focused on flowinduced noise and active noise control.
http://www.nonoise.org/quietnet/tcn/2002.htm

Extractions: of the Acoustical Society of America (ASA) The Technical Committee on Noise (TCN) has had a successful year! Although noise is still defined as "unwanted sound", the interest of those in the Acoustical Society, and of the general pubic at large, in noise issues is strong and is growing. There seems to be a sense of purpose and urgency concerning noise and its control that is unprecedented in recent years. Perhaps the awareness of noise has reached the critical mass needed to achieve real results. As always, your technical committee has been a vital exponent for noise awareness and noise control, in fulfillment of the ASA purpose "to increase and diffuse the knowledge of acoustics and promote its practical application." More on that later. The Technical Committee on Noise met twice in the past year: in the fall of 2001 in Ft. Lauderdale, FL, and in the spring of 2002 in Pittsburgh, PA. Both meetings had a great turnout. The ASA meeting in Ft. Lauderdale was well attended, perhaps due to its attractive location. This was a successful meeting, with 7 technical sessions primarily sponsored by TCN, and 5 additional sessions cosponsored with other technical committees. Nearly 80 papers were presented. Topics included classroom acoustics, noise measurement and control case studies, industrial noise prediction, cruise ship acoustics, community noise and noise effects on marine animals. A retrospective session on Miguel Junger's work was held. In addition, Tony Embleton regaled us with his fascinating tutorial on noise propagation and prediction outdoors!

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