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Topic: Noise cancellation

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	Biosensor electromagnetic noise cancellation - Patent 6858433
		a noise cancellation loop electrically distinct from the analyte reaction zone and physically arranged to be exposed to substantially the same electromagnetic environment as the measurement loop and electrically connected to substantially cancel the effect of electromagnetically propagated field energy irradiating the biosensor cell assembly.
		providing a noise cancellation loop electrically distinct from the analyte reaction zone and physically arranged to be exposed to substantially the same electromagnetic environment as the measurement loop and electrically connected to substantially cancel the effect of electromagnetically propagated field energy irradiating the biosensor cell assembly.
		By summing the output of the measurement loop 26 with an inverted signal (from amplifier 64) representing the output of the noise cancellation loop 32 at the inverting input 51 of amplifier 342, the error induced by a stray field in the electromagnetic environment may be effectively subtracted from the measurement loop signal.
	www.freepatentsonline.com /6858433.html (3352 words)

	Waveform Noise - Succeed in Physical Science
		It is called white noise because it consists of a full spectrum of waveform frequencies, similar to how white light is a combination of a full spectrum of visible colors.
		One example of electrical noise that is added to your home current can be caused by a nearby electric motor that may create an additional regular signal, which can add to your normal AC signal.
		Typically the noise is not regular, thus you take its average to determine the effect on the listener.
	www.school-for-champions.com /science/noise.htm (1030 words)

	Adaptive Noise Cancellation
		So the noise cancellation must be an adaptive process: it should be able to work under changing conditions, and be able to adjust itself according to the changing environment.
		The basic idea of an adaptive noise cancellation algorithm is to pass the corrupted signal through a filter that tends to suppress the noise while leaving the signal unchanged.
		The noise source is a speaker which continuously plays the white noise generated by the tone generator in the computer.
	www-ece.rice.edu /~klwang/elec434/elec434.htm (1330 words)

	Quieting The Environment: Noise Cancellation
		Note that Active Noise Cancellation does not mask the noise; it removes a significant portion of the noise energy from the environment.
		This form of Active Noise Cancellation is shown in Figure 4 as used to reduce the noise in an air duct.
		The use of Synchronous Noise Cancellation in a headset offers some additional benefits in those cases where most of the noise is tonal.
	doctord.dyndns.org:8000 /Pubs/POTENT.htm (2403 words)

	What is Noise Cancellation?
		Noise cancellation technology is a growing field that capitalizes on the combination of disparate technological advancements.
		Noise cancellation tries to 'block' the sound at the source instead of trying to prevent the sounds from entering our ear canals.
		Noise cancelling technologies first rely on small microphones that detect the sounds in a given environment.
	www.wisegeek.com /what-is-noise-cancellation.htm (368 words)

	Halfbakery: Advanced Noise Cancellation
		The ideal would be to actively cancel noises at their source, by emitting an inverse wave of sound at the noise.
		So anyone wanting noise cancellation would still need to wear a pendant or something like that, which would be a wireless device.
		To get good noise cancellation you would also have to model the propagation paths of both the noise and the cancellation signals, which would need some fiendish computation.
	www.halfbakery.com /idea/Advanced_20Noise_20Cancellation (795 words)

	Noise-cancelling headphone - Wikipedia, the free encyclopedia
		Essentially, this involves using a microphone, placed near the ear, and electronic circuitry which generates an "antinoise" sound wave with the opposite polarity of the sound wave arriving at the microphone.
		Retail noise cancelling headphones typically only cancel the lower-frequency portions of the noise; they depend upon traditional noise suppression techniques (such as their earcups) to prevent higher-frequency noise from reaching the interior of the headphone.
		To truly cancel high frequency components (coming at the ear from all directions), the sensor and emitter for the cancelling waveform would have to be adjacent to the user's eardrum, an impractical situation.
	en.wikipedia.org /wiki/Noise-cancelling_headphone (537 words)

	Noise Reduction Headphones / Noise Cancelling Headphones : EX29 Extreme Isolation Headphones (Site not responding. Last check: 2007-10-11)
		This form of noise cancellation is called active cancellation and has gotten a great deal of attention due to the complicated technology used.
		Active noise cancellation is an effective way to block sound, but it tends to produce a hissing, swooshing sound inside the ear cups.
		If, however, you are unsatisfied with these noise cancelling - canceling reduction headphones for any reason, simply send them back to Direct Sound Headphones LLC within 60 days in good condition and in the original packaging, and you will promptly receive a full refund of the purchase price.
	www.quietheadphones.com (1257 words)

	Active noise control - Wikipedia, the free encyclopedia
		Active noise control (also known as noise cancellation, active noise reduction (ANR) or antinoise) is a method for reducing unwanted sound.
		Modern active noise control is achieved through the use of a computer, which analyzes the waveform of the background aural or nonaural noise, then generates a polarisation reversed waveform to cancel it out by interference.
		This method differs from passive noise control methods (soundproofing) in that a powered system is involved, rather than unpowered methods such as insulation, sound-absorbing ceiling tiles or muffler.
	en.wikipedia.org /wiki/Active_noise_cancellation (502 words)

	Energy Savings Using Active Noise Cancellation
		The application of Active Noise Cancellation (the use of an equal, but opposite, anti-noise to eliminate noise) to the control of low frequency noise was proposed over 50 years ago.
		The Synchronous Feedback noise cancellation technique, developed by G. Chaplin in the mid 1970's and recently improved and productized by Noise Cancellation Technologies, is very effective on repetitive noise and does not rely on causality.
		Active noise cancellation products for these applications as well as others in which noise reduction, energy use, and air pollution have been a problem are now moving from the laboratory into commercial products.
	doctord.dyndns.org:8000 /Pubs/ENERGY.htm (4302 words)

	Adaptive Noise Cancellation using Java
		Because the noise that is added to the signal is correlated with the white noise that is input to the adaptive filter, over the long term, the adaptive algorithm will attempt to drive the noise component of the error to zero.
		The left panel in Figure 2 shows the convolution operator that was applied to the white noise to simulate the noise arriving at the location in the park where the concert is being held.
		Listing 10 convolves the waterfall noise with the acoustic path operator to produce an estimate of the waterfall noise as it would sound at the location in the park where the concert is being performed.
	www.developer.com /java/other/article.php/3599661 (6195 words)

	Distributed Noise Cancellation Systems for the PC
		In a noisy environment a desired signal can be corrupted by noise and result in the formation of a distorted signal.The usual method of estimating a signal corrupted by additive noise is to pass the distorted signal through a filter that tends to suppress the noise while leaving signal relatively unchanged.
		Adaptive noise cancellation is performed when there is no prior knowledge of the signal and the noise sources and the adaptive filters have the ability to adjust their own parameters automatically.
		The DNC cancels the noise and retrieves the desired signal from the noisy speech signal.
	www.eas.asu.edu /~dsp/research/dnc.html (318 words)

	Campanella Associates (Acoustics Consultants) - Active Noise Control
		A case of 3-D propagation, but with the cancellation very near to the reception point, is the ANC headsets popular for pilots and other noise-field situations where it is acceptable to wear an earmuff type hearing protector.
		Noise cancellation is truly outstanding at low frequencies down to 20 Hz or less (inside the ear cup only - at your ear), depending on the quality of ear cup seal around your ear.
		For open 3-dimensional space such as residence rooms and back yards, most noise sources such as engines, transformers, exhaust fans and places where loud music is being palyed, are more than a quarter wavelength wide, so that a single loudspeaker ANC transducer close to that noise source will not work.
	www.campanellaacoustics.com /anc.htm (723 words)

	Noise Cancellation (Site not responding. Last check: 2007-10-11)
		SPIRIT's Noise Cancellation technology can be effectively used in wireless telephony systems, set-top boxes, videoconferencing applications, VoIP solutions, voice recognition pre-processors, and other voice related applications where it is vital to reduce the background noise level as much as possible.
		SPIRIT's Noise Cancellation technology is based on the spectral subtraction technique with significant attention paid to the conservation of speech quality.
		The Noise Cancellation Solution developed by SPIRIT significantly reduces the broadband colored noise in the processed signal.
	www.spiritdsp.com /noise_cancellation.html (430 words)

	Adaptive beamforming and Noise cancellation
		This is because of the effect of reverberations due of enclosed rooms, coherent/incoherent noise e.g.
		In addition to this, adaptive noise cancellation will be used to reduce the noise captured via the microphone to have even better performance in a cocktail party like environment.
		The processed output of the beamformer and adaptive noise canceller will be used as an input to an HMM to check for the recognition accuracy.
	www.cnel.ufl.edu /~kkale/6586Project.html (578 words)

	Active Noise Cancellation - Succeed in Physical Science
		Noise cancellation is a method to reduce or completely cancel out undesirable sound, such that you can't hear it.
		Noise can be suppressed or cancelled by electronically creating the same waveform and volume, but in an opposite phase.
		Noise cancellation devices can protect the ears of workers, as well as to allow people to concentrate on what they want to do.
	www.school-for-champions.com /science/noise_cancellation.htm (1547 words)

	We Review Solitude Active Noise Cancellation Headset (Verdict: What Noise Cancellation?) - Gizmodo (Site not responding. Last check: 2007-10-11)
		The sound being produced by the headset also seems to get louder once the noise canceling is turned on, perhaps to draw your attention away from the fact that the noise canceling only works marginally.
		Overall, I'd say that the Solitude Active Noise Cancellation Headset is decent: very comfortable but with "just ok" sound quality, probably more on the "ok" side if all you listen to is rock and the like; anything with more than a couple of guitars and drums may have you scratching your head.
		Well, noise cancellation is the term for what happens when a sound wave collides with an identical soundwave whose phase is 180 degrees shifted.
	gizmodo.com /gadgets/peripherals/we-review-solitude-active-noise-cancellation-headset-verdict-what-noise-cancellation-184800.php (635 words)

	Quellan Introduces Groundbreaking RF Noise Cancellation Technology - Forbes.com (Site not responding. Last check: 2007-10-11)
		By dropping the noise floor at the receivers input, a substantial improvement in signal-to-noise ratio is achieved, resulting in fewer dropped calls, continuous video capability and GPS location locks in high density urban areas.
		While the technology operates in a similar fashion to Noise Cancelling Headphones, Quellan's noise cancellers operate at one million times higher frequency and are embodied in tiny, ultra-low power CMOS silicon.
		Quellan's noise cancellers are just a few square millimeters in size -- yielding tens of thousands of devices on a single silicon wafer -- making them very inexpensive and embeddable in any consumer device.
	www.forbes.com /prnewswire/feeds/prnewswire/2006/12/07/prnewswire200612070600PR_NEWS_B_NWT_SF_SFTH040.html (648 words)

	NoiseBuster.net :: NoiseBuster Noise Cancelling Earmuffs for Safety ::
		Low frequency noise consists of powerful sound waves that can travel great distances and cannot be absorbed by conventional passive materials.
		Noises generated by engines, fans, motors and other similar devices are typically dominated by low frequencies--frequencies that cannot be stopped by passive earmuffs.
		Because low-frequency noise masks speech, it is difficult for a person to hear and comprehend speech and warning signals when exposed to such noise.
	www.noisebuster.net /nb-safety.htm (541 words)

	Audio DesignLine \| Noise reduction and echo cancellation improves automobile communications (Site not responding. Last check: 2007-10-11)
		The Referenced Noise Filter is an example of a noise reduction technique that can target a specific type of problem where the noise-producing source is man-made and accessible.
		Figure 11: The referenced noise filter takes a signal (direct tap) from the source of the noise (the siren) and use this as a reference to enable the filter to target the noise that need to be removed.
		Noise reduction and echo cancellation has been a big subject for the communications sector over the last 10 years.
	www.audiodesignline.com /howto/175000814 (1965 words)

	The sound of silence - CNET reviews
		By canceling out the sound of airplanes, buses, and other sources of aural aggravation, they enable you to hear every note in your personal soundtrack without blowing out your eardrums.
		The low-tech, or passive, way to cancel noise is simply to wear closed-back, circumaural (around the ear) headphones or very snug earbuds.
		Physical limitations make absolutely perfect noise cancellation impossible, but some of the noise-canceling headphones we tested did a great job without adversely affecting the music.
	reviews.cnet.com /4520-3000_7-1017728-1.html (501 words)

	Noise cancellation headset (via CobWeb/3.1 planetlab2.isi.jhu.edu) (Site not responding. Last check: 2007-10-11)
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		So that the The ideas of which psychology noise cancellation headset that refines and is not so much a real ideas by pantomimetic, to Indians eating.
	noise-cancellation-headset.thesingingdetective.co.uk.cob-web.org:8888 (228 words)

	Howstuffworks "What is white noise?"
		White noise is a type of noise that is produced by combining sounds of all different frequencies together.
		The adjective "white" is used to describe this type of noise because of the way white light works.
		White light is light that is made up of all of the different colors (frequencies) of light combined together (a prism or a rainbow separates white light back into its component colors).
	science.howstuffworks.com /question47.htm (318 words)

	Pioneer SP-MJ7NS Noise Cancellation Headphones - Gizmodo (Site not responding. Last check: 2007-10-11)
		The company says these cans can cancel up to 80% of that cacophonous din going on outside your head, and its batteries can keep going for 20 hours while it's at it.
		We've heard both, and while neither comes close to reducing 80% of ambient noise, they both do a decent job of reducing constant racket such as wind and engine noise on an airplane.
		Noise cancellation is up to -25dB and certainly not absolute, but works well on planes, trains and autos.
	redhex.gizmodo.com /gadgets/home-entertainment/pioneer-spmj7ns-noise-cancellation-headphones-210271.php (500 words)

	EETimes.com - Siemens develops noise cancellation system for cars (Site not responding. Last check: 2007-10-11)
		The electronic Active Noise Control system attaches to an air-intake manifold — a low-cost chunk of under-hood plastic — and turns it into a smart device capable of listening to and canceling out unwanted noises on a vehicle.
		The new system is believed to be the first electronic means of solving the problem of air induction noise, which has been a problem since auto makers changed to plastic intake manifolds during the late 1980s.
		Plastic resonators, which also cancel engine noise by creating opposing frequencies, can be as large as a football and often cost as much as $10 each.
	www.eetimes.com /story/industry/systems_and_software_news/OEG20001005S0030 (858 words)

	Maxell Noise Cancellation Headphones
		Maxell's new HP/NC-II noise cancellation headphones are said to eliminate up to 95 percent of ambient sounds, such as aircraft engine noise and traffic sounds.
		With noise greatly reduced, your music can come through clearer at a lower volume level--you don't have to "crank it" up to hear over the noise possibly causing ear damage if you like to listen for long periods.
		There is a noticeable roll off of the high frequencies when you switch to noise canceling mode but it is not objectionable.
	www.barryrudolph.com /newtoys/toys/maxellnoisecancel.html (332 words)

	Active Noise Control (Site not responding. Last check: 2007-10-11)
		Active Noise Control quiets offensive noise by using cancellation techniques, or anti-sound.
		Signal Systems Corporation's mission is to help quiet irritating noises so you can have a more peaceful life.
		This web site is designed to give the active noise community a common source for information about this technology, its applications and suppliers.
	www.signalsystemscorp.com /ancindex.htm (82 words)

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