noise

A term used by analysts of time series data to describe random fluctuations that may obscure the true signal. A sequence of errors, in successive observations, that consists of independent random values from a normal distribution with zero mean is termed white noise.

(1) Extraneous, unwanted signals that invade an electrical or optical system. In electronics, noise can come from strong electrical or magnetic signals in nearby lines, from poorly fitting electrical contacts and from power line spikes. In optics, noise comes from the stray reflections of light that emanate from the various components in the optical system. See signal-to-noise ratio and noise cancellation.

(2) Distortions in analog and digital video images that are caused by a variety of circumstances. The silver grains in the original film create granular noise. Electronic circuits create Gaussian noise. Drop outs and bit errors in digital tapes create impulse noise, and the digitization process creates quantization noise. See Gaussian noise, dynamic noise reduction and artifact.

(3) Distortions in a still image caused by variations in the pixels in the CCD or CMOS sensor. See digital camera.

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Price and volume fluctuations in the market that can confuse one's interpretation of market direction. Used in the context of equities, it is stock market activity caused by program trading, dividend payments or other phenomena that is not reflective of overall market sentiment. Also known as "market noise".

Investopedia Says:
In general, the shorter the time frame, the more difficult it is to separate the meaningful market movements from the noise. Noise traders attempt to take advantage of market noise by entering buy and sell transactions without the use of fundamental data.

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Stock-market activity caused by Program Trades and news and comment affecting prices that is unsubstantiated.

noun

1. Sounds or a sound, especially when loud, confused, or disagreeable: babel, clamor, din, hubbub, hullabaloo, pandemonium, racket, rumpus, tumult, uproar. See sounds/pleasant sounds/unpleasant sounds/neutral sounds or silence.
2. The sensation caused by vibrating wave motion that is perceived by the organs of hearing: sonance, sound¹. See sounds/pleasant sounds/unpleasant sounds/neutral sounds or silence.

verb

1. To make (information) generally known: advertise, blaze², blazon, broadcast, bruit, circulate, disseminate, promulgate, propagate, spread. Idioms: spread far and wide, spread the word. See knowledge/ignorance.
2. To engage in or spread gossip: blab, gossip, rumor, talk, tattle, tittle-tattle, whisper. Idioms: tell tales, tell tales out of school. See words.

Definition: sound which is loud, not harmonious
Antonyms: silence

Sound is an essential form of human communication. However, unwanted sounds, or noise, can lead to a variety of medical problems, including deafness and elevated blood pressure; there is also evidence for an increased pulse rate. There is some evidence suggesting that environmental noise may affect the learning ability of children.

Sound waves are generated by vibrations moving through the air, and they are perceived through a complex interaction of vibrations hitting the inner ear. External vibrations are translated, through bones, into additional vibrations, which are then picked up by hair-like structures in the inner ear. These vibrations are further translated into neurologic signals, which are registered in the brain and received as intelligible information.

Noise can be normal sounds that get in the way of being able to perceive wanted sounds. Sound is measured in units called decibels, and the human ear is well-designed to perceive and interpret sounds at low decibel levels and across a wide spectrum of vibration. Sounds that are too loud, however, can damage the ability of the ear to make sense of what is perceived. A graphic measurement of what one can hear is called an audiogram, and hearing loss can be traced on audiograms. There is some hearing loss that is considered normal with aging, called presbycusis. Additional hearing loss and other physiological damage, may result from excessive loud noise.

There is some controversy as to what level of sound is too high, particularly in workplaces. It is thought that the maximal tolerable noise level for an eight-hour workplace exposure is about seventy-five decibels. The current allowable standard is eighty-five decibels. The standard was decreased from the previous ninety decibel level after a hard-fought battle to try and prevent a significant number of cases of hearing loss. At eighty-five decibels, hearing protection and noise monitoring becomes mandatory. There are several ways that noise can be reduced, either through changes in noise-making equipment itself, or by providing personal protective equipment to individuals who must work in noisy environments. The two basic types of personal protection are earplugs and earmuffs. Earmuffs, which can be put on and taken off more easily, are useful where the noise may be intermittent, such as at airports. Earplugs are more practical for people who spend considerable continuous periods of time in noisy environments.

In addition to noisy workplace environments, there are certain general environments where noise may be a particular problem. Among these are subway systems, where passengers may be intermittently exposed to high noise levels, and in communities located near airports. Over time there has been a considerable effort to diminish the noise around airports, both through the use of quieter engines and through changes in flight paths. In some extreme situations, homes have been bought and people moved out of flight paths near airports to help reduce the risk and annoyance associated with such noise.

(SEE ALSO: Hearing Disorders; Hearing Protection; Occupational Safety and Health)

Bibliography

Moller, A. G. (1992). "Noise as a Health Hazard." In Public Health and Preventive Medicine, 13th edition, eds. J. M. Last and R. M. Wallace. Norwalk, CT: Appleton and Lange.

— ARTHUR L. FRANK

For more information on noise, visit Britannica.com.

Any sound which is unwanted because it is annoying, interferes with speech and hearing, or is intense enough to damage hearing.

Noise, mottling or colour-speckle interference in digital images, usually in shadow areas and at sensitivity equivalents of ISO 400 or higher. Noise levels may be related to factors such as the number of pixels in a sensor, or their configuration and architecture, or heat generated by long exposures, or the camera's processing algorithms. Sustained research by manufacturers has reduced noise, in high-end cameras, to a level at or below comparable grain in film.

— Robin Lenman

1. A term used in information theory to indicate a disturbance that does not represent any part of a message from a specified source.

2. Background stimuli (or information), which a person might or might not be aware of, but which is not directly relevant to the task in hand.

3. In signal detection theory, the random firing of the nervous system; that is background neural activity.

1. a loud, harsh and objectionable sound.
2. interference in an ecological or electronic system, but insufficient to stop the system.
3. in statistics when extraneous, uncontrolled variables cause errors in the distribution of data.

• n. pollution — noise in the environment that adversely affects, in our context, the animal inhabitants. No such ill effects have been demonstrated.

Unwanted electromagnetic radiation within an electrical or mechanical system.

n.

A stench in the ear. Undomesticated music. The chief product and authenticating sign of civilization.

Quotes:

"All this talk and turmoil and noise and movement and desire is outside of the veil; within the veil is silence and calm and rest." - Bayazid Al-Bistami

"For twenty-five centuries, Western knowledge has tried to look upon the world. It has failed to understand that the world is not for the beholding. It is for hearing. It is not legible, but audible. Our science has always desired to monitor, measure, abstract, and castrate meaning, forgetting that life is full of noise and that death alone is silent: work noise, noise of man, and noise of beast. Noise bought, sold, or prohibited. Nothing essential happens in the absence of noise." - Jacques Attali

"The world is never quiet, even its silence eternally resounds with the same notes, in vibrations which escape our ears. As for those that we perceive, they carry sounds to us, occasionally a chord, never a melody." - Albert Camus

"He who sleeps in continual noise is wakened by silence." - William Dean Howells

"In antiquity there was only silence. In the nineteenth century, with the invention of the machine, Noise was born. Today, Noise triumphs and reigns supreme over the sensibility of men." - Luigi Russolo

This article is about noise as an unwanted phenomenon. For other uses, see Noise (disambiguation).

In common use, the word noise means unwanted sound or noise pollution^[1]. In both analog and digital electronics, noise or signal noise is an unwanted random addition to a wanted signal; it is called noise as a generalisation of the audible noise heard when listening to a weak radio transmission. Signal noise is heard as acoustic noise if played through a loudspeaker; it manifests as 'snow' on a television or video image. In signal processing or computing it can be considered unwanted data without meaning; that is, data that is not being used to transmit a signal, but is simply produced as an unwanted by-product of other activities. In Information Theory, however, noise is still considered to be information. In a broader sense, film grain or even advertisements encountered while looking for something else can be considered noise. In biology, noise can describe the variability of a measurement around the mean, for example transcriptional noise describes the variability in gene activity between cells in a population.

Noise can block, distort, change or interfere with the meaning of a message in both human and electronic communication.

In many of these areas, the special case of thermal noise arises, which sets a fundamental lower limit to what can be measured or signaled and is related to basic physical processes at the molecular level described by well-established thermodynamics considerations, some of which are expressible by relatively well known simple formulae.

Contents 1 What is noise and what is not? 2 Acoustic noise 2.1 Regulation 2.2 In film sound 3 Audio noise 4 Electronic noise 5 Visual noise 6 Noisy genes 7 See also 8 Additional Reading 9 References 10 External links

What is noise and what is not?

Calling some signal or sound noise is often a subjective distinction. One person's maximum-volume music listening pleasure might be another's unbearable noise.

An annoying background hiss interfering with short-wave radio broadcasts was found to be due to extra-terrestrial, indeed cosmic, processes; listening to this "noise" to the exclusion of all other signals with ever more sensitive antennas and receivers is now the science of radio astronomy. Radio astronomers are still plagued by noise in their signals—but now it is thermal noise generated in their equipment interfering with wanted signals from the cosmos.

Acoustic noise

When speaking of noise in relation to sound, what is commonly meant is meaningless sound of greater than usual volume. Thus, a loud activity may be referred to as noisy. However, conversations of other people may be called noise for people not involved in any of them, and noise can be any unwanted sound such as the noise of dogs barking, neighbours playing loud music, road traffic sounds, chainsaws, or aircraft, spoiling the quiet of the countryside.

Acoustic noise can be anything from low-level but annoying to loud and harmful. At one extreme users of public transport sometimes complain about the faint and tinny sounds emanating from the headphones or earbuds of somebody listening to a portable audio player; at the other the sound of very loud music, a jet engine at close quarters, etc. can cause permanent irreversible hearing damage.

Regulation

Main article: Noise regulation

Noise regulation includes statutes or guidelines relating to sound transmission established by national, state or provincial and municipal levels of government. After a watershed passage of the U.S. Noise Control Act of 1972[1], the program was abandoned at the federal level, under President Ronald Reagan, in 1981 and the issue was left to local and state governments. Although the UK and Japan enacted national laws in 1960 and 1967 respectively, these laws were not at all comprehensive or fully enforceable as to address (a) generally rising ambient noise (b) enforceable numerical source limits on aircraft and motor vehicles or (c) comprehensive directives to local government.

In film sound

For film sound theorists and practitioners at the advent of talkies c.1928/1929, noise was non-speech sound or natural sound and for many of them noise (especially asynchronous use with image) was desired over the evils of dialogue synchronized to moving image. The director and critic René Clair writing in 1929 makes a clear distinction between film dialogue and film noise and very clearly suggests that noise can have meaning and be interpreted: "...it is possible that an interpretation of noises may have more of a future in it. Sound cartoons, using "real" noises, seem to point to interesting possibilities" ('The Art of Sound' (1929)). Alberto Cavalcanti uses noise as a synonym for natural sound ('Sound in Films' (1939)) and as late as 1960, Siegfried Kracauer was referring to noise as non-speech sound ('Dialogue and Sound' (1960)).

Audio noise

Main article: Colors of noise

In audio, recording, and broadcast systems audio noise refers to the residual low level sound (usually hiss and hum) that is heard in quiet periods of programme.

In audio engineering it can also refer to the unwanted residual electronic noise signal that gives rise to acoustic noise heard as "hiss". This signal noise is commonly measured using A-weighting or ITU-R 468 weighting

Electronic noise

Main article: Noise (electronics)

Electronic noise exists in all circuits and devices as a result of thermal noise, also referred to as Johnson Noise. Semiconductor devices can also contribute flicker noise and generation-recombination noise. In any electronic circuit, there exist random variations in current or voltage caused by the random movement of the electrons carrying the current as they are jolted around by thermal energy. Lower temperature results in lower thermal noise. This same phenomenon limits the minimum signal level that any radio receiver can usefully respond to, because there will always be a small but significant amount of thermal noise arising in its input circuits. This is why radio telescopes, which search for very low levels of signal from stars, use front-end low-noise amplifier circuits, usually mounted on the aerial dish, and cooled with liquid nitrogen.

Visual noise

Main article: Image noise

Noise is also present in images. Electronic noise will be present in camera sensors, and the physical size of the grains of film emulsion creates visual noise. This kind of noise is referred to as "grain."

Noise is also used in the creation of 2D and 3D images by computer. Sometimes noise is added to images to hide the sudden transitions inherent in digital representation of color, known as "banding." This adding of noise is referred to as "dithering." Sometimes noise is used to create the subject matter itself. Procedural noise (such as Perlin noise) is often used to create natural-looking variation in computer generated images.

Noisy genes

Main article: Transcriptional noise

The activity and regulation of our genes are also subject to noise. Transcriptional noise refers to the variability in gene activity between cells in genetically identical populations (even identical twins are non-identical). Noise in gene activity has tremendous consequences on cell behaviour, and must be mitigated or integrated. Noise impacts upon the effectiveness of clinical treatment, with resistance of bacteria to antibiotics demonstrably caused by non-genetic differences. Variability in gene expression may also contribute to resistance of sub-populations of cancer cells to chemotherapy. In certain contexts, such as the survival of microbes in rapidly changing stressful environments, or several types of scattered differentiation, noise may be essential.

See also

• Noise and vibration on maritime vessels
• Noise music
• Association of Noise Consultants
• Opposite: Silence

Additional Reading

Kosko, Bart (2006). Noise. Viking Press. ISBN 0-670-03495-9. 

References

This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (August 2008)

1. ^ http://dictionary.reference.com/browse/silence

External links

Look up noise in Wiktionary, the free dictionary.

Wikiquote has a collection of quotations related to: Sound

• Guidelines for Community Noise, World Health Organization, 1999
• Audio Measuring Articles - Electronics
• Mohr on Receiver Noise: Characterization, Insights & Surprises
• Fundamentals of Electrical Noise
• Noise voltage - Calculation and Measuring of Thermal Noise
• Noise at work European Agency for Safety and Health at Work (EU-OSHA)
• US National Institute for Occupational Safety and Health, - Noise

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - larm, støj, lyd
v. tr. - udbasunere, forkynde vidt og bredt
v. intr. - larme, støje

idioms:

• make (all) the right noises    sige det, der forventes, ytre banaliteter
• noise pollution    lydforurening

Nederlands (Dutch)
lawaai, geluid, gedruis, geruis, kletsen, lawaai schoppen, ruchtbaar maken, veelbesproken zijn (negatief)

Français (French)
n. - bruit, vacarme, (Élec, Télécom) interférences, tapage
v. tr. - rendre public, ébruiter
v. intr. - rendre public, ébruiter

idioms:

• make all the right noises    se montrer complaisant
• make the right noises    se montrer complaisant
• noise pollution    nuisances sonores

Deutsch (German)
n. - Geräusch, Lärm
v. - verbreiten, viel od. laut reden

idioms:

• make all the right noises    vage sprechen
• make the right noises    vage sprechen
• noise pollution    Lärmbelästigung

Ελληνική (Greek)
n. - θόρυβος, ορυμαγδός (κν. σαματάς), κρότος, βοή, (μτφ.) πάταγος, σάλος (κν. ντόρος), ηλεκτρονικά παράσιτα
v. - κάνω βούκινο

idioms:

• make (all) the right noises    έχω όλες τις σωστές αντιδράσεις, λέω αυτά που περιμένουν να ακούσουν
• noise pollution    ηχορύπανση

Italiano (Italian)
suono, rumore, perturbazione sonora

idioms:

• make (all) the right noises    esprimersi chiaramente
• noise pollution    inquinamento acustico

Português (Portuguese)
n. - ruído (m), clamor (m), rumor (m), escândalo (m)
v. - fazer barulho, falar muito, propalar

idioms:

• make (all) the right noises    expressar algo verbalmente
• noise pollution    poluição sonora

Русский (Russian)
шум, помехи

idioms:

• make (all) the right noises    говорить то, что следует
• noise pollution    звуковые помехи

Español (Spanish)
n. - ruido, estrépito, tumulto, alboroto, interferencia
v. tr. - esparcir, rumorear, divulgar
v. intr. - hablar a gritos, gritar, meter ruido

idioms:

• make all the right noises    mostrarse francamente favorable a, hablarse mucho de una cosa
• make the right noises    mostrarse francamente favorable a, hablarse mucho de una cosa
• noise pollution    ruido dañino y molesto

Svenska (Swedish)
n. - buller, ljud, bråk, oljud, rykte
v. - sprida (ut)

中文（简体）(Chinese (Simplified))
喧闹声, 噪音, 噪声, 谣传, 喧闹

idioms:

• make (all) the right noises    随声附和
• noise pollution    噪音污染

中文（繁體）(Chinese (Traditional))
n. - 喧鬧聲, 噪音, 雜訊
v. tr. - 謠傳
v. intr. - 喧鬧

idioms:

• make (all) the right noises    隨聲附和
• noise pollution    噪音污染

한국어 (Korean)
n. - 평판, 헛소리, 소음
v. tr. - 소문 내다
v. intr. - 지껄이다, 소리를 내다

idioms:

• make (all) the right noises    광고나 이목을 끌기에 알맞게 말하다

日本語 (Japanese)
n. - 音, 騒音, 雑音

idioms:

• make (all) the right noises    気を引く
• noise pollution    騒音公害

العربيه (Arabic)
‏(الاسم) ضجيج (فعل) يحدث ضجه‏

עברית (Hebrew)
n. - ‮רעש, קול, תנודות לא-סדירות הנלוות לאות משודר‬
v. tr. - ‮פרסם, הפיץ, רחש‬
v. intr. - ‮פרסם, הפיץ, רחש‬

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