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In common use, the word noise means any unwanted sound. In both analog and digital electronics, noise or signal noise is an unwanted perturbation 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.^ Artificial sounds and recordings are usually played using electric loudspeakers (a notable exception being the acoustic phonograph ).
  • sound@Everything2.com 9 January 2010 17:17 UTC www.everything2.com [Source type: Original source]

.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.^ Sources of ultrasound provide a means to produce a sound wave that is not perceived by humans as being a sound.
  • Physics Demonstrations - Sound 9 January 2010 17:17 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

^ The motion of the plate may be simply produced by dropping it between two vertical grooves, the tuning-forks being properly fixed to a frame above.

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

Subjective distinctions

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.^ Ambient sound (like music, but not patterned in a way one might tire of) includes angelic voices that stream into the soundscape.

.An annoying background hiss interfering with short-wave radio broadcasts was found to be due to extraterrestrial, 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.^ In the first case the waves are more likely to reach and be perceived by an observer level with the source, while in the second case they may go over his head and not be heard at all.

^ Now turning to the receiver, let us consider what length is occupied by the waves which pass him in one second.

^ The more general case of motion of source, medium and receiver may be treated very easily if the motions are all in the line joining source and receiver.

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.^ Since U=n X where U is the velocity of sound, X the wave-length, and n the frequency, it follows that the forward frequency is greater than the backward frequency.

^ Listeners usually report a rapid achievement of relaxation, body awareness, visualization, and reverie than they have come to expect without the use of Shimmer sound.

^ But if the blowing is continued, usually in less than a second the sound dies away to a small fraction of that due to either alone.

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.^ Sounds may be divided into noises and musical notes.

^ Its well suited for musicians, who make music, which involves heavy processing of Sound s, such as techno, trance, ambient, industrial etc.
  • Download Sound Effect Software: Space Effect Mac, Sound Effect Maker, Keyboard Sounder, ... 19 September 2009 7:30 UTC www.filebuzz.com [Source type: FILTERED WITH BAYES]

^ One such technique was called "The Curdler,” or “People Repeller,” a panic-inducing oscillator with the ability to cause deafening impact at short distances.
  • Rhizome | sound 9 January 2010 17:17 UTC rhizome.org [Source type: General]

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.^ Its well suited for musicians, who make music, which involves heavy processing of Sound s, such as techno, trance, ambient, industrial etc.
  • Download Sound Effect Software: Space Effect Mac, Sound Effect Maker, Keyboard Sounder, ... 19 September 2009 7:30 UTC www.filebuzz.com [Source type: FILTERED WITH BAYES]

^ Computers and consumer electronics (such as CD players) take electric sounds one stage further.
  • sound@Everything2.com 9 January 2010 17:17 UTC www.everything2.com [Source type: Original source]

^ By reading the series of numbers in the right order, and moving the speaker to the appropriate position each time, the device can reproduce a very close approximation of the original sound (with CD players, the speaker position is updated 44100 times every second).
  • sound@Everything2.com 9 January 2010 17:17 UTC www.everything2.com [Source type: Original source]

can cause permanent irreversible hearing damage.

Regulation of acoustic noise

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.

Acoustic noise 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.^ Many of the well-known phenomena of optical diffraction may be imitated with sound waves, especially if the waves be short.

.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.^ The more general case of motion of source, medium and receiver may be treated very easily if the motions are all in the line joining source and receiver.

.Sound cartoons, using "real" noises, seem to point to interesting possibilities" ('The Art of Sound' (1929)).^ Goodman catalogs a litany of military uses of sound that seem like sinister science fiction fantasies.
  • Rhizome | sound 9 January 2010 17:17 UTC rhizome.org [Source type: General]

^ These are for the most part interesting rather from the point of view of elasticity than of sound.

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

.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.^ Visits: 305 HiFi Recorder is a mp3 recorder of getting the original Sound recorded, which can record Sound s from all kinds of Sound devices, eg, Microphone, Line In, System Sound .
  • Download Sound Effect Software: Space Effect Mac, Sound Effect Maker, Keyboard Sounder, ... 19 September 2009 7:30 UTC www.filebuzz.com [Source type: FILTERED WITH BAYES]

^ Most microphones have low sensitivity to ultrasonic frequencies, but with a sensitive oscilloscope they can usually be made to indicate the presence of a sound.
  • Physics Demonstrations - Sound 9 January 2010 17:17 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

^ Artificial sounds and recordings are usually played using electric loudspeakers (a notable exception being the acoustic phonograph ).
  • sound@Everything2.com 9 January 2010 17:17 UTC www.everything2.com [Source type: Original source]

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

Non-acoustic noise

Electronic noise

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.^ The tangent to the displacement curve is always parallel to the axis, that is, for a small distance the successive particles are always equally displaced, and therefore always occupy the same volume.

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

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.^ The cleanest effect results from using two sine wave generators of equal amplitude connected to the same loudspeaker, in which case the amplitude varies from zero to twice the amplitude of each source[1-4].
  • Physics Demonstrations - Sound 9 January 2010 17:17 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

^ Commercial noise generators are available that produce the various types.
  • Physics Demonstrations - Sound 9 January 2010 17:17 UTC sprott.physics.wisc.edu [Source type: FILTERED WITH BAYES]

^ We do not use such noise, but rather seek to avoid it.

Noisy genes

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

Additional reading

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

References

External links


Quotes

Up to date as of January 14, 2010
(Redirected to Sound article)

From Wikiquote

Sound is the vibration of matter, as perceived by the sense of hearing. Unwanted or annoying sound is often called noise.

Sourced

  • Which is more musical, a truck passing by a factory or a truck passing by a music school?
    • John Cage, "Communication", the third of the Composition as a Process lectures given in Darmstadt in 1958 and published in Silence. Many of Cage's works use sounds traditionally regarded as unmusical (radios not tuned to any particular station, for instance): he really did believe that the sound of a truck and the sounds made in a factory had just as much musical worth as the sounds made in a music school. There is also a suggestion expressed in the quote that in order to determine the artistic worth of something, it is necessary to examine the context in which it exists.
  • A sound does not view itself as thought, as ought, as needing another sound for its elucidation, as etc.; it has not time for any consideration--it is occupied with the performance of its characteristics: before it has died away it must have made perfectly exact its frequency, its loudness, its length, its overtone structure, the precise morphology of these and of itself.
    • John Cage (1955), quoted in Classic Essays on Twentieth-Century Music, ISBN 0028645812
  • Music has no subject beyond the combinations of notes we hear, for music speaks not only by means of sounds, it speaks nothing but sound.
    • Eduard Hanslick, quoted by Wolfgang Sandberger (1996) in the liner notes to the Juilliard String Quartet's Intimate Letters. Sony Classical SK 66840.
  • You know the sound of two hands clapping; tell me, what is the sound of one hand?
    • Hakuin Ekaku (1686-1769). The phrase is a Kōan, an irrational comment used in Zen Buddhism in order to assist practitioners in reaching enlightenment.
  • Could we not imagine that noise...is itself nothing more than the sum of a multitude of different sounds which are being heard simultaneously?
  • If a tree falls in a forest, and no-one is around to hear it, does it make a noise?
    • Source unknown, but apparently originating in the twentieth century; a 1910 physics book asks "When a tree falls in a lonely forest, and no animal is near by to hear it, does it make a sound? Why?" Charles Riborg Mann, George Ransom Twiss, Physics (1910), p. 235. See also: If a tree falls in a forest.

Unsourced

  • Noise proves nothing. Often a hen who has merely laid an egg cackles as if she has laid an asteroid

External links

Wikipedia
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1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

NOISE (a word of doubtful origin; O. Fr. nogse or nose; Prov. nausa, which points to Lat. nausea, sickness, as the origin; others take Lat. noxia, harm, as the source), an excessive, offensive, persistent or startling sound. .By the common law of England freedom from noise is essential to the full enjoyment of a dwelling house, and acts which affect that enjoyment may be actionable as nuisances.^ He suggests that the propagation of earthquake disturbances is probably affected by the curvature of the surface of the globe, which may act like a whispering gallery.

But it has been laid down that a nuisance by noise, supposing malice to be out of the question, is emphatically a question of degree (Gaunt v. Finney, 1872, 8 Ch. Ap. 8). The noise must be exceptional and unreasonable. The ringing of bells, building operations, vibration of machinery, fireworks, bands, a circus, merry-go-rounds, collecting disorderly crowds, dancing, singing, &c., have been held under certain circumstances to constitute nuisances so as to interfere with quiet and comfort, and have been restrained by injunction. Noise occasioned by the frequent repetition of street cries is frequently the subject of local by-laws, which impose penalties for infringement.


Strategy wiki

Up to date as of January 23, 2010
(Redirected to Category:Noise article)

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Pages in category "Noise"

The following 3 pages are in this category, out of 3 total.

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Simple English

Simple English Wiktionary has the word meaning for:

Noise is another word for sound. It usually means it is not wanted. Noise can also mean data (information) that does not have a meaning, like white noise. Noise is perceived by our ears. They can be damaged by noise.



Citable sentences

Up to date as of December 25, 2010

Here are sentences from other pages on Sound, which are similar to those in the above article.








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