Noise is used in modern English to describe a specific technical phenomenon or a loud harsh sound of any kind. The first appearance of the word in the 12 th century reflects its qualitative use as in: "They all made great joy with suche a joyfull noyse that the paynyms without dyd here it" (Berners Huon lix. 1566, OED). Its negative connotations to do not appear until later when noise comes to describe the aggregate of sounds produced in community centers, as in "Obscured and made weak; as the voyce of a man is in the noyse of the day" (Hobbes Leviathan 1651, OED). Yet the source of noises remains mysterious, both in describing physical sounds and in semiotic models. Chapter 37 in the Book of Job, describes the voice of God as a great thunder "marvellously with his voice: great things doth hee, which we cannot comprehend" (King James 1611). Noise remains something undesired for most of Western thought because of the magic, mystery, and menacing mobs often attributed to its source. Noise has an uncontrolled nature. Confusion then is averted through the construction of moral conventions and signal code.
In media theory and electronics, noise refers to random, unpredictable, and undesirable signals, or changes in signals, that mask desired information content. More generally anything that works against a message reaching its destination. In this sense even the "distortions produced in one's handwriting in a moving train can be attributed to "noise" (Lyons Introd.Theoretical Linguistics ii. 1953, OED). Noises interfere with the intelligibility of a signal and decrease its usefulness.
Umberto Eco elaborates this definition in his book A Theory of Semiotics. Concerned with a theory of communication, Eco uses a watershed model first proposed by Tuttlio de Mauro. An engineer downstream needs to know when a particular watershed reaches saturation level, so that the engineer may open a watergate to maintain acceptable levels. In this model a buoy (the source), reaches danger levels and activates a transmitter capable of emitting an electric signal. This signal travels through an electric wire (channel). A receiver picks up the signal downstream. This device converts the signal into a given string of elements that constitute the message for a destination apparatus, which will tell the engineer to open the watergate. This model is important because it considers the potential presence of noise on the channel. It is possible that in any system a disturbance can alter the nature of the signals, making detection difficult. The solution is to increase and complicate the code. This increases the size and "cost" of the apparatus, but makes the transmission of information more secure. Eco emphasizes that the engineer may now take advantage of this investment and "amortize" it through more a comprehensive exploitation of the new signal code. An analogy can be drawn up between this phenomena and the generation of new versions of software applications. A newer application will include larger amounts of code to handle operations effectively, without noise.
In scientific use noise is a collective term for unwanted fluctuations and disturbances that are part of a signal. In physics it is a broadband energy without periodicity (Glass 1968). These random fluctuations often distort observation and mask meaning. In acoustics, noise is any undesired sound, either one that is intrinsically objectionable or one that interferes with other sounds that are being listened to. Since noise has no periodicity, it creates no recognizable musical pitch or tone quality, sounding like the static that is heard between stations of an FM radio, known in television as snow. White noise in music is a complex signal or sound that covers the entire range of component frequencies, or tones, all which possess equal intensity. Just as white light is the combination of all the colors of the rainbow, so white noise can be defined as a combination of equally intense sound waves at all frequencies of the audio spectrum. White-noise is also aperiodic; its constituent frequencies are of random amplitude and occur at random intervals. The sound of cymbals and snare drums has white-noise characteristics. Electronically synthesized white noise can be filtered so as to produce combinations of frequencies not obtainable on traditional musical instruments; or the white noise itself may be used as an element of music. Other forms of colored noise occur when there is a wide noise spectrum, but within some narrow band of frequencies--as in the case of wind whistling through trees or over wires. In another example, as water is poured into a tall cylinder, certain frequencies of the noise created by the gurgling water are resonated by the length of the tube, so that pitch rises as the tube is effectively shortened by the rising water.
In psychology noise is any unwanted sound that is physiologically arousing and harmful, subjectively annoying, or disruptive of performance (Bartlett 1934). Noise is often psychologically linked to irritability, tension, nervousness, and anxiety; rest and relaxation are interrupted; and efficiency at work is decreased. In addition to hearing loss, continued exposure to loud noise affects a person's nervous system, producing harmful effects on blood flow and pressure. "We may suppose, therefore, that unpredictable noise has consequences equal to those of higher-intensity predictable- noise, and to the extent that intensity relates to performance, the individual should have greater difficulty in performing under unpredictable than predictable noise stimulation" (Glass 1972). The possibility of "adaptation" to noise is apparently left open, different individuals having different threshold levels, yet such an influence is linked to subsequent mental conditions and adverse conduct (Bartlett 1934). Positive effects of noise have been noted when noise masks distracting sound, stimulates an individual to remain alert on an otherwise boring task, or arouses a sleep deprived subject to perform better under quiet conditions (Glass 1968). The FBI may have come to this conclusion after a week of "noise bombing" the Branch Dravidians at their in Waco, Texas compound. [See senses.]
Few theories have developed to describe how noise may work within the semiotic systems of speech and music. In the past these systems were described in different ways with different terminologies, linguistics for speech and musicology for music. Dominant forms of communication and high culture art forms are always described in reference to some noise. This often problematizes theory because noise describes the quantifiable 'other' (the mass, the mob, etc.) and yet simultaneously inhabits many mediums at once. Theorist Theo van Leeuwen points out that this semiotic purism has not always existed.
"In the Middle Ages and the Renaissance the voice was still a musical instrument and music was imbedded in every aspect of everyday life, ... but as clergical plainsong, the cries of the watchmen, and the chanting of the ABC in school were replaced by reading aloud, speech was divorced from music, and much flattened in the process. And as the musical sounds in our cities were replaced by mechanical noises, with music moving indoors, into the concert hall, music and 'noise,' too, became separate categories" (van Leeuwen 1999).
Thus music and the rest of life went their separate ways, conventional arguments try to seal music watertight through the development of acoustics.
This idea of 'separateness' or 'otherness' is further elaborated in Jacques Attali's Noise: The Political Economy of Music. He argues that stylistic change in music develops out of determinate socio-economic circumstances. Music, in Attali's view, articulates a fundamental channeling of violence in society, one that constantly marginalizes new sound and describes it as noise. Movements are always first described as dystopian or noisy because they threaten the status quo. The silencing of noise is mechanized by acoustics and mathematics, preserving the mystery of music through formalism and rules, and concealing the ideological basis of aesthetic conventions. For Attlai, this paradigm explains the higher prestige of culture that is quantifiable and commodified, over just mere expression. In other words a semantic silence is imposed and maintained by theory and music history, by performance practices and educational institutions, to protect the public from free noise. His answer for society is a new music, controlled neither by academic institutions nor by the entertainment industry, but by people dedicated to injecting music with the noise of the body, of the visual, of emotions, and of gender.
Like performance art and minimalism, noise challenges the ideology of academic training and taxonomies, of orchestra and opera houses, and of recording and broadcast networks. The first artist to derive a conception of sound for a music based on noises was Lugi Russolo. Between 1913 and 1930 he constructed a series of new musical instruments in twelve families, the intonarumori ('noise intoners') and later four versions of an instrument that combined several of the earlier families, the rumorarmonio ('noise-harmonium'),  building up a repertory of compositions written for them by himself and by several other composers associated with the Italian Futurist movement. Although Russolo's music and instruments were not particularly radical, later interest in the musical potential of noise owed much to his pioneering work. Most significantly he redefined noise as music. "Let us walk together through the great modern capital with the ear more attentive that the eye, and we will vary pleasure of our sensibilities by distinguishing among [sounds] ...we will have fun imaging our own orchestration" (Russolo 1913).
The pioneers and early theorist of sound film saw it the same way. " It is the business of the sound film to reveal for us our acoustic environment ... ; all that has speech beyond human speech, and speaks to us with the vast conversational power of life and incessantly influences our thoughts and emotions" (Balasz 1970). The results of direct involvement in music by artists included two traditionally notated avant-garde compositions: one of Marcel Duchamp's two identically titled works Erratum Musical (1913); and Yves Klein's Symphonie monoton-silence (1947--61). Visually related concert activities in the 1930s and afterwards included new instruments and sound sources devised independently by two American composers, John Cage and the microtonalist Harry Partch, who used materials chosen for their sculptural as well as auditory qualities. "When Cage opens the door to the concert hall to let the noise of the street in, he is regenerating all of music: he is taking to its culmination. He is blaspheming, criticizing the code and the network. When he sits motionless at the piano for four minutes and thirty-three seconds, letting the audience grow impatient and make noises, he is giving back the right to speak to people who do not want to have it" (Attali 1985).
It is not surprising that both movements are roughly contemporaneous, associated with conventional shifts from an industrial age toward modernity. New recording technology has brought music back into everyday life- through muzak, the transistor radio, the car stereo, the Walkman. Popular composers have also experimented with combinations of musical instruments, singing, and speaking voices, non-musical sound or noise. "Satie added a typewriter to the orchestra, Gershwin a taxi-horn, Zappa a cash register" (van Leeuwen 1999). Van Leeuwen lays out a semiotic model for these new forms experimental of music. For van Leeuwan the semiotics of sound in Western culture should describe sound as a semiotic resource offering its users a rich array of semiotic choices, not as a code telling what to do, or how to use sound correctly. In the history of Western music certain choices become mandatory, conventional, or traditional in certain contexts. Unmeasured sound (what is generally considered noise ) or non-metronomic sound (like free-jazz and other forms of Afro-American music) would be part of these choices that subvert the discipline of the clock and the industrial age. New choices herald a time of clamoring social relations, for what din music may become.