In common use, the word noise means unwanted sound or noise pollution. Sound' is Vibration transmitted through a Solid, Liquid, or Gas; particularly sound means those vibrations composed of Frequencies Noise pollution (or environmental noise) is displeasing human- or machine-created sound that disrupts the activity or balance of human or animal life In electronics noise can refer to the electronic signal corresponding to acoustic noise (in an audio system) or the electronic signal corresponding to the (visual) noise commonly seen as 'snow' on a degraded television or video image. Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical Noise in analog Video and Television is perceived as a random dot pattern which is superimposed on the picture as a result of Electronic noise and Television ( TV) is a widely used Telecommunication medium for sending ( Broadcasting) and receiving moving Images, either monochromatic Video is the technology of electronically capturing, Recording, processing storing transmitting and reconstructing a sequence of Still images In signal processing or computing it can be considered 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. Debt AIDS Trade in Africa (or DATA) is a Multinational non-government organization founded in January 2002 in London by U2 's In Telecommunication, signalling (UK spelling or signaling (US spelling has the following meanings The use of signals for controlling communications In Information Theory, however, noise is still considered to be information. Information theory is a branch of Applied mathematics and Electrical engineering involving the quantification of Information. Information as a concept has a diversity of meanings from everyday usage to technical settings In a broader sense, film grain or even advertisements in web pages can be considered noise.

Noise can block, distort, or change 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. Johnson–Nyquist noise ( thermal noise, Johnson noise, or Nyquist noise) is the electronic noise generated by the thermal agitation In Physics, thermodynamics (from the Greek θερμη therme meaning " Heat " and δυναμις dynamis meaning "

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.

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. Even though Noise is a random Signal, it can have characteristic statistical properties For the band see Broadcast (band Broadcasting is the distribution of audio and/or Video signals which transmit

In audio engineering it can also refer to the unwanted residual electronic noise signal that gives rise to acoustic noise heard as 'hiss'. Audio engineering is a part of audio science dealing with the recording and reproduction of Sound through mechanical and electronic means Electronic noise is an unwanted signal characteristic of all electronic circuits. This signal noise is commonly measured using A-weighting or ITU-R 468 weighting

Electronic noise

Main article: Electronic noise

Electronic noise exists in all circuits and devices as a result of thermal noise, also referred to as Johnson Noise. A-weighting is the most commonly used of a family of curves defined in the International standard IEC616722003 and various national standards relating to the measurement of sound The ITU-R 468-weighting curve (originally defined in CCIR recommendation 468 is widely used when measuring noise in audio systems especially in the UK Europe and former countries of Electronic noise is an unwanted signal characteristic of all electronic circuits. Electronic noise is an unwanted signal characteristic of all electronic circuits. Johnson–Nyquist noise ( thermal noise, Johnson noise, or Nyquist noise) is the electronic noise generated by the thermal agitation Semiconductor devices can also contribute flicker noise and generation-recombination noise. Flicker noise is a type of Electronic noise with a 1/f or pink spectrum Generation-Recombination noise, or g-r noise, is a type of electrical Signal noise caused statistically by the fluctuation of the Generation and Recombination 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. An electronic circuit is a closed path formed by the interconnection of Electronic components through which an Electric current can flow Randomness is a lack of order Purpose, cause, or predictability Electric current is the flow (movement of Electric charge. The SI unit of electric current is the Ampere. Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical Lower temperature results in lower thermal noise. Johnson–Nyquist noise ( thermal noise, Johnson noise, or Nyquist noise) is the electronic noise generated by the thermal agitation 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. In a Communications system, the signal level is the signal power or Intensity at a specified point and with respect to a specified reference This article is about a radio receiver for other uses see Radio (disambiguation. Johnson–Nyquist noise ( thermal noise, Johnson noise, or Nyquist noise) is the electronic noise generated by the thermal agitation 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. A radio telescope is a form of directional Radio antenna used in Radio astronomy and in tracking and collecting data from Satellites A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth Front-end and back-end are generalized terms that refer to the initial and the end stages of a process The low-noise amplifier (LNA is a special type of Electronic amplifier or Amplifier used in communication systems to amplify very weak signals captured by an A parabolic reflector (or dish or mirror) is a Parabola -shaped reflective device used to collect or distribute Energy such as Liquid nitrogen (liquid density at the Triple point is 0707 g/mL is the liquid produced industrially in large quantities by Fractional distillation of

See also

• Association of Noise Consultants
• Noise regulations

External links

• Guidelines for Community Noise, World Health Organization, 1999
• Aercoustics Engineering Limited. The Association of Noise Consultants (ANC is a UK based organisation of companies that are engaged in the business of acoustics noise and vibration consulting Noise regulation includes Statutes or guidelines relating to sound transmission established by national state or provincial and Municipal levels of government Consultants in Acoustics, Noise and Vibration
• 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)