Background noise
Encyclopedia
In acoustics
and specifically in acoustical engineering
, background noise or ambient noise is any sound
other than the sound being monitored. Background noise
is a form of noise pollution
or interference
. Background noise is an important concept in setting noise regulation
s. See noise criteria for cinema/home cinema applications.
Examples of background noises are environmental noises such as waves
, traffic
noise, alarms, people talking, bioacoustic noise
from animals or birds and mechanical noise from devices such as refrigerator
s or air conditioning
, power supplies or motors
.
The prevention or reduction of background noise is important in the field of active noise control
. It is an important consideration with the use of ultrasound
(e.g. for medical diagnosis or imaging), sonar
and sound reproduction.
In astronomy
, background noise or cosmic background radiation is electromagnetic radiation
from the sky with no discernible source.
In information architecture
, irrelevant, duplicate or incorrect information may be called background noise.
In physics
and telecommunication
, background signal noise can be detrimental or in some cases beneficial. The study of avoiding, reducing or using signal noise is information theory
.
In telephony
, artificial comfort noise
is used as a substitute for natural background noise, to fill in artificial silence created by discontinuous transmission
systems using voice activity detection
.
Acoustics
Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics...
and specifically in acoustical engineering
Acoustical engineering
Acoustical engineering is the branch of engineering dealing with sound and vibration. It is the application of acoustics, the science of sound and vibration, in technology. Acoustical engineers are typically concerned with the manipulation and control of sound....
, background noise or ambient noise is any sound
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
other than the sound being monitored. Background noise
Noise
In common use, the word noise means any unwanted sound. In both analog and digital electronics, noise is random unwanted perturbation to a wanted signal; it is called noise as a generalisation of the acoustic noise heard when listening to a weak radio transmission with significant electrical noise...
is a form of noise pollution
Noise pollution
Noise pollution is excessive, displeasing human, animal or machine-created environmental noise that disrupts the activity or balance of human or animal life...
or interference
Interference (communication)
In communications and electronics, especially in telecommunications, interference is anything which alters, modifies, or disrupts a signal as it travels along a channel between a source and a receiver. The term typically refers to the addition of unwanted signals to a useful signal...
. Background noise is an important concept in setting noise regulation
Noise regulation
Noise regulation includes statutes or guidelines relating to sound transmission established by national, state or provincial and municipal levels of government. After the watershed passage of the United States Noise Control Act of 1972, other local and state governments passed further regulations...
s. See noise criteria for cinema/home cinema applications.
Examples of background noises are environmental noises such as waves
WAVES
The WAVES were a World War II-era division of the U.S. Navy that consisted entirely of women. The name of this group is an acronym for "Women Accepted for Volunteer Emergency Service" ; the word "emergency" implied that the acceptance of women was due to the unusual circumstances of the war and...
, traffic
Traffic
Traffic on roads may consist of pedestrians, ridden or herded animals, vehicles, streetcars and other conveyances, either singly or together, while using the public way for purposes of travel...
noise, alarms, people talking, bioacoustic noise
Bioacoustics
Bioacoustics is a cross-disciplinary science that combines biology and acoustics. Usually it refers to the investigation of sound production, dispersion through elastic media, and reception in animals, including humans. This involves neurophysiological and anatomical basis of sound production and...
from animals or birds and mechanical noise from devices such as refrigerator
Refrigerator
A refrigerator is a common household appliance that consists of a thermally insulated compartment and a heat pump that transfers heat from the inside of the fridge to its external environment so that the inside of the fridge is cooled to a temperature below the ambient temperature of the room...
s or air conditioning
Air conditioning
An air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle...
, power supplies or motors
Electric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
.
The prevention or reduction of background noise is important in the field of active noise control
Active noise control
Active noise control is a method for reducing unwanted sound.- Explanation :...
. It is an important consideration with the use of ultrasound
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
(e.g. for medical diagnosis or imaging), sonar
Sonar
Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...
and sound reproduction.
In astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
, background noise or cosmic background radiation is electromagnetic radiation
Electromagnetic radiation
Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...
from the sky with no discernible source.
In information architecture
Information Architecture
Information architecture is the art of expressing a model or concept of information used in activities that require explicit details of complex systems. Among these activities are library systems, Content Management Systems, web development, user interactions, database development, programming,...
, irrelevant, duplicate or incorrect information may be called background noise.
In physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
and telecommunication
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
, background signal noise can be detrimental or in some cases beneficial. The study of avoiding, reducing or using signal noise is information theory
Information theory
Information theory is a branch of applied mathematics and electrical engineering involving the quantification of information. Information theory was developed by Claude E. Shannon to find fundamental limits on signal processing operations such as compressing data and on reliably storing and...
.
In telephony
Telephony
In telecommunications, telephony encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other....
, artificial comfort noise
Comfort noise
Comfort noise is synthetic background noise used in radio and wireless communications to fill the artificial silence in a transmission resulting from voice activity detection or from the audio clarity of modern digital lines....
is used as a substitute for natural background noise, to fill in artificial silence created by discontinuous transmission
Discontinuous Transmission
Discontinuous transmission is a means by which a mobile telephone is temporarily shut off or muted while the phone lacks a voice input.-Misconception:...
systems using voice activity detection
Voice activity detection
Voice activity detection , also known as speech activity detection or speech detection, is a technique used in speech processing in which the presence or absence of human speech is detected.. The main uses of VAD are in speech coding and speech recognition...
.