Noise means any unwanted sound. Noise is not necessarily random. Sounds, particularly loud
ones, that disturb people or make it difficult to hear wanted sounds, are noise. For example,
conversations of other people may be called noise by people not involved in any of them;
any unwanted sound such as domesticated dogs barking, neighbours playing loud music, portable
mechanical saws, road traffic sounds, or a distant aircraft in quiet countryside, is
called noise. Acoustic noise can be anything from quiet
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. This "intolerable
corruption of human space" can be called noise pollution A claim made by Luigi Russolo in
his article, The Joys of Noise is that noise has become so prominent that pure sound no
longer exists. Roland Barthes also observes that noise can
be perceived either physiologically or psychologically. We perceive noise physiologically when we
"hear" it. On the other hand when we "listen" to a noise we are doing this psychologically.
Physiological noise can be explained physiologically of course. When we perceive a physiological
noise we subconsciously feel the vibrations of the noise waves with our particles in our
physical body whereas psychological noise refers to noise that is perceived when our
conscious awareness shifts its attention to that noise rather than letting it filter through
our subconscious where it goes unnoticed. Sound intensity follows an inverse square
law with distance from the source; doubling the distance from a noise source reduces its
intensity by a factor of four, or 6 dB.
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 generally rising
ambient noise enforceable numerical source limits on aircraft and motor vehicles or comprehensive
directives to local government. Underwater noise is one of 11 Descriptors
of Good Enviromental Status according to the EU's Marine Strategy Framework Directive.
Recording and reproduction noise
In audio, recording, and broadcast systems audio noise refers to the residual low level
sound that is heard in quiet periods of programme. This is also known as white noise according
to the Merriam Webster Definition. There is a similar phenomena to "white noise" which
emanates not only from audio recording equipment but from everything and more particularly,
musical instruments. These noises are "impurities." When an instrument plays a pitch, even the
most beautiful sounding instruments, there is noise projected. Henry Cowell claims that
technological advancements have brought machines closer to diminishing these unwanted noises,
but have not been completely successful thus far.
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. See also
Association of Noise Consultants Background noise
Noise and vibration on maritime vessels Noise music
Noise in music Noise pollution
Silence The Hum
References
Further reading Kosko, Bart. Noise. Viking Press. ISBN 0-670-03495-9.
Schwartz, Hillel. Making Noise: From Babel to the Big Bang & Beyond. New York: Zone Books.
ISBN 978-1-935408-12-3. External links
Guidelines for Community Noise, World Health Organization, 1999
Audio Measuring Articles - Electronics Mohr on Receiver Noise: Characterization,
Insights & Surprises Noise voltage - Calculation and Measuring
of Thermal Noise Noise at work European Agency for Safety and
Health at Work Article "Noise Control Techniques"
Mountain & Plains ERC: A NIOSH Education and Research Center for Occupational & Environmental
Health & Safety US National Institute for Occupational Safety
and Health, - Noise