Noise is unwanted sound judged to be unpleasant, loud or disruptive to hearing. From a physics standpoint, noise is indistinguishable from sound, as both are vibrations through a medium, such as air or water. The difference arises when the brain receives and perceives a sound.
Acoustic noise is any sound in the acoustic domain, either deliberate (e.g., music or speech) or unintended. In contrast, noise in electronics may not be audible to the human ear and may require instruments for detection.
In audio engineering, noise can refer to the unwanted residual electronic noise signal that gives rise to acoustic noise heard as a hiss. This signal noise is commonly measured using A-weighting or ITU-R 468 weighting.
Sound is measured based on the amplitude and frequency of a sound wave. Amplitude measures how forceful the wave is. The energy in a sound wave is measured in decibels (dB), the measure of loudness, or intensity of a sound; this measurement describes the amplitude of a sound wave. Decibels (dB) are expressed in a logarithmic scale. On the other hand, pitch describes the frequency of a sound and is measured in hertz (Hz).
The main instrument to measure sounds in the air is the Sound Level Meter. There are many different varieties of instruments that are used to measure noise - Noise Dosimeters are often used in occupational environments, noise monitors are used to measure environmental noise and noise pollution, and recently smartphone-based sound level meter applications (apps) are being used to crowdsource and map recreational and community noise.
A-weighting is applied to a sound spectrum to represent the sound that humans are capable of hearing at each frequency. Sound pressure is thus expressed in terms of dBA. 0 dBA is the softest level that a person can hear. Normal speaking voices are around 65 dBA. A rock concert can be about 120 dBA.
Recording and reproduction
In audio, recording, and broadcast systems, audio noise refers to the residual low-level sound (four major types: hiss, rumble, crackle, and hum) that is heard in quiet periods of program. This variation from the expected pure sound or silence can be caused by the audio recording equipment, the instrument, or ambient noise in the recording room.
In audio engineering it can refer either to the acoustic noise from loudspeakers or 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
Noise is often generated deliberately and used as a test signal for audio recording and reproduction equipment.
White noise is energy randomly spread across a wide frequency band containing all notes from high to low. It is called "white" noise as it is analogous to "white" light which contains all the colors of the visible spectrum.
Environmental noise is the accumulation of all noise present in a specified environment. The principal sources of environmental noise are surface motor vehicles, aircraft, trains and industrial sources. These noise sources expose millions of people to noise pollution that creates not only annoyance, but also significant health consequences such as elevated incidence of hearing loss and cardiovascular disease. There are a variety of mitigation strategies and controls available to reduce sound levels including source intensity reduction, land-use planning strategies, noise barriers and sound baffles, time of day use regimens, vehicle operational controls and architectural acoustics design measures.
Certain geographic areas or specific occupations may be at a higher risk of being exposed to constantly high levels of noise; in order to prevent negative health outcomes, regulations may be set. Noise regulation includes statutes or guidelines relating to sound transmission established by national, state or provincial and municipal levels of government. Environmental noise is governed by laws and standards which set maximum recommended levels of noise for specific land uses, such as residential areas, areas of outstanding natural beauty, or schools. These standards usually specify measurement using a weighting filter, most often A-weighting.
In 1972, the Noise Control Act was passed to promote a healthy living environment for all Americans, where noise does not pose a threat to human health. This policy's main objectives were: (1) establish coordination of research in the area of noise control, (2) establish federal standards on noise emission for commercial products, and (3) promote public awareness about noise emission and reduction.
The Quiet Communities Act of 1978 promotes noise control programs at the state and local level and developed a research program on noise control. Both laws authorized the Environmental Protection Agency to study the effects of noise and evaluate regulations regarding noise control.
The National Institute for Occupational Safety and Health (NIOSH) provides recommendation on noise exposure in the workplace. In 1972 (revised in 1998), NIOSH published a document outlining recommended standards relating to the occupational exposure to noise, with the purpose of reducing the risk of developing permanent hearing loss related to exposure at work. This publication set the recommended exposure limit (REL) of noise in an occupation setting to 85 dBA for 8 hours using a 3-dB exchange rate (every 3-dB increase in level, duration of exposure should be cut in half, i.e. 88 dBA for 4 hours, 91 dBA for 2 hours, 94 dBA for 1 hour, etc.). However, in 1973 the Occupational Safety and Health Administration (OSHA) maintained the requirement of an 8-hour average of 90 dBA. The following year, OSHA required employers to provide a hearing conservation program to workers exposed to 85 dBA average 8-hour workdays.
The European Environment Agency regulates noise control and surveillance within the European Union. The Environmental Noise Directive was set to determine levels of noise exposure, increase public access to information regarding environmental noise, and reduce environmental noise. Additionally, in the European Union, underwater noise is a pollutant according to the Marine Strategy Framework Directive (MSFD). The MSFD requires EU Member States to achieve or maintain Good Environmental Status, meaning that the "introduction of energy, including underwater noise, is at levels that do not adversely affect the marine environment".
Exposure to noise is associated with several negative health outcomes. Depending on duration and level of exposure, noise may cause or increase the likelihood of hearing loss, high blood pressure, ischemic heart disease, sleep disturbances, injuries, and even decreased school performance. There are also causal relationships between noise and psychological effects such as annoyance, psychiatric disorders, and effects on psychosocial well-being.
Noise exposure has increasingly been identified as a public health issue, especially in an occupational setting, as demonstrated with the creation of NIOSH's Noise and Hearing Loss Prevention program. Noise has also proven to be an occupational hazard, as it is the most common work-related pollutant. Noise-induced hearing loss, when associated with noise exposure at the workplace is also called occupational hearing loss.
Hearing loss prevention
While noise-induced hearing loss is permanent, it is also very preventable. Particularly in the workplace, regulations may exist depicting maximum allowed levels of noise. This can be especially important for professionals working in settings with consistent exposure to loud sounds, such as musicians, music teachers and sound engineers. Examples of measures taken to prevent noise-induced hearing loss in the workplace include engineering noise control, the Buy-Quiet initiative, creation of the Safe-in-Sound Award, and noise surveillance.
Roland Barthes distinguishes between physiological noise, which is merely heard, and psychological noise, which is actively listened to. Physiological noise is felt subconsciously as the vibrations of the noise (sound) waves physically interact with the body while psychological noise is perceived as our conscious awareness shifts its attention to that noise.
Luigi Russolo, one of the first composers of noise music, wrote the essay The Art of Noises. He argues that any kind of noise could be used as music, as audiences become more familiar with noises caused by technological advancements; noise has become so prominent that pure sound no longer exists.
- Association of Noise Consultants
- Background noise
- Impulse noise (audio)
- International Noise Awareness Day
- Loud music
- Noise and vibration on maritime vessels
- Noise calculation
- Noise control
- Noise in music
- Noise music
- Noise pollution
- Noise reduction
- Noise (disambiguation)
- Sound level meter
- The Hum
- Elert, Glenn. "The Nature of Sound – The Physics Hypertextbook". physics.info. Retrieved 2016-06-20.
- "The Propagation of sound". pages.jh.edu. Retrieved 2016-06-20.
- "What's The Difference Between Acoustical And Electrical Noise In Components?". electronicdesign.com. 2012-10-03. Retrieved 2016-06-20.
- Richard L. St. Pierre, Jr.; Daniel J. Maguire (July 2004), The Impact of A-weighting Sound Pressure Level Measurements during the Evaluation of Noise Exposure (PDF), retrieved 2011-09-13
- "RECOMMENDATION ITU-R BS.468-4 – Measurement of audio-frequency noise voltage" (PDF). www.itu.int. International Telecommunication Union. Retrieved 18 October 2016.
- "Definition of NOISE". www.merriam-webster.com. Retrieved 2016-06-20.
- "noise: definition of noise in Oxford dictionary (American English) (US)". www.oxforddictionaries.com. Retrieved 2016-06-20.
- Audio, NTi. "How to measure noise". nti-audio.com. Retrieved 2017-11-17.
- "Measuring sound". Sciencelearn Hub. Retrieved 2016-06-20.
- "So How Accurate Are These Smartphone Sound Measurement Apps? | | Blogs | CDC". blogs.cdc.gov. Retrieved 2018-06-15.
- "NoiseScore: A Free Smartphone App for Community Noise Issues With Live Map". Noiseandthecity.org. Retrieved 2018-06-15.
- "soundprint – Find Your Quiet Place". www.soundprint.co. Retrieved 2018-06-15.
- "iHEARu". www.ihearu.co. Retrieved 2018-06-15.
- "Audio Noise-Hiss, Hum, Rumble & Crackle". AudioShapers. Retrieved 2016-06-23.
- Elliot, Barry J. (2002). Designing a Structured Cabling System to ISO 11801 2nd Edition. Cambridge: Woodhead Publishing. p. 80. ISBN 978-0-8247-4130-3.
- Stansfeld, Stephen A.; Matheson, Mark P. (2003-12-01). "Noise pollution: non-auditory effects on health". British Medical Bulletin. 68 (1): 243–257. doi:10.1093/bmb/ldg033. ISSN 0007-1420. PMID 14757721.
- Hammer, Monica S.; Swinburn, Tracy K.; Neitzel, Richard L. (2014). "EHP – Environmental Noise Pollution in the United States: Developing an Effective Public Health Response". Environmental Health Perspectives. 122 (2): 115–119. doi:10.1289/ehp.1307272. PMC 3915267. PMID 24311120.
- Bhatia, Rajiv (May 20, 2014). "Noise Pollution: Managing the Challenge of Urban Sounds". Earth Journalism Network. Retrieved June 23, 2016.
- "Noise Ordinance: Noise Regulations from U.S. Cities". www.kineticsnoise.com. Retrieved 2016-06-23.
- EPA, OA, OP, ORPM, RMD, US (2013-02-22). "Summary of the Noise Control Act". www.epa.gov. Retrieved 2016-06-16.CS1 maint: Multiple names: authors list (link)
- Noise Control Act of 1972, P.L. 92-574, 86 Stat. 1234, 42 U.S.C. § 4901 – 42 U.S.C. § 4918.
- "Text of S. 3083 (95th): Quiet Communities Act (Passed Congress/Enrolled Bill version) – GovTrack.us". GovTrack.us. Retrieved 2016-06-16.
- EPA, OAR, OAA, IO, US (2015-06-03). "Title IV – Noise Pollution". www.epa.gov. Retrieved 2016-06-16.CS1 maint: Multiple names: authors list (link)
- "CDC – Facts and Statistics: Noise – NIOSH Workplace Safety & Health". www.cdc.gov. Retrieved 2016-06-15.
- "CDC – NIOSH Science Blog – Understanding Noise Exposure Limits: Occupational vs. General Environmental Noise". blogs.cdc.gov. Retrieved 2016-06-15.
- "CDC – NIOSH Publications and Products – Criteria for a Recommended Standard: Occupational Exposure to Noise (73-11001)". www.cdc.gov. 1975. doi:10.26616/NIOSHPUB76128. Retrieved 2016-06-15.
- "OSHA Technical Manual (OTM) | Section III: Chapter 5 – Noise". www.osha.gov. Retrieved 2016-06-15.
- "Noise: Policy Context". European Environmental Agency. June 3, 2016. Retrieved June 16, 2016.
- "Directive – Noise – Environment – European Commission". ec.europa.eu. Retrieved 2016-06-16.
- "Standard Summary Project Fiche: Implementation Capacity for Environmental Noise Directive" (PDF). European Commission. Retrieved June 16, 2016.
- "Our Oceans, Seas and Coasts". europa.eu.
- Passchier-Vermeer, W; Passchier, W F (2000-03-01). "Noise exposure and public health". Environmental Health Perspectives. 108 (Suppl 1): 123–131. doi:10.2307/3454637. ISSN 0091-6765. JSTOR 3454637. PMC 1637786. PMID 10698728.
- Passchier-Vermeer, Willy (March 1, 2000). "Noise Exposure and Public Health". Environmental Health Perspectives. 108 (Suppl 1): 123–131. doi:10.2307/3454637. JSTOR 3454637. PMC 1637786. PMID 10698728.
- "CDC – Noise and Hearing Loss Prevention – NIOSH Workplace Safety and Health Topi". www.cdc.gov. Retrieved 2016-06-15.
- Masterson, Elizabeth (2016-04-27). "Measuring the Impact of Hearing Loss on Quality of Life". Centers for Disease Control and Prevention. Retrieved 2016-06-15.
- "Noise-induced Hearing Loss". National Institute on Deafness and Other Communication Disorders (NIDCD). National Institute of Health. March 2014. Retrieved June 16, 2016.
- Kardous, Chuck; Morata, Thais; Themann, Christa; Spears, Patricia; Afanuh, Sue (2015-07-07). "Turn it Down: Reducing the Risk of Hearing Disorders Among Musicians". Centers for Disease Control and Prevention. Retrieved 2016-06-15.
- Murphy, William; Tak, SangWoo (2009-11-24). "Workplace Hearing Loss". Centers for Disease Control and Prevention. Retrieved 2016-06-15.
- "Buy Quiet". Centers for Disease Control and Prevention. Retrieved 2016-06-16.
- Hudson, Heidi; Hayden, Chuck (2011-11-04). "Buy Quiet". Centers for Disease Control and Prevention. Retrieved 2016-06-15.
- Barthes, Roland (1985). The Responsibility of Forms: Critical Essays on Music, Art and Representation. New York: Hill and Wang. ISBN 9780809080755.
- Chilvers, Ian; Glaves-Smith, John, eds. (2009). A Dictionary of Modern and Contemporary Art. Oxford: Oxford University Press. pp. 619–620. ISBN 978-0-19-923965-8.CS1 maint: Uses editors parameter (link)
- Russolo, Luigi (2004). "The art of noises: futurist manifesto". In Cox, Christoph; Warner, Daniel, eds. Audio Culture: Readings in Modern Music. New York: Continuum. pp. 10ff. ISBN 978-0-8264-1615-5.CS1 maint: Uses editors parameter (link)
- Cowell, Henry (2004). "The joys of noise". In Cox, Christoph; Warner, Daniel, eds. Audio Culture: Readings in Modern Music. New York: Continuum. p. 22. ISBN 978-0-8264-1615-5.CS1 maint: Uses editors parameter (link)
- Kosko, Bart (2006). Noise. Viking Press. ISBN 978-0-670-03495-6.
- Schwartz, Hillel (2011). Making Noise: From Babel to the Big Bang & Beyond. New York: Zone Books. ISBN 978-1-935408-12-3.
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- 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 (EU-OSHA)
- Mountain & Plains ERC: A NIOSH Education and Research Center for Occupational & Environmental Health & Safety
- US National Institute for Occupational Safety and Health, – Noise
- European noise laws
- Noise Pollution Clearing House
- Introduction to the fundamentals of acoustic engineering