Physics:Noise measurement

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In acoustics, noise measurement can be for the purpose of measuring environmental noise[1] or measuring noise in the workplace. Applications include monitoring of construction sites, aircraft noise, road traffic noise, entertainment venues and neighborhood noise. One of the definitions of noise covers all "unwanted sounds".[2] When sound levels reach a high enough intensity, the sound, whether it is wanted or unwanted, may be damaging to hearing.[3] Environmental noise monitoring is the measurement of noise in an outdoor environment caused by transport (e.g. motor vehicles, aircraft, and trains), industry (e.g. machines) and recreational activities (e.g. music). The laws and limits governing environmental noise monitoring differ from country to country. At the very least, noise may be annoying or displeasing or may disrupt the activity or balance of human or animal life, increasing levels of aggression, hypertension and stress. In the extreme, excessive levels or periods of noise can have long-term negative health effects such as hearing loss,[4] tinnitus,[5] sleep disturbances,[6] a rise in blood pressure,[7] an increase in stress[8] and vasoconstriction,[9] and an increased incidence of coronary artery disease.[10][11] In animals, noise can increase the risk of death by altering predator or prey detection and avoidance, interfering with reproduction and navigation,[12] and contributing to permanent tinnitus and hearing loss.[13][14]

Various interventions are available to combat environmental noise. Roadway noise can be reduced by the use of noise barriers,[15] limitation of vehicle speeds,[16] alteration of roadway surface texture, limitation of heavy vehicles, use of traffic controls that smooth vehicle flow to reduce braking and acceleration, and tire design.[17] Aircraft noise can be reduced by using quieter jet engines,[18][19][20] altering flight paths and considering the time of day to benefit residents near airports.[21] Industrial noise is addressed by redesign of industrial equipment, shock mounted assemblies and physical barriers in the workplace.[22]

Noise may be measured using a sound level meter at the source of the noise.[23][24][25] Alternatively, an organization or company may measure a person's exposure to environmental noise in a workplace via a noise dosimeter.[26] The measurements taken using either of these methods will be evaluated according to the standards below.

Audio Systems and Broadcasting

Noise measurement can also be part of a test procedure using white noise, or some other specialized form of test signal. In audio systems and broadcasting, specific methods are used to obtain subjectively valid results in order that different devices and signal paths may be compared regardless of the inconsistent spectral distribution and temporal properties of the noise that they generate. In particular, the ITU-R 468 noise weighting was devised specifically for this purpose and is widely used for professional audio and broadcast measurements.

Standards

There are a number of standards for noise measurement, each with a different goal or focus, including:

  • Standard:ITU-R BS 468 widely used in Broadcasting and professional Audio.
  • Standard:IEC A-weighting is widely used in Environmental Noise measurement.
  • Standard:CCIR recommendation 468-4 is now maintained as ITU-R BS 468
  • Standard:CCITT 0.41 refers to 'Psophometric weighting' used on telephone circuits.
  • Standard:CCITT P53 is now continued as CCITT0.41
  • Standard:BS 6402:1983 specifies Personal sound exposure meters.
  • Standard:BS 3539:1968 specifies Sound level meters for motor vehicle noise.
  • Standard:BSEN 60651 supersedes BS 5969:1981 Sound level meters

See also

References

  1. ↑ Audio, NTi. "Unattended Noise Monitoring". http://www.nti-audio.com/Portals/0/data/en/XL2-NoiseScout-Unattended-Noise-Monitoring-Leaflet.pdf. 
  2. ↑ Goines, Lisa; Hagler, Louis (March 2007). "Noise Pollution: A Modern Plague". Southern Medical Journal 100 (3): 287–294. doi:10.1097/smj.0b013e3180318be5. ISSN 0038-4348. PMID 17396733. 
  3. ↑ "CAOHC Noise Measurement Course". https://www.caohc.org/learn-media/CAOHC_Module_1/. 
  4. ↑ "Safety and Health Topics | Occupational Noise Exposure | Occupational Safety and Health Administration". https://www.osha.gov/SLTC/noisehearingconservation/. 
  5. ↑ "Causes" (in en). 2015-03-02. https://www.ata.org/understanding-facts/causes. 
  6. ↑ Halperin, Demian (2014-12-01). "Environmental noise and sleep disturbances: A threat to health?" (in en). Sleep Science 7 (4): 209–212. doi:10.1016/j.slsci.2014.11.003. ISSN 1984-0063. PMID 26483931. 
  7. ↑ Chang, Ta-Yuan; Hwang, Bing-Fang; Liu, Chiu-Shong; Chen, Ren-Yin; Wang, Ven-Shing; Bao, Bo-Ying; Lai, Jim-Shoung (2013-04-15). "Occupational Noise Exposure and Incident Hypertension in Men: A Prospective Cohort Study" (in en). American Journal of Epidemiology 177 (8): 818–825. doi:10.1093/aje/kws300. ISSN 0002-9262. PMID 23470795. https://academic.oup.com/aje/article/177/8/818/134174. 
  8. ↑ "Open Office Noise Increases Stress" (in en). https://www.webmd.com/balance/stress-management/news/20020226/open-office-noise-increases-stress. 
  9. ↑ "Open Office Noise Increases Stress" (in en). https://www.webmd.com/balance/stress-management/news/20020226/open-office-noise-increases-stress. 
  10. ↑ Hansell, Anna L.; Blangiardo, Marta; Fortunato, Lea; Floud, Sarah; Hoogh, Kees de; Fecht, Daniela; Ghosh, Rebecca E.; Laszlo, Helga E. et al. (2013-10-08). "Aircraft noise and cardiovascular disease near Heathrow airport in London: small area study" (in en). BMJ 347: f5432. doi:10.1136/bmj.f5432. ISSN 1756-1833. PMID 24103537. https://www.bmj.com/content/347/bmj.f5432. 
  11. ↑ Hammer Monica S.; Swinburn Tracy K.; Neitzel Richard L. (2014-02-01). "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. PMID 24311120. 
  12. ↑ "Review of noise impacts on marine mammals yields new policy recommendations" (in en). https://phys.org/news/2019-03-noise-impacts-marine-mammals-yields.html. 
  13. ↑ Salvi, Richard; Boettcher, Flint A. (2008), Conn, P. Michael, ed., "Animal Models of Noise-Induced Hearing Loss" (in en), Sourcebook of Models for Biomedical Research (Totowa, NJ: Humana Press): pp. 289–301, doi:10.1007/978-1-59745-285-4_32, ISBN 978-1-59745-285-4, https://doi.org/10.1007/978-1-59745-285-4_32, retrieved 2020-10-10 
  14. ↑ Diaz, Rodney C. (2014). "Noise-induced hearing loss: perspectives". Current Opinion in Otolaryngology & Head and Neck Surgery 22 (5): 373. doi:10.1097/MOO.0000000000000084. ISSN 1531-6998. PMID 25101939. https://pubmed.ncbi.nlm.nih.gov/25101939. 
  15. ↑ Barrier, Hatko (2020-04-20). "How much does noise barrier cost?" (in en-US). https://www.hatkosoundbarrier.com/how-much-does-noise-barrier-cost/. 
  16. ↑ "NPC Resources: Noise Increases with Vehicle Speed". https://nonoise.org/resource/trans/highway/spnoise.htm. 
  17. ↑ atlanticei (2019-03-20). "Reducing Excessive Noise Using Engineering Methods | Atlantic Environmental" (in en-US). https://www.atlenv.com/reducing-excessive-noise-using-engineering-methods. 
  18. ↑ "Leading the way in aircraft noise reduction | Engineering | University of Southampton" (in en). https://www.southampton.ac.uk/engineering/research/impact/leading_the_way_in_aircraft_noise_reduction.page#:~:text=Sound%20absorbing%20%E2%80%98liners%E2%80%99%20placed%20on%20the%20inner%20surfaces,fuel%20efficient,%20advanced%20open%20rotor%20(AOR)%20powered%20aircraft.. 
  19. ↑ Potter, Sean (2018-06-25). "NASA Technologies Significantly Reduce Aircraft Noise". http://www.nasa.gov/press-release/nasa-technologies-significantly-reduce-aircraft-noise. 
  20. ↑ "Reducing Aviation Noise, Advancing the Aviation Enterprise | Volpe National Transportation Systems Center". https://www.volpe.dot.gov/news/reducing-aviation-noise-advancing-aviation-enterprise. 
  21. ↑ "How to Control Aircraft Noise? | Noise Pollution" (in en-US). 2018-03-12. https://www.environmentalpollution.in/noise-pollution/aircraft-noise/how-to-control-aircraft-noise-noise-pollution/4968. 
  22. ↑ "Controls for Noise Exposure | NIOSH | CDC" (in en-us). 2020-06-22. https://www.cdc.gov/niosh/topics/noisecontrol/default.html. 
  23. ↑ "How is Sound Measured?" (in en). 28 January 2019. https://www.noisyplanet.nidcd.nih.gov/have-you-heard/how-is-sound-measured. 
  24. ↑ "How decibel sound level meters work". 2009-01-28. http://www.explainthatstuff.com/soundlevelmeters.html. 
  25. ↑ "Sound-level meter | instrument" (in en). https://www.britannica.com/technology/sound-level-meter. 
  26. ↑ Selwyn, Bob (September 1, 2010). "The Use of Noise Dosimeters in the Workplace -" (in en). https://ohsonline.com/articles/2010/09/01/the-use-of-noise-dosimeters-in-the-workplace.aspx. 

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