Noise, or unwanted sound, is a pollutant and an environmental stressor. The frequency of noise events seems to have increased in recent years while the amount of the day without noise has lessened.
"Noise" is generally defined asunwanted sound and is perceivedas a pollutant and anenvironmental stressor. As opposed tosound, noise involves a significantpsychological component in additionto the physical component of soundperceived by the ear and transmittedby the auditory nerve to the temporallobe in the brain.
Noise characteristics and levels
Typically, sound is described in termsof its intensity or sound pressure level,its frequency, periodicity, and duration.Sound pressure level is measured indecibels (dB). Since the human earresponds differently to different frequencyranges, filter meters that workmore like the human ear are often usedto measure sound pressure levels; insuch cases, the unit is described asdBA, which means that a weightedfilter was used.
Sound is also described in terms ofequivalent sound levels (Leq), measurementsthat address average noiselevels of fluctuating noises. Other characteristics,such as the predictability ofthe noise, its meaning, and the degree ofpersonal control over noise, may influinfluencepeople's responses. The Table listscommon noises and their sound levels.
Grand Canyon at night (birds, wind, no roads)
Typical living room
Bathroom exhaust fan
Inside car, windows closed, 30 mph
Heavy truck (at 50 feet)
Maximum output of stereo
Jet takeoff (at 200 feet)
28 - 33
40 - 43
54 - 55
55 - 65
56 - 58
63 - 66
68 - 73
80 - 95
84 - 89
88 - 94
100 - 110
Adapted from Noise Pollution Clearinghouse
(available at: http://www.nonoise.org/library/ household/index.htm) and other sources.
Exposure to environmental noise,including transport, construction, andindustry noise, is increasing. While theintensity of noise from aircraft and carsmay have diminished, the frequency ofnoise events seems to have increasedin recent years, and the amount of theday without noise has lessened.1
General effects of noise
There are several ways in which people'severyday functioning is disturbed byexposure to noise. The most widespreadresponse to noise is annoyance; thisincludes elements of fear, mild anger,and a belief of being avoidably harmed.2Reactions of annoyance are often associatedwith the degree of interferencethat noise causes in everyday activities.Dose-response relationships betweenthe intensity of noise and annoyancefrom air, road, and rail transport havebeen found in a number of studies.3Severe annoyance typically beginsabove 50 dBA to 55 dBA Leq.4
Exposure to noise during sleep hasbeen related to difficulties in getting tosleep, changes in sleep stages, andawakenings.5 While effects of noiseexposure on sleep are evident in laboratorystudies, these effects are moredifficult to demonstrate in communitystudies, where residents may habituateto prolonged noise exposure.6 There isno evidence that noise exposure, throughinsomnia, triggers depressive illness, althoughthis pathway seems plausible.
There is also limited evidence ofnoise affecting pathophysiology, apartfrom the issue of noise-induced hearingloss. In occupational settings, forinstance, there is evidence of raisedlevels of catecholamines and cortisol inpersons exposed to very high levels ofnoise, typically above 80 dBA.7Although the evidence is less convincing,there are some data that showhormonal responses in relation to environmentalnoise. There is also someevidence that aircraft and road trafficnoise, typically at levels greater than65 dBA to 70 dBA Leq, is related to asmall increased risk of hypertension andcoronary heart disease.8
An important area of the consequencesof noise relates to task performance.Laboratory studies have shown thatnoise exposure increases arousal andcan improve cognitive performance onsimple tasks that require vigilance. Onthe other hand, noise can interfere with more complex tasks, decreasing attentionas well as altering choice of taskstrategy.9
In the so-called irrelevant speecheffect, cognitive performance can bedisturbed when the individual hearsbackground speech that is irrelevant tothe task; it is believed that this may interferewith memory processes.10 Thisphenomenon has obvious implications forpeople working in open-plan offices.
Recent epidemiologic studies ofschoolchildren have found that aircraftnoise exposure at school was associatedin a linear exposure-effect relationshipwith impairment of reading andmemory recognition,11 which confirmedearlier studies.12 The mechanism for thisis uncertain; it may relate to disturbancesin communication between teachersand pupils or maladaptive attentionalstrategies.
Mental health and noise
Because of its effects on annoyance,sleep, and cognitive performance, noisemight be expected to affect mentalhealth. Although there is some evidenceof this effect, the data are by no meansclear-cut.
At the simplest level, noise exposurein the community has been related toan increased incidence of psychologicalsymptoms, including headaches,anxiety, fatigue, and depression.13,14Early studies of mental hospital admissionsand aircraft noise exposure showeda mixed picture,15 and communitysurveys, which are a more appropriatedesign for detecting the effects of environmentalnoise, have only shown effectsin certain subgroups.16
Two epidemiologic studies of roadtraffic noise have found associationsbetween noise exposure and symptomsof mental distress17 and anxietyscores.18 A more recent Sardinianstudy19 examined persons living closeto an airport and matched them withcontrols. Researchers found a higherprevalence of generalized anxiety disorder,as diagnosed by the CompositeInternational Diagnostic Interview, among those exposed to high levels ofaircraft noise than among people livingin quieter areas.
Relationships between militaryaircraft noise exposure and psychologicaldistress have been found in a rangeof Japanese studies, suggesting theremay be more evidence for effects onmental health at higher noise levels.Increased levels of prescriptions ofhypnotics and nonprescription sedativesin areas exposed to aircraft noise(compared with those in quieter areas)can be considered indirect evidence ofthe mental health effects of noise.20,21
Thus, there is a need for more researchto provide additional insight and perhapsstronger evidence for the link betweennoise and psychological distress. Itshould be noted that noisy environmentsare often socioeconomically disadvantagedenvironments, and it is difficult todisentangle the effect of noise on mentalhealth from the effects of other stressors,both social and environmental, thatmay be present.
Mental illness,neighbors, and noise
Noise from neighbors has received littleresearch investigation but may come tothe attention of psychiatrists. In theUnited Kingdom, this is the mostcommon source of noise complaints tolocal government authorities.22
Noise that is continuous, apparentlyindefinite, of uncertain cause or source,emotive or frightening, or apparentlydue to thoughtlessness or lack of considerationis most likely to elicit an adversereaction.23
In some cases, on further inquiry, itbecomes apparent that complaints ofnoise disturbance are related to persecutorydelusions and may be a symptomof psychosis. In these cases, whichoften come to the attention of psychiatrists,the disturbances are typically partof a wider system of persecutory ideasabout neighbors, in which noise is onlyone of many afflictions that the patientbelieves the neighbors are causing him or her. Here, the management relates tothe primary underlying illness, for whichrisk assessment (including assessmentof the risk of aggression against neighbors)will be important. On the otherhand, the clinician should not be tooready to dismiss the reality of the noisecomplaints.
Prolonged exposure to noise can bevery upsetting and intrusive and caninterfere with sleep and everyday activities,especially in poorly built dwellings,where even low-intensity noisesfrom neighbors may be clearly audible.This may be a problem particularlyamong people who are chronicallyanxious and who complain of sensitivityto noise (ie, prolonged noiseexposure may make them more anxiousand unhappy).
There may be a phobic reaction tonoise in some people with noise sensitivitythat might respond to a cognitivebehavioralapproach.24 There isevidence that people with existingdepression and anxiety are more likelyto be sensitive to the effects of noise.24
Perceptions of lack of control overthe noise, unpleasant meanings associatedwith the noise, or a feeling thatothers don't care may exacerbate negativeresponses. Active coping strategies,such as shutting windows, spending moretime in the most quiet areas of their residence,and complaining to the relevantauthorities, may reduce negative responsesto noise. Conversely, passive copingis likely to aggravate noise effects.
Current evidence suggests that environmentalnoise exposure, especially athigher levels, is related to mental healthsymptoms and possibly to increasedanxiety and consumption of sedativemedication. Although noise exposuremay be responsible for only relativelymild psychiatric disorders, it doesinvolve large numbers of people whosequality of life may be impaired significantly.For the fifth of the populationwho are sensitive to noise, chronic noiseexposure can cause considerable disturbanceand misery.16
Dr Stansfeld is professor of psychiatry at theCentre for Psychiatry, Wolfson Institute ofPreventive Medicine, Barts, and The LondonQueen Mary's School of Medicine andDentistry, London. He is also secretary of theInternational Commission on the BiologicalEffects of Noise and has a long-standing interestin research on noise and health.
Dr Stansfeld is a consultant on a project onnoise and vibration impact assessment sponsoredby the United Kingdom Department ofEnvironment.
References1. Wright P, Skinner CJ, Grimwood CJ. The nationalnoise incidence study 2000 (England andWales). BRE Client Report 203938f. Watford, UK.Available at:http://www.defra.gov.uk/environment/noise/research/nis0001/pdf/nis_4m.pdf. AccessedApril 27, 2006.
2. Cohen S, Weinstein N. Non-auditory effects ofnoise on behavior and health. J Soc Issues. 1981;37:36-70.
3. Miedema HM, Vos H. Exposure-response relationshipsfor transportation noise. J Acoust Soc Am.1998;104:3432-3445.
4. Berglund B, Lindvall T, eds. Community noise.Final report to the World Health Organization. ArchCenter for Sensory Res. 1995;2:1-180.
5. Ohrstrom E. Sleep disturbances caused by roadtraffic noise: studies in laboratory and field. NoiseHealth. 2000;2:71-78.
6. Horne JA, Pankhurst FL, Reyner LA, et al. A fieldstudy of sleep disturbance: effects of aircraft noiseand other factors on 5,742 nights of actimetricallymonitored sleep in a large subject sample. Sleep.1994;17:146-159.
7. Babisch W. Stress hormones in the research oncardiovascular effects of noise. Noise Health.2003;5:1-11.
8. Babisch W. Traffic noise and cardiovascular disease:epidemiological review and synthesis. Noise Health.2000;2:9-32.
9. Smith AP, Broadbent DE. Non-auditory effects ofnoise at work: a review of the literature. HSE ContractResearch Report 30. London: HMSO; 1992. Availableat:http://www.hse.gov.uk/research/crr_pdf/1991/crr91030.pdf. Accessed April 21, 2006.
10. Jones D, Morris N. Irrelevant speech and serialrecall: implications for theories of attention and workingmemory. Scand J Psychol. 1992;33:212-229.
11. Stansfeld SA, Berglund B, Clark C, et al. Aircraftand road traffic noise and children's cognition andhealth: a cross-national study. Lancet. 2005;365:1942-1949.
12. Hygge S, Evans GW, Bullinger M. A prospectivestudy of some effects of aircraft noise on cognitiveperformance in schoolchildren. Psychol Sci.2002;13:469-474.
13. Ohrstrom E. Sleep disturbance, psychosocial andmedical symptoms: a pilot survey among personsexposed to high levels of road traffic noise. J SoundVibration. 1989;133:117-128.
14. Belojevic G, Jakovljevic B, Alexis O. Subjectivereactions to traffic noise with regard to some personalitytraits. Environ Int. 1997;23:221-226.
15. Jenkins L, Tarnopolosky A, Hand D. Psychiatricadmissions and aircraft noise from London Airport:four-year, three hospitals' study. Psychol Med. 1981;11:765-782.
16. Tarnopolsky A, Morton-Williams J. Aircraft Noiseand Prevalence of Psychiatric Disorders, ResearchReport. London: Social and Community PlanningResearch; 1980.
17. Halpern D. Mental Health and the BuiltEnvironment. London: Taylor and Francis; 1995.
18. Stansfeld S, Gallacher J, Babisch W, Shipley M.Road traffic noise and psychiatric disorder: prospectivefindings from the Caerphilly Study. BMJ.1996;313:266-267.
19. Hardoy MC, Carta MG, Marci AR, et al. Exposureto aircraft noise and risk of psychiatric disorders:the Elmas survey: aircraft noise and psychiatric disorders.Soc Psychiatry Psychiatr Epidemiol. 2005;40:24-26.
20. Lercher P, Kofler WW. Behavioral and healthresponses associated with road traffic noise exposurealong alpine through-traffic routes. Sci TotalEnviron. 1996;189/190:89.
21. Franssen EA, van Wiechen CM, NagelkerkeNJ, Lebret E. Aircraft noise around a large internationalairport and its impact on general healthand medication use. Occup Environ Med. 2004;61:405-413.
22. Chartered Institute of Environmental Health.Environmental Health Report 1997/8. 1999. London.
23. Grimwood C. Effects of environmental noise onpeople at home. BRE Information Paper 22/93;Birmingham, England: BRE Press; 1993.
24. Stansfeld SA. Noise, noise sensitivity and psychiatricdisorder: epidemiological and psychophysiologicalstudies. Psychological Medicine MonographSupplement 22. Cambridge: Cambridge UniversityPress; 1992.