Robert Koch, Nobel Laureate and greatbacteriologist, had predicted nearly 100 years ago, “A day will come when manwill have to fight merciless noise as the worst enemy of health.” How prophetiche was! The tragic day may not be far off. Of all types of environmentalpollutants, noise is the most prevalent and insidious pollutant, withdeleterious physiological, psychological and social effects.
Noise producesthese damaging effects even when we think we are not disturbed, being soaccustomed to the noise as to be consciously unaware of it. This subtle andinsidious nature of noise makes it a ‘slow agent of death’. The overallloudness and environmental noise is doubling every decade in pace with oursocial and industrial progress, and if the noise pollution escalates unabated,it could become lethal within a few decades.Justwhat is noise? The word is apparently derived from the Latin word ‘nausea’,meaning ‘sickness’. Webster defines noise as “a sound.
.. that lacks agreeablemusical quality or is noticeably loud, harsh or discordant.” Psychologically,noise is any sound which is unpleasant or unwanted. “Noise is a psychological phenomenon,” saysBronzaft, a contributor to the book “Why Noise Matters” (2011). “While the earpicks up the sound waves and sends it to the temporal lobe for interpretation,it’s the higher senses of the brain that determine whether that sound isunwanted, unpleasant or disturbing, and that’s why psychologists need to beheavily involved in this issue.
” Accordingto the International Programme on Chemical Safety (WHO, 1994), an adverseeffect of noise is defined as a change in the morphology and physiology of anorganism that results in impairment of functional capacity, or an impairment ofcapacity to compensate for additional stress, or increases the susceptibilityof an organism to the harmful effects of other environmental influences. Thisdefinition includes any temporary or long term lowering of the physical,psychological or social functioning of humans or human organs. Noiseoften does not produce visible effects, and because there is usually not adistinct cause-and-effect (“dose-response” in medical terms) relationship betweena single noise event and a clear adverse health effect, some people believenoise does not pose a serious risk to human health. But evidence from a numberof recent studies, especially on children, provides ample proof that noiseharms health and decreases quality of life.Thereis fairly consistent evidence that prolonged exposure to noise levels at orabove 80 dB (A) can cause deafness.
The amount of deafness depends upon thedegree of exposure. Almost everyone has had one experience of being temporarily”deafened” by a loud noise. This “deafness” is not permanent, although it isoften accompanied by a ringing in the ears, and one can hear another person ifhe raises his voice. Likewise, normal hearing comes back within a few hours atmost. This sort of partial hearing loss is called Temporary Threshold Shift(TTS) (Bugliarello, 1976). Prolonged exposure to loud noise can lead topermanent hearing loss. The loss is caused by the destruction of the delicatehair cells and their auditory nerve connections in the Organ of Corti, which iscontained in the cochlea (Bugliarello, 1976). Thereare two types of hearing loss: conductive and sensorineural.
In conductivedeafness sound-pressure waves never reach the cochlea, most often as aconsequence of a ruptured eardrum or a defect in the ossicles of the middle ear(Bugliarello, 1976). Sensorineural hearing loss, occurs as a result ofadvancing age as well as exposure to loud noises. In both instances there isdisruption in the Organ of Corti. The Organ of Corti is one of the bestprotected parts of the body, encased as it is within the cochlea, which in turnis deeply embedded in the temporal bone, none the less, loud noise can damagehair cells and the auditory nerve, producing sudden and often total deafness. REVIEW OF RELATEDLITERATUREIthas been postulated that noise acts as an environmental stressor (Passchier-Vermeer,1993; Berglund and Lindvall, 1995). Acute noise exposures activate theautomatic and hormonal systems, leading to temporary changes such as increasedblood pressure, increased heart rate and vasoconstriction. After prolongedexposure, susceptible individuals in the general population may developpermanent effects, such as hypertension and ischemic heart disease associatedwith exposures to high sound pressure levels (Passchier-Vermeer,1993; Berglundand Lindvall, 1995). The magnitude and duration of the effects are determinedin part by individual characteristics, lifestyle behaviours and environmentalconditions.
Manystudies have highlighted the effects of noise on the psychological and socialwell being of individuals:Mental Health EffectsMentalhealth is defined as the absence of identifiable psychiatric disordersaccording to current norms (Freeman, 1984). Environmental noise is not believedto be a direct cause of mental illness, but it is assumed that it acceleratesand intensifies the development of latent mental disorder. Studies on theadverse effects of environmental noise on mental health cover a variety ofsymptoms, including anxiety, emotional stress, nervous complaints, nausea,headaches, instability, argumentativeness, sexual impotency, changes in mood,increase in social conflicts, as well as general psychiatric disorders such asneurosis, psychosis and hysteria. Large scale population studies have suggestedassociations between noise exposure and a variety of mental health indicators,such as single rating of well being; standard psychological symptom profiles;the intake of psychotropic drugs; and consumption of tranquilizers and sleepingpills.Exposureto high levels of occupational noise has been associated with development ofneurosis and irritability; and exposure to high levels of environmental noisewith deteriorated mental health (Stansfeld, 1992). However, the findings onenvironmental noise and mental health effects are inconclusive (Berglund andLindvall, 1995).Interference withSpeech CommunicationNoiseinterference with speech comprehension results in a large number of personaldisabilities, handicaps and behavioural changes. Problems with concentration,fatigue, uncertainty and lack of self confidence, irritation,misunderstandings, decreased working capacity, problems in human relations, anda number of stress reactions have all been identified (Lazarus, 1998).
Particularly vulnerable to these types of effects are the hearing impaired, theelderly,children in the process of language and reading acquisition, andindividuals who are not familiar with the spoken language (Lazarus, 1998).Speechinterference is basically a masking process in which simultaneous, interferingnoise renders speech incapable of being understood. The higher the level of themasking noise, the greater will be the percentage of speech sounds that becomeindiscernible to the listener. Environmental noise may also mask many otheracoustal signals important for daily life, such as doorbells, telephonesignals, alarm clocks, fire alarms and other warning signals. (Edworthy andAdams, 1996). Sleep DisturbanceUninterruptedsleep is known to be a prerequisite for good physiological and mentalfunctioning of healthy persons (Hobson, 1989). Sleep disturbance, on the otherhand, is considered to be a major environmental noise effect. The primary sleepdisturbance effects are: difficulty in falling asleep (increased sleep latencytime); awakenings; and alterations of sleep stages or depth, especially areduction in the proportion of REM sleep (REM=rapid eye movement) (Hobson,1989).
Exposureto night-time noise also induces psychological secondary effects, or so calledafter effects. These are effects that can be measured the day following thenight-time exposure, while the individual is awake. The secondary effectsinclude reduced perceived sleep quality; increased fatigue; depressed mood orwell being; and decreased performance (Ohrstrom; Passchier- Vermeer, 1993;Carter, 1996; Pearsons, et al.
, 1995; Pearsons, 1998).Longterm effects on psychosocial well being have also been related to noiseexposure during the night (Ohrstrom, 1991). Noise annoyance during the nighttime increased the total noise annoyance expressed by people in the following24 hours. Various studies have also shown that people living in areas exposedto night time noise have increased use of sedatives or sleeping pills.Effects of Noise onPerformanceIthas been documented in both laboratory subjects and in workers exposed tooccupational noise, that noise adversely affects cognitive task performance.
Inchildren, too, environmental noise impairs a number of cognitive andmotivational parameters ( Cohen, et al., 1980; Evans and Lepore, 1993; Evans,1998; Hygge, et al., 1998; Haines, et al., 1998). However, there are nopublished studies on whether environmental noise at home also impairs cognitiveperformance in adults. Accidents may also be an indicator of performancedeficits. The few field studies on the effects of noise on performance andsafety showed that noise may reduce some task impairment and increase thenumber of errors in work, but the effects depend on the type of noise and thetask being performed (Smith, 1990).
Laboratoryand workplace studies showed that noise can act as a distracting stimulus.Also, impulsive noise events (e.g.
sonic booms) may produce disruptive effectsas a result of startle responses. In the short term, noise induced arousal mayproduce better performance of simple tasks, but cognitive performancedeteriorates substantially for more complex tasks (i.e. tasks that requiresustained attention to details or to multiple cues; or tasks that demand alarge capacity of working memory, such as complex analytical processes). Someof the effects are related to loss in auditory comprehension and languageacquisition, but others are not (Evans and Maxwell, 1977). Among the cognitiveeffects, reading, attention, problem solving and memory are most stronglyaffected by noise. The observed effects on motivation, as measured bypersistence with a difficult cognitive task, may either be independent orsecondary to the aforementioned cognitive impairments.
Experimentalnoise exposure consistently produces negative after effects on performance(Glass and Singer, 1972). Following exposure to aircraft noise, schoolchildrenin the vicinity of Los Angeles airport were found to be deficient inproofreading, and in persistence with challenging puzzles (Cohen, et al.,1980). The uncontrollability of noise, rather than the intensity of the noise,appears to be the most critical variable.
An important finding was that some ofthe adaptation strategies for dealing with aircraft noise, such as tuningout or ignoring the noise, and theeffort necessary to maintain task performance, comes at a price. There isheightened sympathetic arousal, as indicated by increased levels of stresshormone, and elevation of resting blood pressure (Evans, et al., 1995; Evans,et al., 1998).
Effects of Noise onResidential Behaviour and AnnoyanceNoiseannoyance is a global phenomenon. A definition of annoyance is “a feeling ofdispleasure associated with any agent or condition, known or believed by anindividual or group to adversely affect them” (Lindvall and Radford, 1973; Koelega,1980). However, apart from “annoyance”, people may feel a variety of negativeemotions when exposed to community noise, and may report anger, disappointment,dissatisfaction, withdrawal, helplessness, depression, anxiety, distraction,agitation, or exhaustion (Job, 1993; Fields, et al.,1997, 1998).Noisecan produce a number of social and behavioural effects in residents, besidesannoyance (Berglund and Lindvall, 1995).
The social and behavioural effects areoften complex, subtle and indirect. Many of the effects are assumed to be theresult of interactions with a number of non- auditory variables. Social andbehavioural effects include changes in overt everyday behaviour patterns (e.g.closing windows, not using balconies, turning TV and radio to louder levels,writing petitions, complaining to authorities); adverse changes in socialbehaviour (e.g. aggression, unfriendliness, disengagement, non-participation);adverse changes in social indicators (e.g.
residential mobility, hospitaladmissions, drug consumption, accident rates); and changes in mood (e.g. lesshappy, more depressed).Althoughchanges in social behaviour, such as reduction in helpfulness and increasedaggressiveness, are associated with noise exposure, noise exposure alone is notbelieved to be sufficient to produce aggression. However, in combination withprovocation or pre-existing anger or hostility, it may trigger aggression. Ithas been suspected that people are less willing to help, both during exposureand for a period after exposure.
Fairly consistent evidence shows that noiseabove 80 dB(A) is associated with reduced helping behaviour and increasedaggressive behaviour. Particularly, there is concern that high level continuousnoise exposures may contribute to the susceptibility of school children tofeeling of helplessness (Evans and Lepore, 1993).CONCLUSIONSAccordingto a WHO report to the UN Conference on Environment, of all environmentalproblems, noise is the easiest to control. But the question of control willarrive only after there is awareness among the people of the need for control.Certaincontrol measures are suggested suchas:1. Themost effective method of reducing noise from traffic and factories is to haverational town planning. The residential zones should be placed away from mainroads, factories and shops.2.
Controlof traffic noise can be considered with changes in vehicular design, changes intyres or road surfaces, elimination of noisier vehicles, modification intraffic operations and designing streets, building and areas that produce lessnoise. Smoother surfaces result in less noisier roads but this hassimultaneously to be balanced against the required skid resistance factor ofthe tyres too. And legislative measures can prevent old vehicles from beingused on roads.Somemeasures possible in traffic operations are – rerouting of commercial vehiclesand buses to the extent possible from predominantly residential areas;providing bypasses on ring roads to siphon off traffic entering the town;providing synchronized traffic signals at street crossing to reduce the stopand go traffic flow and consequently eliminating acceleration noise; andprohibiting the blowing of horns by proper signs.
The Central Motor VehicleRules 1989, require a motor vehicle to be fitted with an electric horn forpurpose of warning only and specifies against the use of any multi- toned hornor other sound producing device giving an unduly harsh, shrill or alarmingnoise. Ambulances, fire engines, salvage vehicles or those of police and motorvehicles department are permitted the use of such sound signals (sirens) as maybe approved by the authority. Every motor vehicle is required to be fitted witha silencer to reduce as far as practicable the noise that would otherwiseescape from exhaust gases. 3. Anew concept is to create vegetation buffer zones. Efforts should be made forroadside plantation of trees, which is likely to reduce the noise to the extentof about 8-10 decibels. This is due to the absorption by the foliage on onehand, and multiple scattering of sound, on the other hand.
Similarly, indoorplants are helpful in reducing noise levels.4. Avigorous pursuit of the existing legislative measures, especially during thefestivals and marriage functions should be made to control noise pollution.Stringent punishment should be imposed on creation of unnecessary noise.Theselected framework for standards (India): Area Zone Daytime Limits dB(A) Night time limits dB(A) Industrial Area 75 70 Commercial Area 65 55 Residential Area 55 45 Silence Zone 50 40 Areas should be declared as one of the fourabove mentioned categories by the Competent Authority and the correspondingstandards should apply. Any form of violation should be strictly punished.5.
Publicawakening is very essential for the control and prevention of noise pollution.Masses are still ignorant of the grave effects of noise pollution. In thisregard, television, radio, internet, and newspapers should give a campaign forwide publicity. Lectures, seminars and plays should be staged to spread awarenessamongst the people.
6. Indoornoise can be reduced by locating the corridors, kitchens and bathrooms in thenoisy side and critical areas such as bedrooms and living rooms on the quietside. Floors and ceilings could be insulated using high sound insulationglasses. One can also lessen noise by using carpets or rubber on the floor.Heavy curtains also lessen the propagation of noise. Perforated plywood andspecially made tiles and porous materials are available and can be fixed onwalls, floors and ceilings to have reduction in noise. Doors and windows canalso be specially designed.
Excellent sound insulation is obtained byconstructing glazed windows with double or triple panes of glass. The air spaceat the edges of such panes is filled with sound absorbing material. 7. Attemptsshould be made to reduce the noise at source.
Design and fabrication ofsilencing devices and their use in engines, trucks, cars, motorcycles,industrial machines and home appliances would be an effective measure.TheCentral Pollution Control Board of India also specifies noise limits forvehicles and some domestic appliances and construction equipment as follows: Equipment Noise Limit dB(A) Small motorbike or scooter 80 Passenger Car 82 Small Bus or Commercial Vehicle 85 Medium Bus or Commercial Vehicle 89 Large Bus or Commercial Vehicle 91 Domestic Air Conditioner 68 Refrigerator 46 Domestic Generator 85 Copactors (rollers) Front Loaders, Concrete Mixers, Cranes 75 Sinceit is not possible to have total elimination of annoying sounds, efforts shouldbe made to establish counselling centres in different areas. Residents shouldbe motivated to visit it regularly to gain awareness of the adverse healtheffects of noise and also learn practically useful control measures. Thecounselling centres should employ psychologists to teach effective stressmanagement techniques such as progressive relaxation therapy, behaviourmodification, cognitive restructuring as well as yoga and meditation forreducing the negative psychological impact of noise. Attempts should also bemade to inculcate positive pro-environmental attitudes in the masses.