Robert Webster defines noise as “a sound… that lacks

 Robert Koch, Nobel Laureate and great
bacteriologist, had predicted nearly 100 years ago, “A day will come when man
will have to fight merciless noise as the worst enemy of health.” How prophetic
he was! The tragic day may not be far off. Of all types of environmental
pollutants, noise is the most prevalent and insidious pollutant, with
deleterious physiological, psychological and social effects. Noise produces
these damaging effects even when we think we are not disturbed, being so
accustomed to the noise as to be consciously unaware of it. This subtle and
insidious nature of noise makes it a ‘slow agent of death’. The overall
loudness and environmental noise is doubling every decade in pace with our
social and industrial progress, and if the noise pollution escalates unabated,
it could become lethal within a few decades.

Just
what is noise? The word is apparently derived from the Latin word ‘nausea’,
meaning ‘sickness’. Webster defines noise as “a sound… that lacks agreeable
musical quality or is noticeably loud, harsh or discordant.” Psychologically,
noise is any sound which is unpleasant or unwanted. “Noise is a psychological phenomenon,” says
Bronzaft, a contributor to the book “Why Noise Matters” (2011). “While the ear
picks 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 is
unwanted, unpleasant or disturbing, and that’s why psychologists need to be
heavily involved in this issue.”

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According
to the International Programme on Chemical Safety (WHO, 1994), an adverse
effect of noise is defined as a change in the morphology and physiology of an
organism that results in impairment of functional capacity, or an impairment of
capacity to compensate for additional stress, or increases the susceptibility
of an organism to the harmful effects of other environmental influences. This
definition includes any temporary or long term lowering of the physical,
psychological or social functioning of humans or human organs.

Noise
often does not produce visible effects, and because there is usually not a
distinct cause-and-effect (“dose-response” in medical terms) relationship between
a single noise event and a clear adverse health effect, some people believe
noise does not pose a serious risk to human health. But evidence from a number
of recent studies, especially on children, provides ample proof that noise
harms health and decreases quality of life.

There
is fairly consistent evidence that prolonged exposure to noise levels at or
above 80 dB (A) can cause deafness. The amount of deafness depends upon the
degree of exposure. Almost everyone has had one experience of being temporarily
“deafened” by a loud noise. This “deafness” is not permanent, although it is
often accompanied by a ringing in the ears, and one can hear another person if
he raises his voice. Likewise, normal hearing comes back within a few hours at
most. This sort of partial hearing loss is called Temporary Threshold Shift
(TTS) (Bugliarello, 1976). Prolonged exposure to loud noise can lead to
permanent hearing loss. The loss is caused by the destruction of the delicate
hair cells and their auditory nerve connections in the Organ of Corti, which is
contained in the cochlea (Bugliarello, 1976).

There
are two types of hearing loss: conductive and sensorineural. In conductive
deafness sound-pressure waves never reach the cochlea, most often as a
consequence of a ruptured eardrum or a defect in the ossicles of the middle ear
(Bugliarello, 1976). Sensorineural hearing loss, occurs as a result of
advancing age as well as exposure to loud noises. In both instances there is
disruption in the Organ of Corti. The Organ of Corti is one of the best
protected parts of the body, encased as it is within the cochlea, which in turn
is deeply embedded in the temporal bone, none the less, loud noise can damage
hair cells and the auditory nerve, producing sudden and often total deafness.

 

REVIEW OF RELATED
LITERATURE

It
has been postulated that noise acts as an environmental stressor (Passchier-Vermeer,
1993; Berglund and Lindvall, 1995). Acute noise exposures activate the
automatic and hormonal systems, leading to temporary changes such as increased
blood pressure, increased heart rate and vasoconstriction. After prolonged
exposure, susceptible individuals in the general population may develop
permanent effects, such as hypertension and ischemic heart disease associated
with exposures to high sound pressure levels (Passchier-Vermeer,1993; Berglund
and Lindvall, 1995). The magnitude and duration of the effects are determined
in part by individual characteristics, lifestyle behaviours and environmental
conditions.

Many
studies have highlighted the effects of noise on the psychological and social
well being of individuals:

Mental Health Effects

Mental
health is defined as the absence of identifiable psychiatric disorders
according to current norms (Freeman, 1984). Environmental noise is not believed
to be a direct cause of mental illness, but it is assumed that it accelerates
and intensifies the development of latent mental disorder. Studies on the
adverse effects of environmental noise on mental health cover a variety of
symptoms, 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 as
neurosis, psychosis and hysteria. Large scale population studies have suggested
associations 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 sleeping
pills.

Exposure
to high levels of occupational noise has been associated with development of
neurosis and irritability; and exposure to high levels of environmental noise
with deteriorated mental health (Stansfeld, 1992). However, the findings on
environmental noise and mental health effects are inconclusive (Berglund and
Lindvall, 1995).

Interference with
Speech Communication

Noise
interference with speech comprehension results in a large number of personal
disabilities, handicaps and behavioural changes. Problems with concentration,
fatigue, uncertainty and lack of self confidence, irritation,
misunderstandings, decreased working capacity, problems in human relations, and
a number of stress reactions have all been identified (Lazarus, 1998).
Particularly vulnerable to these types of effects are the hearing impaired, the
elderly,children in the process of language and reading acquisition, and
individuals who are not familiar with the spoken language (Lazarus, 1998).

Speech
interference is basically a masking process in which simultaneous, interfering
noise renders speech incapable of being understood. The higher the level of the
masking noise, the greater will be the percentage of speech sounds that become
indiscernible to the listener. Environmental noise may also mask many other
acoustal signals important for daily life, such as doorbells, telephone
signals, alarm clocks, fire alarms and other warning signals. (Edworthy and
Adams, 1996).

 

Sleep Disturbance

Uninterrupted
sleep is known to be a prerequisite for good physiological and mental
functioning of healthy persons (Hobson, 1989). Sleep disturbance, on the other
hand, is considered to be a major environmental noise effect. The primary sleep
disturbance effects are: difficulty in falling asleep (increased sleep latency
time); awakenings; and alterations of sleep stages or depth, especially a
reduction in the proportion of REM sleep (REM=rapid eye movement) (Hobson,
1989).

Exposure
to night-time noise also induces psychological secondary effects, or so called
after effects. These are effects that can be measured the day following the
night-time exposure, while the individual is awake. The secondary effects
include reduced perceived sleep quality; increased fatigue; depressed mood or
well being; and decreased performance (Ohrstrom; Passchier- Vermeer, 1993;
Carter, 1996; Pearsons, et al., 1995; Pearsons, 1998).

Long
term effects on psychosocial well being have also been related to noise
exposure during the night (Ohrstrom, 1991). Noise annoyance during the night
time increased the total noise annoyance expressed by people in the following
24 hours. Various studies have also shown that people living in areas exposed
to night time noise have increased use of sedatives or sleeping pills.

Effects of Noise on
Performance

It
has been documented in both laboratory subjects and in workers exposed to
occupational noise, that noise adversely affects cognitive task performance. In
children, too, environmental noise impairs a number of cognitive and
motivational parameters ( Cohen, et al., 1980; Evans and Lepore, 1993; Evans,
1998; Hygge, et al., 1998; Haines, et al., 1998). However, there are no
published studies on whether environmental noise at home also impairs cognitive
performance in adults. Accidents may also be an indicator of performance
deficits. The few field studies on the effects of noise on performance and
safety showed that noise may reduce some task impairment and increase the
number of errors in work, but the effects depend on the type of noise and the
task being performed (Smith, 1990).

Laboratory
and workplace studies showed that noise can act as a distracting stimulus.
Also, impulsive noise events (e.g. sonic booms) may produce disruptive effects
as a result of startle responses. In the short term, noise induced arousal may
produce better performance of simple tasks, but cognitive performance
deteriorates substantially for more complex tasks (i.e. tasks that require
sustained attention to details or to multiple cues; or tasks that demand a
large capacity of working memory, such as complex analytical processes). Some
of the effects are related to loss in auditory comprehension and language
acquisition, but others are not (Evans and Maxwell, 1977). Among the cognitive
effects, reading, attention, problem solving and memory are most strongly
affected by noise. The observed effects on motivation, as measured by
persistence with a difficult cognitive task, may either be independent or
secondary to the aforementioned cognitive impairments.

Experimental
noise exposure consistently produces negative after effects on performance
(Glass and Singer, 1972). Following exposure to aircraft noise, schoolchildren
in the vicinity of Los Angeles airport were found to be deficient in
proofreading, 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 of
the adaptation strategies for dealing with aircraft noise, such as tuning
out  or ignoring the noise, and the
effort necessary to maintain task performance, comes at a price. There is
heightened sympathetic arousal, as indicated by increased levels of stress
hormone, and elevation of resting blood pressure (Evans, et al., 1995; Evans,
et al., 1998).

Effects of Noise on
Residential Behaviour and Annoyance

Noise
annoyance is a global phenomenon. A definition of annoyance is “a feeling of
displeasure associated with any agent or condition, known or believed by an
individual or group to adversely affect them” (Lindvall and Radford, 1973; Koelega,
1980). However, apart from “annoyance”, people may feel a variety of negative
emotions 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).

Noise
can produce a number of social and behavioural effects in residents, besides
annoyance (Berglund and Lindvall, 1995). The social and behavioural effects are
often complex, subtle and indirect. Many of the effects are assumed to be the
result of interactions with a number of non- auditory variables. Social and
behavioural 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 social
behaviour (e.g. aggression, unfriendliness, disengagement, non-participation);
adverse changes in social indicators (e.g. residential mobility, hospital
admissions, drug consumption, accident rates); and changes in mood (e.g. less
happy, more depressed).

Although
changes in social behaviour, such as reduction in helpfulness and increased
aggressiveness, are associated with noise exposure, noise exposure alone is not
believed to be sufficient to produce aggression. However, in combination with
provocation or pre-existing anger or hostility, it may trigger aggression. It
has been suspected that people are less willing to help, both during exposure
and for a period after exposure. Fairly consistent evidence shows that noise
above 80 dB(A) is associated with reduced helping behaviour and increased
aggressive behaviour. Particularly, there is concern that high level continuous
noise exposures may contribute to the susceptibility of school children to
feeling of helplessness (Evans and Lepore, 1993).

CONCLUSIONS

According
to a WHO report to the UN Conference on Environment, of all environmental
problems, noise is the easiest to control. But the question of control will
arrive only after there is awareness among the people of the need for control.

Certain
control measures are suggested such
as:

1.      The
most effective method of reducing noise from traffic and factories is to have
rational town planning. The residential zones should be placed away from main
roads, factories and shops.

2.      Control
of traffic noise can be considered with changes in vehicular design, changes in
tyres or road surfaces, elimination of noisier vehicles, modification in
traffic operations and designing streets, building and areas that produce less
noise. Smoother surfaces result in less noisier roads but this has
simultaneously to be balanced against the required skid resistance factor of
the tyres too. And legislative measures can prevent old vehicles from being
used on roads.

Some
measures possible in traffic operations are – rerouting of commercial vehicles
and 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 stop
and go traffic flow and consequently eliminating acceleration noise; and
prohibiting the blowing of horns by proper signs. The Central Motor Vehicle
Rules 1989, require a motor vehicle to be fitted with an electric horn for
purpose of warning only and specifies against the use of any multi- toned horn
or other sound producing device giving an unduly harsh, shrill or alarming
noise. Ambulances, fire engines, salvage vehicles or those of police and motor
vehicles department are permitted the use of such sound signals (sirens) as may
be approved by the authority. Every motor vehicle is required to be fitted with
a silencer to reduce as far as practicable the noise that would otherwise
escape from exhaust gases.

3.      A
new concept is to create vegetation buffer zones. Efforts should be made for
roadside plantation of trees, which is likely to reduce the noise to the extent
of about 8-10 decibels. This is due to the absorption by the foliage on one
hand, and multiple scattering of sound, on the other hand. Similarly, indoor
plants are helpful in reducing noise levels.

4.      A
vigorous pursuit of the existing legislative measures, especially during the
festivals and marriage functions should be made to control noise pollution.
Stringent punishment should be imposed on creation of unnecessary noise.

The
selected 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 four
above mentioned categories by the Competent Authority and the corresponding
standards should apply. Any form of violation should be strictly punished.

5.      Public
awakening is very essential for the control and prevention of noise pollution.
Masses are still ignorant of the grave effects of noise pollution. In this
regard, television, radio, internet, and newspapers should give a campaign for
wide publicity. Lectures, seminars and plays should be staged to spread awareness
amongst the people.

6.      Indoor
noise can be reduced by locating the corridors, kitchens and bathrooms in the
noisy side and critical areas such as bedrooms and living rooms on the quiet
side. Floors and ceilings could be insulated using high sound insulation
glasses. One can also lessen noise by using carpets or rubber on the floor.
Heavy curtains also lessen the propagation of noise. Perforated plywood and
specially made tiles and porous materials are available and can be fixed on
walls, floors and ceilings to have reduction in noise. Doors and windows can
also be specially designed. Excellent sound insulation is obtained by
constructing glazed windows with double or triple panes of glass. The air space
at the edges of such panes is filled with sound absorbing material.

7.      Attempts
should be made to reduce the noise at source. Design and fabrication of
silencing devices and their use in engines, trucks, cars, motorcycles,
industrial machines and home appliances would be an effective measure.

The
Central Pollution Control Board of India also specifies noise limits for
vehicles 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

 

Since
it is not possible to have total elimination of annoying sounds, efforts should
be made to establish counselling centres in different areas. Residents should
be motivated to visit it regularly to gain awareness of the adverse health
effects of noise and also learn practically useful control measures. The
counselling centres should employ psychologists to teach effective stress
management techniques such as progressive relaxation therapy, behaviour
modification, cognitive restructuring as well as yoga and meditation for
reducing the negative psychological impact of noise. Attempts should also be
made to inculcate positive pro-environmental attitudes in the masses.