Noise Pollution & its control
•Noise is undesirable and unwanted sound.
•Noise may not seem as harmful as the
contamination of air or water but it is a
pollution problem that affects human health
and can contribute to a general deterioration
of environmental quality.
•The differences between sound and noise is
often subjective and a matter of personal
Sound is measured in a unit called the
Noise standards recommended
Sources of Noise Pollution
•The main sources of noise are
–Various modes of transportation (like air, road,
–Celebrations (social/religious functions, elections
–Electric home appliances.
Sources of Noise Pollution
Effects of Noise Pollution
Effects of Noise Pollution
Non Auditory effects
•Interference with communication: In a noisy
area communication is severely affected.
•Physiological changes: Continuous exposure
to noise affects the functioning of various
systems of the body. It may result in
hypertension, insomnia (sleeplessness),
gastro-intestinal and digestive disorders,
peptic ulcers, blood pressure changes, etc.
•Psychological/Emotional changes: Noise can also
cause emotional or psychological effects such as
irritability, anxiety and stress.
•Lack of concentration and mental fatigue are
significant health effects of noise. It has been observed
that the performance of school children is poor in
comprehension tasks when schools are situated in busy
areas of a city and suffer from noise pollution.
•As noise interferes with normal auditory
communication, it may mask auditory warning signals
and hence increases the rate of accidents especially in
industries. It can also lead to lowered worker efficiency
and productivity and higher accident rates on the job.
•Noise can cause temporary or permanent
•It depends on intensity and duration of sound
•The most direct harmful effect of excessive
noise is physical damage to the ear leading to
either temporary or permanent hearing loss.
Hearing damage – TTS & NIPTS
•People suffering from temporary hearing loss
called temporary threshold shift (TTS) are unable
to detect weak sounds. However hearing ability is
usually recovered within a month of exposure. In
Maharashtra people living in close vicinity of
Ganesh mandals that play blaring music for ten
days of the Ganesh festival are usually known to
suffer from this phenomenon.
•Permanent loss, usually called noise induced
permanent threshold shift (NIPTS) represents a
loss of hearing ability from which there is no
A standard safe time limit has been set for exposure
to various noise levels. Beyond this ‘safe’
time continuing exposure over a period of a year
will lead to hearing loss.
Control of Noise Pollution
•There are four fundamental ways in which
noise can be controlled:
–Reduce noise at the source,
–Block the path of noise,
–Increase the path length and
–Protect the recipient.
•In general, the best control method is to
reduce noise levels at the source.
Reduction at source
•Muffling vehicles and machinery to reduce the
•Isolating machines and their enclosures from
the floor using special spring mounts or
absorbent mounts and pads and using flexible
couplings for interior pipelines also contribute
to reducing noise pollution at the source.
•Regular and thorough maintenance of operating
machinery can reduce noise considerably.
•Noise levels at construction sites can be controlled
using proper construction planning and scheduling
•Most of the vehicular noise comes from movement
of the vehicle tires on the pavement and wind
resistance. However poorly maintained vehicles can
add to the noise levels.
•Traffic volume and speed also have significant effects on
the overall sound. For e.g. doubling the speed increases
the sound levels by about 9dB and doubling the traffic
volume (number of vehicles per hour) increases sound
levels by about 3dB. A smooth flow of traffic also causes
less noise than does a stop-and-go traffic pattern. Proper
highway planning and design are essential for controlling
•Establishing lower speed limits for highways that pass
through residential areas, limiting traffic volume and
providing alternative routes for truck traffic are effective
noise control measures.
Block the path of noise
•The path of traffic noise can also be blocked by
construction of vertical barriers alongside the highway.
•Planting of trees around houses can also act as
effective noise barriers.
•In industries different types of absorptive material can
be used to control interior noise.
•Highly absorptive interior finish material for walls,
ceilings and floors can decrease indoor noise levels
•Locating noisy equipments away from the construction
site boundary along with creation of temporary
barriers to physically block the noise can help
contribute to reducing noise pollution.
•In industries noise reduction can be done by
using rigid sealed enclosures around
machinery lined with acoustic absorbing
Increasing the path length
•Sound levels drop significantly
with increasing distance from the
•Increasing the path length
between the source and the
recipient offers a passive means of
•Municipal land-use ordinances
pertaining to the location of
airports make use of the
attenuating effect of distance on
Protect the recipient
•Use of earplugs and earmuffs can protect
individuals effectively from excessive noise
•Specially designed earmuffs can reduce the
sound level reaching the eardrum by as much
as 40 dB.