DOC-20230214-WA0019..pptx

Siddharth Mehndiratta, CED MNIT Jaipur
Noise Pollution
Siddharth Mehndiratta
Department of civil engineering

2
Until people at all levels recognize the
inherent dangers of noise pollution, nothing
will change.
Noise pollution is a growing problem that
remains unaddressed.
Society now ignores noise the way it ignored
the use of tobacco products in the 1950s.

3
466
Million
people
live with disabling hearing loss
Source: World health Organization (2018)

400,000
600,000
800,000
1000,000
2015 2020 2025 2030 2035 2040 2045 2050
Number of people with disabling hearing loss in thousands
Source: World health Organization

American adults show signs of hearing loss
Source: World health Organization

6
Indians show signs of hearing loss
Source: World health Organization (2018)

Environmental Studies

Environmental Studies 8

30 db
50 db
60 db
70 db
80 db
85 db
90 db
105 db
115 db
130 db
150 db

70 db
80 db
85 db
90 db
105 db
115 db
130 db
150 db

db meter

Boiler Room

More than 16000 hair cells

NOISE POLLUTION
Topics to be covered:
•What is noise pollution?
•Sources of Noise pollution
•Effects of Noise pollution
•Cause of Noise pollution
•Control of Noise pollution

SOUND
A vibration that propagates as a mechanical wave
of pressure and displacement, through some
medium is called sound.

NOISE
•Noise is basically any unwanted and unpleasant
sound. (EPA)
•It is measured in dB units.

CHARACTERISTICS OF
NOISE
21

KINDS OF NOISE
Continuous Impulsive Intermittent

KINDS OF NOISE
we learn to live without noticing this one
Constant
Eg. Boiler in powerhouse
Continuous
Impulsive Intermittent

KINDS OF NOISE
we will definitely notice this one
Sudden noise
Eg. Explosion or construction
equipment

KINDS OF NOISE
we might or might not notice this one
Increase or decrease rapidly
Eg. Train passing by, factory equipments

NOISE POLLUTION
Kind of pollution in which distracting,
irritating and damaging sound are freely
audible.

Sources of Noise Pollution
•Household sources
•Social Events
•Commercial and Industrial Activities
•Transportation

Household sources

Social Events
Religious function

Commercial and manufacturing process

Sources of Noise pollution
• Automotive and aircraft noise
• Motorcycles
• Scooters
• Noise from rail roads
Transportation
Biggest source of noise pollution

The Mighty Decibel
• It is a unit used to measure the
intensity of a sound.
• On the decibel scale, the smallest
audible sound (near total silence)
is 0 dB
• A sound 10 times more powerful is
10 dB
• A sound 100 times more powerful
than near total silence is 20 dB
• A sound 1000 times more
powerful than near total silence is
30 dB

Near total silence 0 dB
A whisper 15 dB
Normal conversation 60 dB
A car horn 110 dB
A gunshot or fire cracker 140 dB
Some common sound and their decibel rating

AMBIENT NOISE STANDARDS
Area Code Area Limit in dB(A)
Le q
Daytime Nighttime
A Industrial area 75 70
B Commercial area 65 55
C Residential area 55 45
D Silence zone 50 40
Source: CPCB, 1986
A person can complaint to the authority if the noise level
exceeds the ambient noise standards by 10 dB or more given
in the corresponding columns against any area.

Noise level of some point sources
Sources Intensity(dB)
Breathing 10
Trickling clock 20-30
Normal conversation 35-60
Office noise 60 - 80
Traffic 50-90
Motor cycle 105
Jet fly 110 - 120
Source: Centre for hearing and communication

Level: is the ratio of given sound quantity to the
standard sound quantity
Reference sound
20 μPa It will be feeble sound that can be
sensed by human ear
Range: 20 μPa – 200 Pa

sound
ref sound
Q
L
Q
 =
𝑃𝑜𝑤𝑒𝑟𝑠𝑜𝑢𝑛𝑑
𝑃𝑜𝑤𝑒𝑟𝑟𝑒𝑓 𝑠𝑜𝑢𝑛𝑑
2
2
log sound
ref sound
P
L
P
 
  
 
 
Unit: Bells
2log sound
ref sound
P
L
P
 
  
 
 
Unit: Bells
0
20log sound
P
L
P
 
  
 
Unit: dB
P0 = 20 μPa
P = Pressure
=
𝑃2 (𝑠𝑜𝑢𝑛𝑑)
𝑃2 (𝑟𝑒𝑓 𝑠𝑜𝑢𝑛𝑑)

Eg.: If a sound have a pressure of 20 Pa then its level will be
_____ dB?
6
20
20log
20 10
L 
 
  

 
L dB


Variation of sound pressure with distance
 
1
Sound Pressure
Distance from source

Eg.: If a level sensed at 30 m distance from a source is 50 dB then
level of same sound sensed at 60 m distance will be ______?
30
0
50 20log
P
L dB
P
 
   
 
1
P
r
 30
60
2
P
P 
60
60
0
20log
P
L
P
 
  
 
30
60
0
20log
2
P
L
P
 
  
 
30
60
0
1
20log 20log
2
P
L
P
   
 
   
 
 
60 44
L dB


Varying Sound
Leq Concept
50
70
60
80
55
10 15 20 10 5
Level
Time
60 mins
 
/10
10log 10 i
L
eq i
L t
 

Li = Level of ith sound
ti = Time fraction for ith sound
50/10 70/10 60/10 80/10 55/10
10 15 20 10 5
10log 10 10 10 10 10
60 60 60 60 60
eq
L
 
         
 
 

Leq = _____ dB

Eg.: If two sound sources are producing sound of 50 dB
each then equivalent level will be ____ ?
53
eq
L dB

 
50/10 50/10
10log 10 1 10 1
eq
L    

Note: When Sound intensity is doubles this equates to a rise of
3 dB, using a logarithmic scale.
In other words, every increase of 3 dB represents a doubling of
sound intensity.

Why worry about noise?
• It is a hidden health hazard that impacts our physical,
psychological and intellectual well being.

Physical Effects
Examples:
• hearing loss
• Hypertension
• Headaches
• Insomnia
• Fatigue
• heart disease
• birth defects

Psychological Effects
Examples:
• Depression
• Anger
• Aggression
• Anxiety
• increased violence
• alcohol and drug use
• Fatigue
• decreased social skills
• personality disorders
Impaired task performance

Communicative Effects
Examples:
• decreased learning capacity
• decreased academic
performance
• decreased cognitive ability

Auditory Effects
• Acoustic Trauma: Sudden hearing damage
• Tinnitus: Ringing in the Ears
• TTS: Temporary threshold shift
• PTS: Permanent threshold shift
• Interference with Communication

Non-Auditory Effects
• Annoyance
• Sleep Disturbance
• Attention
• Stress
• Cardiovascular problems

Damage risk criteria for hearing
loss(OSHA regulations)
Source: Gayle and Dianna (1997)

Effects on Animals

Effects on Animals
• Affect Nervous System
• Dangerous and Attacking
• Noise affects the acoustic communications in birds while producing sound to
attract a mate
• Noise pollution has caused the death of certain species of whales that beached
themselves after being exposed to the loud sound of military sonar.
• Increase the heart rate, respiratory difficulty and stress.
• Marine Ecosystem

Human made noise must be considered as
a "global pollutant" as it threatens the
survival of more than 100 different animal
species

Noise Control Strategy
The techniques employed for noise
control can be broadly classified as
• Control at source
• Control at receiver’s end.

Control at receiver’s end
For people working in noisy areas ear protection aids
like ear plugs,noise helmets, head phones etc should
be provided it reduces occupational exposures

Noise Control at Source
Design new machines to replace noisy ones. Proper
lubrication and better maintenance of machines.
Installing noisy machine with sound absorbing
materials. Using silencer to control noise from
automobiles etc.
Covering noise producing machine.
Vibration Damping

Control in the transmission path
Zoning
Increased distance between source and receiver by
zoning of noisy industrial areas like bus stand and
railway stations away from the silence zones near
residential areas, educational institutions and hospitals.

Planting vegetation to absorb and screen out noise
pollution – Trees can act as a noise barrier

• Through law
a) Silence Zones must be created near Schools,
hospitals
b) Minimum use of loudspeakers at public places
should be banned/restricted by laws
c)Restriction on unnecessary use of horns and vehicles
1981 ACT: included as an environmental
pollutant

Sound Proofing Materials
If Noise control is desired in
medium 2:
• Material should reflect
more, dissipated more,
transmit less.
• Barriers and enclosures
comes under this category.

Noise Enclosure

Noise Barriers

Sound Proofing Materials
If Noise control is desired in
medium 1 along with medium
2:
• Material should reflect less,
transmit less, dissipated
more
• Absorbers comes under this
category.

• Sound absorbing materials are the materials that is designed
specifically to absorb most of the sound energy incident on them and
reflect back very little sound energy.
Foam Baffles Fabric Panels
Radio Stations
Recording Studios
Auditoriums
Conference Rooms
Theaters
Schools
Etc…

Noise Pollution: A Modern Plague
• Throughout recorded history, mankind has been plagued by a variety of both natural
and manmade ills. In the 21st Century we are experiencing the man-made plague of
environmental noise from which there is virtually no escape, no matter where we are –
in our homes and yards, on our streets, in our cars, at theaters, restaurants, parks,
arenas, and in other public places. Despite attempts to regulate it, noise pollution has
become an unfortunate fact of life worldwide.
• There is growing evidence that noise pollution is not merely an annoyance; like other
forms of pollution, it has wide-ranging adverse health, social, and economic effects.

Thanks!!

DOC-20230214-WA0019..pptx

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