Sound (Noise) Pollution

Noise Pollution
Lectured By:
Dr. Rajendra Singh Thakur

Content
 The Nature Of Sound
 Measurement of sound,
 Sources,
 Effects and
 Control of noise pollution
Dr. Rajendra Singh Thakur 2

The Nature Of Sound
Sound is a physical phenomenon that stimulates the
sense of hearing.
Sound, a manifestation of vibration, travels in wave
patterns through solids, liquids and gases.
Sound waves of equal amplitude with increasing
frequency from top to bottom.

Sound propagation

Amplitude and wavelength
(period)

Sound & Noise
Sound is a form of energy which is emitted by a vibrating
body and on reaching in the ear causes the sensation of hearing
through nerves
The frequency limits of audibility are from 20 HZ to 20,000
HZ, Sounds of frequencies less than 20 HZ are called
Infrasonics and greater than 20,000 HZ are called
Ultrasonics.

Elements of Noise
Source Path Receiver
Path Receiver
Source
Barrier

How sound is heard

What is Noise Pollution?
The terms “noise” may be define as an unwanted sound at a wrong
time and a wrong place… although noise is undesirable.
Noise Pollution
Meaningful
Attention
Expecting a
consequent
Meaningless
Irresponsible
or
Disturbing and
annoying
Persons
Wanted
Loud less
Music
Soft, Rhythmic
or Short time
Unwanted
Load,
Random or
Prolonged

What is Noise Pollution?
It is an underrated environmental problem because of the fact that we
can’t see, smell, or taste it.
Unwanted sound that penetrates the environment any noise irritating to
one's ear which comes from an external source.
Sound that is unwanted or disrupts one’s quality of life is called as
“noise”. When there is lot of noise in the environment, it is termed as
noise pollution.
In relatives terms one’s enjoyment may be pollution to other. Sound
which pleases the listeners is music and which causes pain and
annoyance is noise.
Noise affect us in hearing, ability to communicate and behavior.
Sound becomes undesirable when it disturbs the normal activities such
as working, sleeping, and during conversations.

SOUND
• Pleasant to hear
• Constant pitch
• Regular periodic motion
• Produces meaningful
communication
• Unit is Hertz (Hz)
Hz= cycle/sec.
NOISE
• Unpleasant to hear
• Constantly varying pitch
• No regular periodic motion
• Produces no meaningful
communication
• Unit is decibel (dB)
dB=10 log(intensity
measured/reference
intensity)

Basic Terminology
• Sound: Physical properties among which frequency and intensity
are the most relevant.
• Pitch: Human precipitation of a sound frequency (some extant)
• Loudness: Human precipitation of a sound intensity (some extant)
• Frequency: Frequency is the no of cycles repeated in unit time
duration. Its unit is cycle/sec or Hz(1Hz=1Cycle/sec)
• Intensity: Amount of sound energy received / sec is known as
intensity of sound. Its Unit is decibel(dB).

• Decibel: Decibel is define as the logarithm to the base 10 to
ratio of two intensities
Lt =10 log(I/I0)dB
Where,
 I=Measured Intensity
 I0=Reference Intensity
 Lt=Level of noise in dB

Ambient Noise Standards
Area code Category of Area Limits in dB
Day Night
A Industrial area 75 70
B Commercial area 65 55
C Residential area 55 45
D Silence zone 50 40
Day time: 6 am to 9 pm
Night time: 9pm to 6 am

Sources of Noise
 The noise pollution has two sources, i.e. industrial and non-industrial
 he industrial source includes the noise from various
industries and big machines working at a very high speed
and high noise intensity
 Non- industrial source of noise includes the noise created by
transport/vehicular traffic and the neighborhood noise
generated by various noise pollution can also be divided in
the categories , namely, natural and manmade

Sources of Noise
 Road Traffic Noise
 Air Craft Noise
 Noise from railroads
 Construction Noise
 Noise in Industry
 Noise in building
 Noise from Consumer products

Measurement
The intensity of sound is measured in sound pressure levels
(SPL) and common unit of measurement is decibel, dB.
The zero on a decibel scale is at the threshold of hearing, the
lowest sound pressure that can be heard, on the scale.
On the scale 20 db is whisper, 40 db the noise in a quiet
office. 60 db is normal conversation, 80 db is the level at
which sound becomes physically painful.

Bels and decibels

Sound power and intensity

Sound pressure level

Noise Measurement

Noise Levels of Sources
Source Noise level
dB
Source Noise level,
dB
Air compressors 95-104 Quiet garden 30
Diesel generator 95 Ticking clock 30
Milling machine 112 Computer rooms 55-60
Power operated
portable saw
108 Type institute 60
Trucks 90-100 Printing press 80
Car horns 90-105 Sports car 80-95
Jet takeoff 120 Trains 96

Harmful Effects of Noise
Pollution
• Physiological effects
• Psychological effects
• Loss of hearing
• Annoyance
• Health effects
• Interference with communication
• Working efficiency

• Physiological effects – acute effect caused by noise depend upon the
pressure and frequency
• At 150dB immediate permanent hearing impairment
• At 120-150dB effect on-
 Respiratory systems
 Dizzying
 Disorientation
 Loss of physical control
 Stress
 Nausea
 Vomiting
• 70dB can measurable physiological effect, load sound secretion of many
hormones at the pituitary gland –Adrino cartico tropic hormone(ACTH),
turn simulated adrenal gland and that trigger-
 Enhancement of sensitivity
 Blood sugar
 Suppression of immune system
 Decreasing the efficiency of liver to detoxify blood

• Psychological effects –temporary effects such as
deterioration in concentration and mental disorientation
at high noise level, more load reduces-
• Working efficiency
• Interfere for communication
• Increase the frequency may accident
• Reduce mental capability
• Emotional stability
• Contribute to distress
• Emotional disturbance
• Aggressive any existing psychological condition
• Mental illness

Loss of hearing – due to exposure of noise, which
termed as artificial hearing loss.
1. Noise induced temporary threshold shifts (NITTS)-
due to exposure to loud noise like bursting of
crackers. Recovered in a short period of time.
2. Noise induced permanent threshold shifts (NIPTS)-
because of exposure to loud noise for long period
time.

Annoyance – subjective matter for sound/noise.
• Someone may like classical music, it may annoy
others.
• Annoyance is felt about 75 to 85 dB.
• Blood vessel get constricted, breathing rate affected.
Health effects –
Effects on physical health.
• Auditory effects- short time and long time effects.
Acoustic trauma due to high intensity impulsive noise
of about 150 dB or more.
• Non-auditory effects- exposure to loud noise increase
pulse rate and blood pressure change.
• Effects on mental health- lack of conc. at high noise
level and mental disturbance.

Interference with communication – background noise
affect the efficiency of offices, schools and other
places where communication is vital importance.
• External sound also interfere with conversation
and use of telephone as well as enjoyment of radio
and TV.
• Maximum acceptable limit of noise 55dB.

Working efficiency – decrease the working
efficiency drastically. Experiments indicate that
irregular bursts of noise are more disruptive than
steady noise.
• Sound levels of 90 dB may interfere with the
performance of a task.
Other effects
• Sleep interference
• Personal comfort interference
• Effects on wild life
• Increased industrial accidents.

Harmful Effects

EQUIPMENT USED FOR
NOISE MEASUREMENT

Noise Hazard Evaluations may be
performed by:
 Industrial Hygienists –
(primary responsibility)
 Audiologists
 Trained technicians

Table :
Equipment used in the measurement of noise levels

Sound level meter

Equipment Used
 Sound Level Meter
(SLM) – used to
screen for noise
hazards
– if the screening detects
noise levels above 84 dB, a
dosimeter is then used to
determine individual noise
dose

Equipment Used (cont.)
 Dosimeter – measures the average decibel
exposure level over an 8 hour day

Control of Noise Pollution
Noise Control at Source
 Reducing the noise levels from domestic sectors
 Maintenance of automobiles
 Control over vibrations
 Low voice speaking
 Prohibition on usage of loud speakers
 Selection of machinery
 Maintenance of machines

Control in the transmission path
 Installation of barriers
 Design of building
 Installation of panels or enclosures
 Green belt development
Using protection equipment
 Job rotation
 Exposure reduction
 Hearing protection

• Can never be eliminated completely, but it can be controlled.
• Noise pollution can be controlled by paying attention to one or all
of the three elements involved:
 Source:- can be modified by changing in design, treatment of
machine surface, noise source could be stopped or operation
limited to certain times.
 Transmission path:- sound insulating enclosure, construction of
noise barrier, absorbing materials along the path.
 Receiver :- altering the work schedule, by provision of ear
protection.

• Reducing the noise levels from domestic sectors: The domestic noise coming from radio, tape
recorders, television sets, mixers, washing machines, cooking operations can be minimised by
their selective and judicious operation. By usage of carpets or any absorbing material, the noise
generated from felling of items in house can be minimised.
• Maintenance of automobiles: Regular servicing and tuning of vehicles will reduce the noise
levels. Fixing of silencers to automobiles, two wheelers etc., will reduce the noise levels.
• Control over vibrations: The vibrations of materials may be controlled using proper
foundations, rubber padding etc. to reduce the noise levels caused by vibrations.
• Low voice speaking: Speaking at low voices enough for communication reduces the excess
noise levels.
• Prohibition on usage of loud speakers: By not permitting the usage of loudspeakers in the
habitant zones except for important meetings / functions. Now-a-days, the urban Administration of
the metro cities in India, is becoming stringent on usage of loudspeakers.
• Selection of machinery: Optimum selection of machinery tools or equipment reduces excess
noise levels. For example selection of chairs, or selection of certain machinery/equipment which
generate less noise (Sound) due to its superior technology etc. is also an important factor in noise
minimisation strategy.
• Maintenance of machines: Proper lubrication and maintenance of machines, vehicles etc. will
reduce noise levels. For example, it is a common experience that, many parts of a vehicle will
become loose while on a rugged path of journey. If these loose parts are not properly fitted, they
will generate noise and cause annoyance to the driver/passenger. Similarly is the case of machines.
Proper handling and regular maintenance is essential not only for noise control but also to improve
the life of machine. Dr. Rajendra Singh Thakur 42

Others steps to control noise pollution
• Noise pollution (Regulation and control) Rules, 2000.
• Vehicular noise can be controlled by proper maintaince.
• Industrial noise controlled under the factory act, 1948.
• Legal laws to control blaring loudspeakers, playing of music system at loud level.
• Use of better technology in design of systems like fan, AC, washing machines and
refrigerators.
• Proper town planning can help in avoiding noise pollution (construction from major
noise sources).
• Proper zoning and separation of buffers.
• Thick and high vegetation can absorb much noise.
• Aerodrome should be located away from the city.
• Aeroplanes should take off in direction readily away from the city.

Noise barrier: Highway in Melbourne, Australia

Legal Control
 Constitution of India
 Right to Life
 Right to Information
 Right to Religion and Noise
 Directive Principal of State Policy
 Fundamental Duties
 Cr.P.C. Section 133
 I.P.C. Public Nuisance 268-295
 Law of Torts Noise pollution is considered as civil wrong
 Factories Act Reduction of Noise and Oil of Machinery
 Motor Vehicle Act. Provision Relation to use of horn and
change of Engine
 Noise Pollution Control Rule 2000 under Environment
Protection Act 1996

Thank You

Sound (Noise) Pollution

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