written by chinedu J.E
ABSTRACT
Nigeria has experienced rapid development and
high influx of people with the implication of increased generation of noise.
Hence the need to evaluate the noise pollution level of the city. Measurement
of equivalent noise level was carried out in 35 locations around the city using
a CR811C integrated sound level meter. Result showed that the day time mean
equivalent noise level of the city ranged from 73.2 dBA to 83.6 dBA. Result
also showed that the night time mean equivalent noise level of the city is of good
quality as it ranged from 44 dBA to 56.8 dBA. The night time therefore serves
as a recovery time for those who are exposed to high noise value during the
day. Result further showed that the Central Business District of Abuja has the
highest day-night noise value of 82 dBA while the lowest day-night noise level
was obtained from Asokoro district with a value of 71 dBA. The average
day-night noise level of the City was obtained as 76.4 dBA. It is recommended
that those whose daily activities confine them to areas with unhealthy noise
level should make sure they have at least 10 hours of recovery time in areas
where the sound level is less than 65 dBA. The government is called upon to
improve the traffic situation in the city so as to prevent traffic built up in
areas with high noise values. On average,
population is exposed to daytime noise levels higher than 70 dB and nighttime
noise levels higher than 55 dB. These levels are relatively high for
Europe. This paper relates the results of a research project conducted
in 2014 on the impact of noise pollution and assessment’ comfort in two
mixed-use neighborhoods in the city, and on public measures to abate the
negative impacts of noise.
TABLE OF CONTENT
TITLE PAGE
CERTIFICATE PAGE
DEDICATION
ACKNOWLEDGEMENT
ABSTRACT
TABLE OF CONTENT
CHAPTER ONE
1.0
INTRODUCTION
1.1 Background
1.2
Origin of noise?
1.3 Noise
1.4 Types of noise
1.5 Noise barrier
1.6 Sources of noise
1.7 Control of Noise Pollution
1.8 NOISE
Impacts on urban
neighborhoods
1.9
Institutional context for noise pollution management
CHAPTER TWO
2.0
Literature review
CHAPTER THREE
3.0 Noise measurement instruments
3.1 Impacts of noise
3.2 Documentation of noise measurements
3.3 Application in Environmental Impact
Assessment (EIA) studies
3.4
Noise impact
assessment
CHAPTER
FOUR
4.0 SUMMARY
4.1 CONCLUSION
REFERENCES
CHAPTER ONE
1.0
INTRODUCTION
Noise is an environmental pollutant
that is increasing very rapidly as a result of improvement in commercial
industrial and social activities. It is referred to as an undesirable sound
which results from the activities of man. The study of sound covers all fields
of sound production, propagation and reception and is measured as sound
pressure. Sound pressure level depends on the power output of the noise source
and the environment. The ear has the remarkable ability to handle an enormous
range of sound. However, sound becomes a problem when it interferes with our
activities such as sleep, work, recreation and reading .The human hearing
mechanism responds to changes in sound pressure in a relative rather than
absolute manner. This is why a logarithmic scale called the decibel (dB) is
used to measure sound pressure level.
The weakest sound that the human ear
can detect is referred to as the threshold of hearing and it corresponds to
0dB. On the other hand, the level of sound pressure that will cause pain to the
ear is referred to as the threshold of pain and it corresponds to 120 dB . A
change of 3 dB in sound level is just enough to make such a change noticeable.
However, an increase of 10dB is perceived as doubling the loudness of the
sound. In the measurement of sound, two weighting network namely the A and C
network are employed. However, for environmental purposes, the measurement is
made using an A-weighted scale (dBA) because this scale measures sound level in
approximately the same way as the human ear Noise pollution has been recognized
as a major treat confronting the world today. The WHO reveals that noise is a
dangerous agent which affects human health and the environment [4, 5]. However,
People in Nigeria do not pay significant attention to the seriousness of noise
pollution and its dangerous
environmental consequences. This is however not the case with other countries
of the world where necessary actions have been put in place to control and
regulate this peril. The determination of noise level in some towns in Delta
State, Nigeria shows that most noise pollutions are caused by lack of public
awareness and the ignorance of the people. This is why a lot of people in
Nigeria are subjecting themselves to loud noises. Anomohanran and Osemeikhian also
identify automobiles, commercial motorcycles, recording houses and the use of
electricity generators as the factors responsible for most of the noise
experienced in Nigeria. In the same light, the study conducted
at Agbor, Nigeriashows that noise from
most points in the city are caused by big trucks
such as lories and luxurious buses and
also by commercial activities. However, Olayinka and Abdullahi in a study
conducted in Ilorin, Nigeria, observed that the population growth of the city
which increased over 50% between 1980 and 2006 was partly responsible for the
rise in noise pollution. They also asserted that road traffic is the
predominant and most generalized noise source in Nigeria. This is also the case
in other cities noise is recognized as a serious public health
concerns.
Noise
impact assessment is a process which identifies and evaluates the key noise
impacts of a development for the purposes of informing its design and the
planning decision process
1.1 BACKGROUND
The word "noise" is derived
from the Latin word "nausea
“meaning seasickness. Noise, defined as
unwanted or excessive sound, is an undesirable by product of our modern way of
life. We experience noise in a number of ways. On some occasions, we can be
both the cause and the victim of noise, such as when we are operating noisy
appliances or equipment. There are also instances when we experience noise
generated by others just as people experience second hand smoke. While in both
instances, noises are equally damaging. Secondhand noise is more troubling
because it has negative impacts on us but is put into the environment by
others, without our consent. The air into which second hand noise is emitted
and on which it travels is commons, for all people . It belongs to no one
person or group, but to everyone. People, businesses, and organizations,
therefore, do not have unlimited rights to broadcast noise as they please, as
if the effects of noise were limited only to their private property. On the
contrary, they have an obligation to use the commons in ways that are
compatible with or do not detract from other uses.
1.2 ORIGIN OF NOISE
Noise originated from sound
A
sound is created when the particles in a medium (usually air in our world) are
set moving and forced out of a state of rest. This happens, for example, when
we speak. Our vocal chords produce audible pressure variations (high and low
pressure) in the air. Sound travels in air at a speed of approximately 340
metres per second. It spreads like a wave and is a mechanical vibration.
Remember:
A
sound is created when the particles in a medium are set moving and forced out
of a state of rest
Our
vocal chords produce audible pressure variations (high and low pressure) in the
air
The
origin of noise pollution?
Noise can come from many places. Let us see a few good sources:
Household sources:
Gadgets like food mixer, grinder, vacuum cleaner, washing machine and dryer, cooler, air conditioners, can be very noisy and injurious to health. Others include loud speakers of sound systems and TVs, ipods and ear phones. Another example may be your neighbor’s dog barking all night everyday at every shadow it sees, disturbing everyone else in the apartment.
Social events:
Places of worship, discos and gigs, parties and other social events also create a lot of noise for the people living in that area. In many market areas, people sell with loud speakers, others shout out offers and try to get customers to buy their goods. It is important to note that whey these events are not often, they can be called 'Nuisance' rather than noise pollution.
Commercial and industrial activities:
Printing presses, manufacturing industries, construction sites, contribute to noise pollutions in large cities. In many industries, it is a requirement that people always wear earplugs to minimize their exposure to heavy noise. People who work with lawn mowers, tractors and noisy equipment are also required to wear noise-proof gadgets.
Transportation:
Think of aero planes flying over houses close to busy airports like Heathrow (London) or Ohare (Chicago), over ground and underground trains, vehicles on road—these are constantly making a lot of noise and people always struggle to cope with them.
Noise can come from many places. Let us see a few good sources:
Household sources:Gadgets like food mixer, grinder, vacuum cleaner, washing machine and dryer, cooler, air conditioners, can be very noisy and injurious to health. Others include loud speakers of sound systems and TVs, ipods and ear phones. Another example may be your neighbor’s dog barking all night everyday at every shadow it sees, disturbing everyone else in the apartment.
Social events:Places of worship, discos and gigs, parties and other social events also create a lot of noise for the people living in that area. In many market areas, people sell with loud speakers, others shout out offers and try to get customers to buy their goods. It is important to note that whey these events are not often, they can be called 'Nuisance' rather than noise pollution.
Commercial and industrial activities: Printing presses, manufacturing industries, construction sites, contribute to noise pollutions in large cities. In many industries, it is a requirement that people always wear earplugs to minimize their exposure to heavy noise. People who work with lawn mowers, tractors and noisy equipment are also required to wear noise-proof gadgets.
Transportation: Think of aero planes flying over houses close to busy airports like Heathrow (London) or Ohare (Chicago), over ground and underground trains, vehicles on road—these are constantly making a lot of noise and people always struggle to cope with them.
1.3 NOISE
In simple terms, noise is unwanted sound.
Sound is a form of energy which is emitted by a vibrating body and on reaching
the ear causes the sensation of hearing through nerves.
Sounds produced by all vibrating bodies
are not audible. The frequency limits of audibility are from 20 HZ to 20,000
HZ. A noise problem generally consists of three inter-related elements- the
source, the receiver and the transmission path. This transmission path is
usually the atmosphere through which the sound is propagated, but can include
the structural materials of any building containing the receiver.
Noise may be continuous or
intermittent. Noise may be of high frequency or of low frequency which is
undesired for a normal hearing. For example, the typical cry of a child produces
sound, which is mostly unfavorable to normal hearing. Since it is unwanted sound,
we call it noise.
The discrimination and differentiation
between sound and noise also depends upon the habit and interest of the
person/species receiving it, the ambient conditions and impact of the sound
generated during that particular duration of time. There could be instances
that, excellently rendered musical concert for example, may be felt as noise
and exceptional music as well during the course of the concert!
Sounds of frequencies less than 20 HZ
are called infrasonics and greater than 20,0000 HZ are called ultrasonics.
Since noise is also a sound, the terms noise and sound are synonymously used
and are followed in this module.
1.4 TYPES OF NOISE
Steady
Impulse/blast
Atmospheric noises
Extraterrestrial noises
Man-made noises or
industrial noises.
Thermal noise or white
noise or Johnson noise
Shot noise.
Transit time noise
Miscellaneous internal
noise.
Steady: Continuous noise of sudden or gradual
onset and long duration (more than 1 second). Examples: aircraft power plant
noise, propeller noise, and pressurization system noise. According to the
Occupational Safety and Health Administration (OSHA)[1], the maximum
permissible continuous exposure level to steady noise in a working environment
is 90 dB for 8 hours.
Impulse/blast: Noise pulses of sudden onset
and brief duration (less than 1 second) that usually exceed an intensity of 140
dB . Examples: firing a handgun, detonating a firecracker, backfiring of a
piston engine, high-volume squelching of radio equipment, and a sonic boom
caused by breaking the sound barrier. The eardrum may be ruptured by intense
levels (140dB) of impulse/blast noise. It is not a global problem because sound
energy is not accumulated and the area, which suffers from noise, is limited to
that around the noise source.
External
noise cannot be reduced except by changing the location of the receiver or the
entire system. Internal noise on the other hand can be easily evaluated
Mathematically and can be reduced to a great extent by proper design. As
already said, because of the fact that internal noise can be reduced to a great
extent, study of noise characteristics is a very important part of the
communication engineering.
Atmospheric
Noise
Atmospheric
noise or static is caused by lighting discharges in thunderstorms and other
natural electrical disturbances occurring in the atmosphere. These electrical
impulses are random in nature. Hence the energy is spread over the complete
frequency spectrum used for radio communication.
Atmospheric
noise accordingly consists of spurious radio signals with components spread
over a wide frequency range. These spurious radio waves constituting the noise
get propagated over the earth in the same fashion as the desired radio waves of
the same frequency. Accordingly at a given receiving point, the receiving
antenna picks up not only the signal but also the static from all the thunderstorms,
local or remote.
The
field strength of atmospheric noise varies approximately inversely with the
frequency. Thus large atmospheric noise is generated in low and medium
frequency (broadcast) bands while very little noise is generated in the VHF and
UHF bands. Further VHF and UHF components of noise are limited to the
line-of-sight (less than about 80 Km) propagation. For these two-reasons, the
atmospheric noise becomes less severe at Frequencies exceeding about 30 MHz.
Extraterrestrial Noise
There
are numerous types of extraterrestrial noise or space noises depending on their
sources. However, these may be put into following two subgroups.
Solar noise
Cosmic noise
Solar Noise
This is the electrical noise emanating
from the sun. Under quite conditions, there is a steady radiation of noise from
the sun. This results because sun is a large body at a very high temperature (exceeding 6000°C on the surface), and
radiates electrical energy in the form of noise over a very wide frequency
spectrum including the spectrum used for radio communication. The intensity
produced by the sun varies with time. In fact, the sun has a repeating 11-Year
noise cycle. During the peak of the cycle, the sun produces some amount of
noise that causes tremendous radio signal interference, making many frequencies
unusable for communications. During other years. the noise is at a minimum
level.
Cosmic noise
Distant
stars are also suns and have high temperatures. These stars, therefore, radiate
noise in the same way as our sun. The noise received from these distant stars
is thermal noise (or black body noise) and is distributing almost uniformly
over the entire sky. We also receive noise from the center of our own galaxy
(The Milky Way) from other distant galaxies and from other virtual point
sources such as quasars and pulsars.
Man-Made Noise (Industrial Noise)
By
man-made noise or industrial- noise is meant the electrical noise produced by
such sources as automobiles and aircraft ignition, electrical motors and switch
gears, leakage from high voltage lines, fluorescent lights, and numerous other
heavy electrical machines. Such noises are produced by the arc discharge taking
place during operation of these machines. Such man-made noise is most intensive
in industrial and densely populated areas. Man-made noise in such areas far
exceeds all other sources of noise in the frequency range extending from about
1 MHz to 600 MHz
Thermal Noise
Conductors
contain a large number of 'free"
electrons and "ions"
strongly bound by molecular forces. The ions vibrate randomly about
their normal (average) positions, however, this vibration being a function of
the temperature. Continuous collisions between the electrons and the vibrating
ions take place. Thus there is a continuous transfer of energy between the ions
and electrons. This is the source of resistance in a conductor. The movement of
free electrons constitutes a current which is purely random in nature and over
a long time averages zero. There is a random motion of the electrons which give
rise to noise voltage called thermal noise.
Thus noise generated in any resistance due
to random motion of electrons i5
called thermal noise or white or Johnson noise.
The
analysis of thermal noise is based on the Kinetic theory. It shows that the
temperature of particles is a way of expressing its internal kinetic energy.
Thus "Temperature" of a body can be said to be equivalent to
the statistical rms value of the velocity of motion of the particles in the
body. At -273°C (or zero degree Kelvin) the kinetic energy of the particles of
a body becomes zero .Thus we can relate the noise power generated by a resistor
to be proportional to its absolute temperature. Noise power is also
proportional to the bandwidth over which it is measured. From the above
discussion we can write down.
From
equation (2), we see that the square of the rms noise voltage is proportional
to the absolute temperature of le resistor, the value of the resistor, and the
bandwidth over which it is measured. En is quite independent of the Frequency.
Example
R.F.
amplifier is saving an input resistor of 8Kr and works in the frequency range
of 12 to 15.5 MHz Calculate the rms noise voltage at the input to this
amplifier at an ambient temperature of 17oC?
Solution:
Shot
Noise
The
most common type of noise is referred to as shot noise which is produced by the
random arrival of 'electrons or holes at the output element, at the plate in a
tube, or at the collector or drain in a transistor. Shot noise is also produced
by the random movement of electrons or holes across a PN junction. Even through
current flow is established by external bias voltages, there will still be some
random movement of electrons or holes due to discontinuities in the device. An
example of such a discontinuity is the contact between the copper lead and the
semiconductor materials. The interface between the two creates a discontinuity
that causes random movement of the current carriers.
Transit
Time Noise
Another
kind of noise that occurs in transistors is called transit time noise.
Transit
time is (he duration of time that it takes for a current carrier such as a hole
or current to move from the input to the output.
The
devices themselves are very tiny, so the distances involved are minimal. Yet
the time it takes for the current carriers to move even a short distance is
finite. At low frequencies this time is negligible. But when the frequency of
operation is high and the signal being processed is the magnitude as the
transit time, then problem can occur. The transit time shows up as a kind of
random noise within the device, and this is directly proportional
to the frequency of operation.
MISCELLANEOUS
INTERNAL NOISES Flicker Noise
Flicker
noise or modulation noise is the one appearing in transistors operating at low
audio frequencies. Flicker noise is proportional to the emitter current and
junction temperature. However, this noise is inversely proportional to the
frequency. Hence it may be neglected at frequencies above about 500 Hz and it,
Therefore, possess no serious problem.
Transistor
Thermal Noise
Within
the transistor, thermal noise is caused by the emitter, base and collector
internal resistances. Out of these three regions, the base region contributes
maximum thermal noise.
Partition
Noise
Partition
noise occurs whenever current has to divide between two or more paths, and
results from the random fluctuations in the division. It would be expected,
therefore, that a diode would be less noisy than a transistor (all other
factors being equal) If the third electrode draws current (i.e.., the base
current). It is for this reason that the inputs of microwave receivers are
often taken directly to diode mixers.
Signal
to Noise Ratio.
Noise
is usually expressed as a power because the received signal is also expressed
in terms of power. By Knowing the signal to noise powers the signal to noise
ratio can be computed. Rather than express the signal to noise ratio as simply
a number, you will usually see it expressed in terms of decibels.
1.5
NOISE BARRIERS
Noise barriers (such as trees or green
walls), ban of heavy and/or old vehicles within the urban area, building permit
requirements to soundproof new housing construction, and zoning regulations
that require wide building setbacks from traffic streets and do not allow noise
sources (night clubs, bakeries, wood workshops, gas stations) in neighborhoods
that are mostly residential.
Due to increasing resident complaints
on nighttime noise, some clubs in the owerri and other central locations have
partially soundproofed their spaces. However, soundproofing of new housing is
minimal. One construction firm has started using inexpensive soundproofing
materials, such as polysterol on the internal walls.
1.6 Sources of noise
Where does it generate from? The sources of noise may vary according
to daily activities. They sources may be domestic (movement of utensils,
cutting and peeling of fruits/vegetables etc.) natural (shores, birds/animal
shouts, wind movement, sea tide movement, water falls etc.), commercial (vendor
shouts, automobiles, aeroplanes, marriages, laboratory, machinery etc.)
industrial (generator sets, boilers, plant operations, trolley movement,
transport vehicles, pumps, motors etc.).
1.7 Control of Noise Pollution
Noise generation is associated with
most of our daily activities. A healthy human ear responds to a very wide range
of SPL from - the threshold of hearing at zero dB, uncomfortable at 100-120 dB
and painful at 130-140 dB(3). Due to the various adverse impacts of noise on
humans and environment (See LO-5), noise should be controlled. The technique or
the combination of techniques to be employed for noise control depend upon the
extent of the noise reduction required, nature of the equipment used and the
economy aspects of the available techniques.
The various steps involved in the noise
management strategy is illustrated at Fig 4.
Reduction in the noise exposure time or
isolation of species from the sources form part of the noise control techniques
besides providing personal ear protection, engineered control for noise
reduction at source and/or diversion in the trajectory of sound waves.
1.8
NOISE IMPACTS ON URBAN NEIGHBORHOODS
Resident surveys indicated that
perceived noise levels are very high in the Bllok (4.2 out of a maximum of
5). Also, residents reported a high
level of discomfort from noise (an average of 4.2 out of 5). Almost half of the
respondents reported thinking daily about noise disturbance. In fact, Bllok’s
residents were more preoccupied with noise levels than other major concerns
such as air pollution, car traffic, lack of parking spaces and green areas,
illegal construction, and the quality of road infrastructure in their
neighborhood.
Most residents said that noise levels
have been on the rise in the last 5 to 10 years, a perception confirmed by
public research. They pointed to car traffic as the main source of daytime
noise, and the loud music from bars and night clubs as the main source of
nighttime noise. The latter was considered more bothersome by the majority.
Weekend evenings and nights were reported to be the nosiest and most stressful
times.
Respondents in households that included
young children or older adults were well aware of the detrimental health
impacts of noise. They cited sleep disturbance, irritation, inability to
concentrate, high blood pressure, headaches, hearing problems, and stress as
observed effects of noise exposure on children and seniors.
The author conducted interviews with
staff members of the following public institutions:
Department of Environment
Police
Institute of Public Health
Ministry of Environment, Forestry, and
Water
National Environmental Agency
Prefecture of Tirana
Regional Environmental Agency
State Police
These institutions are connected to
each other according to the
In addition, the author interviewed
An employee of a night club in the
owerri
A real estate representative
An employee of a construction firm
The interviewed public officials
indicated that noise related complaints received by public institutions are
numerous. Owerri’ residents lead in terms of number of complaints; however,
other central areas of neekde are considerably affected by noise. Residents
most affected by noise are those who live near main traffic streets, bars and
clubs, schools (especially music schools), and areas with large construction
activity. It must be noted that, in the last two decades, Tirana has
experienced a construction boom, which turned the city into a permanent
building site. However, the construction wave has recently significantly
abated.
CHAPTER TWO
2.0
Literature review
The
levels of environmental noise vary for a substantial part of the world
population, especially in areas with a dense population and dense
transportation networks. It is estimated that in the European Union during day
time approximately 77 million people (22% of the total EU population in 1994)
are exposed to transportation noise levels exceeding 65 dB, a level that many
countries consider to be unacceptable. Noise,
like other forms of pollution, has wide ranging adverse health, social, and
economic effects.
GABRIEL(2005) Took surveys
in two mixed-use neighborhoods: Bllok and Selvia (50 surveys in each), selected
due to their contrasting settings. He
observed that Bllok is a vibrant city center
in which most high-end shopping and entertainment activities are
concentrated, in addition to housing constructions which activated noise level
in that area. He further concluded his research by plentiful cafés,
restaurants, and music venues, which generate pedestrian and car traffic until
late at night, have been known to present a disturbance for residents and a
campaign was drawn.
Olayinka (2006) made
research on the level of noise pollution conducted at illorin metropolisNigeria
where he observed that noise generated by nightclubs, several bars and traffic
was unbearable, especially at night. through the report the daily press coverage of noise impact issues and
complaints, prompted the City to issue high fines to several bars and clubs in
the area, which played loud music at night, enforcement was not consistent, and
after a brief period of tranquility, club owners ignored the law. He further
concluded that the level of noise in that area was alarming and he adviced that
it should be controlled.
Parsons
(1998) also made research to make a
noise modelling study on assessment aims to model existing noise sources and to
predict boundary noise levels before and after the proposed extension to verify
compliance with the limits, and to provide the operator with a noise contour
map of the site and adjoining land area, this was his observation.
Ayman
N. Al-Dakhlallaha*, (2005) they investigated on how to quantify the levels of
noise which are generated from road traffic and
these measured levels were compared against appropriate standards for
noise of this type. They Measured level of traffic noise using a noise level
meter type 4426.
They
further located measure site and chose them so as to provide as far as possible
a comprehensive coverage over the urban area. They concluded that the study
established that residential areas adjacent to the sites where traffic noise
was measured are subjected to noise levels of up to 78 dB(A).
In the framework of the
project interviews were conducted with nine representatives of public
institutions, which are involved in environmental protection issues, regarding
their efforts in noise abatement and prevention. Interviews were also conducted
with (1) a night club employee in the Bllok on club owners’ responses to
resident complaints, (2) a real estate agency on the impact of noise on
condominium prices, and (3) a construction firm on the use of noise insulation
in new construction and the noise level is increasing rapidly.
Deepak
Prasher (2007). He investigated noise levels using an investigator system was
used to record noise levels in streets around the towns and city centres. Some
surprising results in the survey were identified. Some small towns showed
higher levels of noise than expected such as Darlington, Doncaster and
Gillingham appearing in the top 10 noisy places. The Tyne Bridge in
Newcastle–upon-Tyne was the number one noise spot exceeding the first action
level of the noise at work regulations with levels exceeding 80dB LAeq. Torquay
was the quietest of the 41 places surveyed with a level of just over 60dB and john B (2007). Also
observed noise level in London were by a
london Road Traffic Noise Map was created, The noise calculations covered an
area of over 1,600 km2, the map contains about 16,575,000 calculation points.
The method used in this report is the Calculation of Road Traffic Noise (CRTN).
The project achieved its goal of producing a strategic road traffic noise map
for the Greater London area, The level of noise recorded in this study varies
between acceptable and unacceptable noise.
Ozer(2008)
Made a research on noise
levels in the ‘small Market Tunnel’ he Scored a lot of goals in his study when
he measured the noise level in the tunnel, he established a map of different
activities inside the tunnel (distribution of people and their location). He
indicated the subjected levels inside the tunnels by making a comparison between
the two established maps. Finally he compared his results with the
international and local standards. The readings were recorded during the
24,25,26 of Ramadan at an average of 1:30 hour for each day and the noise
founded there is higher than the acceptable level.
Suhela
Murtathay,Bezen Bena (2009)investigated the evaluation of noise pollution in
isfahanz urban area and the sound levels was sampled and taken from most crowded areas. This research is based on the results of
outdoor sound level measurements carried out in a total of 18 different urban
locations in Isfahan city. The indices include values such as main percentiles
(L1, L10, L50, L90), SEL, Leq and NPL. Results: The results
showed that Max Leq was 74.4 dB(A). The level of SEL varied from 96.4 to 107.4
dB(A). The level of SEL was over 104 dB(A) at some of the stations. It was also
found that level of TNI varied from 60.6 to Max of 77.2 dB(A) and this research
was used for evaluation of noise level.
CHAPTER
THREE
3.0 Noise measurement instruments
Noise measurement is an important
diagnostic tool in noise control technology. The objective of noise measurement
is to make accurate measurement which give us a purposeful act of comparing
noises under different conditions for assessment of adverse impacts of noise
and adopting suitable control techniques for noise reduction.
A sound level meter consists basically
of a microphone and an electronic circuit including an attenuator, amplifier,
weighting networks or filters and a display unit. The microphone converts the
sound signal to an equivalent electrical signal. The signal is passed through a
weighting network which provides a conversion and gives the sound pressure
level in dB.
The instructions laid down by the noise
level meter manufacturers shall be followed while using the instruments.
3.1
Impacts of noise
Why bother about noise? Often neglected, noise induces a severe
impact on humans and on living organisms. Some of the adverse effects are
summarised below.
· Annoyance: It creates
annoyance to the receptors due to sound level fluctuations.
The aperiodic sound due to its
irregular occurrences causes displeasure to hearing
and causes annoyance.
· Physiological effects: The
physiological features like breathing amplitude, blood
pressure, heart-beat rate, pulse rate,
blood cholesterol are effected.
· Loss of hearing: Long exposure
to high sound levels cause loss of hearing. This is mostly unnoticed, but has
an adverse impact on hearing function.
· Human performance: The working
performance of workers/human will be affected as they'll be losing their
concentration.
· Nervous system: It causes
pain, ringing in the ears, feeling of tiredness, thereby effecting the
functioning of human system.
· Sleeplessness: It affects the
sleeping there by inducing the people to become restless and loose
concentration and presence of mind during their activities
· Damage to material : The
buildings and materials may get damaged by exposure to infrasonic / ultrasonic
waves and even get collapsed.
3.2 Documentation of noise measurements
where noise survey is the first step of
noise management strategies. By now, the reader might be conversant with the
terminology, impacts, significance and control technology of noise pollution.
Hence, it is felt to place this section just before the end of the module to
avoid any confusion for the reader.
Noise surveys will be conducted in an
area (or zone) to find out the ambient noise levels or noise levels at the work
environment. The field data will be analyzed and documented for decision
making. The parameters to calculate however, vary with the objective. But in most
cases, Leq, Ldn, NC are the likely deciding parameters
For a systematic presentation, the
noise survey reports for a typical industrial noise level survey should contain
the following information (3)
· Reference to individual standard(s)
· Description of the machine and its
conditions of installation and operation
· Description of the test environment
with respect to its ability to reflect, dissipate or absorb noise and location
of the machine.
· Number of workers exposed and
duration of exposure
· Description of the measuring
apparatus used and method of calibration
· Time constant and weighting network
used
· Position of measuring points.
· Results of SPL instruments either A
-scale or octave band analysis
· Background noise levels and sound
pressure values corrected for background noise, if any.
The same principles can be applied for
documentation of community (ambient) noise levels and is left as an exercise to
the reader.
3.3 Application in Environmental Impact
Assessment (EIA) studies
The EIA study will be carried
out to evaluate and assess the impacts of any proposed (or existing) activity
on the environment. Noise is one of the environmental attributes, on which the
likely impacts due to the proposed (or existing) activity need to studied.
The likely steps to be carried out
while conducting noise level studies for an EIA project are summarized below.
The EIA will be carried out for either proposed or existing activities. The
sequential steps involved will be same for both the activities.
· The likely activities that generate
noise from the proposed activity are to be identified
· The typical sound (noise) levels of
the noise generating sources are to be assessed
either from literature or from a
similar source
· The likely exposure time of a worker
at a noise generating source is to be assessed from the plant / utility records
· The workspace environment noise
levels are to be checked with OSHA standards
If the noise exposure levels are
higher, suitable noise control measures
like personal protective equipment,
installation of barriers, enclosures etc., need to be suggested
· The EIA will usually be carried out
in an impact circle of radius 3 Km to 25 Km or even more depending on the
objective and the likely activities of the proposed project. The representative
baseline (or back ground) status of the ambient noise levels need to be collected
by monitoring at various stations in the study zone
· The ambient noise levels are to be
analysed for the prescribed parameters like, Leq, Ldn etc., and compared with
the ambient noise level standards (Table 1.7) for the study region. If these
values are higher than the prescribed limits, the likely causes for the high
values need to be assessed
· The likely impact of the noise levels
from the proposed activity on the local environment keeping in view the
baseline status of noise levels need to be predicted
· If the predicted impact is adverse,
suitable measures for attenuating the noise levels like, green belt
development, in-plant control measures etc., need to be suggested.
· The objective of the EIA study is to
make ensure that, the local environment, say
noise, will not get affected by
the noise levels emanated from the proposed activity. If the ambient noise
levels are high, then control measures be suggested to the project proponent to
ensure that, ambient noise levels will not increase due to the proposed activity.
3.4
Noise impact
assessment
The basic principle of any noise impact
assessment is to assess thechange in the acoustic environment that will be brought
about by the proposed development. It is important to appreciate that the
assessment of change can, and should be,
both qualitative and quantitative. This
Technical Advice Note aims to provide guidance on the assessment of
significance of noise impacts for variouscommon situations.Where a possible
quantitative change in noise level is to be assessed it is essential to ensure
that the most appropriate noise metrics, sampling periods and survey duration are
used. For example,it would be inappropriate to assess the level of change in
noise likely to occur following the introduction of a bus depot into a suburban
area by comparing the predicted LA10,18h with existing LA10,18h
noise levels; when the main noise level
changes are likely toarise due to large numbers of buses leaving, or returning, to the depot over shorter periods
of time outside the standard 0600 to
2400 time period A qualitative noise change may be described in various ways.
Typically, a useful qualitative guide when assessing noise impacts is whether
or not there are likely to be changes in behaviour as a consequence of the
noise generated by,associated with,or potentially impacting upon the proposed
development, for example, will changes
in the noise climate be such that it causes people to change their behaviour by
closing windows, raising their voice or not using their gardens as before
. The impacts can also be
positive.Before undertaking a noise impact assessment, it is important that the
person undertaking the assessment has a thorough understanding of the project
and its context. This would involve:
•understanding the nature of the
development;
•understanding the nature and character
of the prevailing noise environment;
•identifying all the potential new
noise sources that will arise from the proposal, during the construction,
operation and, where relevant, decommissioning phases;
•understanding the nature of the new
noise sources that will arise from the proposal, including such features as
tonal characteristics, intermittency, duration and timing (diurnally and
seasonally)
•Identifying potential noise sensitive
receptors
CHAPTER FOUR
4.0 SUMMARY
AND CONCLUSION
4.1 SUMMARY
Whether
knowingly or unknowingly, everyone of us contribute to noise pollution, because
most of our day-to-day activities generate some noise. Often neglected, noise
pollution adversely affects the human being leading to irritation, loss of
concentration, loss of hearing. identify the sources of noise pollution. Once
identified, the reason(s) for increased noise levels to be assessed. Now,
efforts shall be made to reduce the undesired noise levels from (unwanted)
noise generating sources. This leads to marginal reduction of noise levels. It
is still un-bearable scientific methods of noise control shall be employed.
The
statutory Regulations have prescribed the noise level exposure limits. The
public may complain to the statutory Board for violation of noise level limits
by any noise generator.
Suitable
action will be taken to attenuate the noise levels and controlling pollution.
It is advisable that suitable noise control measures be taken and reduce the
interference of Statutory Board. It is high time that everyone should do this
bit in curbing the noise pollution, which is otherwise becoming as effective as
slow poisoning.
4.2 Conclusion
In
the present study we can conclusively suggest that excessive noise persecutes everyone,
especially school students and teachers. Generally, educational centers often have
higher standards to control noise pollution but this study satisfactorily evaluated
that the noise pollution is a major cause of discomfort for the teachers and students.
Therefore, the present study safely concludes that the schools in different regions
of the problems in terms of noise pollution. Fortunately, all school authorities
were aware of this issue and with all facilities and special arrangements had tried
to resolve the debilitating. Problem nevertheless, the major factor responsible
for the noise pollution is out of their control.
Furthermore, corruption and favoritism are
rampant at all government levels.
Within this framework, a portion of
business owners, who belong to the upper income groups, resist restrictions on
activities that generate nighttime noise and are able to bend the law in their
favor. Any past interventions to protect residents from nighttime noise
pollution have been the result of the will of individual politicians, which
makes long term rule enforcement uncertain. No clear institutional system has been
set to permanently and consistently deal with noise management.
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