Chapter 8 noise mitigation and measurement

UNIT KEJURUTERAAN ALAM SEKITARUNIT KEJURUTERAAN ALAM SEKITAR
JABATAN KEJURUTERAAN AWAMJABATAN KEJURUTERAAN AWAM
POLITEKNIK SULTAN IDRIS SHAH
CHAPTER 8CHAPTER 8
NOISE MITIGATION ANDNOISE MITIGATION AND
MEASUREMENTMEASUREMENT
2

Upon completion of this course,
student should be able to :
 Explain the noise pollution mitigation for reduce noise pollution,
control noise pollution on sources and protect noise pollution
from receiver.
 Apply noise mitigation to overcome noise pollution
 Explain noise pollution measurement
 Apply noise pollution equipment (Sound Level Meter and
Dosimeter)
 List the procedure of calibration for noise pollution equipment
 Describe measurement procedures
 Determine physical conditions for measurement
 Determine the regulations on noise pollution control (motor
vehicles)

Noise pollution mitigation for reduce noise
pollution, control noise pollution on sources and
protect noise pollution from receiver

Reduce noise pollution
 Noise pollution can negatively impact the body in
significant ways, including elevated blood
pressure, impaired cognitive functioning, and
other effects of chronic stress.
 Limit The Noise
-Double-Paned Windows and Weather
Stripping

Basic control of the noise path
 Noise can be reduced if the passage was blocked
by obstacles and spread like a wall, land
reclamation and so on. This is because the sound
has been absorbed or filtered and dispersed by
the blockage.
 For example, the construction of the wall can
reduce noise by 10-15 dBA. Principles of access
and dissemination controls on noise and suitable
for use in the City to reduce noise. However, the
factors of height, thickness and type of wall used
to determine the level of noise can be reduced.

Basic control of the listener
 Control principles to the listener means to prevent
noise from the sound received by the audience.
Through this principle, an action may be taken on
behalf of the noise.
 What can be done is to put the receiver noise is far
from the noise source or place obstacles that can
prevent a lot of noise until the receiver noise.
 Methods of site planning and good landscape design
is one method that is best done based on this
principle. These methods include the layout plan,
landscape approach and area activities. In addition,
the use of hearing protection devices are also effective
to reduce the noise problem.

Barriers through the provision of
physical resistance
 Barriers through the provision of physical resistance
 Physical resistance - usually done by setting up a brick or concrete wall and
land reclamation. Appropriate to prevent the traffic noise.
 Planting of trees and open spaces - trees with large leaves and thick and
heavy branches can be used as noise insulation.
 Non-residential buffer zone - this method means putting activity is less
sensitive to noise as a buffer zone between areas sensitive to noise.
Example, shops, offices or light industry which is placed between a noisy
road and residential areas.
 Traffic management
 Separate the motor from the receiver by means such as the construction of
ring roads, provision of pedestrian walkways, limiting the vehicle through an
area with a limitation of time and prepare and set the minimum distance
between new residential traffic.
 Improve the flow of traffic to reduce congestion for example through the
provision of direct access and encourage use of public transport.
 Use of barrier and buffer zones.
 Isolate the vehicle from the recipient - separate the heavy vehicles to home
by providing the street itself.

Other methods of control
 The provision of pedestrian.
 Encourage the use of public transport.
 Layout of the house.

 Noise mitigation is a set of strategies to
reduce noise pollution.
 The main areas of noise mitigation or
abatement are: transportation noise
control, architectural design, and occupational
noise control.
 Roadway noise and aircraft noise are the most
pervasive sources of environmental noise
worldwide, and little change has been effected
in source control in these areas since the start
of the problem a possible exception being the
development of hybrid and electric vehicles.

Roadway
 The most fertile areas for roadway noise mitigation are
in urban planning decisions, roadway design, noise
barrier design, speed control, surface pavement
selection and truck restrictions.
 Speed control is effective since the lowest sound
emissions arise from vehicles moving smoothly at 30
to 60 kilometres per hour.
 Above that range, sound emissions double with each
five miles per hour of speed.
 At the lowest speeds, braking and (engine)
acceleration noise dominates. Selection of surface
pavement can make a difference of a factor of two in
sound levels, for the speed regime above 30
kilometres per hour.

 Quieter pavements are porous with a negative
surface texture and use medium to small
aggregates; the loudest pavements have a
transversely grooved surface, and/or a positive
surface texture and use larger aggregates.
 Surface friction and roadway safety are important
considerations as well for pavement decisions.
 A computer model is required to design the barrier
since terrain, micrometeorology and other locale
specific factors make the endeavor a very complex
undertaking.
 For example, a roadway in cut or strong prevailing

Aircraft
 Variations in aircraft types, flight patterns and local
meteorology can be analyzed along with benefits of
alternative building retrofit strategies such as roof
upgrading, window glazing improvement, fireplace
baffling, caulking construction seams and other
measures.
 The computer model allows cost effectiveness
evaluations of a host of alternative strategies.

Architectural Solution
 Firstly, airborne sound travels through walls or floor
and ceiling assemblies and can emanate from either
human activities in adjacent living spaces or from
mechanical noise within the building systems.
 The second type of interior sound is called Impact
Insulation Class (IIC) transmission.
 Designing special purpose rooms has more exotic
challenges, since these rooms may have requirements
for unusual features such
as concert performance, sound studio recording, lecture
halls.

Industrial
 The most common techniques for noise protection of
workers consist of shock mounting source equipment,
creation of acrylic glass or other solid barriers, and
provision of ear protection equipment.
 In certain cases the machinery itself can be re-designed
to operate in a manner less prone to produce grating,
grinding, frictional or other motions that induce sound
emissions.
 Other solutions may involve researching the quietest
models of office equipment, particularly printers and
photocopy machines.

EXPLAIN NOISE POLLUTION
MEASUREMENT
 In 1929 when the New York City noise survey was in
progress, Dr. Harvey Fletcher from the Bell Telephone
Laboratories explained in a radio talk “How Noise is
Measured and Why.” It continues to be helpful to illustrate
how a noise level of 90 decibels really sounds. (He used a
recording of applause at one of the receptions for Charles
Lindbergh.) He demonstrated a reduction of noise level of
10 decibels. (He did not say 10 dB.) He gave the elements
of “a piece of apparatus” that today we call a sound level‐
meter. He led to the easy conclusion that noise level is the
same as sound level, and that you measure it with a sound‐
level meter. There was no entanglement with logarithms;
simply “the decibel is a unit used to describe an amount of
noise.”

MEASUREMENT OF NOISE :
 The two most important measurement of noise
are, sound pressure and sound intensity, these
are measured in different units, and the scale
of the magnitude id different and very
 large in relation to noise.
 The unit of measurement of sound is decibel
(dB). It is ratio expressed as logarithmic scale

 relative to a reference sound pressure level
intensity measured (I )
Sound Intensity Level = 10 log 10 ___________________
reference intensity (Io)
 The reference intensity used is the “threshold of hearing”
which is a sound that can be first heard at sound pressure of
2X105
N / M2
of a sound intensity of 10 – 12 W / M2
.
 It is quite important to note that doubling of sound pressure
produces an increase of 6 dB
 and doubling of sound intensity produces an increase of 3
decibels, which is implicit in


Apply Noise Pollution Equipment
Sound Level Meter
 Sound level meters measure sound pressure level and are
commonly used in noise pollution studies for the quantification
of almost any noise, but especially for industrial,
environmental and aircraft noise.
 Sound level meters, also known as decibel meters and noise
dosimeters, are designed to measure the sound pressure of a
particular event.
 The sound level meter is the most common device used to
measure overall workplace noise by OSHA
 The sound level meter is generally placed in a central location
at a worksite to collect data, which is then analyzed to
determine average, lowest and highest noise levels during a
given work period.

 Data from sound level meters can be used to
determine proper hearing protection for
employees, design sound-proof or sound-
absorbing materials and position them
correctly to absorb sound, and to measure the
effect of sound on the general population,
which can also lead to reduction or absorption
measures.

How To Use Sound Level Meter
 Insert the battery into the sound-pressure level meter. Point
the microphone of the SPLM at the source and take the
measurements of the sound coming out of the speakers.
 A wind shield must be used if the air velocity is noticeable. It
should anyway be used all the time as a dust shield.
 Choose the response time, either fast or slow. Use slow to
measure average sound levels and fast to measure peak
levels.
 Mount the SPLM on a tripod by screwing it into the mount
threads on the bottom of the SPLM. Using a tripod will get
you the most accurate measurements.
 Calibrate your speakers by playing noise from your CDs
through your speakers.

 Be sure to stand off to the side of the SPLM while doing
this to ensure accuracy. Should be to get a reading as
close to 0 for each of the test tones. Fiddle with the
speaker placement to get this.
 The SLM must be calibrated before any measuring
session using a calibrator . If the temperature of the
instrument is significantly different from the ambient
temperature where it will be used, it should be first
warmed up before calibration and use. The calibration
must be checked at the end of the session. If the
instrument is not calibrated anymore, the data might
have to be discarded and the reasons for this calibration
change should be investigated as this might indicate an
important malfunctioning of the instrument.

Sound Level Meter Calibrator
 Calibrate the sound level meter before
conducting the stationary sound test. Use only
calibrators approved by the sound level meter
manufacturer :
o Turn on the calibrator and the sound level meter.
o Set range switch to correct range.
o Make sure calibrator is mounted to sound level
meter correctly.
o Adjust sound level meter to give correct reading.

Dosimeter
 Dosimeters measure an individual's or an object's exposure to
something in the environment - particularly to a hazard
inflicting cumulative impact over long periods of time, or over
a lifetime.
 The noise dosimeter is similar to sound level meters, but
instead of being positioned in one place, it is worn by
individual employees.
 Employees wear the dosimeter throughout their shifts, and the
dosimeter collects information about how, when and how
much noise they are exposed to during a typical work day.
 A dosimeter can calculate on the spot whether an employee is
nearing or over the OSHA limits for noise doses in a day or
over longer periods of time.
 Dosimeter data is used to determine hearing protection for
workers, schedule work in noisy areas in ways that are safer
for employees, and design sound absorption materials and
determine their placement

Use of Noise Dosimeter
 The noise dosimeter is clipped to the workers' clothes with the
microphone close to the ear, and can be worn without
hampering work. The dose provided by the instrument is of
course dependent on the duration during which the instrument
is used.
 Therefore, it should first be corrected for an 8 hour period and
then converted to the daily noise exposure (LEX,8) level
according to the relevant formula (ISO or OSHA).
 It is important to know that some old dosimeters do not take
into account levels below 89 dB(A) or 80 dB(A), as they
assume that lower levels do not lead to hearing impairment.
 The LEX,8 is then physically not correct. These dosimeters
are obsolete and should be discarded. On certain
instruments, a warning marker is activated if the peak level
ever exceeds 140 dB.

 It is worth noting that the characteristics of the dosimeters
have never been standardized.
 Furthermore, they are extremely limited as they provide one
single value at the end. It is strongly recommended to
abandon this type of instrument and use the personal sound
level meters described in the next section.

The Procedure of calibration for noise
pollution equipment
 Procedures sound level meter: -
 Height (m) of the SLM device is 1.2 meters above
ground level.
 Angle / degree position SLM device is 450.
 Distance from the root SLM noise is not more or less
than 2.5 meters.
 Spout in SLM is directed to cause noise.

 Position intake data for the study of noise levels in the environment.
 The steps for the measurement of environmental noise levels.
 Position distance for data taking in the surrounding noise level.
 Position distance for data taking the noise level in the building.
 The method of measurement is made more observations in the data
taken for 12 hours from 6 am to 6 pm. This is to see the difference
and comparison of noise that occurs on that day. The data taken
was done in 15 minutes in the next 12 hours.

Procedure Dosimeter :-
 Dosimetermeasurement procedures include:
 Advising the employee being monitored.
 A pre and post calibration and battery check.
 Microphone located on the individual’s shoulder and
fastened to not interfere with safety or performance of the
individual.
 The dosimeter shall be reset and started according to
manufacturer’s instructions.
 Dosimeter is set to standby at end of measurement period.

Measurement procedure
1. The microphone of the sound level meter should be located between a
height of 1.2 and 1.5 metres above the ground.
2. The measurement point should be no less than 3.5 metres from any
reflective surface, such as walls or buildings, other than the ground.
3. The surface on which a noise source (such as an air conditioner) is located
and the property boundary from where the noise is emitted are not
considered as reflective surfaces.
4. Where it is not possible to locate the measurement point 3.5 metres from
reflective structures, such as outdoor measurements near buildings, the
preferred measurement positions are one metre from the façade and 1.2 to
1.5 metres above each floor level of interest.

Eq uivale nt co ntinuo us so und pre ssure le ve l(Le q ) fo r no ise unde r
asse ssm e nt The sound level meter must be set on A-frequency
weighting and equivalent continuous sound pressure level (Leq)
integrating function. The level should be determined over a sufficiently
long time to be representative of the noise and will be measured for not
less than five minutes. The level must not include extraneous noise that
could affect the level of the noise being assessed — extraneous noise
must be excluded using the pause function of the meter.
Measurement settings

PHYSICAL CONDITION FOR
NOISE MEASUREMENT
PLACE OF MEASUREMENT
When the premises receiving the noise has a building or
buildings and surrounding land, the noise may be measured
either outside the buildings and within the boundary, or inside
the buildings, but can only be measured inside if
 the use of the building is directly associated with the type of
premises receiving the noise, for example, the building is an
office on a Commercial premises or a house on a noise-
sensitive premises; and
 the building is of a type of construction that is typical of
buildings so used. For example, one would not carry out a
sound measurement inside a tent, as its construction is not
typical of a house. Where the premises receiving the noise is
a caravan park or camping ground, measurements are to be
made outside of a caravan, camp or park home.

The measurement is taken inside where -
 there is no surrounding land; or
 the noise is coming through a common wall or
from another part of the building. Where a
measurement is made inside, the measured
level is adjusted by –
 +15 dB if the external doors and windows are
shut; or
 +10 dB if the external doors and windows are
open.

Sketch measurement position on the standard noise
measurement formand include:
 living areas identified as likely to be particularly
affected by the source noise;
 noise sensitive areas of premises;
 noise source direction and approximate distances;
 relevant barriers, mounds, vegetation and ground
cover in the separation zone;
 wind direction and speed;
 location of measurement position(s) indicating
distances from fixed reference points which are
unlikely to change; and
 identification of other land uses in the vicinity of the
affected premises.

 MICROPHONE POSITION
 The microphone must be at least 1.2 metres
above the ground and at least three metres
from any other sound reflecting surface, if
practicable, to avoid the effect of sound
reflections. Indoor measurements must be
made at least one metre from any open
external window or door.
 Measurement of airblast levels during blasting
must be done outdoors, with the microphone
1.2 to 1.6 metres above the ground and at
least five metres from any other reflecting
surface.

8. Determine The Regulations On Noise Pollution Control (Motor Vehicles)
 Environmental Quality Act, 1974 is an act associated with noise control even
though it has no specific regulations on this issue.
 The minister of science, technology and environment after consultation with
the environmental quality council, may make laws with respect to the noise
problem and determine the noise level to be acceptable.
 The Act also states that other than those already granted a license, no
person shall remove or cause or permit the occurrence of any sound louder
in volume, intensity or quantity of the conditions specified.
 Regulations under the Environmental Quality (Motor Vehicle Noise, 1987),
Minister of Science, Technology and Environment with the Department of
Road Transport plays an important role to control the maximum level of
noise by introducing a line of law.
 Environmental Quality (Motor Vehicle Noise) Regulations 1987, and shall
come into force on the 16th July 1987.
 These regulations are the maximum permissible noise levels for some
categories of vehicles and the maximum permissible noise level in the unit
dB (A) in accordance with the standards set.

 There are three standard set of standard A which is allocated to the maximum
permissible sound levels for motor vehicles with two or three wheels.
 While Standard B was for the maximum permissible sound levels for vehicles with
two or three wheels manufactured or assembled on or after the January 1, 1990.
 Further, the Standard C is allocated to the maximum permissible sound levels for
motor vehicles having more than three wheels.
SCHEDULE 1: MAXIMUM SOUND LEVEL PERMITTED FOR MOTOR
VEHICLES HAVING TWO WHEELS OR THREE WHEELS
STANDARD ACategory of vehicle Maximum sound level
Permitted (dB (A))
1. 125 cc. and below 95
2. Above 125 c.c 99

STANDARD B
SCHEDULE 2: MAXIMUM SOUND LEVEL PERMITTED FOR MOTOR
VEHICLES HAVING MORE THAN THREE WHEELS
Category of vehicle Maximum sound level
Permitted (dB (A))
1. Below 90 cc. 92
2. 90 c.c and above 95
Category of Vehicle Maximum sound level
permitted (dB (A))
1. Used for the carriage of
passengers and comprising not
more than 9 seats (including
the driver’s seat)
80

2. Used for the carriage of passengers and
comprising more than 9 seats. Permitted
maximum weight does not excedd 3.5 tonnes
81
3. Used for the carriage of goods. Permitted
maximum weight does not exceed 3.5 tonnes.
Engine is less than 200 h.p. DIN
81
maximum weight exceeds 3.5 tonnes. Engine is
less than 200 h.p.DIN
82
200 h.p DIN or more
85
maximum weight exceeds 3.5 tonnes.
200 h.p. DIN or more
86
88

Chapter 8 noise mitigation and measurement

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