Chapter 5 introduction of noise and noise pollution

UNIT KEJURUTERAAN ALAM SEKITARUNIT KEJURUTERAAN ALAM SEKITAR
JABATAN KEJURUTERAAN AWAMJABATAN KEJURUTERAAN AWAM
POLITEKNIK SULTAN IDRIS SHAH
CHAPTER 5CHAPTER 5
INTRODUCTION OF NOISEINTRODUCTION OF NOISE
AND NOISE POLLUTIONAND NOISE POLLUTION
2

Upon completion of this course,
student should be able to :
 Explain the standard of noise pollution
 Apply World Health Organization (WHO) standard for
noise pollution
 Apply Department of Safety and Health (DOSH)
standard for noise pollution
 Understand the level of noise pollution
 Explain noise measurement unit (decibel) for noise
pollution
 Explain the types of noise pollution level
 Discuss noise pollution criteria
 Determine sound pressure level and frequency

DEFINATION
Noise Pollution or Sound Pollution, exposure of
people or animals to levels of sound that are
annoying, stressful, or damaging to the ears.
Although loud and frightening sounds are part of
nature, only in recent centuries has much of the
world become urban, industrial, and chronically
noisy.

SOUND
 Sound is a travelling wave which is an
oscillation of pressure transmitted through a
solid, liquid or gas are composed of
frequencies within the range of hearing and of
a level sufficiently strong to be heard or the
sensation stimulated in organs of hearing by
such vibrations. In our ears, it gives the
sensation of hearing. It is excited by vibrating
bodies and transmitted to our ears without
sensible motions of the air.

PROPERTY OF SOUND
 Sound is a disturbance of mechanical energy that propagates
through matter as a wave. Sound is characterized by the properties
of waves, which are frequency, wavelength, period, amplitude, and
speed.
 Humans perceive sound by the sense of hearing. By sound, we
commonly mean the vibrations that travel through air and are
audible to people. However, scientists and engineers use a wider
definition of sound that includes low and high frequency vibrations
in air that cannot be heard by humans, and vibrations that travel
through all forms of matter, gases, liquids, solids, and plasmas.

Standards of noise
pollution
Under the Malaysia Noise Regulation, the prefectural
governors have been empowered to designate residential
areas, schools of preserving living environment through
prevention of noise, while designation such areas
prefectural governors shall establish “ regulatory
standard” ( maximum permissible level of noise ) for
specified hours in respective zones.
Malaysia Environmental Quality Standards for Noise in
different areas and for various sources of noise, the
maintenance of which is desirable for preservation of the
living environment and conductive to the protection of
human health are shown in table

Area Code Category Of Area Environmental Noise
standards Leq Db ( A )
Day Time Night Time
A Industrial Area 75 70
B Commercial Area 65 55
C Residential Area 55 45
D Silence Zone 50 40
Environmental Noise standards

World Health Organization (WHO) standard for noise pollution

Maximum premissible sound level (Laeq) of new development (roads, rails, industrial)
in areas of existing high environmental noise climate

Limiting sound level (Laeq) From Road Traffic (For Proposed
New Roads And/Or Redevelopment Of Existing Roads)
Receiving land use
category
Day time
7 am– 10 pm
Night time
10 pm– 7 am
Noise sensative areas
low density residential
(medium density)
55 dBA 50 dBA
Suburban residential
(medium density)
60 dBA 55 dBA
Urban residential (high
density)
65 dBA 60 dBA
Commercial, business 70 dBA 60 dBA
Industrial 75 dBA 65 dBA

World Health Organization
Standard
Specific Environment Critical Health Effects LAeq
(dBA)
Time
Base
(Hours)
LAma
x
Fast
(dB)
Outdoors living area Serious annoyance, daytime and evening
Moderate annoyance, daytime and evening
55
50
16
16
-
-
Dwelling, indoors Speech intelligibility & moderate annoyance,
daytime & evening
35 16
Inside bedrooms Sleep disturbance, night-time 30 8 45
Outside bedrooms Sleep disturbance, window open (outdoor
values)
45 8 60
School class rooms
and pre-school,
Indoors
Speech intelligibility, disturbance of information
extraction, message communication.
35 During
class
-
Pre-school bedrooms,
indoor
Sleep disturbance 30 Sleepin
g time
45

Specific Environment Critical Health Effects LAeq
(dBA)
Time
Base
(Hours)
LAmax
Fast
(dB)
School ,
playground outdoor
Annoyance (external source) 55 During
play
-
Hospital, ward
rooms, indoor
Sleep disturbance, night-
time
Sleep disturbance, daytime
and evenings
30
30
8
16
40
-
Hospital,treatment
rooms, indoor
Interference with rest and
recovery
#1
Industrial,
commercial
shopping and
traffic areas,
indoors and
outdoors
Hearing impairment 70 24 110
Ceremonies,
festivals and
entertainment
events
Hearing impairment
(patrons:<5 times / year
100 4 110

Specific Environment Critical Health Effects
LAeq
(dBA)
Time
Base
(Hours)
LAmax
Fast
(dB)
Public adressess,
indoors and
outdoors
Hearing impairment 85 1 110
Music and other
sounds through
headphones/
earphones
Hearing impairment (free-field
value)
85 # 4 1 110
Impulse sounds
from toys, firework
and firearms
Hearing impairment (adults)
Hearing impairment (children)
-
-
-
-
140
#2
120
#2
Outdoors in
parkland and
conservations
areas
Disruption of transquillity #3
#1: as low as possible
#2: peak sound pressure (not LAF, max) measured 100mm from the ear
#3: existing quiet outdoor areas should be preserved and the ratio of intruding noise to natural
background sound should be kept low
#4: under headphones, adapted to free-field values

DOSH STANDARD FOR NOISE POLLUTION IN MALAYSIA
 Requires factory owner to conduct initial
exposure monitoring.
 Determine whether any of his employees are
exposed to noise greater than the action level
of 85 dB(A).
 Deviation from such ethical practice may result
in the factory owner taking wrong course of
action which may lead to unwanted
repercussion in the future.

DOSH STANDARD FOR NOISE POLLUTION IN
MALAYSIA
 To avoid such incident, competent persons
must be thorough in categorizing employees in
the various occupational groupings and
carefully selecting the high risk employee to
represent the exposure for the group.
 The instrument used must at all-time meet the
specified level of accuracy while during
monitoring adequate sampling time must be
taken to minimize the spasmodic variation in
noise level

DEPARTMENT OF SAFETY AND
HEALH STANDARD
 The Factories and Machinery (Noise Exposure)
Regulations 1989 requires factory owner to conduct
initial exposure monitoring.
 The purpose is to determine whether any of his
employees are exposed to noise greater than the
action level of 85 dB(A).
 Since this is a preliminary requirement to determine
further compliance with the employee exposure
monitoring requirements, competent person are
reminded to conduct the monitoring in all aspect with
high degree of professionalism.
 Deviation from such ethical practice may result in the
factory owner taking wrong course of action which may
lead to unwanted repercussion in the future.

The level of Noise Pollution
 This particular pollution is ever increasing with due
to the rise in the utilization of heavy duty
machineries of industrial facilities and vehicles,
synonymous to the increase in the standard of living
in most countries. We make sounds practically every
seconds of our day, but to the extend it has reached
an unfavorable high intensity which had cause many
disturbances and irritation to others emotionally that
has adverse effects on our daily activities.

Noise levels can be measured by
decibel method:
 Decibel - one tenth of a bell where one bell
represents a difference in level between two
intensities I1, I0 where one is ten times greater than
the other. Thus, the intensity level is the comparison
of one intensity to another and may be expressed:
 Intensity level = 10 log10 (I1/I0) (dB)
 For instance, the difference between intensities of
10-8
watts/m2
and 10-4
watts/m2
, an actual difference of
10,000 units, can be expressed as a difference of 4
bels or 40 decibels.

These are the few examples of threshold decibels of
noises made:
Rustling leaves 20 dB Food blender(3 feet) 90 dB
Quiet whisper (3
feet)
30 dB Subway (inside) 94 dB
Quiet home 40 dB Diesel truck (30 feet) 100 dB
Quiet street 50 dB Power mower (3 feet) 107 dB
Normal
conversation
60 dB Pneumatic riveter (3 feet) 115 dB
Inside car 70 dB Chainsaw (3 feet) 117 dB
Loud singing (3
feet)
75 dB Amplified Rock and Roll (6 feet) 120 dB
Automobile (25
feet)
80 dB Jet plane (100 feet) 130 dB

NOISE POLLUTION LEVEL (NPL)
 A noise measurement procedure recently
introduced in the U.S. in an attempt to relate
various earlier studies of community noise.
The measurement is conceived so that it
combines the ambient noise level with the
degree of steadiness in time of the noise
(assuming that the less steady it is, the more
distracting and annoying it becomes). The
basic definition is:
 LNP = Leq + ko

 where Leq is the equivalent energy level
measured in dBA or PNdB, k is a constant
which is provisionally given the value 2.56,
and kis the standard deviation of
instantaneous levels in time. This
measurement system applies to any
environment, unlike those specifically
concerned with aircraft and traffic. As a result,
however, it is incapable of determining
whether the noise being measured is wanted
or unwanted sound.

A measure of sound pressure level, given the symbol L.
Various subscripts define the nature of the measurement,
most commonly as follows
 L10: sound level exceeded 10% of the time
(peak level)
(average or mean level)
(ambient level) LA: sound level in decibels
measured on the A scale
 Leq : equivalent energy level
 LNP : noise pollution level

DECIBEL
 The decibel is widely known as a measure of sound pressure
level, but is also used for a wide variety of other
measurements in science and engineering:
 acoustics,
- to quantify sound levels relative to a 0 dB reference
which has been defined as a sound pressure level of .
0002 microbar, or 20micropascals
 Electronics
- to express power or amplitude ratios (gains),
 control theory
 other disciplines.

Method of Sound Measurement
• The test must be done at noisy area.
• Make sure that the area is on planning guidelines
noise limits and control
• Set up the microphone 1.2-1.5 metre from the ground.
• Keep away the microphone from any structure that
can reflected the sound at least 3.5 metre.
• The SLM reading is depends on:
 rain
 wind
 electronic object

HISTORY OF DECIBEL
 The decibel originates from methods used to
quantify reductions in audio levels in telephone
circuits.
 Named the "bel" in honor of the Bell System's
founder and telecommunications pioneer Alexander
Graham Bell.
 The bel is seldom used, as the decibel was the
proposed working unit.

NOISE POLLUTION LEVEL
 Noise pollution level (Lnp) is a method to make
noise assessment without knowing the source of
the noise.
 Produce according Leq, Leq is a equivalent
continuous sound pressure level .
 The formula of noise pollution level is :
Lnp = Leq + Ko
o : Standard deviation sound level that time.
K : Constant (value : 2.56)

 The formula can also be summarize as :
Lnp = Leq + ( L10 - L90 )
Where :
Leq shows the level of energy sound and (L10 – L90)
Shows the suitability of disturbance that causes
from fluctuation of noise level

NOISE POLLUTION
CRITERIA
Frequency, or its inverse, the period
Wavelength
Wave number
Amplitude
Sound pressure
Sound intensity
Speed of sound
Direction

Wavelength
 The distance between any point on a wave and
the equivalent point on the next phase.
Literally, the length of the wave.

Amplitude
 The strength or power of a wave signal. The
"height" of a wave when viewed as a graph.
 Higher amplitudes are interpreted as a higher
volume, hence the name "amplifier" for a
device which increases amplitude.

Frequency
 The number of times the wavelength occurs in one
second. Measured in kilohertz (Khz), or cycles per
second. The faster the sound source vibrates, the higher
the frequency.
 Higher frequencies are interpreted as a higher pitch. For
example, when you sing in a high-pitched voice you are
forcing your vocal chords to vibrate quickly.

Sound Pressure
 Sound pressure or acoustic pressure is the local
pressure deviation from the ambient (average, or
equilibrium) atmospheric pressure caused by a
sound wave. Sound pressure in air can be
measured using a microphone, and in water using
a hydrophone. The SI unit for sound pressure p is
the pascal (symbol: Pa).
 Sound pressure level (SPL) or sound level is a
logarithmic measure of the effective sound
pressure of a sound relative to a reference value.
It is measured in decibels (dB) above a standard

Sound Intensity
 In physics, intensity is a measure of the energy
flux, averaged over the period of the wave. The
word "intensity" here is not synonymous with
"strength", "amplitude", or "level", as it sometimes
is in colloquial speech. For example, "the intensity
of pressure" is meaningless, since the parameters
of those variables do not match.
 To find the intensity, take the energy density (that
is, the energy per unit volume) and multiply it by
the velocity at which the energy is moving. The
resulting vector has the units of power divided by
area (i.e. W/m²). It is possible to define the
intensity of the water coming from a garden
sprinkler, but intensity is used most frequently with
waves (i.e. sound or light).

The Speed of Sound
 A sound wave is a pressure disturbance that
travels through a medium by means of particle-
to-particle interaction. As one particle becomes
disturbed, it exerts a force on the next adjacent
particle, thus disturbing that particle from rest
and transporting the energy through the
medium. Like any wave, the speed of a sound
wave refers to how fast the disturbance is

Sound Pressure Level and
Frequency
The frequency (f), which is the number
of pressure variation cycles in the
medium per unit time, or simply, the
number of cycles per second, and is
expressed in Hertz (Hz). Noise is
usually composed of many frequencies
combined together. The relation
between wavelength and frequency

Frequency
 Defined as the difference in sound pressure entering and will
be detected by the ear. Pressure level variations per second
is called frequency. Frequency of vibrations per second the
number one center or the number of complete revolutions
per second and in depthwith the unit hertz (Hz). Sound
produced are different in frequency. At low frequency the air
particle vibrate slowly produces a ‘bass’. While at high
frequency of air particle vibrate rapidly which produces a
‘soparno’ ( barben 1976 )

Sound pressure level
 Source of energy flow in a pressure of sound
waves is generally more suitable for use in
measuring the noise level (SPL) compared with the
volume. sound pressure generated in the space
depending on the content of the acoustic
space. sound produced in a confined space will
have many differences compared to that produced
in the open air. sound pressure does not directly
depend on the source but also on the
environment. distance of the sound pressure in

 since the relationship between the volume is proportional to
the field that links the sound pressure sound pressure
level (SPL) can be described in the following logarithmic

SPL = 20 log10 (p/ Pref ) dB
 In which

P : sound pressure produced in the unit decibel (dB)
 Pref : racial reference at the threshold
of human hearing out of 2 x 10-5
N/m2

 measurement of sound is dependent on the above
formula for the rate of different sound pressure
level at different conditions in terms of sound
output and environmental impact.

Level - weighted sound pressure level A, B,
C and D
 Type - type of weights are:
 Units of dB (A): the extent of 55 dB sound
pressure
 Units of dB (B): the
sound pressure between 55 and 85 dB
 Units of dB (c): high sound pressure

Chapter 5 introduction of noise and noise pollution

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Chapter 5 introduction of noise and noise pollution