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UNIVERSITI PUTRA MALAYSIA
DEVELOPMENT OF NOISE DATABASE FOR NOISE IMPACT ASSESSMENT EXPERT SYSTEM
CECELIA LAKAI
FK 1998 3
DEVELOPMENT OF NOISE DATABASE FOR NOISE IMPACT ASSESSMENT EXPERT SYSTEM
By
CECELIA LAKAI
Thesis Submitted in Fulfilment of the Requirements for the Degree of Master ScieDce iD the
Faculty of Engineering U Diversiti Putra Ma\aysia
October 1998
ACKNOWLEDGEMENTS
Praise be to my Lord Jesus for giving me the utmost strength to have this
project completed successfully. I would like to express my profound gratitude and
thanks to my supervisory committee chairman, Dr. Ir. Mohamed Daud , for his
continuos guidance, encouragement and help through the course of this study.
Sincere appreciation and thanks are due to Prof Dr. Ir. Dato' Mohd Zohadie Bardaie
and Dr. Abd. Rahman Ramli for their kind support and assistance. Last but not least,
I would like to express my appreciation to the members of Expert System for
Environmental Impact Assessment Research Group for their helpful, support and
comments.
TABLE OF CONTENTS
Page
ACKNOWLEDG�S . . . ... . . . . . . . . . . . . .. . ... '" ...... ... ... ... ... ... ... ........ , ... ... .... 11
LI ST OF T ABL ES . .. . . . '" ... ...... '" ... ...... ...... ... ... ... ...... '" ...... ... ... ... '" ... '" . VI
LI ST OF FI GURES . .. . , . ...... '" .. , ., . ... ...... ... ... ... ...... ... ... .. , ... '" ... ...... ... ... .. , VII
LI ST OF ABBREVI ATI ONS .. . . . , . . . '" '" '" . . . . . . . . . . .. . . . ... . ,. . . . . . . . . . . . . . . . . . . . . . . . . . . . viii ABST RACT . . . '" ... ..... , ... ... '" ...... ... ... '" ... '" ... ...... '" ... .... , .. , . ...... '" .,. ... .. IX
ABST RAK.. . . . . . . . .. . .. . . . . . . . . . . . . . .. . . .. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . X
CHAPTER
I I NTRODUCTI ON .. . .. . . . . ... .. . . . . . . . . . . . . . . . ... . .. .. . . . . . . . . . . . . . . . . . . . . . . . 1
II
Prologue . .. .. . . . . '" '" ............... '" ... ...... ... ...... ... ...... '" ......... 1 Statement of Problem . . . . . . . .. . . . . .. . . . . . .. ... . . . . . . . . . . . . . . . . . . ... . . . .. . . .. . 3 Research Objectives . .. . . . . .. . .. . . . . . . .... . . . . . . . . .. . . .. . . . . . . . . . . . . . .. . . . . . . 4 Organisation of the Study ............... ... ...... ... ...... ... ... ...... ... .... 5
REL ATED STUDIES Characteristics of Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . '" . . . . . . . . . .. . . . . . , . . . .
7 7
Ho w Noise is Transmitte d . . . . . . ... . .... . . .. . .. . . . . . . . . . . . . .. . . . . . . . .. 8 Noise Measurement . . . . . . . . . . .... . . . . . .. . .. .. . ... . .. .. . . . . ... .. . ... .. . 9
Effects of Noise Pollution .. , ...... ... ... . ,. '" ...... .. , .. , ... '" '" ... ... . ,. 10 Physiolo gical Effects .. . . . . .. . . . . . . . .... . . ... '" '" ...... ... '" ... '" ... 12 Effe cts on Activit ies ... ... '" .. , ...... '" ... '" .................... , .. . . 13 Psychosociolo gical Effects .. , " . ... '" ... ... ... ... '" ., . ... ... ... '" .. 14 Other Effects '" ......... '" ... '" ...... ... '" '" '" ... ... ... '" '" ... .. , 15
Noise Mitigating Measures . . . . . . . . . . . . '" . . . . . . .. . . . . '" .. . . . . . . . . .. .. . . . . . . Source -Path -Receiver -Concept . . . . .. . .. ' " '" '" .. . .. , .. . ' " '" '" . . . Con trol of Noise Throu gh Laws and Regula tions . . . . . . . . . . . . . . . . .
Environmental Noise M anagement . . . ' " ' " . . , . . , . .. '" '" '" . .... . . .. . . . . . Environ mental Impact Assessment In Respect to Noise . . . . . , .. . . . . . . . . . Expert System for Environmental Applications . . . . . ... . . . . . . . . . . . . . .. . . . . CL IPS as Expert System Tool . . . . , . . . . ' " .. . . .. . .. . . . . . . . . . . . . . .. . . . . . . . .. . . Clos ure . . . '" . . . ... . . . . . . . .. . . . . . . . . . . . . . . . '" . . .. . . . . . . . . . . . . . , '" .. . .. .. . . . . . . .
15 17 19 22 23 25 27 28
ill FUNDAMENT AL OF ENVIRONMENT AL IMPACT 30 ASSESSMENT AND EXPERT SYST EM DEVEL OPMENT . . . . . . . . . Env ironmental Im pact Assessment . . . . . . . . . . . . . '" . . . . . .. . . . . . . . . . '" .. . . . .
EI A Pr ocedures . . . . . . . . . . . . . , . .. .. . ... . . . .. . . . . . . . ... ' " ' " . . . . . , . . . " .. . 30 31
Timing . .. .. . . . . . . .. . . . . . . . . . . . . '" .... , . . ,. ... ... ... ... ... ... ... ... ....... 33 Expert System Develo pment . .. . .. ... . , . ......... ... '" ... ... ... '" '" '" .. , 34
Struct ure of Expert System . . . . , .... '" ... ... ...... '" ... '" ... ... .... 35 Phases of Develo pment .... . .. . .. '" '" ...... ... '" ... ... ... ... ... ...... 35
Inference Mechanism . . . . . . . . .. . . . . . . . . .. . .. . . . . . . . . . . .. . . . . . . . . . . . . .. . . .. .. . 38
III
CL IPS as Expert System T ool .. . . . . . . . . . . . . . . . . . . . . . . . . '" ... ... ... ... ...... 38 User Inte rface '" ... . , . .. , ... ... .. , ... ... '" ... ... ... '" ... '" ... '" ... ... ..... 39
IV METHOOOL OOY . . . .. . . . . .. . . . . . .. . . , ......... ... '" ... '" ...... ...... .. , ... 40 Kno wledge Ac qu is it ion . .. . . . . . , ... '" ...... ... ... ... ... ... ......... '" ... ... . 41 Kno wledge Representat ion . .. . . . . . . . . . '" ... " ...... ... ... ... '" ., . ... ... " . 43
Var iables Used for Stat is tical Analys is . . . . . . . . . . , .. , ... ... ... ... .... 45 Dec is ion Making Approach ..... ........ ....... ....... ..... ...... . .... ....... . ...... ......... 45
Significant of No ise Effe cts ...... ... ... ...... ... ... ... . " ... ... ... " . . 46 Development of No ise Assessment Database Expert System . . . . .. '" .. 49
System Assum ptio n . . . . . , ... ... ... ... ... . .. ... ... ... ... ... ... ... ... ... . 49 Conce ptual isat ion . . , .. , ..... , ... ...... '" .. , ....................... , .. . 51 Fo rmal izat ion .. . . . . . . . . . . . . . '" .. , '" ... '" ... '" ... ... .. , ... ... ... ..... 51 Val idat ion . . . . . . . . . '" ... ... ... ... ... ... ... ... ... ... ...... ... ... ...... " . 52
User Interface Des ign . . . . .. . . . . . . '" ... '" ... ... ... . .. ... ... ... ... ... ... ..... 52 Displa y Screen . . . '" ... ..... , ... ... ... ... ... ... ... ... ... ... ... ... ... .... 53
Quest ion Screen . . . . . . . . . . . . . . . . . . . .. . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. 53 System Development Tool .... . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . ... . .. .. 53 Doma in Experts .. . . , . ... .. , ... . , .... ... '" ... '" ... '" ... ...... '" ... '" ... .. . 54
V RESULT S AND DI SCUSSI ONS . .. . . . .. . . '" ... '" ... '" ... '" ... '" ... '" 56 ElA Reports Rev ie wed .. . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .. . . . .. . . . . . . . . . . . 56
Bas ic Contents of ElA Reports .. . . . . .. . . . .. . . . . . . . . . . . . . .. . . . . . . . . . .. . . . . . .. 58 Stat ist ical Anal ys is Results ..... ... . .................................................. . ..... . 60
No ise Basel ine Data .................................................................... 60 No ise Sampl ing Locat ions ........... ...... .... ........ ........... ...... . .. . .... .... 60 Sources of No ise .. ..... ....... ....... ...... ....... .............. ......................... 60 Amb ient No ise Level . . . ............ ............ ..... ................... ......... . ..... 63
No ise Im pact Assessment . . . . .. ....... ....... . .......................................... ... 64 Potent ial No ise Impact .. . . . .... .... . ...................................... . ....... .... 65 No ise Im pacts Reduct ion ....... .......... .................................... ....... 66
Ou tput of NADES ....................................................................... . . . ' " . 67 Ma in Frame ... .................. ..................... ....... ................................ 67 P RESCRIBED ACTIVIT IES Button ....... ........ ........... .......... . . . 69 EXIST ING ENVIRONMENT Button . .. . . . .. . . . . . . . . . . . . . . . . .. . 73
P OT ENTI AL IMPACT S MITI GAT ING MEASURES Button ' " ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .... 78
Test ing and Ver ificat ion of NADES . . . . .. . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. 81 Closure '" ... '" .. , '" ... '" ... '" ... ... .. , ... ... ... ... ...... ... '" ... '" ... ..... 83
VI CONCL USIONS AND SUGGESTION FOR FUTURE STUDy .. . . . . 84 Suggest io n for Future Study . ....... ........................... . . .. .......... .... .... ....... 85
REFERENCES . .. . . . . . . . , . ... ... ... ... ... ... ... ... ... '" ., . '" ., . '" ., . '" ... '" ... ... ... ... 86
lV
APP ENDI CES
VIT A
I Env ironmental Qual it y Act , 1974 ... . .. ... ... ... . . . ... . . 92 II Env ironmental Qual it y (Prescri bed Activ ities )
(Envi ronmental Im pact As sessment ) Orde r, 1987 94 III No ise Impact Assess ment Produced b y the NADES 97 IV So urce Code 99 V Questionna ires 114
115
v
LIST OF TABLES
Table Page
4.1 Permissible Noise Exposure Limits .............. . ....... . .. . . ....... .... . . . . . .... ........ . . . .. 48
4.2 Criteria for Significant of Changes in the Noise Environment . . ....... . . . . . . .... 48
5.1 Summarized of EIA Reports Content .......................................................... 59
5.2 Frequency Table for Sources of Noise ......................................................... 62
5.3 Crosstabulation Results of Sources of Noise and Sampling Locations .... . .. 63
5.4 Summary of Noise Level Results .. ... ... ...................................................... 64
5.5 Kruskalis Wallis One-Way ANOVA for Factors Influence Noise Levels .... 64
5.6 Summarization of Noise Effects Mitigating Measures During Operational Stage ........ ...... .. . . . . . . . . . . . . . ... '" ...... ... ... ... ... ... ... . , . .. , ... ... ... '" ... ..... 68
5.7 Information Used to Test the NAD ES .. . .... . . . . . . . . . . . .. . .. . . . . . . . .... . '" ... .. 82
VI
LIST OF FIGURES
Figure Page
1.1 Organisations of this Study . . . . . . . . . . . . .. . . . . . . , ... ... ... ... ... ... . . . ... .. . . .. ... .. . 5
2.1 Schematic Diagram of Transmission of Noise . . . ... ... ... ... ... ... ... ... ... ... .. 8
2.2 Process of the Development of Health Effects of Noise . . . '" ..... ... ... ... ... 11
3.1 Simplified EIA Procedures in Malaysia... ... ... ... ... ... ... ... ... ... ... ... ... ... 34
3.2 Typical Structure of an Expert System . . . '" ... ... ... ... ... ... ... ...... '" ... .... 37
4.1 Simplified Noise Assessment Database Expert System... . . . ... ... ... ... ... 40
4.2 Format of the EXCELL Table .. . '" ... ... ... ... ... ... '" ... ... ... ... ... ... ... ... ... 43
4.3 Decision Making Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . '" ... ... .. 49
5.1 Distribution of Reports Reviewed in terms of Prescribed Activities . .. . . . .... 57
5.2 Reports Distribution Based on Existing Land Use ..... ............ . . . . . ..... ....... ..... 58
5.3 Main Frame . . . . . . . . . ... . . . '" ... ... '" ... ... ... ...... ... '" ... ... '" ... '" ... ... ... .. 70
5.4 Output for PRESCRIBED _ACTMTIES Button . . . ... ... ... ... ... ... .......... 72
5.5 Dialog-Box for Prescribed Activities . . . ... . . . ... ... .. . ... ... .. . ... ... . .. ... ... . . . 73
5.6 Message Appeared from EXISTING_�ONMENT Button ... ...... .... 74
5.7 Output for Agriculture Land Use . . . '" ... ... ... ... ... ... ... ... '" ... ... '" ... ..... 75
5.8 Output for Project Boundary Sampling Points . . . ... ...... ... ...... ... ... ... .... 76
5.9 Output for Sampling Point at 100 Ian away ... ... ... ... ... ... ... ... ............ 76
5.10 Final Output for Existing Environment . . . '" ... ... '" ... ... ... ... ...... '" ... . . . 77
5.11 Output for Impacts and Mitigating Measures During Construction Stage(Residential Area) ' " ... ... ... ...... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 79
5.12 Output for Noise Assessment During Operational Stage ... '" ... ... '" . .. ... .. 81
Vll
ANOVA
CLIPS
dBA
DOE
EIA
EIS
EPA
ES
GUI
NASA
NADES
PTS
TREES
TTS
LIST OF ABBREVIATIONS
Analysis of Variance
C Language Integrated Production System
decibel (A-Weighted)
Department of Environmental
Environmental Impact Assessment
Environmental Impact Statement
Environmental Protection Agency
Expert System
Graphical User Interface
National Aeronautics and Space Administration
Noise Assessment Database Expert System
Permanent Threshold Shift
Tree Recommendation Expert System
Temporary Threshold Shift
Vlll
Abstract of thesis submitted to the Senate ofUniversiti Putra Malaysia in fulfillment of the requirements for the degree of Master of Science
DEVELOPMENT OF NOISE DATABASE FOR NOISE IMPACT ASSESSMENT EXPERT SYSTEM
By
Cecelia Lakai
October 1998
Chairman: Mohamed Daud, Ph.D., P.Eng.
Faculty: Engineering
The Noise Assessment Database Expert System (NADES) was designed to identify
the characteristic of changes in the existing noise environment as a result of the a
proposed development, noise effects and proposed mitigating measures to reduce
these impacts. The NADES was developed using the C Language Integrated
Production System (CLIPS) version 6.04, an Expert System Shell which is designed
by NASA (National Aeronautics and Space Administration). The development of
NADES was based on Environmental Impact Assessment (EIA) reports submitted to
Department of Environment (DOE) and also on three assumptions: all reports are
subjected to the Environmental Quality (Prescribed Activities) (Environmental
Impact Assessment) Order 1978, project activities are as listed under the Checklist of
Project Activities for Prescribed Activities and all EIA reports reviewed were
approved by DOE. The NADES have the basic components of a typical expert
system and it was developed to produce an EIA report in a much shorter time.
IX
Abstrak tesis diserahkan kepada Senat Universiti Putra Malaysia sebagai memenuhi syarat�syarat yang diperlukan untuk ijazah Master Sains.
DATABASEE BAGI SISTEM PAKAR PENILAIAN KESAN KEBISINGAN
Oleh
Cecelia Labi
Oktober 1998
PeDgerusi: Mobamed Daud, Pb.D., P.EDg.
Fakulti: KejuruteraaD
Database bagi Sistem Pakar Penilaian Kesan Kebisingan (NADES) direka bagi
mengenalpasti ciri-ciri perubahan pada keadaann sedia ada bunyi bising yang
disebabkan oleh sesuatu projek, impak-impak dan mencadangkan langkah�langkah
tebat. la direka menggunakan program 'C Language Integrated Production System'
(CLIPS) versi 6.04, iaitu satu sel sistem pakar yang telah dicipta oleh NASA.
NADES in dicipta berdasarkan kepada maldumat-maldumat yang telah diekstrakkan
daripada laporan-Iaporan Penilaian Kesan-kesan Impak (EIA) dan dengan tiga
andaian: semua laporan tertakluk kepada Akta Kualiti Alama Sekeliling 1974 untuk
aktiviti-aktiviti yang tersenarai dalam Araban Aktiviti Terjadual, 1987, projek
aktiviti adalah seperti yang tersenarai dalam senarai "Checklist of Project Activities
for Prescribed Activities dan yang ketiga, semua laporan ini telah diluluskan oleh
pihak Jabatan Alam Sekitar (JAS). NADES ini mempunyai komponen-komponen
asas suatu sistem pakar and yang mana ianya direka supaya penyediaan laporan EIA
akan menjadi lebih cepat.
x
CHAPTER I
INTRODUCTION
Prologue
Types of environmental impacts can be expected to include population
growth; high-density urbanisation; industrial expansion; resource exploitation; air,
water and noise pollution; undesirable land use patterns; damage to life systems; and
other consequences adverse to environmental goals. The assessment, both
qualitative and quantitative, of these impacts require the use of many disciplines.
Environmental Impact Assessment (EIA) is a study to identify, predict,
evaluate and communicate infonnation about the impacts on the environment due to
a proposed project and to detail out the mitigating measures prior to project approval
and implementation. EIA is essentially a planning tool for preventing environmental
problems due to an action. It seeks to avoid costly mistakes in project
implementation. In Malaysia, EIA is used as a tool to integrate environmental
considerations into project planning. Activities subject to EIA are prescribed under
the Environmental Quality (Prescribed Activities) (Environmental Impact
Assessment) Order 1987.
1
2
Land developments may affect noise levels in the short tenn by construction,
and in the long term by changes in vehicular and pedestrian traffic, industrial
processes, and other activities (Rau, 1980). One way to incorporate noise control
considerations mto land use planning is the Environmental Impact Assessment.
Preparation of noise impact assessment requires environmental assessment topics
such as description of existing noise environment; physical description of noise;
assessing noise impacts for various noise-sensitive land uses; and designing
mitigating measures to alleviate potential community noise problems (Mestre and
Wooten, 1980). For a more detailed assessment and a more technical reader, noise
assessment will include the fundamentals and equations necessary to project noise
levels for a variety source under a variety of conditions.
Noise assessment in an environmental impact assessment includes
considerations of the potential damage to hearing, potential physiological responses,
annoyance and general community responses. Nevertheless, a typical noise
assessment in an EIA will take the form of a comparison between the existing noise
level and anticipated noise levels with the criteria established by various agencies
and the local government. Typical considerations in environmental noise assessment
can be divided into two separate categories: those relating to the noise source and
those relating to potential receivers.
Noise level in sensitive area such as schools, hospitals and residential areas
were found to be high and exceeded the noise level recommended by the World
Health Organisation (Leong, 1982). Goh (1983) indicates in his study that the
number of complaints received by the OOE can reflect the public attitude towards
3
noise pollution. He concluded that the number of complaints even though small, are
increasing every year and most complaints were made by residents whose houses are
located near factories or main roads.
Statement of Problem
There are two major factors that contribute to the ineffectiveness of EIA in
environmental conservation: prolong approval process and lack of expertise.
Initially, all preliminary EIA Reports are processed and approved by the State DOE
except for Kedah and Pedis. This will take approximately one to two months from
the date of report submissions. Currently, the procedures have been changed where
the DOE headquarters issue the final approval for an EIA Report. This will take
another two weeks thus prolonging the approval process of an EIA study. Hence,
this indirectly will slow down the proposed project, as well as cause pilling up of
EIA reports that need to be reviewed and evaluated by the DOE headquarters and
also will degrade the quality of an EIA report.
Lack of expertise is one of the major problems faced by EIA consultants and
has contributed to the costly price of an EIA study. An EIA study requires the
involvement of multiple experts and gathering of relevant data. Gathering of data is
always considered to be time consuming, expensive and introduces unnecessary
delays in the implementation of a project. For example environmental noise;
environmental noise is one component of the physico-chemical environment
required in an Environmental Impact Assessment (EIA) report. Lately, noise
pollution has attracted the authority's attention especially community noise. In the
4
1993 Environmental Quality Report (EQR), noise was ranked third after air and
water pollution in tenns of number of complaints received by DOE.
Noise impact assessment requires a person who has the knowledge on the
characteristics of noise pollution and its impacts to the existing environment. There
is a valid need to develop techniques and tools for perfonning environmental noise
impC1"t analyses that can be used by both the environmental analysts and the viewers
of environmental impact assessments. The introduction of Noise Assessment
Database Expert System (NADES) for noise expert system will assist all EIA
consultants, project initiators and approving authorities in gathering, describing and
evaluating the existing noise level, its impacts and mitigating measures to control
these impacts. Besides for description of the existing noise level and prediction of
noise impacts, this NADES can be used by the approving authority as cross
references in reviewing the submitted EIA reports.
Research Objectives
The objectives of this research are as follows:
(a) To develop a nOIse assessment database expert system for the
development of noise expert system.
(b) To develop a more clearly ambient noise measurement and
monitoring for an EIA study.
5
(c) To design rules for noise impact assessment and recommendation of
mitigating measures.
Organisation of the Study
The structure of this study is as illustrated by Figure 1.1 and is divided into
six chapters.
I INTRODUCTION I
I RELATED STUDIES I
I THEORY OF EIA PROCEDURES AND I EXPERT SYSTEM DEVELOPMENT
I METHODOLOGY I
l RESULTS AND DISCUSSION I
I CONCLUSION I
Figure 1.1 : Organisations of this Study
(a) Introduction - This chapter gives the introduction to this study, which
includes objectives, statement of problems and organisations of the
study.
6
(b) Related Studies - This chapter discussed some related studies on
noise impact assessment and application of expert systems in
environmental field.
(c) Theory of EIA and Expert System Development - This chapter is
divided into two parts: the first part explained theory of EIA study in
Malaysia and second part discussed the typical stages of expert
systems development.
(d) Methodology - This chapter gives the method used for data
collection, analysis and the development of the NIifEs prototype.
Method used was based on the typical procedure of developing an
expert system.
( e) Results and Discussion - This chapter discussed results obtained
from the data collection and analysis; and output of the NADES. The
final output of the NADES is discussed and presented in this chapter.
(f) Conclusion - The chapter presents the final conclusion of this study
and recommendation for future development of a more
comprehensive noise expert system.
CBAPTER ll
RELATED STUDIES
This chapter discussed some related studies on noise impact assessment and
expert systems application in environmental field. Noise is a very wide topic to
study therefore, for the purpose of this study, literature review was limited to noise
impact assessment. This is to obtain a clearer vision on effects of noise, which is the
major component of an EIA study in relation with noise pollution. For the same
reason, related studies on expert systems application are limited to environmental
field.
Characteristics of Noise
Noise has been recognised as an important area of research, along with other
forms of pollution, in determining the quality of our environment. This is evident
from a number of studies, which have been carried out in various parts of the world
(Kumar and Jain, 1994). Noise is defined as unwanted sound, annoying or even
damaging sound. Sound by itself is not pollution but when it interferes with a
person's 'territory', it can create nuisance to the receptor. In order to mitigate
adverse effect cause by this unwanted sound, one has to understand the
7
8
characteristics of noise. Characteristics of noise are discussed in tenn of its
transmission and measurement.
How Noise Is Transmitted
Noise generally varies with the time of day-relatively quiet at night, when
people's activities are at minimum, and noisier in the morning and late afternoon
during the commuter-traffic rush hours (Eldred, 1975). Noise reaches a listener by
several of paths (Harris, 1979). It first must propagate or travel at some distance
through air, before it can reach the ear. Briefly, the diagram in Figure 2.1 explained
the transmission of sound from a source to the listener. The diagram also shows the
interaction between the source, path and receiver, as shown by the broken lines. The
source represent more than one sound generator point and the path in which the
sound is transmitted consist of one or many paths (Harris, 1979). Receiver who is
affected by the sound or noise may refer to single person, group of people,
community or equipment where the operation is affected by noise. These three
elements are not always constant but it depends on the path and receiver.
SOURCE � ..... �I,-_P_A_1H_----J� ..... �I RECEIVER
Figure 2.1: Schematic Diagram of Transmission of Noise
9
Noise Measurement
Methods used to measure noise depend on several factors but the most
important one is the purpose of noise measurement. There are many reasons why
noise measurement is made for example, for occupational safety purposes, to
evaluate complaints from affected elements, to determine if a given environment
condition is acceptable or for legal purposes. Community noise surveys have been
carried out in numerous countries over the past 30 years (Brown and Lam, 1987).
Generally, basic factors that should be taken into considerations during noise
measurement are selection of noise instruments, microphone positions, and
reflections from nearby surfaces.
Besides these factors, selection of appropriate noise descriptor is also
important (Garcia and Faus, 1991). This will lead to a much simpler short time
measurement techniques, without producing a serious loss of any relevant
information. The equivalent continuous A-weighted sound pressure level is
recommended as a measure of any environmental noise (Makarewicz, 1991). The
calculation was made under the assumption that many buildings (interference) affect
the noise propagation. The Noise Advisory Council in United Kingdom are
concerned about the multiplicity of noise emission measures used. Hence, a
recommendation was made, which is the use of Leq for quantification of the noise
environment due to each source and from all sources together.
Basic instrument for noise measurement is the sound level meter and it is
normally positioned so that an adequate sampling is obtained of the sound field in
10
the area of concern (Harris, 1979). The number of sampling locations should be
sufficient to describe the ambient level or the existing noise environment. It is
important to take note that environmental conditions either indoors or outdoors have
a considerable effect on measured sound. The choice of measurement site,
microphone height and position may be dictated by particular circumstances but care
should be taken to avoid the influence of obstructions and reflecting surfaces. For
the purpose of comparison study, it is important that all noise measurements are
made according to the same standards following the same rules. This is important
when noise measurement is conducted for Environmental Impact Assessment
studies.
Effects of Noise Pollution
The problem with noise is not only that it is unwanted but also that it
negatively affects human health and well being. Noise pollution can be defined as
unwanted sound, which discharge into the atmosphere without considering the
adverse effect it may be having (Chattwal et. al., 1989). Several surveys and opinion
polls have shown that noise is a major disturbances and source of complaints in the
daily life of citizens in the Organisation for Economic Co-operation and
Development (OECD) countries. However, all noise effects should be considered as
health hazards. This is because "health is a state of complete physical, mental and
social well-being, and not merely the absence of disease or infirmity (WHO, 1960).
11
Impacts can be defined as the striking of one body against another (Urdang
and Flexner, 1968). There are various effects of noise on people and they are often
interrelated. These effects can be categorised into three categories: physiological
effects, effects on activities and psychosociological effects. The effects of exposure
to noise depend on the noise level, the length of exposure to noise, and the type of
noise (Kirk-Othmer, 1981). The developmental process of noise effects can be
simplified as in Figure 2.2 (Osada, 1988). Based on this figure, the direct and
indirect noise effects lead to a perception of annoyance (a type of psychosiological
effects) and behavioural response. Both perceived annoyance and behavioural
reactions are the integrated and composite effects of noise.
-----. direct effocts
Cerebral cortex
Auditroy Area
Noisiness
Other area
Discomfort Sleep disturbacne
Decreased performance
Body
Ph sical reaction
...... indirect effocts
Annoyance
Behaviomal
r nse
-+ Integrated effocts
Figure 2.2: Process of the Development of Bealth Effects of Noise
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Physiological Effects
Physiological effects of noise can be categorised as auditory and nonauditory.
Auditory effects referred are those related to human auditory system. Example of
auditory effect is hearing loss. It is well known that long-term exposure to high
noise levels can result in permanent hearing loss (ANON, 1980). The earliest
reference to noise-induce hearing loss was the noise of water falling over falls and
rapids in the Nile River cause hearing loss in the natives who lived and fished near
the river (Kirk-Othmer, 1981). It is feared that noise levels experienced in the day
to-day environment may cause, in the long term, loss of auditory acuity (partial
hearing loss). There are two types of auditory effects: temporary threshold shift
(TTS) and permanent threshold shift (PTS). TTS refers to hearing loss as a result of
exposure to intense noise over a short period and which is follow-up by partial
recovery. The amount of TIS is related to the exposure duration (Smith, et. ai.,
1982). PTS refers to any hearing loss, which is persistent.
Nonauditory effects usually occur after auditory effects. It occurs when other
parts of the cerebral cortex are stimulated by impulses excited from the auditory area
through nervous connection within the cortex (Osada, 1988). Examples of non
auditory physiological effects are such as: increase in blood pressure, heart rate and
breathing speed, muscles tense, and hormone are released into the bloodstream. It is
considered plausible that some disorders, especially cardiovascular disorders and
increased susceptibility to diseases are accelerated by higher levels of noise.
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Effects on Activities
Effects of noise on activities are the most significant and best identified ones.
Activities that are likely to be affected by noise are sleep, communication and
performance. Sleep interference is probably the most important in terms of its
potential effects on human health after long-term exposure. Effects on sleep depend
on the type and level of noise, on the psychophysiological state of the person and the
time of at night when noise is produced. Sleep disturbances or interference are
defined as measurable and/or experienced deviations from the usual or from the
desired sleep behaviour and they are indicated by primary and after effects
(Griefabn, 1991).
A study was conducted to elucidate the importance of number of noise events
with a high maximum noise level for sleep disturbance effects in terms of body
movements, SUbjective sleep quality and performance (Ohrstrom and Rylander,
1990). In this paper, one of the most important environment noise sources for sleep
disturbance is road traffic noise. Based on this study. to protect people from sleep
disturbance effects it is not sufficient to base the noise criteria on 24 hour the
equivalent continuos level. It is necessary then to consider the number of vehicles
over a certain maximum noise level. When the maximum noise level is 60 dB(A)
and the number of noise events is around 16 per night the sleep quality as well as
performance is reduced. The maximum noise level between 45 dBA and 55 dBA is
critical with regard to noise disturbance during sleep (Ohrstrom and Rylander, 1990).
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The most obvious of environmental noise is its interference with
communication. This is because at a certain level noise masks the sound one is
listening to. The fundamental nature of speech and listening, and the frequency of
their use in almost all-human activities, make it clear that interference with speech
and listening is one of the worst effects of noise. Noise can distract a person
involved in a specific task, this distraction depends on the meaningfulness of the
noise and on the psychophysiological state of the person. Possible indicators of the
effects of noise on performance are identified as (Canter, 1977):
( a) An increase of accidents in very noisy places
(b) A less than average language development and reading ability among
children exposed to high noise levels at school and at home.
Psychosociological Effects
In addition to the direct effects of noise, there are indirect and more ill
defined effects of annoyance which result from these direct effects (Anon, 1980).
These effects are influenced by various psychological and social factors. In several
surveys concerning living conditions, noise is one of the most frequently cited
sources of annoyance in the neighbourhood. The annoyance due to road traffic noise
was studied in 18 areas in five countries by Rylander, et. aI., (1986). Their study
indicates that the number of events above a certain limit will not increase the extent
of annoyance: the highest noise level from single vehicles determines it. A model