Mosque is a worship place for Muslims. Its function not just performs salat purposely but it can be as well as a center for information, education, and dispute settlement. As we know, mosque basically dealing with sounds which in delivering religious matters such as Friday sermon and lectures which most important speech activities in mosque. Through these activities, the congregation will be hearing messages of reminder of their religious and social duties.
A study was carry out about acoustics and speech intelligibility quality of Kampung Laut Mosque, Kota Bharu (Ngasri Dimon, 2007), they determine the acoustic quality of the mosque such as reverberation time (RT60), speech level distribution in the main hall and speech intelligibility quality which involving different type of situation. In this study, they undergoes several acoustic quality analysis which are RT60 analysis, ray tracing analysis, sound pressure level (SPL) analysis and speech intelligibility prediction based on Speech Transmission Index (STI) and Rapid Speech Transmission Index (RASTI) lead to indicate that mosque posses good quality and good speech intelligibility when 'kuliah' or 'khutbah' is performed.
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Acoustic is a very important nowadays, it does not restrict to the study of musical only. Acoustics is such a wide course which related to physical acoustics, psychoacoustics, electro acoustic, noise control, shock and vibration, underwater acoustics, physiological acoustic and etc. In Malaysia, there is standard that organized by Department of Occupational Safety and Health on the noise control. Noise is unwanted sound that harmful and will effects to our hearing sense. Consequences from that, it will lead to accident. The normal range of hearing for a healthy young person is from approximately 20 Hz (Hertz) to 20,000 Hz (20 kHz).
1.2 Problem Statement
Acoustic quality in mosque is very important. Mosque is a building where worshipper perform for their pray. So, it must be conducive in term of sound which audibility. The worshipper can't get the message or unpleasant to do their religious activity sometimes and it need to be improve.
Several studies have been made about the acoustic quality which most of them come from out of our country. In Malaysia, acoustic engineering does not wide like other engineering. So, to implement this kind of quality does not taking serious. Most of our mosque here, the buildings more focus on the decent architectural design. Besides that, in the main hall prayer also come with astonishing look which somehow adaptation from other great design in the world. This is good regarding to modernization of architectural design but acoustical quality also should be considered too.
According to CAHRISMA project that researched by Zerhan Karabiber about ancient buildings, it states conservation and restoration of the architectural heritage were restricted with material means until now. However, it is obvious that, preserving an architectural heritage also should includes with acoustical heritage, especially the spaces that has acoustical importance.
Al-Wathiqu Billah Tuanku Mizan Zainal Abidin Mosque,Â UiTMÂ Shah Alam is newly mosque upgrading from their old building which formerly known as Pusat Islam UiTM. This mosque fully finished their renovation on 2010 which come out with new architectural design in their main hall prayer. Tuanku Mizan Mosque is not same like other mosque, it just only has one beautiful minaret and upper space of the building is flat which does not have dome.
Upon to its uniqueness, a study should be made to evaluate whether this mosque has good acoustical quality. In addition, throughout this study also, we can improvise and learns in spite of implement the acoustic learning course offered in Faculty of Mechanical Engineering, UiTM. The result of this study can be aid to design a new mosque in the future.
The main objective is to study the acoustic quality in Al-Wathiqu Billah Tuanku Mizan Zainal Abidin Mosque,Â UiTMÂ Shah in order to gain understanding about the good criteria needed in designing acoustic in mosque
To determine the reverberation time, RT60 during semi-fully and fully occupied.
To study the signal-to-noise ratio in the mosque during semi-fully and fully occupied.
1.4 Scope of Project
The scope of the project is to investigate the good criteria needed in designing acoustic in mosque. There are several criteria need to carry out in this project such as study of reverberation time (RT60), Speech intelligibility, Noise Control and etc. As a result, sound contour mapping will be determined for RT60 at certain places in main hall prayer in the mosque. Besides that, throughout the studies also we could understand circumstances that effect to acoustic in the mosque and the way to counter it.
1.5 Significant Project
Always on Time
Marked to Standard
This study was carrying out to gain the understanding about acoustic quality in the mosque. Thus, it will promote the value of acoustic in a building which does not focusing on the mosque only. In addition, it will help to improve the deficiency of acoustic quality and performing some guidance on designing mosque in future.
Mosque is defined as the place of worship for Muslim. One of the most repeated building types in Muslim countries. In Malaysia, lot of mosque resembles mosque found in Java. The mosque serves as a place whereÂ MuslimsÂ can come together forÂ salatÂ (prayer) as well as a center for information, education, and etc.
Figure 2.1 : First mosque in the world, Quba Mosque
First mosque (Figure 2.1) in the world built in Quba, Medina in Saudi Arabia. It was built during prophet Muhammad S.A.W on his way for emigration from Mecca to Medina, Saudi Arabia. The present mosque of Quba is a rebuild building. When Abdel-Wahed El-Wakil, Egyptian architectÂ was commissioned on 1980's, he conceived larger mosque and preserve the older design but the client eventually decided to pull down the old mosque and completely replace with new building. This mosque is a significant building to Muslim people nowadays due to its history.
2.1.2 Architectural / Room Acoustic
Room acoustic or architectural acoustic is the science of noise control within the building. This acoustical design quite important in making a hall that has acoustical purpose such as lecture hall, auditorium and etc. This study is to provide for maximum intelligibility of the speech while also in maintaining a natural voice. The first implementation of the architectural acoustic is in the opera houses then concert halls. Every single building has its own acoustic requirement depending to the purpose of the building.
Süleymaniye Mosque(Figure 2.2), was built by Architect Sinan in 1557 is a great architectural acoustic building. The uniqueness of this building has the mosque's main dome was found to have 256 symmetrically placed cubes measuring 15 centimeters around the front and 45 centimeters in length, which contribute to very good acoustic quality in this mosque. Some coresspondance said no need microphone there and the speech intelligibility very good. Unfortunately, after a few restorations relating to its heritage, the mosque already lost their uniqueness. Local people claimed that they cannot hear the sermon clearly as usual after that.
Figure 2.2 : Süleymaniye Mosque in Istanbul, Turkey
2.1.3 History of Al-Wathiqu Billah Tuanku Mizan Zainal Abidin Mosque,Â
UiTMÂ Shah Alam
Al-Wathiqu Billah Tuanku Mizan Zainal Abidin Mosque,Â UiTMÂ Shah Alam is located at top of hill nearby with Kolej Seroja and Faculty of Applied Science, about 1.5 km from Faculty of Mechanical Engineering. This Mosque has their own history which is known as Islamic Education Centre (IEP) at beginning of their established onÂ 1st April 1983.
In order with modernization, this centre was revised its name by Y.Bhg.Â Dato'Â SeriÂ Prof Dr.Â Ibrahim Abu Shah, Vice Chancellor UiTM on 1st January 2004 become CentreÂ for Islamic Thought and Understanding (CITU). CITU was supervised by a director and assist with two vice director that responsible to Islamic academic and non-academic in the UiTM Shah Alam campus. The establishment of CITU in UiTM is a combination of Islamic Education Centre (IEP) with the Religious Advisory Centre (non-academic) in which all Islamic activities governed by the University under one roof with the Islamic Centre at the university. After a few years, CITU has undergone renovation which incriminates a few parts that need to be maintaining in its building such as a new minaret and its main hall prayer.
In 2010, UiTM move one step ahead in elevate Islam as main religion in our country and desire emerge as World Class University by introducing Al-Wathiqu Billah Tuanku Mizan Zainal Abidin Mosque,Â UiTMÂ Shah Alam.
2.1.4 Mosque Features
The area and volume of this mosque is calculated based on Architectural drawing that been provided by 'Unit Rekabentuk & Projek, Bahagian Fasiliti UiTM', a department that responsible to plan or proposing the features of this mosque.
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Figure 2.3: Site plan on architecture drawing of UiTM mosque
The mosque has an estimated volume is 62,720 m and it can accommodate 7000 person at a time. The floor area of the mosque about 3136 m and for the main prayer hall floor area estimated of 1600 m. It is 56 x 56m, with height of 20m. Each area calculations of main prayer hall is as shown in Table 1.
TABLE 2.1 Summarise area of Al-Wathiqu Billah Tuanku Mizan Zainal Abidin Mosque,Â UiTMÂ Shah Alam
Area (S), m
2.2.1 Sound & Mechanical Wave
Sound is defined as pressure variation in term of mechanical wave that travels through a medium from one location to another. This phenomenon occurs when the wave is set off; it sets the nearest layer of particles of air into motion and corresponding energy to it in example vibration disturbance. This transport of mechanical energy through a medium by particle interaction is what makes a sound wave a mechanical wave. A vibrational disturbance is interpreted as (audible) sound if its frequency lies in the interval from 20 Hz to 20 000 Hz.
Depending on the properties of the medium, sound propagates at different speeds.
Speed of sound (m/s)
Sound wave behaviour is same with light and other wave behaviour's. The sound wave may exhibits reflection, interference (two waves superimpose to execute resultant wave), refraction and diffraction.
2.3 Early Decay Time (EDT)
In describing the decay of a reverberant "tail" of sound energy in room, Sabine's equation states the relationship between low absorption to its internal volume. Sabine in his study was discovered that sound like many other quantities which have a "half-life". These produce an exponential curve that against increasing time graph (Figure 1). This pattern of graph much like the decay of radioactive material or carbon-14 that been use by archaeologist in the dating process. In other example to describe the decay time is the decay of light in a light -emitting diode (LED) and the voltage across a capacitor. The behaviour of this kind of energy, Sabine through its equation estimates the time required for energy to reflect until becomes inaudible (-60 dB) after the sound source been interrupted - the RT60.
Figure 2.4 : reverberant energy decays exponentially
EDT is roughly defined as the sensation of RT. It is better indicator of subjective feeling of reverberation time, and is critical defining the acoustical quality of a music hall. By comparing the initial rate of reverberant sound decay and reverberation time likely appears initial rate more important than the total reverberation time. Decay time likely important too since it more rapid initial decay is interpreted by the human ear as meaning that the reverberation time is short. EDT should not be higher than Â± 10% for good acoustics. For liturgical purposes, EDT should be between 2.7 and 3.85 (Templeton, 1993).
Things to avoid in design include the following:
Echoes. An echo is a strong reflected sound that is arriving at the listener after the direct sound sufficiently delayed that it can be heard as a separate entity rather than as a continuation of the original sound. When echoes are heard, the most likely culprit is the rear wall of the room.
Flutter echoes. Flutter echoes are a series of echoes that occur in rapid succession; they usually result from reflections between two parallel surfaces that are highly reflective.
Sound focusing. Focusing of sound can be caused by reflection from large concave surfaces. Certain sounds will be heard too loudly near the focus of a curved surface.
Sound shadows. Under balconies at the rear of an auditorium or church there may be insufficient early sound, since most of the reflections from the side walls and ceiling do not reach this area even though they are in a direct line of sight to the performer and therefore receive the direct sound. 
2.4 Speech Intelligibility
Speech intelligibility is the measure of the effectiveness of speech which it's expressed of percentage of a message that correctly delivered and understood. In term of understanding, speech intelligibility does not same with speech quality because speech quality refers to message that want to delivers that may be understood by the listener. A message that lacks quality may still be intelligible.
Table 2.2 : Speech Inteligibilty Test Method
Table above shows speech intelligibility test method which standardizes by International Electrotechnical Commission (IEC) and International Standards Organization (ISO) standards that already incorporate objective methods for evaluating speech intelligibility.
Time that required for a sound in a room to dies out which specifically decays by 60 dB in a room after the sound from its source has stopped is known as reverberation time (RT). RT is the basic parameter that should be calculated in the study of acoustic. Reverberation time specifying the efficiency of sound decays in a room for fulfilling the acoustical requirement depending upon the activities conducted in certain time.
JBL Professional Sound System Design Manual reverberation time was simply described about the length of time required for a very loud sound to die away to inaudibility. It was later defined in more specific terms as the actual time required for sound to decay 60 decibels. RT60 was found by Wallace Clement Sabine, a professor at Harvard University in the early 1900s who was the first person that quantifies this quality subject. W.C. Sabine has come out equation below due to his study on acoustic of the Fogg lecture hall:
V = volume in cubic meters,
S = total surface area of the room in square meters,
= average absorption coefficient in the room
According to past study in the mosque, RTis 7.48 s in the middle frequencies. This much longer than the optimum level even for liturgical purposes. Liturgical purpose refers to orchestra, chorus or organ which the optimum range level for reverberation time is about 3.0 to 3.5 s for spaces larger than 1000 m(Egan, 1994). Long sound decay at low frequencies can reduce the intelligibility of speech. For good intelligibility, RT values at low octave band should remain flat down to 100 Hz. At low frequency, an increase in RT values of around 10%-20% would still yield a natural sound.
2.6 Signal-to-Noise Ratio
Noise is a sound which known as unwanted signal or damaging sound that may damage your hearing. It also can cause to other health effects such as stress, increased heart rate level, increased blood pressure and hypersensitivity to no noise. It can also interfere with communication at work, which could lead to accidents. For healthy young person, the normal range hearing is from approximately 20 Hz (Hertz) to 20,000 Hz (20 kHz). Our ears are more sensitive to the middle frequencies, which range from 500 Hz to 4000 Hz - the speech frequencies.
Signal-to-noise ratio defined as a measure of desired signal level to unwanted signal (noise). It is also known as the ratio of signal power to the noise power in a space. This describes the level of noise that exerts from output device such as fan and refrigerant, in relation to signal level.
Figure 2.5 : Two signal which referring to wanted signal which does not disturb and unwanted signal (alternate amplitude).
Due to ratio between noise and signal, it often expressed in logarithmic decibel scale.
Signal-to-noise ratio (dB) = 10
= Pressure for signal (dB)
= Pressure (signal + noise) in dB
Research methodology is one of the important parts in this study. A systematic methodology was created which to ensure that the research will be running smooth and successfully. In order to carry out the research, this methodology comes out with 5 stages which stated in the flowchart below. This flowchart is important to describing the way or designing the method that being use.
Flowchart of the proposal methodology
3.1 Preliminary Preparation
3.1.1 Introduction to acoustic and understanding on the basic concept of the study.
In this stage more on understanding of the basic concept about the study. This includes by doing some observation on past study and the sources that will provide the information that related to this study such as from library, book, internet, journals and etc. There are some keyword been highlighted regarding to the research includes acoustic, speech intelligibility, architectural acoustic, sound propagation, and reverberation time (RT60). This fundamental knowledge is quite important to understand about study that will carry out to perform a good research. The keyword had been discussed in the literature review.
3.1.2 Collecting information details about the study
Collecting data is quite tough job need to handle. As mentioned in the objective, object that will carry out for the experiment is UiTM Shah Alam Mosque. For your information, this mosque was built past 20 years ago and basically there is no research done on this mosque. So the information about the mosque is quite limited. A lot of stages needed in determining the details about the mosque:
Observing the features inside the object about the experiment will carry out, UiTM Shah Alam Mosque includes:
Glass doors (11 Units)
Pillars in wooden covered (6 Units)
Speaker (6 Units)
Collect some detail about the history in making the mosque from Arkib UiTM Shah Alam
Dealing with 'Unit Fasiliti, UiTM Shah Alam' regarding to get the dimension and drawing about the object.
Contacting the architect that handle the latest renovation to get some point and view about the material that been used in the object that will carry out for the experiment.
3.2 Experimental Study
3.2.1 Reverberation time (RT60)
For experimental study stage, sound level meter plays its role in obtaining the sound pressure level in decibel (dB). Referring back to the objective, the study is to determining the reverberation time (RT60) which the time required for sound level from present level down to 60dB. The sound level meter will be placed in certain position in main hall prayer area. From this we can see the variation of the sound propagation inside the hall. This variation of the sound propagation will be translated into sound contour mapping by using Matlab software which inserting the time required from the experiment.
3.2.2 Signal-to-noise ratio
This parameter will be determined by using sound spectrum analyzer. This spectrum analyzer is worked to differentiate the signal and noise in a space. The result from this observation, we can obtain the noise level in the condition as stated in the objective of the study.
Figure 3.1 : Spectrum analyzer
3.3 Simulation using software
Stage 3 which need to carry out the simulation by using software in computer lab provided in Faculty of Mechanical Engineering, UiTM Shah Alam. Regarding to Dr. Valliyappan David Natarajan, it is a new software that bought by the faculty conjunction to expanding demand in acoustics field. The software abilities can generate the architectural design instead of stimulates the sound propagation and speech intelligibility in the hall.
3.4 Data Analysis
After computing both result by using experiment and simulation, it continue with the organizing all the result for the simulation and experiment. This analysis referred to do comparison for both conditions which is reverberation time and signal-to-noise ratio related to semi fully occupied and fully occupied people (peak hour) inside the hall. This analysis will come out in the plotted graph. In addition, the result of the analysis will be discussed. In spite of that, the result of experimental pattern will be compared with simulation that executed by the software. The comparison will be discussed in the short essay.
3.5 Report writing
After going through in preparing the proposal, experiment and simulation, finally translate the entire chapter into report writing. The report writing consists of 6 chapters which the report must be below 100 pages.