Compilation

School of Architecture, Building and Design
Bachelor of Science (Hons) in Architecture
BUILDING SCIENCE II (ARC 3413 / BLD61303)
Project 1
Auditorium: A Case Study on Acoustic Design
(Cempaka Sari Auditorium)
Heng Sy Hua 0321999
Koo Jian Xiang 0322975
Carlson Ko 0319564
Madeline Liew Zhi Qi 0322150
Phares Phung Chi Meng 0323554
Ong Von Wan 0323364
Aaron Chong Yu Ho 0320270
Dixon Kee 0323944
Khoo Ming Sen 0319659
Tutor: Mr. Edwin

A Case Study on Acoustic Design: Cempaka Sari Auditorium
Table of Content
1. Introduction
1.1. Acknowledgement
1.2. Aim and Objectives
1.3. Site Information
1.4. Historical Background
1.5. Drawings
2. Acoustical Theory
2.1. Acoustic in Architecture
2.2. Sound Intensity Level
2.3. Reverberation, Attenuation, Echoes and Sound Shadows
2.4. Issues of Acoustic Design Strategies
2.5. Acoustic Design for an Auditorium
3. Methodology
3.1. Measuring Equipment
3.2. Method of Data Collection
3.3. Sound Equipment (maybe this and the specification can be tgt)
3.4. Equipments Specification
4. Acoustical Analysis
4.1. Auditorium Design Analysis
4.2. Material and Properties
4.3. Acoustic Treatment and Components
4.4. External noise
4.5. Internal noise
4.6. Sound Propagation and Related Phenomena
4.7. Reverberation Time
5. Observation, Recommendation and Conclusion
5.1. Recommendation
5.2. Conclusion
6. References
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PART 1:
INTRODUCTION
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1.1 Acknowledgement
Sincerely, we would like to thank our lecturers Mr Azim and Mr Edwin that guide us
through this project by teaching us all necessary theories about Acoustic studies. They
also placed much effort by organising study trips and most importantly willing to answer
all our question patiently. Our tutor, Mr Edwin also guided us with suggestion that had
given us new perspective to increase the richness of our report. Without any doubt, i
would also like to thank the School of Architecture Building and Design (SABD) to
provide us a comfortable environment for discussion and gives us the opportunity to
carry out our research topics. Last but not least, we are also thankful for all of our fellow
friends and groupmates that support us both physical and mentally throughout the whole
project without all the encouragement and contribution, we would not able to produce
this report.
Diagram 1.1.1 Group photo for site visit.
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1.2 Aim and objectives
Acoustic design is one of the architectural and engineering techniques to control the
quality and behaviour of sound in an enclosed space. For this project, we are required to
investigate the acoustic design in an auditorium. With this study, we are able to
understand the purpose of improving sound distribution in an enclosed space and
enhancing the desired sound suited for respective program. Another aim for acoustic
design is to get rid of undesirable sound that could affect the sound quality in the space.
Hence, through this project we are able to determine how the materiality, design layout
and space will affect the the acoustic design. Also, the design consideration in acoustic
analysis so that best acoustic effect can be achieved.
1.3 Site Information
Name of auditorium: Auditorium Cempaka Sari
Location: Persiaran Perdana, Presint 3, 62100 Putrajaya, Malaysia.
Type if auditorium: Multi purpose auditorium
Total volume: approx. 19000 cubic metre
Year of construction: 2012
Total seats: 610 cushioned seat
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1.4 Historical Background
The auditorium of cempaka sari situated in Putrajaya and is one of the landmark
building along the road, Persiaran Perdana. Surrounding Cempaka Sari, Grand mosque
sits to the west and Palace of Justice at the east. A mixture of contemporary architecture
mixed with islamic architecture can be seen as the Perdana Putrajaya Complex is
connected to the auditorium. The auditorium consist of 5 floors and it is connected to a
low rise medium size complex through a pedestrian link where some boutique and retail
space are located at the complex. Cempaka Sari is a multipurpose auditorium where all
kinds of events including talks, art performance and musical performance, product
launch event and seminars can be held in the space.
Diagram 1.4.1 Interior of Cempaka Sari Auditorium.
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1.5 Drawings
AUDITORIUM PLAN
SCALE : NOT TO SCALE
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SECOND FLOOR PLAN
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THIRD FLOOR PLAN
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REFLECTED CEILING PLAN
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SECTION
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Part 2
Acoustical Theory
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2.1 Acoustics in Architecture
Architecture acoustics is the investigation of the way toward overseeing how both
airborne and effect sound is transmitted and controlled inside a building design. Each
component inside a room, from floor covers to furniture influences the sound levels to
some degree or another. The essential segments that architects use to control sound are
floor/ceiling gatherings, wall partitions and ceiling frameworks. Sound waves go through
numerous physical protests speedier and with less misfortune vitality than they go
through air. Sound travels through building spaces most ordinarily through air, however
the essential segments can likewise transmit both airborne sound, for example, human
voices and music, and effect sounds, for example, strides or entryways opening. The size
and state of a room could likewise influence how stable waves go as it decides how stable
hits surfaces and bearings in which it is reflected.
2.2 Sound Intensity
Sound intensity is characterized as the sound power per unit zone. The general setting is
the estimation of sound force noticeable all around at an audience's area and the essential
units are watts/m² or watts/cm². Numerous sound force estimations are made with
respect to a standard edge of hearing power 10, which is
In any case, sound intensity levels are cited in decibels (dB) significantly more regularly
than sound escalates in watts per m². Decibels are the unit of decision in the logical
writing and also in the well-known media. The purposes behind this selection of units are
identified with how we see sounds. How our ears see sound can be all the more precisely
depict by logarithm of the force as opposed to straightforwardly to the power. The sound
intensity level β in decibels a sound having a force I in watts per meter squared is
characterized to be
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Where is Io = 10-12
Wm-2
is a reference intensity. Io is the least or limit power of sound a
man with typical hearing can see at recurrence of 1000Hz. Sound force level isn't the
same as power. Since β is characterized as far as a proportion, it is a unitless amount.
The units of decibels (dB) are utilized to demonstrate this proportion is duplicated by 10.
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POSITIONS SILENT (dB) TALKING (dB)
A 20 67
B 20 65
C 22 66
D 25 71
E 20 68
F 30 74
G 35 75
H 38 73
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2.3 Reverberation, Attenuation, Echoes and Sound Shadows
Reverberation
Reverberation is the collection of reflected sounds from the surfaces in an enclosure like
an auditorium. It is a desirable property of auditoriums to the extent that it helps to
overcome the inverse square law dropoff of sound intensity in the enclosure.
Reverberation is frequency dependent: the length of the decay, or reverberation time,
receives special consideration in the architectural design of spaces which need to have
specific reverberation times to achieve optimum performance for their intended activity.
Attenuation
The intensity of a sound traveling through a medium diminished with distance. The
weakening in the energy is a result of two different causes, absorption and scattering.
Scattering of a sound is the reflection in direction of its propagation away from its
original direction. Absorption occurs when sound energy is converted to other forms of
energy. Attenuation is the combined effect of scattering and absorption of the sound.
Echoes
Echo is a reflection of sound that arrives at the listener with a delay after the direct
sound. The delay is proportional to the distance of the reflecting surface from the source
and the listener. A true echo is a single reflection of the sound source.
Sound Shadows
Sound shadow, also known as Acoustic shadow, is an area through which sound waves
fail to propagate, due to topographical obstructions or disruption of the waves. The effect
produced is perceived as a reduction in loudness depending on the observer's position
with respect to the sound source and obstructing object and is greatest when the three
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are aligned. High frequencies are more easily absorbed than lower ones, and are less
susceptible to diffraction, that is, they move less easily around objects because of their
short wavelengths. Therefore, the attenuation of high frequencies is noted in a sound
shadow.
3.4 Issues of Acoustic Design Strategies
Clarity of Sound
Acoustical condition is achieved when there is clarity of sound in every corner of the
space. The sound should reach to an intensity when needed with no distortion and
echoes of the original sound with the suitable reverberation time. To achieve that clarity
of sound, these acoustical deficiencies has to be identified and rectified. Acoustical
reflectors and diffusers are implemented to adequately reduce interfering reflections in
any one direction by spreading the sound more evenly across the space and to avoid areas
where the sound quality is either weak, too excessive or cannot be heard clearly. Besides
that, acoustic diffusion or sound reflection serves as a broader sound coverage for speech
and music. It is often used to enhance speech intelligibility and clarity in assembly halls,
auditoriums, recording studios, theaters and classroom.
2.5 Acoustic Design for Auditorium
Selection of the Site
Before development the principal huge factor to be considered is the area. The proposed
site ought to be as far away as conceivable from uproarious spots, similar to railroad
tracks, roadways, modern zones and airplane terminals for brilliant acoustical nature of
the corridor.
Volume
The size of the hall ought to stay ideal, as little hall would make uneven conveyance of
sound due the arrangement of stationary waves while excessively huge halls would make
longer resonation time that would bring about perplexity and unsavoury sound.
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Shape and Form
Rather than parallel walls, spade walls are favoured and curved surfaces ought to be
worked with appropriate care to produce concentration of sound in a specific area. Great
planning is likewise a need to guarantee the reduction of echoes.
Use of Absorbents
The utilization of absorbents is imperative and a typical methodology in auditorium
design as the utilization of legitimate absorbent material improves the quality of sound.
They are frequently utilized on the back wall of the assembly hall, and also the ceiling as
the reflection sound that happens around these regions are of no great.
Reverberation
Resonation time must be controlled to an immaculate adjust (0l5 seconds for assembly
room, 1.2 seconds for concert halls and 3 seconds for theatres). If the reverberation times
is low, the power will be weak while if high, the sound will be unpleasant. The best
possible utilization of absorbent materials, sorts of furniture utilization, the presence of
open windows and limit of the gathering of people are all the key parts that influence the
reverberation time.
Echelon Effect
The normal interims separating of reflecting surfaces amongst staircase and sets of hand
railings may create repeated echoes and this bothers the quality of the first sounds
delivered. In this way, thick covering of carpeting and wide gaps between stairs are for
the most preferred.
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PART 3:
METHODOLOGY
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3.1 Measuring Instruments
Measuring Devices
Diagram 3.1.1 Measuring tape and laser distance measurer.
These two devices are used to get the measurement of Auditorium Cempaka Sari and to
measure the distance of the sound level meter from the sound source when sound levels
data were taken. Size of the cushioned seatings and the stage are also being taken for
research purposes.
Digital Sound Level Meter
Diagram 3.1.2 Digital sound level metre.
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This device is used to measure the sound levels at a particular point within the
auditorium. The unit of measures decibels (dB). It is commonly a hand-held instrument
with a microphone and the diaphragm of the microphone responds to changes in air
pressure caused by sound waves. With this tools, the level of sound in different point and
situations are recorded down during the site visit.
Digital Camera
Diagram 3.1.3 Digital camera.
A digital camera is used to document the existing context within our auditorium and aid
on our analysis after the site visit. Images and videos were taken as evidence. Pictures of
texture and design of each components are also being taken to analysis it characteristics
and usage in acoustic design.
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Smart Phone
Diagram 3.1.4 Smartphone.
Smart phone was used to play music in the auditorium that act as a source at a single
point. Some pictures are also being taken by smartphone by the group members whom
didn't bring a digital camera.
3.2 Data Collection Method
To assure that the site visit could be carried out smoothly and without interruption,
formal arrangements were made with the person in charge , Mr. Fazrul prior the visit
through emails and phone call. This effort is made to make sure that the auditorium will
be unoccupied and available for us to carry out our investigation. Also, this act is to make
sure that the management of Auditorium Cempaka Sari had given us the permission to
take detail pictures and necessary readings. Hence documented as many details as
possible during the visit with the help of all the tools mentioned above along with all the
necessary measurements required to assist our analysis.
3.3 Sound Equipment
Auditorium Cempaka Sari utilizes a stereo speaker system that provides a more diverse
and richer depth to the acoustic image by adding a panning function to the speakers. The
stereo speakers are located on two sides of the stage to distribute the sound to the users
equally in a horizontal manner. This system is usually utilized for functions like
prerecorded music and speech reinforcement.
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Diagram 3.3.1 Shows how sound are spreaded in the auditorium
The auditorium utilizes subwoofers at the staircase on the main stage. The subwoofers
are placed on two sides of the stage as a stereo system that produces bass and low
frequency tones equally to the users from a lower angle.
Diagram 3.3.2 Shows the position of speaker in order to get the best sound quality.
Stereo speakers are hung on two sides of the ceiling above the stage of Auditorium
Cempaka Sari. The speakers distributes the sound waves equally to the whole auditorium
as it placed at horizontal level to the highest seat.
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Diagram 3.3.3 Shows the position of subwoofer beside the stage.
3.4 Equipment Specifications
PRODUCT BRAND SENNHEISER
MODEL
PRO X SUB L FL
WEIGHT 67 Ibs
DIMENSIONS (H) 685mm x (W) 455mm
SOUND LEVEL 96 dB
FREQUENCY 45 Hz - 20,000 Hz
POWER CONSUMPTION 1500 W RMS, 4 Ohm
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PRODUCT BRAND BEHRINGER
MODEL
B 1220 PRO
WEIGHT 55.2 Ibs
DIMENSIONS (H) 640mm x (W)
400mm
SOUND LEVEL 95 dB
FREQUENCY 55 Hz - 18,000 Hz
POWER
CONSUMPTION
300 W Constant, 1200 W
Peak
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PART 4:
ACOUSTICAL ANALYSIS
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4.1 Auditorium Design
4.1.1 Shape
The unique horseshoe shaped auditorium ensures that the message are transferred
effectively to the listeners due to good visibility. As the communication between the
presenter and the listeners are what determines whether a presentation is successful or
not.
Some of the disadvantages of this geometrical form is that sound are not spread equally.
This is because of the gaps in the back of the room. This concentration of reflection
creates a situation where acoustics cannot be transmitted efficiently. This is because the
excessive reverberation between the presenter and the one listening.
Diagram 4.1.1 Expected sound path of the auditorium
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4.1.2 Massing
Cempaka Sari Auditorium is built in a hovering egg like structure. Columns are used to lift the
egg structure in the air. With this larger space is separated from the lobby area to the auditorium
to decrease the noise destruction from outside the building as well as the exhibition area below.
Double layer shell structure creates air gap between the walls and thus act as a sound insulation
system preventing sound from entering or escaping the auditorium.
Diagram 4.1.2 Section of the auditorium.
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4.1.2 Volume
The height of the auditorium is approximately one-third of the width of the room. This is
determined through the approximate amount of the room volume. This total volume
ultimately effects both reverberation and loudness.
4.1.3 Leveling of Seats and Stage
One of the most effective configuration that helps in enhancing the relationship between
the speaker and the floor are raked seats and raised stage. This unique arrangement of
seats ensures that the audience from the furthest seats can listen to the presentation
clearly. When reverberation does not exist or is at its lowest due to it not interrupted by
any blocking objects or objects absorbing it, the efficiency of the sound waves reaching
each and every one of the ears present in the auditorium is enhanced. This is to ensure
the optimal sound travel to every audience. Elevated source arrangement will decrease
the loss of SIL
Diagram 4.1.3 Leveling of seats and stage used by Auditorium Cempaka Sari.
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4.1.4 Arrangement of Seats
The seat arrangement within the auditorium is a hybrid between fan shaped and end
stage arrangement which ensure a maximum number of seats are fitted in and to get a
clear view from any seats to the stage itself. When sound are emitted from the presenter,
a spherical wavefront will be formed. This layout ensures that the most effective acoustic
quality are delivered as all seats are within the angle of the existing sound projection area,
which, in this case, is the presenter.
Diagram 4.1.4 Existing sound source with optimum 140 degree wide layout ensuring high
frequency sound are able to be discerned
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4.1.5 Layout of boundary surfaces
This hybrid configuration between a convex shape and a stepped ceiling aids in the
reflection of sound back towards the audience seating area, thus, this increases the
volume of the sound when it reaches their ears. This convex shaped ceiling separate the
sound to the middle and to the back part of the auditorium. The ceiling is however,
parallel to the floor, therefore, a small amount of flutter echoes can be slightly heard on
the stage.
Diagram 4.1.5 Expected sound reflection from the stage to the audience.
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4.2 Material and Properties
The cempaka sari auditorium are constructed by using various elements and materials to
create the current acoustic environment.
Absorbent or reflector materials are divided depends on the Noise Reduction Coefficient
(NRC) rating. Designers have to balancing their choice of materials to achieve the level of
reverberation time that they wanted by using the NRC ratings to calculate the
reverberation time. Where the most reflective materials and most absorbent materials is 0
and 1 respectively.
4.2.1 Interior Material Noise Reduction Coefficient
Building
Component
Material Surface
Finishes
Coefficient
125 Hz 500 Hz 2000 Hz
Flooring Timber Veneer 0.18 0.42 0.83
Nylon Carpet - 0.60 -
Wall Granite Uneven
Surface
0.01 0.02 0.03
Timber Laminated 0.18 0.42 0.83
Ceiling Battens Gypsum
Plasterboard
0.29 0.08 0.04
Stairs Timber Laminated 0.18 0.42 0.83
Nylon Carpet - 0.60 -
Seating Timber and
Fabric
-- 0.13 0.59 0.61
Door Timber Laminated 0.14 0.06 0.10
Curtain Velour - 0.14 0.50 0.70
Partitions Timber Laminated 0.18 0.42 0.83
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Acoustic
Panel
Perforated
Veneer
Chipboard
Laminated 0.41 0.58 0.68
Porous Fibre -- 0.85 0.80 0.90
Cotton Felt Muslin
Fabric
0.15 0.70 0.95
4.2.2 Exterior Material Noise Reduction Coefficient
Building
Component
Material Surface
Finishes
Coefficient
125 Hz 500 Hz 2000 Hz
External
Façade
Cladding
Stainless
Steel
Polished 0.35 0.44 0.54
4.2.3 Misc Item Noise Reduction Coefficient
Building
Component
Material Surface
Finishes
Coefficient
125 Hz 500 Hz 2000 Hz
Air - - - - 0.007
Human - - 0.21 0.46 0.51
Ventilation
Grille
Aluminium Powder
Coated
0.60 0.60 0.60
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4.3 Acoustic Treatment and Components
A huge part of the audience’s experience in your auditorium design will be the acoustics.
The ideal acoustic environment in an auditorium is one where the visual and auditory
experiences are both captivating, intimate, and efficient. The auditory experience is
uniquely shaped by the acoustics of each room. This brief overview of natural acoustics is
aimed at giving designers some basic fundamentals on how the room acoustics of a space
are effected by design choices that an architect would make. We will start off with a brief
description of how our ear works in the context of listening.
Diagram 4.3.1 Shows the components used for the wall of the auditorium.
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Diagram 4.321 Shows the components used for the plan view of the auditorium.
4.3.1 Main Acoustic Treatment principle:
1. Shoebox-shaped rooms provide for strong early lateral reflections (even more
important for music, but quite helpful for speech as well)
2. Reflections down from a ceiling can often provide early reflections, and therefore
should be made acoustically hard (reflective)
3. The back walls of an auditorium have a risk of providing late reflections – both to
the audience and to the stage: Providing acoustic absorption at such locations is
usually helpful. This could be in the form of fabric panels, slatted wood finish,
acoustic plaster or even acoustic drywall.
4. The audience seats and the audience themselves are usually the biggest acoustic
absorption in the room. The use of the right amount of acoustic absorption in the
seats can serve as a great way to achieve the acoustic goals of the space.
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4.3.2 Stage Flooring
4.3.2.1 Timber Veneer Flooring
Timber veneer is made out of multiple layers of thin wood. It is prone to splitting or
cracking. Its natural characteristic is very strong, which makes it very durable compare to
other normal woods. Aesthetically wise, timber veneer has smooth and flat finishing
surface, which has the tendency to reflect on sound, thus it creates footstep noise while
walking on it.
Diagram 4.3.2.1 and 4.3.2.2 Closed up view of the stage timber veneer flooring.
4.3.2.2 Nylon Carpet Flooring
Nylon carpet is dubbed the most durable synthetic carpet on the current market. Its
function is to diminish the sound and transfer it onto the lower level. In this case, it helps
with absorbing the vibration from speakers, mainly subwoofers, from the auditorium. The
noise reduction coefficient for typical commercial carpets is around 0.60. The placement
of subwoofer are also placed on the carpet to reduce direct impact with the floor
structure.
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Diagram 4.3.2.3 and 4.3.2.4 Closed up view of the nylon carpet flooring.
4.3.3 Wall
4.3.3.1 Granite Surface
The granite wall found in the auditorium has one special characteristic – it’s surface is
uneven. It makes the granite wall panel a low level absorption material because it diffuses
acoustic sound. For instance, it transposes the sound waves from the speaker to the
audience. The granite panels also have a thermal finish.
Diagram 4.3.2.5 shows close up view of Granite surface
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4.3.3.2 Timber Veneer
This material is same as the flooring to create a continuity effect for visual as well as
maintain the acoustic quality
Diagram 4.3.2.6 shows Timber veneer walls around the stage.
4.3.4 Ceiling
4.3.4.1 Gypsum Plasterboard Ceiling
Gypsum plasterboard is a lightweight material with the capability of fire-proofing. It is
thicker in mass to resist vibration from the speakers, thus it creates a different leveling
and profile for sound to disperse and reflect. In this auditorium, the ceiling profile has
both curved edge and plane surface, to help reflect and disperse soundwave to the
audience.
Diagram 4.3.2.7 and 4.3.2.8 shows the ceiling in the auditorium and its close up view.
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4.3.5 Stairs
4.3.5.1 Timber Stairs with Nylon Carpet
The nylon carpet on the steps at the aisle of the auditorium help reduces footstep noises
when users walk up or down. It acts as a sound absorbent for the component. Also, it can
perform dual role of floor covering and versatile acoustical aid. Nylon carpet can also
help decrease the risk of airborne noise transferring to the neighbouring floor.
Diagram 4.3.2.9 shows the Nylon carpet stairs.
Diagram 4.3.2.10 shows the section stairs details.
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4.3.6 Door
4.3.6.1 Solid Timber Door
There is a door located beside the VIP seating connecting to the VIP lounge. The door is
entirely made out of timber without any carvings or design to maintain its functionally as
sound insulation. Timber is good in reflecting sound wave and insulation, however,
greasing need to be done to ensure the door does not give out squeaky sound and create
internal noise.
Diagram 4.3.2.11 and 4.3.2.12 shows the door in VIP seating and the close up material view.
4.3.6 Acoustic Panels
4.3.6.1 Timber perforated acoustic panels
Perforated panels are the most economical way to get an acoustic treatment with a high
degree of absorption. The main purpose of acoustic panels is to absorbs and dampen the
sound waves from the stage. With several variations of patterns and hole diameters,
different levels of absorption and aesthetic results can be achieved. It is used for acoustic
correction, which is applicable to walls and ceilings.
The panels in the auditorium has a hole diameter of 34 mm and spacing of 115x117mm
align with each other. The thickness of the hole is either 12mm or 16mm. The perforated
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panels are placed surrounding the auditorium and in a diagonal shape.
Diagram 4.3.2.13 and 4.3.2.14 shows perforated panels and its alignment in the auditorium.
4.3.6.2 Muslin Fabric with Cotton Felt
This type of panels can be found surrounding the VIP seating and its entrance. The
panels are used to absorb the walking sound as well as the door opening sound made by
the people. Apart from the the panel also function as absorbing the sound that coming
from outside the hall and improve the sound insulation.
Diagram 4.3.2.15 and 4.3.2.16 shows fabric panels and its location in the auditorium.
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4.3.7 Curtain
4.3.7.1 Cotton Velour Curtain
These curtains can be found on the stage and its main usage in acoustic design is to
reduce high frequency echo and excessive reverb in a room. The heavier the curtain, the
better the sound absorption. Hence, adding extra layers through double facing or lining
will indeed provide additional sound dampening effect. The 2 key factor in sound
absorption are mass and air space. Although the increasing of mass of the curtain are
relatively less effective than increasing the air space cotton fabrics still tends to perform
slightly better than synthetic material due to its added mass. The porous textile has tiny
sound traps that will capture and absorbs the sound energy and thus dampening the
sound wave. The pleated curtain also exposed larger surface area for the sound
absorption to occurs and providing a better acoustic effect during the performance.
Diagram 4.3.2.17 and 4.3.2.18 shows pleated cotton curtains and its close up view.
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4.3.8 Seating
4.3.8.1 Timber Frame with Fabric Cushion
Cempaka Sai Auditorium used upholstered chairs for better human circulation among
the seatings. Cushion is lined on top of the seating to increase the comfort as well as
increase sound absorbent. With this, the reverberation time of the auditorium can be
reduce. Also, the cushions add on the acoustical absorption of the auditorium while it is
empty so that the space has similar acoustic quality no matter how full the crowd in the
auditorium is.
Diagram 4.3.2.19 and 4.3.2.20 shows the overall seating in the auditorium and the close up view of
the seating cushion.
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4.4 External noise
The location of Cempaka Sari Auditorium is not an ideal location, because sound
pollution creates from the main road of Jalan Persiaran Perdana will affect the building
itself.
Diagram 4.4.1 Location Map of Cempaka Sari Auditorium
Diagram 4.4.2 Street view of Persiaran Perdana
Event located at the entrance downstairs is also one of the source of external noise. The
events uses sound amplifier devices hence create noise penetration into the auditorium
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Diagram 4.4.3 shows the entrance of exhibition hall below the auditorium.
Diagram 4.4.4 shows the event held below the auditorium.
External noise also happened when people gather around at the lobby of the auditorium
which has a huge space and also sitting areas.
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Diagram 4.4.5 Auditorium Lobby
4.5 Internal noise
Diagram 4.5.1 Overall Internal Noise source in the auditorium
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Source of internal noise can be found on top of the stages, because of the wood materials
of the flooring of the stage causes noises.
Diagram 4.5.2 Highlight of the stage
Internal noise can be found on the wall of the backstage that made out of pure concrete
without covering it with any sound absorbent materials.
Diagram 4.5.3 Highlight of the backstage
Air blower located at the end of the stage also one of the noise source to the auditorium
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Diagram 4.5.4 Air blower in the auditorium.
Anti-slip rubber along the edge of the staircase also creates noise when people stepped
on. Woman shoes, especially high heels would also creates more noises.
Air-conditioning at the ceiling of the auditorium is also source of noise. Because of the
huge size of the auditorium, circulation of air flow is important. Hence full fan speed is
needed sometimes to change the freshness of the air rapidly.
Diagram 4.5.5 Pictures of ceiling air-conditioning
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Diagram 4.5.6 Ceiling plan of the auditorium.
VIP entrance is also one of the source of the internal noise. While VIP's enters the lounge,
it will create noises while also bringing external noises in simultaneously.
Diagram 4.5.7 Entrance from VIP lounge
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4.6 Sound Propagation and Related Phenomena
The measurement taken for the auditorium has played from a fixed sound source,
outputting a constant 500Hz at 80dB, has resulted in the following findings:
1. The horseshoe form of the auditorium has influenced the clarity of sound at
certain spaces.
2. The back seats receives excessive sound reflections.
3. The auditorium receives excessive reverbs, influencing the delivery of speech.
4.6.1 Sound Concentration
Due to the horseshoe form of the auditorium, a non-uniform spread of sound can be
found in the auditorium. It is caused by the early sound reflection at the back of the
auditorium. The sound concentration zone of the auditorium can be determined with the
measurement of the sound intensity level from the sound source. A distinct sound
concentration can be found at the back of the auditorium.
Diagram 4.6.1 : SIL Measurement of Cempaka Sari auditorium
49

Diagram 4.6.2 Sound Reflection Diagram. The detrimental design of the auditorium reflecting the
sound path towards the back seats
.
Diagram 4.6.3 Sound Reflection Diagram with absorbent and reflective materials.
50

The authorities at Cempaka Sari auditorium has implemented timber perforated acoustic
panels at the side to reduce the impact of sound concentration. The back concrete facade
resulted in a large amount of sound reflection at the back sea
4.6.2 Sound Reflections
Reflection is used in room acoustic to deliver and reinforce sound wave transmitted to
the audience. Only 10% of the sound heard by the audience is direct sound; the other 90%
sound is reflected by reflective surfaces to redirect sound to the audience. Hence, the
added design of reflection must be determined carefully to minimize the sound defection
by echoes. Audience hear sound from both direct sound and reflected sound waves.
Diagram 4.6.4 Direct sound wave(blue dotted line) and reflected sound wave(orange line)
directed to the audience .
In Cempaka Sari Auditorium, the plasterboard ceiling reflects the sound back to the
audience effectively. To minimize the resultant sound reflection, the floor has been
covered with carpet to act as absorbent material to ensure the sound transmission clarity.
With the combination of absorbent material implemented to the auditorium design, it
created a rich soundscape for the audience yet there is a flaw in the design. The rear
facade made from concrete has resulted in excessive sound reflection at the back seat,
hence disturbing audience’s experience in the auditorium.
51

Diagram 4.6.5 Sound propagation towards audience at front rows, proving the lack of reflected
sounds.
Diagram 4.6.6 Sound propagation towards individual at VIP seat area, proving adequate sound
reflection to the audience.
52

Diagram 4.6.7 Sound propagation towards individual at back seats, proving excessive sound
reflection to the back seats, disturbing the audience experience.
4.6.3 Echoes and Sound Delay
Echoes occurs when the audience hear a reflected sound wave from a source in less than
0.1 second after the original sound wave. By using the formula of [R1 + R2 -D = delay
distance ], we can find out the delay time of sound wave at different point in the
auditorium.
Time Delay = [ T = (R1 + R2 -D) / Vs ]
Diagram 4.6.7 The time delay for row 3 is 54.7ms, which is not suitable for a speech-oriented
auditorium.
53

Diagram 4.6.8 The time delay for the VIP seat in row 8 is 32.9ms, which is suitable for a
speech-oriented auditorium.
Diagram 4.6.9 The time delay for the back seat at row 16 is 10.6ms, which is suitable for a
speech-oriented auditorium.
Reflective surface plays a significant role as an effective sound source delay in a
auditorium. Thus, in Cempaka Sari auditorium, a sound delay of 40ms and above is
considered as an echo as it is designed to cater for multipurpose usage.
The front seat can experience intelligible sound caused by echoes as it has a sound delay
that exceed the optimum level of 40ms. The sound delay in the VIP seats and the back
seats are most favorable for the delivery of a speech.
54

4.7 Reverberation Time Calculation
Diagram 4.7.1 Surface Absorption of Materials in Cempaka Sari auditorium.
Surface Absorption:
Material Surface Area
(m2
)
500 Hz
Absorption
Coefficient
Absorption
units (m2
sabins)
Perforated Acoustic Panels 351.4 0.80 281.12
Nylon Carpet 1336 0.60 801.60
Chairs 318.8 0.59 188.10
Velour Curtain 273.5 0.50 136.75
Timber Veneer Flooring 409.9 0.42 172.16
Timber Veneer Wall 96.32 0.42 40.45
Total Absorption (A) 1620.18
Reverberation Time:
RT = 0.16V
A
= 0.16 (19000m3
) / 1620.18m2
sabins
= 1.88 seconds
55

As Cempaka Sari auditorium is categorize as a multipurpose hall, the reverberation time
of 1.88 seconds is in the range of the desired values. The range of 1.0 - 2.0 second is a
desirable reverberation time range for a large-sized, multi purpose auditorium that is to
be used for both speech and music. In addition, Sabine’s formula tend to overestimate the
reverberation time from other unforeseen variables.
56

Part 5:
Observation, Recommendation and
Conclusion
57

5.1 Recommendation
Various kind of act can be take in place in order to maintain the quality of the auditorium
and ensure the acoustic effect is functioning
Firstly, scheduled maintenance should be held to fix the loose screw, bolt and grease the
door hinge and handle to prevent unwanted noise that would affect or decrease the
acoustic effect. Also major maintenance also have to be organized by inviting professional
sound specialist to test out the acoustic level and make sure it is well maintained.
Next, Cempaka Sari Auditorium can reduce its reverberation time to the desirable length
by adding in more sound absorbent to increase its acoustic effect.
Thirdly, old carpets and cushion should be replace from time to time as new carpets are
relatively softer and better. This is will indirectly improve the acoustic issue in the
auditorium. With better absorption of sound, echoes are able to be absorb and sound
quality can be improved.
Last but not least, air conditioning system should be serviced occasionally in order to
reduce the noise destruction. Also ventilation system will be improved so that portable air
blower that will give out huge noise to the space can be eliminated.
5.2 Observation and conclusion
In summary, this auditorium case study project has brought us a huge learning outcome
for us. It let us understand how the acoustic design works better depends on the
functions of the auditorium and uses the acoustic design to make the users comfort. The
auditorium layout and the materials used on the structure and furniture, such as walls,
floor, chairs, etc, can effectively affect the acoustic inside the auditorium hall and even
can efficiently affect the sound from the outside of the auditorium hall.
An auditorium is a special room built to enable an audience to hear and watch
performances and may be used for rehearsal, presentation, performing arts productions.
Apart from entertainment, an auditorium also used for a space for speech delivery such
as lecture theatres, reading performances and competitions. A successful design of and
auditorium depends on its acoustic design such as the auditorium layout and absorption
58

materials used to preserve and enhance the desired sound and to eliminate noise and
unwanted sound.
Based on our analysis and calculation, the auditorium has a optimum reverberation time
for a multipurpose hall, which create echoes that is suitable for both speech musical
performance. Besides that, opening and closing of the doors can be a disruption to the
environment due to the squeaky noise that are created. In addition to that, the
uncarpeted timber floors in the auditorium creates loud footstep noises when walked on.
59

Part 6:
Reference
60

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14. Barron, M. (n.d.) Auditorium acoustics and architectural design. Retrieved from
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