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1. School Of Architecture, Building and Design
Bachelor of Science (Hons) in Architecture
Building Science II
Project 1
Auditorium: A Case Study on
Acoustic Design
Ang Averllen
Foong Wing Hoe
Ignatius Jee Shao Lang
Tan Wui Xiang
Tan Yik Ting
Tan Yincy
Yen Wei Zheng
Yong Man Kit
0321444
0320085
0320069
0321128
0325043
0318355
0320266
0319778
Tutor: Mr. Azim Sulaiman

2. CONTENTS
1.0 Introduction
1.1 Acknowledgement
1.2 Aim and Objectives
1.3 Historical Background
1.4 Site Information
1.5 Drawings
2.0 Methodology
2.1 Measuring Instruments
2.2 Data Collection Methods
2.3 Sound Equipments
2.4 Equipments Specification
3.0 Acoustical Phenomena
3.1 Acoustic in Architecture
3.2 Sound Intensity
3.3 Reverberation, Attenuation, Echoes and Sound
Shadows
3.4 Issues of Acoustic Design Strategies
3.5 Acoustic Design for Auditorium
4.0 Acoustical Analysis
4.1 Auditorium Design Analysis
4.2 Material and Properties
4.3 Acoustic Treatment and Components
4.4 Sound Sources
4.5 Noise Sources
4.6 Sound Propagation and Related Phenomena
5.0 Reverberation Time
6.0 Observation, Recommendation and Conclusion
7.0 References
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Topic

4. Acoustic design is one of the architectural and engineering techniques to control the behavior
of sound in an enclosed space, which is an auditorium in this case. The purpose is to improve sound
distribution in the enclosed space by enhancing the desired sound suited for the program. Acoustic
design also aims to eliminate noise and undesired sound that would negatively affect the desirability
of the sounds. For instance, specific measures will be taken to make sure the speech is more
intelligible or to make music sound better for the users. Building materials, architectural designs and
layouts of a space will be taken into consideration while engaging in acoustic designs.
1.2 Aim and Objectives
The auditorium Cempaka Sari is one of the landmark buildings along Persiaran Perdana. To the
west sits the Grand Mosque and to the east across Persiaran Perdana, lays the Palace of Justice. The
auditorium is connected to the Perbadanan Putrajaya Complex and it is a contemporary interpretation
of traditional Islamic architecture. The auditorium is designed as a complex consists of low-rise
medium sized buildings that are connected by pedestrian links with boutique retail spaces on the
ground floor of each component. Auditorium Cempaka Sari is best suited for events such as
exhibitions, meetings, product launch events, seminars and social events.
1.3 Historical Background
1.1 Acknowledgement
First and foremost,
we would like to thank Mr. Azim
for his guidance throughout this
project that had helped us to
improve our knowledge and
understanding on the analysis of
auditoriums. Besides, we would
also like to thank Ar. Edwin that
had given us a lecture which is
helpful to our study. Last but not
least, we are grateful to Mr.
Nazrul, whom allowed us to
conduct a site visit to the
Cempaka Sari Auditorium,
Putrajaya so that we were able to
investigate and analyze the
acoustic sound system present in
the auditorium.
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5. 1.5 Drawings
Auditorium Plan
Scale : NTS
1.4 Site Information
Name of auditorium : Auditorium Cempaka Sari
Location : Persiaran Perdana, Presint 3, 62100 Putrajaya, Malaysia
Type of auditorium : Multi purpose auditorium
Total volume : ~19000 m³
Year of construction : 2012
Total seats : 610 fixed and cushioned
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6. Third Floor Plan
Scale : NTS
Second Floor Plan
Scale : NTS
04

7. Section
Scale : NTS
Reflected Ceiling Plan
Scale : NTS
05

9. 2.1 Measuring Instruments
Digital Sound Level Meter
This device is used to measure the sound levels at a particular point within the auditorium. The
unit of measure is 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.
Measuring Devices
Measuring Tape Laser Distance Measurer
These two devices are used to obtain the measurements of our chosen auditorium and to
measure the distance of the sound level meter from the sound source when sound levels data were
taken.
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10. Digital Camera
Smart Phone
2.2 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 to make sure that the auditorium would be
unoccupied, enabling us to conduct our investigation. We 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.
Smart phone were used to play music in the
auditorium that act as a sound source at a single point.
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.
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11. The surround system that Auditorium Cempaka Sari
use is stereo system that allows panning and it adds
depth to the acoustic image. This system is perfect to
accomodate function such as speech reinforcement
and greatly enhances live or pre-recorded music. The
speakers is located at both side of the stage to give
the best horizontal coverage that listeners are well
covered by the pattern.
The speakers located at the highest position in the
auditorium beside the stage facing the crowd to
spread the sound uniformly to the whole area.
The subwoofer located at the staircase of the stage
produce bass tones and low frequency tones at the
left and right corners.
2.3 Sound Equipments
Diagram 2.3.1 Sound Are Spreaded Into the
Auditorium Uniformly
Diagram 2.3.2 The Speaker is Located at This
Position to Ensure it Reaches its Maximum
Effect
Diagram 2.3.3 The Subwoofer is Placed Beside
The Stage
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12. Product Brand Sennheiser
Dimension 685 x 455mm
Power Consumption 1500 W RMS, 4 Ohms
Weight 67lbs
Frequency 45Hz-20kHz
Sound Level 96dB
Product Brand Behringer
Dimension 640 x 400mm
Power Consumption 300W Constant, 1200W
Peak
Weight 55.2lbs
Frequency 55Hz-18kHz
Sound Level 95dB
2.4 Equipments Specification
PRO X SUB L FL
B1220 PRO
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14. 3.1 Acoustics in Architecture
Architectural acoustics is the study of the process of governing how both airborne and impact
sound is transmitted and controlled within a building design. Every element within a room, from floor
coverings to furniture affects the sound levels to some extent or another. The primary components
that designers use to control sound are floor/ceiling assemblies, wall partitions and ceiling systems.
Sound waves travel through many physical objects faster and with less loss of energy than they travel
through air. Sound moves through building spaces most commonly through air, but the primary
components can also transmit both airborne sound, such as human voices and music, and impact
sounds, such as footsteps or doors opening. The size and shape of a room could also affect how sound
waves travel as it determines how sound hits surfaces and the directions in which it is reflected.
3.2 Sound Intensity
Sound intensity is defined as the sound power per unit area. The general context is the
measurement of sound intensity in the air at a listener's location and the basic units are watts/m2 or
watts/cm2. Many sound intensity measurements are made relative to a standard threshold of hearing
intensity I0, which is
However, sound intensity levels are quoted in decibels (dB) much more often than sound
intensities in watts per meter squared. Decibels are the unit of choice in the scientific literature as well
as in the popular media. The reasons for this choice of units are related to how we perceive sounds.
How our ears perceive sound can be more accurately described by the logarithm of the intensity
rather than directly to the intensity. The sound intensity level β in decibels of a sound having an
intensity I in watts per meter squared is defined to be
where I0 = 10−12 W/m2 is a reference intensity. I0 is the lowest or threshold intensity of sound a
person with normal hearing can perceive at a frequency of 1000 Hz. Sound intensity level is not the
same as intensity. Because β is defined in terms of a ratio, it is a unitless quantity. The units of decibels
(dB) are used to indicate this ratio is multiplied by 10.
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15. Positions Silent
(dB)
Talking
(dB)
A 23 68
B 26 70
C 22 67
D 27 73
E 32 75
F 37 74
Sound Data Collection Table
A
B
D
E
F
C
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16. 3.3 Reverberation, Attenuation, Echoes and Sound Shadows
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. Hard surfaced rooms normally will
have a longer reverberation time than rooms finished with sound absorbing materials. When a sound
wave travels outward in all directions and encounters an obstacle such as a wall, floor or ceiling
surface the direction of the sound will be changed or reflected. The direction of travel of the reflected
sound will be at the same angle as the original sound striking the surface. However, if it is excessive, it
makes the sounds run together with loss of articulation and the sound would become muddy and
garbled.
When sound travels through a medium, its intensity diminishes with distance. This weakening
in the energy of the wave results from two fundamental causes, scattering and absorption. Scattering
is the reflection of sound in directions other than its original direction of propagation. Absorption is
the conversion of sound energy to other forms of energy. The combined effect of scattering and
absorption is called attenuation.
An acoustic shadow or sound shadow is a phenomenon caused by the absorption or
obstruction of sound wave by an object in its path. The effect produced is perceived as a reduction in
loudness depending on the observer's position concerning the sound source and obstructing object
and is greatest when the three are aligned. High frequencies are more easily absorbed than lower
ones and are less susceptible to diffraction, where they move less easily around objects because of
their short wavelengths. Therefore, the attenuation of high frequencies is noted in a sound shadow.
More reflected sound from the environment is also likely to be received than direct sound.
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17. 3.4 Issues of Acoustic Design Strategies
Acoustical conditions in an enclosed space are achieved when there is clarity of sound in every
part of the occupied space. The sound should increase to a suitable intensity everywhere with no
echoes or distortion of the original sound with a correct reverberation time. Thus, these acoustical
deficiencies in buildings are essential to be identified, diagnosed and rectified. To distribute the sound
evenly and to avoid areas where the sound quality is either weak, too excessive or cannot be heard
clearly, acoustical reflectors or diffusers are implemented. Reflectors and diffusers are used to
adequately reduce interfering reflections in any one direction by spreading the sound more evenly
across the space. Besides that, acoustic diffusion or sound reflection serves to accommodate a
broader sound coverage for speech and music and is often used to enhance speech intelligibility and
clarity in assembly halls, auditoriums, recording studios, theaters and classroom.
3.5 Acoustic Design for Auditorium
Selection of the Site
Before construction the first significant factor to be considered is the location. The proposed
site should be as far away as possible from noisy places, like railway tracks, highways, industrial areas
and airports for excellent acoustical quality of the hall.
Volume
The size of the hall should remain optimum, as small halls would cause uneven distribution of
sound due to the formation of stationary waves while overly large halls would create longer
reverberation time that would result in confusion and unpleasant sound.
Shape and Form
Instead of parallel walls, spade walls are preferred and curved surfaces should be built with
proper care to produce a concentration of sound in a particular precinct. Great planning is also a
necessity to assure the reduction of echoes.
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18. Use of Absorbents
The use of absorbents is imperative and a common strategy in auditorium design as the use of
proper absorbent material enhances the quality of sound. They are often used on the rear wall of the
auditorium, as well as the ceiling, as the reflection sound that occurs around these areas are of no
good.
Reverberation
Reverberation time must be controlled to a perfect balance (0.5 seconds for auditoriums, 1.2
seconds for concert halls and 3 seconds for theatres). If reverberation time is low, the intensity will be
weak while if high, the sound will be unpleasant. The proper use of absorbent materials, types of
furniture used, the presence of open windows and the capacity of the audience are all the key
components that affect the reverberation time.
Echelon Effect
The regular intervals spacing of reflecting surfaces between staircase and sets of hand railings
may produce repeated echoes and this disturbs the quality of the original sounds produced. So, thick
carpeting and wide gaps between stairs are generally preferred.
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20. 4.1 AUDITORIUM DESIGN
4.1.1 Shape and Massing
The horseshoe shaped auditorium ensure good visibility, a sense of proximity to the sound
source and mutual eye contact between the spectators. The geometry of the auditorium determines
some gaps due to a concentration of the early sound reflections on the back of the room, involving the
last rows of seats, thus causing a non-uniform spread of sound in the auditorium. This concentration
of reflections does not create optimal conditions for good acoustics due to excessive reverberation
and negative influence on the listening to music performances.
4.1.2 Volume
The ceiling height is about the one-third of the room width which is determined by the overall
room volume. The volume influences both reverberance and loudness.
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Diagram 4.1.1 Expected sound path of Auditorium Cempaka Sari

21. 4.1.3 Levelling of Seats and Stage
Raked seats and raised stage are in the most effective configuration that defines the
relationship between the speaker on stage and the audience. This arrangement of seats allow the
occupants in the furthest-most seats to hear clearly. This is possible due to the effectiveness of the
sound waves reaching the ears of the occupants when uninterrupted by any objects blocking or
absorbing it.
4.1.4 Arrangement of seats
The seat arrangement within the auditorium is a hybrid configuration which are fan shaped
and end stage. This ensures a maximum number of seats are fitted, and obtain an optimum sightline
to stage area from every seat. As spherical wavefront will be formed when sound emits from the
source, this layout helps to achieve the most effective acoustic quality as all seats fall within the angle
of the existing sound projection area.
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Diagram 4.1.2 Levelling of seats and stage used by Auditorium Cempaka Sari. This ensures optimal sound travel
to all audience. Elevated source arrangement reduce SIL loss.

22. 4.1.5 Layout of boundary surface
The hybrid configuration of convex shaped and stepped ceiling that aids in reflecting the sound
back towards the seating area and increasing the volume of the sound as it reaches the ears of the
occupants. The convex shaped ceiling scatter the sound to the middle and back part of auditorium. As
the ceiling is parallel to the floor, a little flutter echoes are being noted on stage.
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Diagram 4.1.3 Existing sound source with optimum 140 degrees wide layout ensure high frequency sounds are
able to be discerned.
Diagram 4.1.4 Expected sound reflection from ceiling of Auditorium Cempaka Sari to all audience.

23. 4.2 Material and Properties
The Cempaka Sari Auditorium uses a wide variety of components and materials to
produce the acoustic environment it currently has.
Diagram 4.2.1 Section of the auditorium showing materials and components used.
The materials can be divided into absorbent or reflector, depending on their Noise
Reduction Coefficient (NRC) rating, where the most reflective is 0 and the most absorbent is 1. In
order to achieve the desired level of reverberation time, designers have to balance their choice of
materials, and using the NRC ratings, calculate the reverberation time.
Diagram 4.2.2 Plan of the auditorium showing the floor materials..
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24. Building
Component
Material Surface
Finishers
Coefficient
125Hz 500Hz 2000Hz
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 0.05 0.07
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 0.03 0.15 0.5
Partitions Timber Laminated 0.18 0.42 0.83
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
4.2.1 Interior Material Noise Reduction Coefficient
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25. 4.2.2 Exterior Material Noise Reduction Coefficient
Building
Component
Material Surface
Finishers
Coefficient
125Hz 500Hz 2000Hz
External
Facade
Cladding
Stainless
Steel
Polished 0.35 0.44 0.54
Building
Component
Material Surface
Finishers
Coefficient
125Hz 500Hz 2000Hz
Air - - - - 0.007
Human - - 0.21 0.46 0.51
Ventillation
Grille
Aluminium Powder
Coated
0.6 0.6 0.6
4.2.3 Misc. Item Noise Reduction Coefficient
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26. Auditorium Cempaka Sari is best suited for events such as exhibitions, meetings, product launch
events, seminars, social events etc. Loud music performance or concert is not so suitable because
the acoustic quality of this auditorium caters well to talks. The equipment installed in the
auditorium along with the selected material provide better acoustic experience to speech giving or
even enhance the volume with a microphone.
i. Timber Veneer Flooring
The choice of using timber as the stage’s flooring varies. For structural and aesthetic
purpose, this type of flooring is generally much more stable and durable. While solid wood can be
prone to warping and splitting, veneer is made of layers of thin wood glued together, the chance
for splitting or cracking is reduced. Furthermore, the glue provides additional strength, resulting it
to be stronger than natural wood. Not to mention its natural tendency to reflect sound.
4.3 Acoustic Treatment and Component
4.3.1 Stage Flooring
Diagram 4.3.1.2 Close up of veneer
flooring
Diagram 4.3.1.1 Timber veneer flooring of
stage
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27. ii. Nylon Carpet Flooring
Nylon carpet fiber is a well-known synthetic carpet fiber that is considered the most
durable. Manufacturer today is able to produce the carpets in thinner, finer strands, considering
softness is a big factor for sound absorbent.
Nylon carpet flooring in the auditorium prevents hard contact with the floor, although of
no help against airborne sound transmission, it at least diminished impact sounds. The noise
reduction coefficient for typical commercial carpets is around 0.60.
Diagram 4.3.1.3 Floor carpet Diagram 4.3.1.4 Stage carpet
The vibration of the bass playing subwoofer placed on the floor compared to hard finish flooring,
reducing the direct impact from transferring to the floor structure.
Diagram 4.3.1.5 Comparison of surface Diagram 4.3.1.6 Subwoofer on carpet
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28. i. Granite (w/ uneven surface)
Granite wall has very low absorption, good for reflecting acoustic sound. Though it has a
rough and uneven surface so that the sound reflected are dispersed instead of directly reflected.
Installed on both rear of the auditorium’s interior, they help traject the sound wave from the
speaker to the audience. The granite panels have a thermal finish.
4.3.2 Wall
ii. Timber Veneer
Part of the walls in the auditorium uses the same material as the floor. The continuous use
of timber veneer is repeated at the wall near the stage.
Diagram 4.3.2.1 granite wall panels Diagram 4.3.2.2 granite surface
Diagram 4.3.2.3 timber veneer wall Diagram 4.3.2.4 timber veneer casing
26

29. 4.3.3 Ceiling
i. Gypsum Plasterboard Ceiling
The ceiling profile of Cempaka Sari has both curved edge and plane surface, to help reflect
and disperse sound wave to the audience. The gypsum plasterboard installed on battens allow
different wavelengths of sound to be reflected at various position which improves the acoustic
intimacy, clarity, and strength of the overall room’s sound.
The ceiling is plastered with a thicker gypsum board to resist any vibration. Other
properties of gypsum board includes lightweight material and also fire resistance.
Diagram 4.3.3.1 Plastered ceiling Diagram 4.3.3.2 Auditorium ceiling profile
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30. 4.3.4 Stairs
i. Timber with Nylon Carpet
The steps at the aisle of the auditorium are entirely covered with nylon carpet to reduce
the noise produced by footsteps. Carpet is an excellent sound absorptive material. This particullar
material can perform dual role of floor covering and versatile acoustical aid. Carpet can also helps
decrease the risk of airborne noise transferring to the neighbouring floor.
Nylon carpet
Acoustic
underlay
30mm acoustic
plaster board
Fixing batten
Acoustic mineral
wool
Diagram 4.3.4.1 Nylon carpet stairs Diagram 4.3.4.2 Nylon carpet aisle
Diagram 4.3.4.3 Carpet stairs section detail
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31. 4.3.5 Seating
i. Timber Structure with Fabric Cushion
The Cempaka Sari Auditorium uses timber upholstered chairs for its seating. The cushion
of the chair not only provides comfort, it also serves well as an sound absorbent, which can help
reduce the reverberation time in the auditorium.
Diagram 4.3.5.1 Upholstered tip-up chair Diagram 4.3.5.2 Upholstered tip-up chair overview
Diagram 4.3.5.3 Location of upholstered
chair on plan
It adds to the acoustical absorption of an empty
auditorium and allows the space to achieve a
similar quality of sound whether the auditorium is
filled to partial or maximum capacity. A solid, hard
material changes the acoustic performance of the
auditorium depending on the number of occupants
and the reflected sound vibrations.
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32. 4.3.6 Door
i. Solid Timber Door
The door located right beside the VIP aisle is made entirely out of timber. While the door
does not have any fancy soundproofing component, it is still extremely functional in term of
acoustic insulation, as a solid chunk of timber is naturally good at reflecting sound waves.
However, the door seems to create squeaky noises when opening/closing, and can thus create
interruption in the acoustic environment.
Diagram 4.3.6.1 Solid Timber Door beside VIP aisle
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33. 4.3.7 Curtain
i. Cotton Velour Curtain
Velour curtains can dramatically reduce high frequency echo and excessive reverb in a
room. Velour curtains primarily intended for sound absorption need to be as heavy as possible
with 75% - 100% fullness. Adding extra layers through double facing or lining will provide
additional sound dampening. The heavier the finished curtain, the better the sound absorption.
The two key factors in sound absorption are mass and air space.
The air space decouples the layers of mass. Increasing the thickness(mass) of the curtain
will have some effect, but less of an effect than increasing the air space. The biggest initial
gain in sound absorption comes by creating the air space to begin with.
Cotton fabrics tend to perform slightly better than synthetics due to the added mass. This
highly porous textile act as thousands of tiny sound traps, which capture and absorbs the
energy. The pleated curtain expose more surface area for sound absorption to occur,
hence, providing a better acoustic performance.
Diagram 4.3.7.1 Double layer curtain damping the sound wave
Diagram 4.3.7.1 Double layer curtain Diagram 4.3.7.2 Pleated cotton curtain
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34. 4.3.8 Partitions
i. Timber partitions with acoustic panels
The VIP Area is surrounded by timber partitions to distinguish itself amongst the rest. The
partitions are made out of timber panels with timber structures, with nothing but void in it.
Because of that, when the occupants accidentally hit the partition, it can create a loud noise,
which can be extremely disruptive. To counteract that, the partitions are installed with fabric
acoustic panels, which can help reduce the impact. Not only that, the acoustic panels also help
reduce the echo in the small echo chamber which is the VIP area.
Figure 4.3.1 The VIP Area in Cempaka Sari Auditorium
32

35. 4.3.9 Acoustic Panels
i. Timber Perforated Acoustic panels
Perforated panels are the most economical way to get an acoustic treatment with a high
degree of absorption. It comes in various pattern and hole diameter, different intensity in sound
absorption and aesthetic results can be achieved.
The acoustic material absorbs or dampen the sound waves that emits from stage.
Generally, the idea is to prevent the sounds from echoing off the walls of an enclosed space. If
this issue is left unchecked, it would leave the audience with a confusing experience.
Mostly used as acoustic correction, applicable to walls and ceilings, but in this case the
auditorium had the installations with exposed covering on the walls in lacquered surface finishes.
Features
● HOLE DIAMETER: 34mm
● SPACING: 115x117mm align
● PERFORATED SURFACE: 3.4%
● THICKNESS: 12mm/16mm
Diagram 4.3.9.1 Timber Perforated Panels
15mm Barricade noise barrier
10mm Gypsum board
10mm Mineral wool
insulation
10mm Acoustic
plasterboard
5mm Acoustic fabric
Air cavity
34mm Diameter hole opening
Timber Perforated Panel
Diagram 4.3.9.3 Construction Detail of Timber Perforated Panels (example)
Diagram 4.3.9.2 Acoustic panel section detail
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36. ii. Muslin Fabric with Cotton Felt
The sound absorption panels can be found at the VIP entrance, as well as the
on the partitions of the VIP area. The placement of the panels is to absorb the
sound produce from the people walking up and down the stairs beside the VIP area.
Preventing disruption from footsteps and squeaky noise produce by the loose
timber floor panel. Besides that, the acoustic panel also help absorb noise from
outside coming in through the doorway, as well as the squeaky noise produce by
the door itself.
Diagram 4.3.9.4 Acoustic panel around the
entrance
Diagram 4.3.9.5 Muslin fabric
material texture
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37. i. Double Sheet Stainless Steel Skin
The exterior of the auditorium is cladded with polished stainless steel. The
stainless steel cladding serves as a primary insulator against noise pollution from
the exterior environment. However, due to the lack of thickness of the steel plate
used, the steel plates might absorb sound waves and proceed to vibrate, which can
contribute to the noise pollution.
4.3.10 Exterior Facade
Diagram 4.3.10.1 Stainless Steel Cladding
35

38. i. Powder Coated Aluminium Grille
The Cempaka Sari Auditorium consists of four ventillation grilles. The openings of
ventilation grilles allow sound waves to escape or enter the auditorium, and thus it is best
installed high up on the wall.
4.3.11 Ventilation Grille
Diagram 4.3.11.1 Ventilation Grill
36

39. The external noise that affect the user experience in
the auditorium is the event that located at entrance
downstairs. The event uses sound amplifier devices
to amplify the voices hence create noises penetrate
into the auditorium
The lobby of the auditorium before entering the
spaces has sitting area and people would gather
around it creates some external noises as well.
As the Cempaka Sari Auditorium is located beside of
the main road which is Jalan Persiaran Perdana
causes it to create sound pollution and affect the
event in the building itself.
4.4 External Noise
Diagram 4.4.2 The Lobby Before Entering
Auditorium
Diagram 4.4.1 The Event At Ground Floor That
Create Noise
Diagram 4.4.3 Highlighting The Road That In
Front of Auditorium
37

40. The internal noises that can be found in the auditorium hall
is the stage, because of flooring material factors that it made
from wood.
The next internal noises is is that the wall of the backstage
is made out of pure concrete without any other absorbent
material.
The VIP entrance or sitting area of the auditorium is also one
of the internal noises because of its wooden flooring. While
the VIP enters the lounge sitting area it will create noises as
they are secondary entrance at the sitting area which direct
the external noises in there
4.5 Internal Noise
Diagram 4.5.1 Highlighting The Stage
Diagram 4.5.2 Highlighting The Back Stage
Diagram 4.5.3 Highlighting The Entrance
To The VIP Area
38

41. Air-conditioning at the ceiling create noises when its
switch on at full fan speed. As the sizes of the auditorium is huge
so the circulation of air flow by constantly changing the freshness
of air is very important hence the air-conditioning is one of the
main internal noises.
Air blower located at the end of the stage to help
circulate the air is also one of the noise contributor to the space.
Anti-slip rubber at the edge of the staircase caused noise
when it is stepped on. Woman shoes especially high heels would
contribute to more noise.
Diagram 4.5.5 Anti-slip rubber
Diagram 4.5.4 Portable Air Blower
Diagram 4.5.3 Air Conditioning Vents
39

42. 4.6 Sound Propagations and Related Phenomena
The measurement of the auditorium from a fixed sound source, outputting a constant 500Hz at
80dB, has resulted in the following findings:
1. The auditorium’s form has severely affects the clarity of sounds at certain spaces.
2. The back seats receives multiple sound reflections.
3. The auditorium receives excessive reverbs, affecting the speech intelligibility.
4.6.1 Sound Concentration
The sound concentration zone of the auditorium can be determined through the measurement of
the sound intensity level (SIL) from the sound source. There is a distinct sound concentration at
the back of the auditorium.
The varies in sound concentration causes by the horseshoe form of the auditorium, resulting in an
early sound reflections on the back of the room and thus, created a non-uniform spread of sound
in the auditorium.
Diagram 4.6.1 SIL measurement of the auditorium
40

43. The sound concentration zone is created through the auditorium’s horseshoe form.
Insufficient usage of sound absorbent materials at the back of auditorium has caused the sound to
be concentrated in the back seats.
Diagram 4.6.2 Sound Reflection Diagram. The detrimental design of the auditorium reflecting
the sound path towards the back seats.
Absorbant
Absorbancy coefficient at
500Hz > 0.1
Reflective
Absorbancy coefficient at
500Hz < 0.1
Diagram 4.6.3 Sound Reflection Diagram with materials.
The authorities has taken steps to reduce the impact of sound concentration in the
auditorium through the implement of timber perforated acoustic panels at the sides. The rear
concrete facade causes large amount of sound reflection at the back seats.
41

44. 4.6.2 Sound Reflections
The sound is reflected back towards the audience in order to increase the acoustic quality of the
auditorium. However, the added design of reflection and the amount of these reflection must be
controlled to minimize the sound defection by echoes.
The plasterboard ceiling functions effectively to reflect the sound back to the audience.
Nonetheless, the auditorium floor has to be covered with absorbent materials to minimize the
resultant reflected sound to ensure clarity of sound transmission.
Absorbant
Absorbancy coefficient at
500Hz > 0.1
Reflective
Absorbancy coefficient at
500Hz < 0.1
Diagram 4.6.4 Sound propagation towards individual at Row 3, proving the lack of
reflected sounds.
Absorbant
Absorbancy coefficient at
500Hz > 0.1
Reflective
Absorbancy coefficient at
500Hz < 0.1
Diagram 4.6.5 Sound propagation towards individual at Row 8, proving adequate
sound reflection to the vip seats.
42

45. The authority has implemented a combination of absorbent materials onto the auditorium’s
flooring and facade to create a rich soundscape. However, the concrete rear facade has resulted in
excessive sound reflection at the back seats, severely obstructing the audience’s experience.
Diagram 4.6.6 Sound propagation towards individual at Row 16, proving excessive
sound reflection to the back seats.
Absorbant
Absorbancy coefficient at
500Hz > 0.1
Reflective
Absorbancy coefficient at
500Hz < 0.1
4.6.3 Echoes and Sound Delay
Echoes are the distinctive repetition of the original sound whereas a reverberation is
perceived when the reflected sound wave reaches subject’s ear in less than 0.1 second after
the original sound wave.
In an auditorium, the reflective surface plays the major role as an effective source of sound
delay. In Cempaka Sari auditorium, sound delay of 40ms and above will be considered as an
echo as it is an auditorium catering for speech.
Time Delay
= (12.6+12.2-6.2)/0.34
=54.7ms
Diagram 4.6.7 A time delay of 54.7ms towards row 3 exceeded the optimum sound
delay for a speech auditorium.
43

46. Direct Sound
Time Delay
= (16.0+11.0-15.8)/0.34
=32.9ms
Diagram 4.6.8 A time delay of 32.9ms towards row 8 is acceptable for a speech-oriented
auditorium.
Time Delay
= (25.7+7.8-30.1)/0.34
=10.0ms
Diagram 4.6.9 A time delay of 10.0ms towards row 16 is acceptable for a speech-oriented
auditorium.
In conclusion, the sound delay in the VIP area and the back seats are optimum and suitable for
the use of speech. The front seats may suffer intelligible sound caused by the echoes as it has a
sound delay higher than the optimum level of 40ms.
44

48. 5.0 Reverberation Time Calculation
The reverberation in Cempaka Sari auditorium is considered as excessive as the desirable
reverberation for an auditorium falls between 1.4 to 2.0. The reverberation time of Cempaka Sari is
2.16 seconds, which is not conducive for good speech intelligibility.
Surface Absorption
Perforated Acoustic
Panels
=351.4m2 x 0.80
=281.12m2 sabins
Carpet
=1336m2 x 0.60
=801.60m2 sabins
Curtain
=273.5m2 x 0.50
=136.75m2 sabins
Total absorption of room surface
= (281.12 + 801.60 +136.75+188.10)
= 1407.57m2 sabins
Diagram 4.6.10 Surface
Absorption of materials
implemented in Cempaka Sari
Auditorium
Reverberation Time
=0.16(19000m3 )/1407.57m2 sabins
= 2.16seconds
Diagram 4.6.11 Reverberation time of Cempaka Sari Auditorium.
19000m3
Fabric Chairs
= 318.8m2 x 0.59
=188.10m2 sabins
46

50. 6.1 Observations
Based on our analysis and calculation, the auditorium has an high reverberation time,
which create echoes that is more suitable for musical performance, rather than speeches and talks.
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.
Despite all the issues, the auditorium does have a few good side about it. For example, sounds
can be heard loud and clear throughout the entire auditorium, even without the use of microphones.
The auditorium is also very welly soundproofed, with thick concave walls surrounding the space as
well as sealed door, both helps prevent sound waves from going out of the interior space, and vice
versa.
48

51. Maintenance
Scheduled maintenance, to fix loose screw
and bolt, greasing door hinge and handle to
prevent unwanted noise that would affect or
disturb the auditorium’s acoustic experience.
6.2 Recommendations
More absorbent
The Cempaka Sari Auditorium can benefit
from installing more absorbent materials such
to reduce the reverberation time to a much
more desirable length.
49
Air-conditioning
Provide sufficient air conditioning or better
ventilation to avoid using portable ventilation
system, which may perform poorly and
produce loud noise.
Replacing old carpets
Replace and refurbish the auditorium with
new carpets that are softer and with better
enhanced synthetic material as it could help to
improve the acoustic issue. Better absorption
of sound to cancel the echoes.

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7.0 References
51