Auditorium

1. AUDITORIUM:
A CASE STUDY ON ACOUSTIC DESIGN
BUILDING SCIENCE II
ARC3413/BLD61303
SEMESTER 5
BACHELOR OF SCIENCE (HONS) IN ARCHITECTURE
SCHOOL OF ARCHITECTURE BUILDING AND DESIGN
LECTURER: MR. AZIM SULAIMAN
GROUP MEMBERS:
ALAN KOO
CANISIUS BONG
JOYCE WEE
KAN SOOK SAN
LIEW JIN
LUM SI CHU
MAXIMILIAN LIM
ONG EUXUAN
RICCO SOH
0318757
0318914
0319602
0319326
0318449
0319502
0319604
0319050
0319890

2. 2
TABLE OF CONTENT
INTRODUCTION ……………………………………………………..3
Historical Background
- Organization
- Building
Auditorium
DRAWINGS………………………………………………………….6
Plans
Section
SOUND ABSORPTION………………………………………………...9
Finishing Materials
- Floors
- Walls
- Ceilings
- Seats
Acoustic Wall Panelling / Treatment
- Stretched Fabric Panels
- Hardwood Wall Slats
SOUND SOURCE………………………………………………….….18
Sound Systems
- Single Speaker Cabinets
- Line Array Speakers
- Stage Monitors
Noise Intrusion Areas
SOUND PATH /
PROPOGATION………………………………………25
Sound Shadow Area
Sound Reflection
- Ceilings
- Walls
Sound Diffraction
REVERBERATION TIME……………………………………………..33

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INTRODUCTION

4. 4
HISTORICAL BACKGROUND
Organization: Sidang Injil Borneo Kuala Lumpur (SIBKL)
As one of the most established protestant churches in Malaysia, Sidang Injil Borneo was started in
Sarawak, and has been around for nearly ninety years. In 1999, SIBKL became a cell church for the
Sidang Injil Borneo, and operates more than 90 cell groups for people of all ages across the region.
Case Study Location: Bangunan Yin, Jalan Damansara
Weekly Sunday sessions of SIBKL are carried out every Sunday in Bangunan Yin, located in Phileo
Damansara,Petaling Jaya. Bangunan Yin is a multi-storey building that houses the church, as well as
smaller offices during the weekdays.

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AUDITORIUM
SIBKL Auditorium, Bangunan Yin, Jalan Damansara
Type ofAuditorium: Multipurpose (Speech and Music)
Shape: Fan-shaped
Total Volume: 11393 m3
Total Floor Area: 2120 sqm
Year of Completion:
Sunday sessions and church events are carried out in the auditorium of Bangunan Yin, located on the
fifth and sixth floor of the building. The auditorium has two floors, and has a seating capacity for more
than 1500 people. It has a fan-shaped balcony that hovers over the auditorium, multiplying its space,
allowing the auditorium to hold more audience.

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DRAWINGS
FloorPlans

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Fifth Floor Plan of Bangunan Yin
Sixth Floor Plan of Bangunan Yin
SECTIONS

8. 8
Sections of Bangunan Yin

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SOUND ABSORPTION
Sound absorption is defined as the change in sound energy into heat energy, as the incident sound that
strikes a material that is not reflected back. It is also one of the major factors in creating good acoustic
space, especially when controlling reverberation. Soft and porous materials like fabrics serve as good
acoustic insulators which means it absorbs most of the sound.
Finishing Materials
Floor

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Location of carpeted floor on auditorium plans
Material: Carpet (Porous Absorber)
Absorption coefficient for thick pile carpet: 0.50
Carpet is the antithesis of hard, echoing surfaces. Sound waves are effectively absorbed and deflected
by the carpet and by the padding under the carpet,and the level of sound absorption can be enhanced
with a thicker pad.
Walls

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Material 1: Fabric
Absorption coefficient for fabric: 0.90
The walls of the auditorium is covered with fabric wrapped wall panels. These wall panels serve to
reduce echo and reverberation in the auditorium, improving the intelligibility of sound within the space.
Material 2: Timber Hardwood
Absorption coefficient for Belian timber hardwood: 0.42
Timber is also greatly used on wall slats in the auditorium. Its reflective nature performs strongly for
acoustics.Due to internal friction within the substructure of wood, timber has a strong sound dampening
capacity, allowing to control its echoand reverberation by reducing the transmission of sound vibration.
Ceiling

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Location of timber finishing on auditorium reflected ceiling plans
Material 1: Timber Hardwood
Absorption coefficient for timber hardwood: 0.42
The ceilings of the auditorium are lined with timber convex reflective surfaces. Parts of the ceilings are
also comprised of strips of timber slats. Timber is reflective and has a strong sound dampening capacity.

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Location of gypsum boards on auditorium reflected ceiling plans
Material 2: Gypsum Board
Absorption coefficient for plaster board:0.08
Gypsum board is a plasterboard panel material. It is constructed with joints and fastener heads that will
eventually be covered with a joint compound system to create a continuous surface for ceilings and
walls. In the case of this auditorium, it is used to produce edges and concave surfaces that would help
with the reflection of sound.

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Seats
Location of cushioned seatings on auditorium plans
Material: Cushioned Fabric Seatings (Porous Absorber)
Absorption coefficient for cushion fabric: 0.64
There is a total of 1584 cushioned seats in the auditorium (1117 seats at the bottom seating region, 467
seats on the balcony’s upper seating region).
To make the hearing conditions satisfactory when the room is full or partly full, upholstered seats with
absorbing material at the bottom are used, so that the absence or presence of audience does not affect
the reverberation time.

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Acoustic Wall Panelling/ Treatment
This auditorium installed individual panels of slit wooden resonators that alternate between stretched
fabric panels on its walls to maximize the sound absorbing quality of the space.

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Stretched Fabric Panels
Material 1: Stretched Fabric Panels (Membrane Absorber)
These wall panels are used to reduce echo and reverberation in the auditorium. They are constructed
from a rigid acoustical board, and are covered with acoustically transparent fabrics. The fabric on the
panels help to reduce echo and reverberation.
Advantages of fabric wrapped panel absorber:
- Maximize absorption of broadband sound frequencies, from 40 Hz to 20 kHz.
- Reduce excessive reverberation, flutter echo and primary reflections, increasing the
intelligibility of speech and clarity of sound.
- Easy installation
- Impact resistant, sturdy, lightweight construction
- Easy maintenance

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Hardwood Wall Slats
Materials: Hardwood Wall Slats (Cavity Absorber)
Beyond the cavities of the wall panels are narrow necks that lead down to air spaces.The enclosed body
of air are contained within these rigid panels. The sound that propagates within the auditorium will be
trapped in these air spaces to reduce sound reflection within the space.

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SOUND SOURCE
Sound source is the source of where sound waves are generated. It creates vibrations in the
surrounding medium, allowing them to propagate. Generally, within an auditorium, the source of
sound is usually the sound system speakers.
Sound Systems

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A typical sound system in an auditorium may include a combination of microphones, signal processors,
amplifiers and loudspeakers in speaker cabinets. These systems reinforce sound to enhance its volume,
then distribute it to a larger audience.

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The sound system in the auditorium is controlled by an audio mixing board that makes live sounds
louder, and also distributes those sounds to a wider audience. It may also enhance or add effects the
sound of the sources on stage.

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Single Speaker Cabinets
Single Speaker Cabinets ultimately reproduces tone as sound waves in the air—which are what reaches
the listener’s ear,or a studio microphone.
Position of speaker cabinets on auditorium plan
There are 8 speakers placed at the front of the stage. Instead of placing them on the floor, the speakers
are placed elevated on stage platform so that the high frequencies project over the heads of the audience
members closest to the stage. 2 of the speakers are placed slanted to the left and right to balance the
sound waves in the auditorium.

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Line Array Speakers
A line array speaker is a loudspeaker system that is made up of a number of usually
identical loudspeaker elements mounted in a line. The distance betweenadjacent drivers is close enough
that they constructively interfere with each other to send sound waves with a more evenly distributed
sound output pattern.
Position of speakers
There are 2 ofthese speakers placed in the hanging position above the stage on the left and right. These
speakers are curved with the bottom part angled down to provide extra coverage at locations close to
the front of stage, where else the top half will be angled upwards towards the audience at the top
mezzanine floor of the auditorium.

23. 23
Stage Monitor Speakers
A stage monitor is a type of speaker used on stage in auditoriums and halls where accurate audio
reproduction is crucial. These speakers help amplify the sound when acoustic instruments or voice are
used, allowing the performers on stage to hear themselves.
Position of studio monitors on auditorium plan
There are 2 ofthese speakers placed in front of the stage by the stairs. They are placed on the ground,
allowing it to project sound towards the stage, helping musicians on stage to focus and monitor the
audio, allowing acoustic instruments and vocals to be heard over electronic instruments and drums.

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Possible Noise Intrusions
Noise intrusion on fifth floor plan
The possible noises that could affect the auditorium is the lift lobby and the auditorium lobby where
guests and users gather or enter the auditorium.
Noise intrusion on sixth floor plan
The other possible noises could be from the lobby of the mezzanine floor where people gather or first
enter the auditorium.

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SOUND PROPAGATION
Sound propagation (or sound path) shows the movement of sound traveling. During the propagation
of sound, these sound waves can be reflected, refracted, diffracted, or attentuated by the medium.

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Sound path in section
Sound path in plan

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Sound Shadow Area
Sound shadow is an acoustic defect where an area through which sound waves fail to propagate. The
sound shadow area in this auditorium is the seating area located under the balcony.
Sound shadow area shown in section
The balcony cantilevers over the seating area on the fifth floor of the building, making the jutted out
structure a obstruction, blocking sound waves from entering the region.

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Solution
Single speakers are added on the ceiling at the bottom of the balcony, projecting sound towards the
audience in the sound shadow area, preventing sound shadowing, thus allowing them to receive the
sound waves.
Location of additional single speakers in floor plan and reflected ceiling plan
Sound shadow area solved shown in section

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Sound Reflection
Sound reflection occurs when a wave reaches the boundary between objects, part of the waves
undergoes reflection and another part undergoes transmission across the boundary. Despite he fact that
auditoriums typically avoid using hard and smooth materials in the construction of their inside halls,
these reflective surfaces may still be of use to distribute and reinforce sound.
Ceilings
Tilted Ceiling
The ceiling of the auditorium is irregular, and properly tilted to allow more useful reflection of sound.
As opposed to a flat ceiling, the range of useful ceiling reflections is wider.
Tilted ceiling in section

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Convex Surfaces
Sound is reflected on hard surfaces in the auditorium. They tend to reflect off flat surfaces uniformly,
but when they hit convex surfaces,it causes sound dispersion. Convex reflecting surfaces are lined on
the ceilings and are used to disperse sound.
Convex surfaces in section

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Walls
Tilted Walls
The irregular walls of the auditorium are properly tilted to allow more useful reflecion of sound. These
walls are lined and covered with fabric panels as well as hardwood. The hardwood surface allow the
reflection of sound within the auditorium.
Tilted walls in plan

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Sound diffraction
Sound diffraction occurs when the sound waves pass through an opening or around a barrier in their
path, causing a change in direction.
In the case of this auditorium, the balcony that houses the audio console became the obstruction that
splits the sound waves that propagates from the speakers. The sound waves then pass through different
directions, going to different floors of the auditorium.
The cantilevered balcony is a narrow obstruction, giving the sound waves bigger wavelengths.

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REVERBERATION TIME

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On the basis of the presented results, we can see that the reverberation time is 0.6 seconds and is still
within the exceeded normal RT of theater for speech, which is a maximum of 1 second. We have
concluded that the reverberation time obtained is slightly shorter for the function of the room.
Neverthelessit is still considered favorable because the paths of direct sounds wavesto audience should
be as short as possible, to reduce sound energy loss.
Area (m2) Absorption
Coefficient
Absorption Units
Floor
Carpet 2138.4 0.5 1069.2
Parquet Wood 116.34 0.07 8.14
Ceiling
Gypsum Plaster Board 909.4 0.15 136.42
Timber Hardwood 337.1 0.42 141.58
Wall
Left
Fabric Panel 142.1 0.9 127.9
Belian Timber Hardwood 150.3 0.42 63.1
Gypsum Wall Board 24.7 0.08 1.98
Right
Fabric Panel 137.7 0.9 123.9
Belian Timber Harwood 151.4 0.42 63.6
Gypsum Wall Board 24.7 0.08 1.98
Front
Belian Timber Harwood 9.4 0.42 3.9
Gypsum Wall Board 163.9 0.08 13.11
Curtain 236.5 0.4 94.6
Back
Fabric Panel 127 0.9 114.3
Belian Timber Harwood 195.1 0.42 81.9
Glass 2.88 0.1 0.29
Other

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Cushioned Fabric 1948.3 0.64 1246.9
3292.8
Total Volume: 11393 m3