Acoustical analysis of DPAC

SCHOOL OF ARCHITECTURE, BUILDING AND DESIGN BACHELOR
OF SCIENCE (HONS) IN ARCHITECTURE
Building Science II [BLD 61303]
Project 1
Case Study on Acoustic Design
Prepared by :
Chong Jia Yi
Ee Yun Shan
Lee Ning
Lee Zi Ying
Lim Zia Huei
Ong Shi Hui
Rachael Cheong Kah Yen
Teo Kuo Chien
0320869
0319990
0320125
0320435
0321031
0320303
0319926
0320195
Tutor : Mr. Azim Sulaiman

1
1.1 Aim and Objectives
1.2 Site Information and Historical Background
2
.1 Floor Plan
2.2 Reflected Ceiling Plan
23 ections
3
3.1 Architectural Acoustics
3.2 Issues of Acoustic Design Strategies
3.3 Acoustic Design for an Auditorium
4
4.1Measuring Equipments
4.2Method of Data Collection
5
Material Absorption Coefficient-hazel
Identification of Existing Sound Source/ Noise - fish
6
7
TABLE OF CONTENTS
INTRODUCTION
1.2 Site Information and Historical Background
ARCHITECTURAL DRAWINGS
2.1 Floor Plan
2.2 Reflected Ceiling Plan
2.3 Sections
ACOUSTICS PHENOMENA
3.1 Introduction of Acoustics
3.2 Acoustics in Architectural
METHODOLOGY
4.1 Measuring Equipments
4.2 Method of Data Collection
ACOUSTICAL ANALYSIS
5.1 Material Absorption Coefficient-hazel
5.2 Identification of Existing Sound Source/ Noise
ANALYSIS AND FINDINGS
6.1 Sound propagation
6.2 Different Phenomena in Sound
ACOUSTICAL DEFECTS AND DESIGN ISSUES
7.1 Poor Ensemble
7.2 Sound shadow
7.3 Poor Sound Isolation
7.4 Mechanical Noises
CONCLUSION8

AUDITORIUM VIEW
Figure 1 : View of auditorium from stage
Figure 2 : View of stage

1 INTRODUCTION
The aim and objectives of this report is to showcase our analysis and understanding on the acoustic theory in a
particular auditorium. Learning outcome are as followed:
- To study and understand the influences of the auditorium layout towards the public address system in a
auditorium hall
- To study the characteristic and elements of the acoustic features of an auditorium hall and understand
the function of the specific feature.
1.2 Site
1.2.1 Basic Information
Name of Auditorium : Damansara Performing Arts Centre
Location : H-01, DPAC, Empire Damansara,
Jalan PJU 8/8, Damansara Perdana,
47820 Petaling Jaya, Selangor, Malaysia.
Type of Auditorium : Multipurpose Auditorium
Total Seat : Maximum 200 seat capacity
Stage Size : 11.25m (width) x 7.25m (depth)
1.2.2 Historical Background
In the year of 2013, DPAC Dance Company (DDC) was formed along with the establishment of Damansara
Performing Art Center (DPAC), under the guidance and direction of Artistic Director, Wong Jyh Shyonh. The aim of
the company was to present an in-house dance production with the engagement of local artists and collaborative
projects between Malaysian and international dance artist. Damansara Performing Arts Centre (DPAC) taking
form of a new arts space to meet the growing needs of arts practitioner and arts aficionados in the Damansara
district since then.
Dedication of Damansara Performing Arts Centre (DPAC) is strong in promoting arts through learning, practising,
and appreciating arts in Malaysia. Since the establishment of the company, DPAC aims to further enhance public
awareness on the importance of art-forms that enrich lives while shaping today’s world. DPAC has a proscenium
theatre, a black box, an experimental theatre, an indoor theater-foyer and several dance studios. All facilities are
all state-of-the-art equipped to cater professional practices of different performing arts practitioners in various
forms.
Damansara Performing Arts Centre are not a standalone building, but was fitted into the site between the carpark
and office building. Multiple modification are was made to accommodate the auditorium. A column was removed
to accommodate more seats and avoid view disturbance, metal truss are used to replace the column and to hold
up the roof. Room were extended to increase the sound insulation,and industrial metal containers and plates are
used for interior finishes. These multiple modification can accommodate up to 200 people with two changing
rooms, with one at the back stage and one on the level above.

2 ARCHITECTURAL DRAWINGS
2.1 Floor Plan
Scale 1 :150

2.2 Ceiling Plan
Scale 1 :150

2.3 Section
Scale 1 : 150

3 ACOUSTIC PHENOMENA
3.1 Introduction of Acoustics
Acoustic is a study of vibration in the air, which produces frequency that can be detected by human’s ears, where
sound is formed. There are two basic characteristics of acoustics which include intensity and frequency.
Intensity knows as loudness, is measured in decibels, abbreviated dB. The level of 1 decibel is the lowest noise
an average person’s ear. Frequency is the number of times per second a sound vibration occurs, 1 vibration per
second is a hertz (abbreviated Hz). Humans hear vibrations the range from 20 per second(low frequency) to
10000 per second(high frequency).
3.2 Acoustics in Architecture
Acoustics is the term used to describe the “science of sounds”. It deals with the study of all mechanical waves in
matters such as gases, liquids and solids. “Sound”, however, can be defined as vibration in an elastic medium like
gases, liquids (air, water) or any solid, physical object that can return to its normal state after being deflected.
Sound can be reflected, absorbed, transmitted and diffracted. It is comparatively different to “noise”, though the
two are often associated and mistaken for one another by the public. The difference is in its meaning; “sound” is
any sort of vibration that can be deemed desirable, or pleasant, “noise”, on the other hand, is undesirable and
often disturbing. Whilst it is often considered to be a hindrance, noise in its own service, is important. For
example, the sounds of fire alarms or loud music can be deemed irritable, but can also be beneficial in certain
cases when it can be controlled. Understanding these differences and knowing how to utilize building materials,
system designs and technologies are key factors behind any successful acoustical design. While the science
behind sound is well understood, using that knowledge to create an efficient acoustical performance within a
specific building or room is a complex practice. There is no single “solution” or “formula” that can be universally
applied to any building design as each built environment offers its own unique set of acoustical parameters.
3.2.1 Sound Intensity Level (SIL)
Sound energy is conveyed to our ears by means of a wave motion through some elastic medium (gas, liquid, or
solid). At any given point in the medium, the energy content of the wave disturbance varies as well as the square
of the amplitude of the wave motion. That said, if the amplitude of the oscillation is doubled, the energy of the
wave motion is quadrupled. The common method in gauging this energy transport is to measure the rate at which
energy is passing a certain point. This concept is dubbed as “sound intensity”. Consider an area that is normal to
the direction of the sound waves. If the area is a unit, namely one square meter, the quantity of sound energy
expressed in Joules that passes through the unit area in one second defines the sound intensity. The time rate of
energy transfer is then referred to as its "power" – written in the unit: “Watt” (1W is equal to 1 Joule/s). In
simpler terms, this means that the sound intensity is the power per square meter. Normally, sound intensity is
measured as a relative ratio to some standard intensity. The response of the human ear to sound waves closely
follows a logarithmic function of the form “R = k logI", where “R” is the response to a sound that has an intensity
of “I”, and “k” is the constant of proportionality. Thus, we define the relative sound intensity level as SL(dB) =
10log I Io The unit of SL is called a “decibel” (abbreviated as dB). “I” is the intensity of the sound expressed in
watts per meter and “Io” is the reference intensity defined to be 10-12 W/m2. This value of “Io” is the threshold
(minimum sound intensity) of hearing at 1 kHz, for a young person under the best circumstances. Notice that
“I/Io” is a unit-less ratio; the intensities need only to be expressed in the same units, not necessarily W/m2.

3.2.2 Reverberation, Attenuation, Echoes and Sound Shadows
Sound reverberation is the persistence of sound reflection after the source of the sound has ceased.
Reverberation can have both a positive and a negative effect in architectural design. For example, specifying
highly reflective ceiling panels directly above the stage area in an auditorium will help direct the sound toward
specific seating areas, thus enhancing the room’s acoustical performance. However, that same reflective
performance will become a negative factor if said highly reflective walls and ceiling materials are installed in the
rear of the auditorium. That’s because the sound reflections from the rear of the room take too long to reach the
audience, resulting in a distracting echo effect. When sound travels through a medium, its intensity diminishes
with distance. In idealized materials, sound pressure (signal amplitude) is only reduced by the spreading of the
wave. Natural materials, however, all produce an effect which further weakens the sound. This further weakening
results from scattering and absorption. Scattering is the reflection of the sound in directions other than its
original direction of propagation. Absorption is the conversion of the sound energy to other forms of energy. The
combined effect of scattering and absorption is called attenuation. An acoustic shadow or sound shadow is an
area through which sound waves fail to propagate, due to topographical obstructions or disruption of the waves
via phenomena such as wind currents, buildings, or sound barriers. A short distance acoustic shadow occurs
behind a building or a sound barrier. The sound from a source is shielded by the obstruction. Due to diffraction
around the object, it will not be completely silent in the sound shadow. The amplitude of the sound can be
reduced considerably however, depending on the additional distance the sound must travel between source and
receiver. Sound reflection occurs when sound waves bounce off smooth, hard wall, ceiling and floor surfaces.
Concave surfaces tend to concentrate or focus reflected sound in one area. Convex surfaces do just the opposite;
they tend to disperse sound in multiple directions.
Acoustical conditions in an enclosed space is achieved when there is clarity of sound in every part of the
occupied space. For this to occur, the sound should rise to a suitable intensity everywhere with no echoes or
distortion of the original sound, and with a correct reverberation time. Thus, these acoustical defects in buildings
are important to recognize, diagnose and rectify. Acoustical reflectors or diffusers are implemented to evenly
distribute the sound and to avoid areas where the sound quality is either weak, too excessive or cannot be heard
clearly. Acoustic diffusion or sound reflection helps to provide a wider sound coverage for speech & music, and
are often used to improve speech intelligibility and clarity in theatres, assembly halls, auditoriums, recording
studios and classrooms. In addition to this, reflectors and diffusers are used to effectively reduce interfering
reflections in any one direction by distributing the sound more evenly across the space.

3.4.1 Selection of the site
The proposed site for the auditorium should be as far away as possible from noisy places, like railway tracks,
roads with heavy traffic, airports, and industrial vicinities.
3.4.2 Volume
The size of the auditorium should remain optimum: small halls leads to irregular distribution of sound because of
the formation of standing waves. On the other hand, overly large halls create a weaker intensity and longer
reverberation time which may result in serious hearing issues.
3.4.3 Shape and Form
One of the most important parameters to be considered for an acoustically efficient auditorium design is the
shape and form. Reflections are mainly created due to the presence of side walls and roof of the auditorium; thus,
great planning is a must to ensure the reduction of echoes. In the case of parallel walls, splayed side walls are
preferred. Curved surface on walls, ceilings or floors are also ideal when the aim is to produce a concentration of
sound in a specific region.
3.4.4 Use of Absorbents
When the construction of an auditorium is completed; there are still certain inaccuracies that require further
improvements to achieve a better acoustical design. Hence, the use of absorbents is essential and a common
strategy in amphitheater design. They are often used at the rear wall of the amphitheater, as well as the ceiling,
as the reflection sound that occurs around these areas are of no benefit.
3.4.5 Reverberation
Reverberation time must be controlled to be a perfect balance (e.g. 0.5 seconds for auditoriums, 1.2 seconds for
concert hall and 2 seconds for theatres). The proper use of absorbent materials, the capacity of audience,
presence of open windows, types of furniture used, are all examples of important components that affect the
reverberation time.
3.4.6 Echelon Effect
In an auditorium, any set of hand railings, staircases or any regular spacing of reflected surfaces may produce a
musical note due to regular succession of echoes of the original sound. This disturbs the quality of the original
sounds produced.

3 ACOUSTIC DESIGN ANALYSIS
3. 1 Shape and Massing
The auditorium is a basic rectangular shape with a slight angle inward to the stage from the view at the entrance.
The seating space right in front of the entrance form an extra capacity to fit more audience but with that odd
location of seat it became a sound shadow area where direct and reflected sound can hardly approach.
Sound
shadow
Diagram 1 : The shape of auditorium

3. 2 Levelling of Seats
In order to ensure that sound waves reach the ears of every occupants within the auditorium clearly, the designer
should take in consider the levelling of the seating area.
Diagram 3 : Elevated seats arrangement.
Diagram 2 : Seats arranged in single level.
When the seats are arranged in a single level, the sound waves could not travel to the furthermost seat. The
sound energy will be absorbed by the sound absorbers along the way such as people and cushioned seats. Hence,
the sound waves will die out by the time it reached the second.
By raising the level of seats, the listener can receive the direct sound without blocking by absorbers.

3. 3 Arrangement of seat
The arrangement of seats in DPAC are efficient as sound able to transmit to all parts of the theatre. The distance
between the sound sources (stage) and the back seats are within the range of 15m, the optimum distance for
human voice to be heard clearly. Moreover, theatre seats are placed within a 140-degree angle of sound
projection. This allowed the high frequency sound to be discern. The row of the seats at the side of the theatre
are tilted to face the stage for allow visual intimacy as well as acoustical consideration as the sound travel in
spherical order. Therefore the arrangement of seats of DPAC are considered well configured except for the seats
that fall into sound shadow zone.
Diagram 4 : Plan showing the efficiency of seats arrangement in aspect of dimension and position
Sound
shadow

4 METHODOLOGY
4.1 Equipment
4.1.1 Digital Sound Level Meter
The digital sound level meter is used to measure the sound level from a particular point within the auditorium. The
unit is measured in decibels (dBA).
4.1.2 Photography Device
Digital camera and Smartphone are used to capture photos of the build material of the auditorium, equipment
installed in the auditorium (speaker, lighting, air-conditioning system, ceiling… etc), finishing material of the
auditorium, position of sound source as a mean of evidence for our analysis.
Figure 3 : Digital sound level meter
Figure 4 : Digital camera Figure 5 : Smartphone

4 METHODOLOGY
4.1.3 Measuring Devices
Measuring tape and laser distance measurer are used to measure the dimension of the auditorium for drawing
purposes and to measure the distance of the sound source to the digital sound level meter for calculation
purposes.
4.2 Data Collection Method
Prior arrangement were made before the visit to ensure the auditorium are unoccupied to conduct a more
accurate analysis without disturbance. Architectural drawings are obtain prior to the site visit, measurement of
the auditorium are checked to ensure an accurate result. In order to obtain a more accurate analysis, all
recordings are obtained in 3 decimals points. Every recording are taken 2 times and the average recording are
used. Measurement of the auditorium were taken for drawing and calculation purposes.
Figure 6 : Measuring tape Figure 7 : Laser distance measurer

5 ACOUSTICAL ANALYSIS
5.1 Material and Absorption Coefficient
5.1.1 Wall
Acoustically treated wall
The wall of DPAC is an acoustically treated wall. It consists of three layers, which are fibre board, rock wool and
concrete. The wall of DPAC is designed to absorb sound because most of the materials used are high reflection.
Rockwool is a soft material that combine with both thermal and sound absorption. It also has fire retardant
properties. Fibreboard is easy to work with and quick to install. It is dense but breathes to allow the sound
transfer through it. Fibreboard makes the wall more effective absorber as it absorbs high frequencies than rock
wool.
Zig-zag steel panels
Zig-zag steel panels are installed to serve as acoustical and aesthetic purpose which hiding the lighting wires. It
create sound diffusion that improve the liveliness of the theatre. However, excessive placement of it would trap
noise in theatre which will affect the auditory response of the audience.
25mm Fibreboard
Diagram 5 : The placement of acoustically treated wall Diagram 6 : Detail of the wall
Diagram 7 : The placement of steel panels Figure 8 : Zig-zag steel panels
10mm Plaster
100mm Rockwool
25mm Fiberboard
250mm Concrete
10mm Plaster

5.1.2 Ceiling
The material of ceiling in DPAC is concrete. Concrete is a strong reflection material. Sound consideration is
important for a theatre. The used of concrete will create excessive sound reflection due to the hard surface of
the concrete. Thus, a layer of spray form has been applied on the surface of the ceiling to decrease the sound
reflection.
Reflector Panel
Plywood reflector panel is a suspended panel that are used in DPAC. It hanged by steel and attached to the
concrete slab above. The function of panel is to disperse sound evenly across audience. Plywood reflector panel
installed at the front and side. It covered partially to avoid redundant sound reflection. The placement and the
material of panel brings a huge impact to the theatre. Due to the placement of the panel, it improves the sound
distribution in the theatre.
Concrete
Spray form
Figure 9 : Ceiling
Diagram 8 : The placement of ceiling
Diagram 9 : Detail of ceiling
Diagram 10 : The placement of reflector panels Figure 10 : Reflector panels

5.1.3 Flooring
Concrete is mostly used for flooring in DPAC. Plywood and vinyl sheet are only applied on the stage. The plywood
has good strength and durability. It is economical as compared to solid wood. One of the reason of using plywood
is to balance the material used. The wall is covered with steel panels and plywood can gives a warm feeling in
theatre. This theatre is a multipurpose theatre. It is not only for orchestra, but also other performance such as
ballet. The plywood flooring is applied with a layer of vinyl sheet to increase slip resistance. Black vinyl sheet on
the flooring would not affect the attention of audience during the shows.
5.1.4 Staircase
The material of staircase is plywood and metal. Plywood is used at the tread for aesthetic purpose and more
noticeable because it is different material with flooring. Due to hard surface, it creates sound reflection. When
walking on the plywood stair, it would create noise and disturb the audience during the show. The metal plate is
placed at the riser. The function is to reflect the sound.
Concrete
Plywood
Metal Plate
Diagram 11 : The placement of flooring
Figure 11 : Vinyl sheet
Figure 12 : Vinyl sheet
Diagram 13 : Detail of staircaseDiagram 12 : The placement of flooring Figure 13 : Staircase

5.1.5 Curtain
Duvetyn
Duvetyne is a brushed matte finish that used in the front curtain of DPAC. It is a bit lighter and used as masking
throughout the theatre. Moreover, it looks like velour but does not work as well as velour. It allows pinholes of
light to show through if there is a very high concentration of light behind it.
Velour fabric
Velour fabric is installed at the entrance of Damansara Performance Art Centre(DPAC). It is extremely durable.
The purpose is to reduce sound penetration and avoid sound transfer through the structure. It is a sound
absorption material because of its soft characteristic. Also, the curtain is attractive and act as a welcoming
element.
Bolton twill fabric
Bolton twill fabric is used as covering the service room entrance. It is cheaper and lighter which easier to work
with. Due to the complex pattern, surface dust and dirt are less visible, it always a good choice for theatrical
curtain. Light may leak through but it does not matter because of the function is to hide the door.
Diagram 14 : The placement of curtain
Figure 14 : Duvetyne Figure 16 : Bolton twill fabricFigure 15 : Velour fabric

5.1.6 Seat
Upholstered tip-up seats
The seats used in DPAC’s audience area are upholstered tip-up seats which made of plywood and red cushion.
Red cushions enhance the visual beauty of the theatre. The purpose of using cushion is to provide comfortable
sitting area for audience. It is a great porous absorber in the theatre. Besides, the metal stands are installed in
every seat as a supporting structure and air conditioning outlet.
5.1.7 Door
Plywood is used at the outer door of the entrance. Sound are able to penetrates through the door . So, acoustic
door is built to reduce sound penetration. Acoustic doors are constructed by plywood and rock wool. Rock wool is
one of the material that are used for the acoustically treated wall. The function is to absorb unnecessary sound.
Other than that, double door system is applied to reduce the noise from the exterior and block the sound from
inside.
10mm Plywood
10mm Plywood
25mm Rockwool
Metal Stand
PlywoodCushion
Diagram 15 : The placement of audience seats Figure 17 : Audience seats Figure 18 : Component of audience seats
Diagram 16 : The placement of doors Diagram 17 : Detail of acoustic door

AREA COMPONENT MATERIALS COLOUR SURFACE
FINISHES
COEFFICIENT
PHOTO MATERIAL DESCRIPTION 125
Hz
500
Hz
2000
Hz
Exterior Curtain Velour
fabric
Exterior
curtain,
Entrance door
curtain
Red Soft 0.03 0.25 0.5
Entrance
Door
- Plywood Entrance door Brown Smooth 0.1 0.05 0.04
Interior:
Sitting
area
Seat Fabric
-Upholster
ed
Empty Red Soft 0.49 0.8 0.82
Fully
-Occupied
Red Soft 0.6 0.88 0.93
Plywood Empty Brown Smooth 0.32 0.42 0.43
Fully
-Occupied
Brown Smooth 0.5 0.76 0.86
Flooring Concrete - Grey Rough 0.1 0.1 0.2
Staircase Steel The riser is
steel
Dark
grey
Hard - 0.08 -
Plywood The tread is
plywood
Brown Smooth 0.05 0.05 0.05
Reflector
Panel
Plywood Suspended on
the front and
side ceiling
Black Smooth 0.05 0.05 0.05
Zig-Zag
Steel Panel
Steel Steel panel is
covering the
wall
Black Smooth - 0.88 -
+ Rockwool Entrance door Brown Smooth 0.1- -

AREA COMPONENT MATERIALS COLOUR SURFACE
FINISHES
COEFFICIENT
PHOTO MATERIAL DESCRIPTION 125
Hz
500
Hz
2000
Hz
Acoustically
treated wall
- Concrete
+ Rock
wool +
Fibreboar
d
250mm:
concrete
100mm:
rockwool
10mm:
Fibreboard
Grey Smooth - 0.55 -
Curtain Bolton
twill
fabric
Covered the
service
room’s door
Black Soft - 0.1 -
Upper floor
slab
Concrete Concrete slab
+ Spray form
Grey Rough - 0.15 -
Interior:
Stage
area
Cyclorama - Plywood Back panel Brown Smooth 0.05 0.05 0.05
Curtain Duvetyn Layering of
curtain
Black Soft - 0.2 -
Proscenium Plywood A frame
separating
stage and
auditorium
Dark
grey
Smooth 0.05 0.05 0.05
Flooring Plywood
+ Vinyl
sheet
Vinyl sheet is
applied on the
plywood
flooring
Grey Uneven 0.02 0.03 0.03

5.2 Identification of Existing Sound Source/ Noise
5.2.1 Sound and noise
The term sound and noise can be defined as an " undesired or disagreeable sound" or any other disturbance. From
the acoustics point of view, it’s constitute as the same as a phenomenon of atmospheric pressure fluctuations
which means an atmospheric pressure. Sound or noise is the result of pressure variations, or oscillations, in an
elastic medium such as air, water or even solids which generated by a vibrating surface, or turbulent fluid flow.
5.2.2 External Noises
I. Air borne noise - Environmental sound
The quietness of a theatre is degraded when outside noise gets inside. The theatre is located right beside a
roadside which could cause some unpleasant noise and disturbance whenever there's a heavy traffic during a
peak hour ( Vehicle noise from Jln pju 8/8 ). Even just the sound of a motorcyclist engine could be listen through
the door from the sound system affecting the audience who seats nearby the section.
II. Air borne noise - Entrance door
There multiple origins of noise, like the sound produced by opening and closing the door or even the sound of
talking taking place outside the theatre. However, there is a sound lock which prevent the noise from interfering
the audience that seats near to the door. The sound lock within the inner and outer door at the main entrance of
the theatre serves as a function to trap the sound waves as a result to bring down the noise level to less than 40
bB. The addition of acoustic absorbent linings to the sound locks can also further enhance the sound insulation
Sungai buloh Kepong
Damansara
perdana
Mutiara
Damansar
LDP Toll
Mon’t Kiara
LDP
The curve
DPAC
Jln pju 8/8
DPAC
TNB
Entrance
Sound system
room
JalanPJU8/8
Figure 19 :
Position of DPAC beside a roadside
Diagram 18 : Site context Diagram 19 : Floor plan, Noises from roadside
coming from sound system room
Diagram 20 :
Floor plan, sound lock
Figure 21 : The outer door of the entranceFigure 20 : The inner door of the
entrance, Double door system
Sound lock

III. Air borne noise - Back door ( to basement carpark )
There's is a back door behind the stage acting as an entrance for the performers which also leads to a basement
parking lots, this is also another sound intrusion could be found in the theatre. However, with the solution of
designing the door with the combination of a rock wool core, this could prevent the vehicular noises from entering
the theatre which then solve the issues.
Rock wool is one of the most effective acoustic insulation solution because they provide airborne sound
absorption which can dramatically improve the acoustics which due to its high density, non directional fibres that
trap the sound waves and absorb vibration.
5.2.3 Internal Noises
I. Air borne noise - FCU air conditioning
There are many factors that could affect on designing a comfortable theatre to provide comfort to building
occupants. Temperature is one of the element. One may feel very cold in an empty room, but when it’s fill up
with people, it can heat up real quick. Therefore, the seats were designed in such way that the metal stand
beneath incorporates air conditioning openings on every seats, for a more convenient way to control the
temperature of the theatre.
FCU Air
Conditioning
Entrance Seating area Front Stage
Loadingbay/basmentcarpark
Backstage
Diagram 21 : Floor plan, Noises from Loading
bay / Basement carpark
Sound source
Reflected
Backstage
Diagram 22 : Sound absorption and reflection
shown in door detail section
Absorb & Reflected
Rockwool
Wood conglomerate
Plywood
Diagram 23 : FCU air conditioning below the seating area shown in section.

Internal Noises
I. Air borne noise - FCU air conditioning ( Continued )
To achieve such result, it requires a Centralised Air-Conditioning with delivery ducts. A fan coil unit (FCU) is a very
simple and flexible device that consist a heating and cooling heat exchanger. It’s is a part of an HVAC system which
has a low noise unit. The noise output level can be as low as NR25.
MAX. NOISE RATING LEVEL APPLICATION
NR 25 Concert halls, broadcasting and recording studios, churches
NR 30 Private dwellings, hospitals, theaters, cinemas, conference rooms
NR 35 Libraries, museums, hospitals, operating theatres and wards,
NR 40 Halls, restaurants, night clubs, shops
NR 45 Department stores, supermarkets, canteens
NR 50 Typing pools, offices with business machines
NR 60 Light engineering works
NR 70 Foundries, heavy engineering works
Foam layer
reduce air friction and
absorb sound from FCU
AHU duct
Openings
FCU unit
Diagram 24 : Detail section of the seat
Table 1 : Maximum noise rating level on different application Figure 22 : Images showing
the openings for air conditioning
Figure 23 : Treated AHU duct beneath the seats

Internal Noises
II. Air borne noise - Ducting and diffuser
`
Backstage
Ducting
Backstage
Ducting & Diffuser
Front stage
Diffuser
Seating area
Ducting & Diffuser
Elements Examples and details Remark
Centralized Air
Conditioning with
delivery ducts
Fan Coil Unit
(FCU)
Selection of fan with low noise FCU might require acoustics
box up if it’s installed within
a sensitive room to reduce
noise.
Silencer Silencer are used to reduce airborne
noise which could maximum insertion
loss (noise reduction), low static
pressure drop
Diffuser Selection of diffusers with low
regeneration noise
Excessive air or high velocity
of air flows thru diffusers
blades will generate noise.
Air speed and volume per
diffuser are essential
Ducting With Internal lining of Rockwool and
thermalrock with tissue facing or GI
sheets
Recommended specification
Figure 24 : Images showing the internal noise source coming from ducting and diffuser.
Table 2 : Recommended specification on Centralized Air Conditioning with delivery ducts

Internal Noises
III. Structural borne noise - Squeaky stairs
It’s extremely disturbing when the audience happens to enter and leave in the middle of the performance, and
the squeaky sound from the stairs and even the footsteps on the a floor can be heard clearly. The noises are
transmitted through a structural borne, resulting from an impact or the vibration against it. The structural fabric
can lead to the sound being radiated from an adjacent vibrating surface such as the solid hard surface layer of
the thread on stairs which made of plywood and the concrete flooring. The solution to reduce the noise can
simply done through a selection of softer material like carpets to cover over the stairs.
IV. Structural borne noise - Stage flooring system.
Figure 25 : Showing the overall view of the flooring material
on the seating area
Stairs
Floor
Plywood
Concrete
Figure 26 : Stairs (Plywood)
Floor (concrete)
Figure 27 : Showing the material of the stage and the depthness of the stage
Marley “Vinyl” flooring

Internal Noises
IV. Structural borne noise - Stage flooring system ( Continued )
The theatre is mainly serve for a small scale dance, drama and musical production. It is always advisable to consider
the possibility of sprung floor as they provided some degree of bounce and flex under impact. Performers need this
to absorb shock and protect their joints from inanity. Especially when performing jumps.
The stage is made of plywood as plywood is a great choice for sound control as it bounces high frequencies,
resonating better sound quality, and absorbing bass energy. Besides, plywood is ideal for social dancing, because it
is less liable to wrap and shrink and has more durability and economical.
But due to space limit the theatre was built with a shallow apron causing the distance between audience and the
stage to be closer where the sound of footfalls of a jump might be very loud to the audience. Therefore, the stage is
covered with Marley “vinyl” which mainly increase slip resistance for the performers but it also helps to reduce
noise.
Marley “Vinyl” performance floor
Plywood
Dual density shock dampening elastomer
blocks at predetermined intervals
Stage
Audience
Apron
Diagram 25 : Sprung floor system Figure 28 : Distance away from
audience to stage
Audience Apron Stage
Diagram 26 : Distance between audience and the stage in section view

Internal Noises
V. Light fixture as a source of noise
Internal noise also includes the light fixtures as some might produce the buzzing noise, one might not have any
impact to the environment but too much light can cause serious impact on producing noise. For example, the inner
side on each of the steel panel on the wall is covered by LED strip on the sides where the buzzing noise could be
heard if one were seating right beside the steel panel.
The reason why the LEDs are making the buzzing noise is due to improper dimming or electromagnetic interference
from other devices which causes vibrations in the light bulb. The solution is to fix the dimmer you are using that is
compatible with the LEDs to ensure there's no humming sound.
Area affected
Steel panel
Figure 29 : Images showing the steel panel beside the seats. Diagram 27 : Showing the affected area by the buzzing noise
of LED lights on the steel panel.

6 ANALYSIS AND FINDINGS
6.1 Sound propagation and concentration
The reading of the sound is taken from different
position of the stage as the sound propagation are
varied, outputting a constant 255Hz sound at
60dB, which is a normal speech level. The findings
shows that the layout and the use of material of
DPAC are not appropriate as:
a) it produce unpleasant sound at certain
area,
b) Uneven sound distribution
6.1.1 Sound concentration
According to the reading of sound at different zone
of the theatre, we found that the front seats of the
stage receive relatively less sound compared to
other zone due to the absorbent material of the
front stage and the inefficient placement of
reflective wall and ceiling panel (refer to diagram
28 ) Diagram 28 : SIL readings of the theatre
Diagram 29 : The concentration of sound
The concentration of sound at the centre back which
is VIP seats of the theatre due to the excessive
reflective material placed near the corner.

6.1.2 Sound reflection
There are 3 types of reflections that we usually hear in a auditorium: early reflection, late reflection and
reverberation. Early reflection are desirable to amplify sound so the sound could be hear more clearly. As the
reflected sound arriving from the sides are more contributed to the overall reverberance of the room, the steel
wall panel of the auditorium plays more important role to amplify the direct sound in a natural way. While the
late reflection will create echoes that affect the clarity of the sound sources.
Note that the sound reflection from the centre of stage are relatively lesser, result to varied sound level when
performer walking around stage. It is caused by the ineffective placement of vertical reflective panel above
the stage. The ceiling panel should be placed further from the stage so that it would reflect the sound from
the centre stage more productively.
The reflective sound also failed to convey uniformly to all of the audience as it concentrated at the VIP seats.
It is due to the flat ceiling reflective panel that are ineffective and not well configured.
Diagram 30 : The sound propagation from the centre of stage
Diagram 31 : The sound propagation from the back of the stage
Vertical reflective panel

Diagram 32 : Sound path of speaker on the ground
Diagram 33 : Sound path of speaker on top
The position of the speaker above the stage are much more ideal than the speaker placed on ground as
transmit the sound more directly and evenly to all part of the theatre. Position of the speaker A and B are not
appropriate as:
a) Face directly to the audience, hence the sound convey unevenly
b) Produce structure-borne noise due to the larger area of contact to the floor
Figure 31 : Position of speaker above the stageFigure 30 : Position of speaker on two
sides of the stage
A
B
C

6.1.3 Sound absorption
As it is an art and performance theatre, the less the absorption of the sound, the livelier the acoustic theatre is.
Therefore, the strategy of sound absorption is minimal, mostly absorption of sound are provided by the audience
and the acoustic wall.
The acoustic wall panel which are absorptive are placed behind of the zig zag steel sound reflector to prevent the
occurrence of echo in between the wall and panel as the wall absorbed partial of the reflected sound.
Notice that the choice of the material at its stage are varying from the audience seats, the sound absorbance
drapery are installed, provide a tunable acoustical control ( sound reflective level ) at the stage. For instance,
the drapery are closed while scene changing, so that the noise produced by the crews behind the drapery are
reduced. It also eliminate the echoes and noise produced from the backstage to transmit to the audience seats.
Diagram 34 : Plan showing the reflective and absorbance material used
Diagram 35 : Section showing the reflective and absorbance material used

6.1.4 Sound diffusion
Diffusers which scatter sound are critical in acoustical theatre
design to improve the sound quality in frequencies throughout the
middle and high range of the spectrum,. It keeps sound waves
from grouping, so there are no hot spots or nulls in a room,
making the instrumental or any sound source sounds more natural
as the human ear is used to reflections and reverb trails from a
single sound source arriving at the inner ear at multiple intervals.
Moreover, diffusion allows reverb to decay more naturally while
still preserving the sound energy as well as addressing issues
with resonance.
Zig zag steel panel that place all over the wall of the theatre are
the only method of DPAC to provide sound diffusion. It cover about
90% of the theatre. It making the theatre space more lively and
create illusion of the larger space. However, as it placed in front
of the acoustic wall, some of the noise are dispersed before it
being absorb by the wall, affecting the acoustical quality of the
space.
Corrugated surface of the
steel panel diffuse the sound
evenly to the aud
Figure 32 : Coverage of the steel panel
Diagram 36 : Sound diffusion ray explained in the plan

Diagram 38 : Sound diffusion to centre rows
Diagram 37 : Sound diffusion to front rows
Diagram 39 : Sound diffusion to VIP seats
The front rows of the theatre receive more direct sound that reflected and diffusion sound because of the
placement of the steel panel and the sound absorption of the drapery at the front stage.
The seats located at the side of the theatre received more diffusion sound as it is nearer to the steel panels on
the wall. Therefore, the diagrams above well explained why the SIL reading at centre-front of the theatre are
relatively lower than other zone of the theatre (referring diagram 39)

6.2 Different Phenomena in Sound
6.2.1. Echo and Sound Delay
Echo and reverberation are two distinctly different things. Echo happens when the sound waves of a sound or
series of sounds reflect from a surface back to the listener. Different functions of the spaces have different
desired sound delay period, and thus different perceptions of echo.
For this analysis, only reflective surfaces will be treated as effective sources of sound delay. For space used for
speech, time delay above 40m sec will be deemed as an echo. In other hand, as for auditorium for music
purpose, sound delay above 100msec is deemed as an echo.
6.1.1 Sound concentration
According to the reading of sound at different
zone of the theatre, we found that the front seats
of the stage receive relatively less sound
compared to other zone due to the absorbent
material of the front stage and the inefficient
placement of reflective wall and ceiling panel
(refer to diagram 6.1.3.2 )
Diagram 6.1.1.1 SIL readings of the theatre
Diagram 40 : 40m sec sound delay is acceptable for a performance-oriented auditorium.

Diagram 41 : 11.2m sec and 8.8msec are quite short for a performance-oriented auditorium.
Diagram 42 : 29.1m sec is acceptable for performance-oriented auditorium.

Diagram 44 : 12.65msec is quite low for performance-oriented auditorium.
Diagram 43 : 42.94msec is acceptable for performance-oriented auditorium.

Diagram 45 : 14.7msec is quite low for performance-oriented auditorium.
After the calculations, we can conclude that echo doesn’t exist in this auditorium if it is used for performance
and music purposes. However, it does exist if it used as speech-oriented auditorium.
6.2.2. Flutter Echo
Flutter echo is a rapid succession of noticeable small echoes that is created when a short burst of sound is
produced between parallel sound-reflective surfaces.
DPAC does not create flutter echo as the walls of the auditorium are non-parallel. Besides that, the curtains
have absorbed the sounds reflected on it
Diagram 46 : Flutter echo doesn’t exist in this auditorium.

6.2.3. Reverberation
Reverberation is different from echo. Reverberation is said as a sound that echoes, but the echoes that create
reverberation are extremely complex. It also defined as prolongation of a sound and is produced when a sound or
signal is reflected causing a large number of reflections to build up and then decay as the sound is absorbed by
the surfaces of objects in the space which could include furniture, people, and air.
To differentiate echo and reverberation, the better way is to see the number of repetitions of sound per
millisecond. A reverberation is perceived when the reflected sound wave reaches our ear in less than 0.1 second
after the original sound wave.
A desirable reverberation time depends on the types of space as the graph below:
Table 3 : Desirable reverberation time depending on function of the space.
Source: https://acousticalsolutions.com/wp-content/uploads/2015/04/reverb_time_chart_525.jpg

The reverberation is influenced by the size and shape of the room that the sound echoes in.
Diagram 47 : The Reverberation time of DPAC.
In this case, the room of DPAC provides lesser reflective surfaces compared to cathedral by just looking at the
shape as it was squarish in shape. However, the material of the finishing of the room whether the floorings or
the walls provide more hard surfaces. The harder the surface, and the more surface angles and lengths of the
room, the longer repetition of echoes occur, resulting in a longer tail or reverberation time.
The original sound wave and reflected sound wave tend to combine as one very prolonged sound wave. DPAC
used the auditorium as music and performance hall, hence, the longer reverberation time or decay can be used
to enhance harmonic structure in their performances. Generally, the construction of a music hall attempts to
produce a reverberation time that lasts anywhere from 1.2 to 3 seconds or longer. The characteristics include
an audible cluster of initial reflections followed by a full body and a decay that ends with a roll off of
high-frequency content.

7.1 Poor Ensemble
7 ACOUSTICAL DEFECTS AND DESIGN ISSUES
Acoustical defects can be found in a theatre if it is not designed in an appropriate way to its function or due to
the later stage development of the theatre. Sometimes, these defects can be solved just by a few tips in an
acoustic room at the design stage.
Diagram 48 : The spots of sound in DPAC (Situation 1)

From the first diagram, the play of sound reflection and the propagation of the sound make the design of the
auditorium seems reasonable. But in the second diagram, when the speaker is moving forward, the sound will
concentrate at the back of the auditorium, the front and the VIP zone will start to suffer from the dead spot as
there is no reflected sound from the ceiling applied. In the third diagram, the poor sound ensemble is strongly
highlighted when the speaker is moving backward to the stage. Only minimum part of the ceiling reflector is
functional at this position.
This becomes a weak point of DPAC from being a great auditorium if there is a large team of classical orchestra or
choir team performing on stage. This is because the sound from the back of the stage is hardly heard or received by
the audience.
7.2 Sound shadow
Sound shadow area is also one of the defects found in DPAC theatre. In the diagram, the seating area below the
control stage overhung is determined as a sound shadow area. At the sound shadow area, the reflected sound that
is supposingly transfer to that particular area has been blocked by the stage above.
This defect can be easily solved by lifting the stage higher to prevent the blockage of sound to the area.
7.3 Poor Sound Isolation
In the theatre, lights, HVAC ducting and diffusers are placed out-and-out everywhere in the theatre. A lot of internal
noises are produced and created an unpleasant environment. The lights and cooling system that are probably
enhance the visual effects and comfort level has totally affected the sound effects in the theatre.
The ducting system and the diffusers should be covered by a ceiling. Whereas, the lightings should undergo periodic
inspection and maintenance to prevent the internal noises in the theatre.
Diagram 51 : Sound Shadow in DPAC
Figure 33 : Noise Sources in DPAC

FCU Air
Conditioning
Entrance Seating area Front Stage
The openings under the chair to allow the air flow from the FCU also created a minimal mechanical noises in the
theatre. Besides that, the machines of FCU Air Conditioning system are placed under the seating area and sit on
the ground. This causes the noises from the machines to transfer along the horizontal surfaces.
The installation of floated floor can be considered as it will prevent the mechanical noises from entering the
theatre and isolate the mechanical noises within the space below the seating area.
7.4 Mechanical Noises
Diagram 52 : Mechanical Noise transfer diagram of DPAC

To sum up a conclusion from our accumulated findings and subsequent analysis, Damasara Art Performing
Centre, DPAC is an auditorium that is not suitable for any large live performances which are unassisted and
unamplified. It depends on electronic audio suites to overcome its shortcomings and yet still not a guarantee to
its ability to serve as an acoustically efficient auditorium. Many events are still held within its hall despite its
issues. Though it has been known as a “multipurpose” auditorium, its suboptimal layout, poor ensemble of
sound, poor isolation of interior sound and the presence of numerous sources of unnecessary noises make it
does not deserve this title. Its overall approach and operation strongly suggests a focus towards
speech-related events or smaller group of stage play only.
8 CONCLUSION

8 REFERENCES
The Five Main Types of Reverb, and How to Mix with Them. (2017, August 03). Retrieved September 30, 2017,
from
https://sonicscoop.com/2013/11/03/the-five-main-types-of-reverb-and-how-to-mix-with-them-by-jamey-staub/
Reflection: Echo vs. Reverberation. (n.d.). Retrieved September 30, 2017, from
http://www.physicsclassroom.com/mmedia/waves/er.cfm
Lee, R. (2014, November 27). How does echo happens? Retrieved September 30, 2017, from
https://prezi.com/sfakufilqziv/how-does-echo-happens/
ansaripv. (2017). Ultrasound artifacts. Slideshare.net. Retrieved 2 October 2017, from
https://www.slideshare.net/ansaripv/ultrasound-artifact
(2017). Retrieved 2 October 2017, from
http://www.colorado.edu/physics/phys1240/phys1240_fa05/notes/Chapter5.pdf
models. (2017). Sfu.ca. Retrieved 2 October 2017, from https://www.sfu.ca/~truax/models.html
Enhanced acoustical design. (2017). Building Design + Construction. Retrieved 2 October 2017, from
https://www.bdcnetwork.com/enhanced-acoustical-design
http://www.rockwool.in/files/RW-IN/pdfs/product_brochures/ROCKWOOL%20SnS%20TECHNICAL%20MANUAL%2
0LR.pdf
Suggs, B. (2017). Creating a Comfortable Auditorium Atmosphere - Ministry Serving Ministry. Ministry Serving
Ministry. Retrieved 2 October 2017, from
http://ministryservingministry.com/2016/10/12/creating-comfortable-auditorium-atmosphere/#.Wc_TS2iCyUk
http://aus.harlequinfloors.com/uploads/3/downloads/Stage_technology_guide_-_AUS_-_LR1.pdf
Sound-Absorbing Drapery: Theory & Application. (2017). AcousticsFREQ.com. Retrieved 2 October 2017, from
http://acousticsfreq.com/sound-control-acoustic-curtain/
http://www.kineticsnoise.com/interiors/pdf/soundreflectionwhitepaper.pdf
http://www.iatselocal4.org/Docs/Study_Guides/Carpentry_Handbook_Rev2.pdf
(2017). Retrieved 2 October 2017, from http://www.kineticsnoise.com/interiors/pdf/Interior2.pdf
(2017). Retrieved 2 October 2017, from http://www.acoustic.ua/st/web_absorption_data_eng.pdf
https://cds.cern.ch/record/1251519/files/978-3-540-48830-9_BookBackMatter.pdf

8 REFERENCES
A brief introduction to acoustic treatment. (2017). Audiomasterclass.com. Retrieved 2 October 2017, from
http://www.audiomasterclass.com/newsletter/a-brief-introduction-to-acoustic-treatment
Concert Hall: How To Get The perfect Acoustics (Part 2).. (2017). Soundzipper. Retrieved 2 October 2017, from
https://www.soundzipper.com/blog/the-acoustics-of-a-concert-hall-part-2/
Damansara Performing Arts Centre - Floor Plan | Venue Directory. (2017). Venue.myceb.com.my. Retrieved 2
October 2017, from http://venue.myceb.com.my/floor-plan/damansara-performing-arts-centre-floor-plan
MUCH MORE TO SEATING THAN CUSHIONS AND COMFORT - Gaillard Foundation Latest News. (2017).
Gaillardfoundation.org. Retrieved 2 October 2017, from
http://www.gaillardfoundation.org/latest-news/much-more-to-seating-than-cushions-and-comfort/
MUCH MORE TO SEATING THAN CUSHIONS AND COMFORT - Gaillard Foundation Latest News. (2017).
Gaillardfoundation.org. Retrieved 2 October 2017, from
http://www.gaillardfoundation.org/latest-news/much-more-to-seating-than-cushions-and-comfort/
Soundproofing Absorption Coefficent Charts. (2017). Soundproof Your Home. Retrieved 2 October 2017, from
http://soundproofyourhome.com/absorption-coefficient-chart/

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