Case Study on acoustic design of DPAC

1. BUILDING SCIENCE II
BLD 60803
Chai Phey Chiat
Chow Wei Qi
Goretty Lee Pey Shy
Joslyn Siew Zi Tong
Koh Jing Fan
Ong Yi Teng (Crystal)
Serene Lim Jia Yi
Toh Yi Lin
Yap Shu Won
0334480
0331447
0326837
0334488
0330792
0326486
0334258
0327984
0331392
Project 1:
Auditorium: A case study on Acoustic Design
Tutor : Mr. Edwin

2. 1.0 INTRODUCTION
1.1 Aim and Objectives
1.2 General information
1.3 Historical Background of DPAC
1.4 Context and Location
1.5 Floor Plan
1.6 Reflected Ceiling Plan
1.7 Section
2.0 ACOUSTIC DESIGN ANALYSIS
2.1 Sound Source
2.2 Sound Propagation
2.2.1 Sound Distribution
2.2.2 Sound Reflection
2.2.3 Sound Diffraction
2.2.4 Sound Delay and Echo
2.2.5 Sound Shadow
2.2.6 Echo Flutter
2.3 Potential of Noise Intrusion
3.0 CONSTRUCTION MATERIALS ANALYSIS
3.1 Construction Materials Used
3.2 Calculation ( Reverberation Time )
4.0 SOUND DEFECTS AND DESIGN ISSUES
5.0 CONCLUSION
6.0 REFERENCES
CONTENT

3. 1.0
INTRODUCTION

4. 1.1 Aim and Objectives
We are required to conduct a case study on a local auditorium in a group of eight and
produce a report towards the acoustical analysis study in the auditorium.
The aim of the project is to allow students to understand the acoustical theories in a chosen
auditorium. The objectives of this project include:
• To analyze the acoustic characteristics of an auditorium
• To determine the use of the construction materials in an auditorium that affect the transfer
of sound
• To determine the acoustic qualities of an auditorium and ways to improve them
• To allow exploration and understand the design of an auditorium to the public

5. 1.2 General Information
Name of Auditorium : Damansara Performing Arts Centre
Address : H-01, DPAC, Empire Damansara,
Jalan PJU 8/8, Damansara Perdana,
47820 Petaling Jaya, Selangor, Malaysia.
Chosen Auditorium : Proscenium Theatre
Total seats : Max. 200 pax
Stage : 11.25m (width) x 7.25m (depth)

6. 1.3 Historical Background of DPAC
Built in 2013, Damansara Performing Arts Center (DPAC) was the end-result of its Artistic
Director, Wong Jyh Shyong’s hard work and dedication towards a better platform to enable
local dance artists to have more engagement with international artists. The establishment of
DPAC was also missioned to accommodate the sheer growing numbers of arts practitioners in
Damansara and neighbour districts.
DPAC is dedicated in promoting arts through learning, practising and appreciating arts in
Malaysia. It aims to enhance public awareness on how art-forms are able to enrich people’s
lives and shape a better world. DPAC has a proscenium theatre, a black box, an experimental
theatre, an indoor theatre-foyer and several dance studios. These are all state-of-the-art
facilities to ensure professional practices could be carried out regardless of the forms of the
arts performed.
DPAC does not contain itself in a standalone building. It is located inside the car park in an
office building. Since it was an add-on to the building, several modifications had to be made to
facilitate the construction of DPAC. A column of the building had to be removed to
accommodate more seats and to remove view disturbance. As a result of this, metal truss then
replaced the removed column and supported the rood. To enhance sound insulation, the area
of the rooms had to be extended and the interior was finished with industrial metal containers
and plates. All of these modifications had resulted in two changing rooms, one at the back
stage and another on the level above.

7. 1.4 Context and Location
Empire
Damansara
Empire City
Menara
Gamuda
LDPHighway
Metropolitan
Square Condo
PJ Trade Centre
Damansara Performing Arts Centre (DPAC) is located within Empire Damansara, Damansara
Perdana, a mixed development that satisfies both business and lifestyle needs. It is located in
a prime location in Petaling Jaya and can be accessible easily from different directions through
many major highways.
It is sits comfortable more than 150 meters from Lebuhraya Damansara - Puchong highway
which is one of the main road connecting between Damansara and Puchong and it is mainly
congested during peaks hours including lunch time, increasing the sound travelling distance
and therefore reducing the noise.
However, DPAC is facing to the northwest of a large contour area of vegetation, which as a
partial sound absorber that helps in aiding the reduction of background sound. When one is
inside DPAC, you could hardly hear any noises from the busy road.
DPAC

8. 1.5 Floor Plan Scale 1:200

9. 1.6 Reflected Ceiling Plan Scale 1:150

10. 1.7 Section Scale 1:200

11. 2.0
ACOUSTIC
DESIGN ANALYSIS

12. Plan of DPAC
Sound
Sounds are vibrating waves that could be produced by musical instruments, human vocal cord,
running engine, vibrating loudspeaker diaphragm and so on. Sound can be propagated through
a medium such as air, water or even solid. Difference between sound and noise is noise are
unpleasant, loud and disturbing.
1.Speakers
2.1 Sound Sources in DPAC

13. Locations of Speaker
Section of DPAC

14. 2.Human Vocal Chord(Performers such as Acapellas)
Human vocals of performers are also consider as sound source as they are well-trained before go
on stage to perform.
Plan of DPAC
Section of DPAC

15. 3.Musical Instruments
Music made by musical instruments are also consider as sound because musics are desirable.
Plan of DPAC

16. Propagation of sound can be simply defined as a sequence of waves of pressure traveling
through a compressible media. In the event of propagating, the sound waves can be
reflected, refracted, or attenuated by the medium. Sound propagates outwards from a point
source in a spherical wavefront as shown below:
Diagram 2.2.1 shows spherical propagation of sound
The diagram below shows the scenario of sound under reflection, diffusion, dispersion,
diffraction and also other factors of propagation:
2.2 Sound Propagation
Diagram 2.2.2 Scenario of sound propagation

17. Seats are set back from the stage at a distance to accommodate the shown reflected sound
without being interrupted by the vertical reflective panel. The front seats are strategically
located to receive the smallest angle of reflected sound from the sound source.
Direct Sound
Reflected Sound
2100mm
Audience seating layout affected by sound reflection
2.2.1 Sound reflection
When sound travels in a given medium, it strikes the surface of another medium and
bounces back in some other direction, this phenomenon is called the reflection of sound.In
the case of this theatre, sound sources from the stage reflects on the reflective panels to the
audience.
It is important to make sure to obtain an early reflection (99%) as it is used to reinforce
direct sounds (1%). However, we have to be careful to reduce late reflection as it will
contribute to echoes.
Vertical reflective panel
Diagram 2.2.3 shows reflection of sound on the surface of certain medium
Surface
Direct sound Reflected sound
i r
i = r
Diagram 2.2.4 set back of audience seating

18. The walls of the DPAC theatre are not symmetrical on plan view, this results in a messy
reflection of sound waves that leads to various different directions. This leads to a difference
in sound distribution on both sides of the audience.
There is no intention in leading the reflected sound towards certain direction that might
potentially help with the overall quality of sound propagation. However, on the positive side,
a wider range in the audience can be covered
This side of the theatre has
more concentrated sound
distribution. However, the
reflected sound only reaches
a small range of audience
before it loses energy.
This side of the theatre has a
wider reflected range due to
the angled walls.
Sound reflection analysis on plan
Diagram 2.2.5 Sound reflection on plan view

19. Sound reflection analysis on section
Vertical panel is placed
attached to the ceiling in
between the audience
and stage to prevent the
stage lighting to affect
the audience experience.
This degrades the
efficiency of sound
reflection.
Diagram 2.2.8 Sound reflection on the suspended side ceiling panels
Diagram 2.2.7 Sound reflection on the suspended front ceiling panels
Diagram 2.2.6 Reflective ceiling plan with
indication of suspended reflective panel
In order to create a wider
area of useful reflective
ceiling and also effectively
reflect sound to the
audience, sound reflecting
panels are placed
suspended from the ceiling.
Suspended front reflective
panel
Suspended side reflective
panel
The grey area shown in the diagram 2.2.7 is the “live” area. This shows a slight defect as the
center-to-back of the audience seemingly receives less of the reinforced reflected sound.
However as shown in the previous analysis on plan,the reflected sound mostly leads
towards said area so it makes up for this defect.
The suspended side reflective panels reflect the sound waves towards the walls to later be
diffused for a more even sound distribution.

20. Looking at the diagrams above, we can conclude that by introducing the
suspended reflective steel panels it lengthens the range of useful ceiling
reflection, reaching a wider range of audience.
Diagram 2.2.9 Live area with suspended reflective panel
Diagram 2.2.10 Live area without suspended reflective panel
3375mm
4790mm

21. 2.2.2 Sound diffusion
Sound diffusion is a method of spreading out sound energy with a desired element, a
diffuser, for better sound in a certain space (Calder, 2018), These “diffusers” are usually in
the form of corners, edges, scattering and irregularities of elements. These “diffusers” helps
to diffuse high frequency sound with short wavelength which breaks and disperse
throughout the theatre. In the case of DPAC, there are a few prominent “diffusers”:
1. Zig zag reflective steel panels
2. Lightings
3. Cornerings
4. Stairs
Below shows the diffusion of sound on the zig zag reflective steel panels. The rest of the
“diffusers” act according to the same method of diffusion:
Diagram 2.2.11 shows corrugated Surface of The Steel
Panel Diffuse The Sound Evenly to The Audience
Direct sound
Diffused sound
Direct Sound Diffusion of Sound Sound source
1
2
33
4
11
3
3 1
4
4
Referring to the part ‘Construction of materials used’ in this report , it is shown that the
zig-zag reflective steel panels covers a majority of the walls surrounding the audience in the
theatre. Hence, a wide portion of the sound that are reflected by the panels are diffused,
resulting in a considerable evenly distributed sound around the theatre. Furthermore, the
other “diffusers” are also positioned in various spots around the theatre as shown in the
above diagram. Therefore, the diffusion of sound in DPAC is effective. This can be shown in
the sound distribution data collected.
Diagram 2.2.12 Sound diffusion on section view
Diagram 2.2.13 Sound diffusion on
plan view

22. Direct Sound
Sound Source
Reflected Sound
Listener
D
R1
R2
R3
R4
R1 = 10.2m
R2 = 11.0m
R3 = 10.3m
R4 = 10.5m
D = 11.2m
Calculation
Time Delay 1
= (R1 + R2 - D) / 0.34s
= (10.2 + 11.0 - 11.2) / 0.34
Time Delay 2
= (R3 + R4 - D) / 0.34s
= (10.3 + 10.5 - 11.2) / 0.34
Sound delay calculation on plan perspective
Sound delay is simply a repetition of a same sound at a later time (techtalk, 2019). These
are usually the resultant of reflection of sound. However, depending on the time taken of the
reflected sound to reach the listener, it will result in either a effectively reinforced sound or
would end up as an echo. This can be calculated by the following formula:
Time delay = (R1 + R2 -D)/0.34
Time delay 30msec - Effective reflective sound
Time delay 40msec - Delay
2.2.3 Sound delay and echo
Diagram 2.2.14 Sound delay calculation of center-back position in audience

23. Direct Sound
Sound Source
Reflected Sound
Listener
D
R1
R2
R1 = 10.6m
R2 = 18.2m
D = 14.0m
Calculation
Time Delay
= (R1 + R2 - D) / 0.34s
= (10.6 + 18.2 - 14.0) / 0.34
= 42.35msec
.. . Sound delay
Diagram 2.2.15 Sound delay calculation of left-back corner position in
audience

24. Direct Sound
Sound Source
Reflected Sound
Listener
D
R1
R2
R1 = 10.6m
R2 = 17.6m
D = 14.0m
Calculation
Time Delay
= (R1 + R2 - D) / 0.34s
= (10.6 + 17.6 - 14.0) / 0.34
= 41.76msec
.. . Sound delay
Diagram 2.2.16 Sound delay calculation of right-back corner position in
audience

25. Direct Sound
Sound Source
Reflected Sound
Listener
D
R1
R2
R1 = 11.0m
R2 = 12.0m
D = 16.2m
Calculation
Time Delay
= (R1 + R2 - D) / 0.34s
= (11.0 + 12.0 -16.2) / 0.34
= 20msec
.. . Effective
Diagram 2.2.17 Sound delay calculation of back position in audience

26. Direct Sound
Reflected Sound
D
R1
R2
R1 = 8.0m
R2 = 6.0m
D = 8.4m
Calculation
Time Delay
= (R1 + R2 - D) / 0.34s
= (8.0 + 6.0 - 8.4) / 0.34
= 16.47msec
.. . Effective
Direct Sound
Reflected Sound
D
R1
R2
R1 = 13.6m
R2 = 3.9m
R3 = 12.0m
R4 = 7.0m
D = 15.0m
Calculation
Time Delay 1
= (R1 + R2 - D) / 0.34s
= (13.6 + 3.9 - 15.0) / 0.34
= 7.35msec
.
R4
R3
Time Delay 2
= (R3 + R4 - D) / 0.34s
= (12.0 + 7.0 - 15.0) / 0.34
= 11.76msec
Diagram 2.2.18 Reflected ceiling plan with
indication of ceiling and reflective panel
Sound delay calculation on section perspective
Diagram 2.2.19 Time delay calculation in section view reflected on the
suspended reflective panel
Diagram 2.2.20 Time delay calculation in section view reflected on the suspended reflective panel and ceiling

27. D = 2.0m
H = 3.2m
2H = 6.4m
Calculation
2.2.4 Sound shadow
The previous calculation shows that there is no sound shadow below the deck. To further
prove this aspect, the calculation below will show that the dimensions respects the theory
shown:
.. . No sound shadow
D 2H
D
H
.. . D 2H
Conclusion
The time delay calculations shows alternate results. Therefore, it shows that the theater has
a seemingly poor sound delay performance.
Diagram 2.2.21 Sound shadow calculation

28. 2.2.5 Echo Flutter
Echo flutter is an energy that’s trapped between two parallel surfaces, resulting in a
repetition of the same ‘track’ in a span of only a few milliseconds (Foley, 2014). It is important
for a theatre like DPAC to eliminate as much echo as possible. However, the theatre itself
exists in a rather right angled form, which directly promotes the existence of echo flutter.
Below shows how DPAC have used simple solutions to overcome this defect:
R
h
c
c
o
The walls on one side is slightly slanted
at an 85 degree angle, which disrupts
the originally parallel walls on both sides
of the theatre. Hence, flutter echo fails to
occur
The distance from the backdrop of the
stage towards the wall at the back of
the audience that is supposingly
parallel are far enough apart to
minimise the effect of echo flutter.
d = 17.2m
Diagram 2.2.22 Indicating angled wall and distance between
stage backdrop and back wall

29. Diagram2.2.25SounddistributionofHuawei
smartphonemusicwithhighestvolumeinthe
seatingarea
34.5dB
33.2dB
35.5dB35.2dB
34.0dB
35.8dB35.3dB
Soundsource
Diagram2.2.23Sounddistributionofnoise
(air-borne,structure-borne,insidenoise)inthe
seatingarea
32.0dB
30.5dB31.6dB30.1dB
30.4dB30.9dB30.1dB
Diagram2.2.24Sounddistributionofnormal
speechleveltheseatingareatakenfromthe
stage
44.1dB
45.4dB46.6dB44.9dB
45.6dB47.1.1dB45.7dB
Soundsource
eadingsfromthedigitalsoundlevelmeterisrecordedindifferentpositionsintheseatingsofthetheatrewithaconstantsoundsource
thestage.Wehaverecordeddifferentscenariosofsoundincluding:silent(withoutairconditioningsystemrunning),Normalspeechlevel
uaweismartphonemusicwithhighestvolume,toanalyseamoreaccuratedata.
Sounddistribution
Analysis
Accordingtodiagram2.2.23,thenoiseisconsiderablydistributedevenlywithdifferenceofnotmorethan1dBatdifferentposition.The
positionsidingtheentrancehasahigherreadingduetoitbeingunderadeck(refertosection)wheretherearefunctioningequipments
thatemitsnoise.Therecordingindiagram2.2.24hasamorefluctuatedreadingduetotheinconsistentdeliveryofsoundamplitude
duringaspeechwhereasindiagram2.2.25Ismoreconsistentandaccurate.Overall,thesounddistributionisconsiderablyevenly
distributedandatthesametimeshowsthatthesoundpropagationstrategiesappliedisinanacceptablerangebutwithpotentialfor
betterimprovements.

30. 2.3 Potential of Noise Intrusion
Noise is unwanted sound judged to be unpleasant, loud or disruptive to hearing.
From a physics standpoint, noise is indistinguishable from sound, as both are
vibrations through a medium, such as air or water.
For noise intrusion, two main groups can be identified:
1. External noise sources
There are multiple noise sources from the outside of the auditorium. It can
be produced by the road traffic, opening on closing of the doors, human sounds
and human chatters.
2. Internal noise sources
Some of the noises comes from the electrical appliances. The acoustics
door, flooring and stages also produce some noises. Besides, the audience
from the seats also creates various noises such as chatters, sneezing, body
movement, etc. There are some preventions were made to minimize the
noise intrusion in the auditorium hall.
There are two ways in which noise (or sound in general) can be transmitted in
acoustics hall:
1. Air-borne Sound Transmission
The noise is transmitted through the air from its sources. Along the
continues air paths through opening,such as open doors, cracks around
doors and electrical fixtures.
2. Structure-borne Sound Transmission
Sound energy from a sources sets into vibration solid parts of the building
structure, it is transmitted directly through the structure is radiated from
building structure.
Levels of Noises Produce Both Psychological and Physiological Effects:
65 dBA: up to this level of noise may create annoyance, but its result is only
physiological (bodily fatigue). Above this level, psychological effects such as
mental and nervous effects, may occur.
90 dBA: many years of exposure to such noise levels would normally cause
permanent hearing loss.
100 dBA: with short period of exposure to this level, the aural acuity may be
impaired temporarily, and prolonged exposure is likely to cause irreparable
damage to the auditory organ.
120 dBA: causes pain.
150 dBA: causes instantaneous loss of hearing (deafness).

31. External Noise Source
Vehicles (Air borne noise)
DPAC is located inside Empire Damansara, Petaling Jaya. It is sits comfortable more than 150
meters from Lebuhraya Damansara - Puchong highway which is one of the main road
connecting between Damansara and Puchong and it is mainly congested during peaks hours
including lunch time, increasing the sound travelling distance and therefore reducing the noise.
The vehicles passing by the street causes transportation noise in the building. This noise
source is transmitted through airborne as well as structure-borne transmission. In this case,
the building itself acts as a receive of noise.
However, DPAC is facing to the northwest of a large contour area of vegetation, which as a
partial sound absorber that helps in aiding the reduction of background sound. When one is
inside DPAC, you could hardly hear any noises from the busy road as it is quite far from the
main road too.
TNB
DPAC
JALAN PJU 8/8
Diagram 2.3.5 shows position of DPAC beside
a roadside
Diagram 2.3.5 shows site context of DPAC

32. External Noise Source
Entrances (Air borne noise)
Sound intrusion can be identified when there is opening and closing the door or even the
sound of human talking taking place outside the theatre. However, there is a sound lock
which prevent from interfering the audience that sit near to the door and it serves as a
function to trap the sound waves in sound lock with the outer door.
Figure 2.3.1 Door to enter the Sound Lock area Figure 2.3.2 Door to enter the Auditorium

33. External Noise Source
Backstage door (Air borne noise)
There is a backstage door acting as an entrances for the performances which also lead to the
basement parking lot and loading bay. It is also another sound intrusion could be founded.
However, the backstage door is designed with the combination of 25mm rockwool core infill
which can absorb and minimize the noise from entering into theatre.
Rockwool is one of the effective acoustics insulation solution as they provide airborne sound
absorption which can remarkably improve the acoustics which due to its high density, non
directional fibres that trap the sound waves and absorb vibration.
Diagram 2.3.2 Location of the Backstage Door

34. Internal Noise Source
Light fixture (Air borne noise)
Light fixture as lighting system might produce some buzzing sound. There are LED strip
was kept inside by the internal steel panel where the buzzing noise would be heard if
someone are sitting right beside the steel panel.
LED strip are making the buzzing noise is due to improper dimming or electromagnetic
interference from others devices causes vibration in the light bulb which will produce
some buzzing sound.
The solution was fix the dimmer that compatible the LED strip to ensure there are no
more humming sound produced.
Diagram 2.3.4 The Location of the Light Fixtures
Diagram 2.3.5 The Location of the Light Fixtures

35. Internal Noise Source
Ducting & Diffuser (Air borne noise)
Ducting and diffuser supply positive pressure distribution systems and negative pressure
ducting for exhausting air from rooms. It is one type of sound intrusion that could be
identified due to the high pressure of air distribution.
In DPAC, Centralized Air Conditioning with delivery duct is used, such as Fan Coil Unit,
diffuser and ducting. Fan Coil Unit with low noise and diffuser with low regeneration noise
is one of the selection for acoustics hall. Ducting with internal lining of rockwool and
thermalrock with tissue facing to ensure acceptable indoor air quality as good as thermal
comfort.
Figure 2.3.6 shows the ducting above the stage Diagram 2.3.6 shows the location of
ducting and diffuser
Figure 2.3.7 shows the ducting at the back stage Figure 2.3.8 shows the ducting at the

36. Internal Noise Source
Air conditioning system (Structural borne noise)
In any indoor room, the noise of a functioning air-conditioning unit is inevitable. It is the
type of sound transmitted through structural borne in which sound is vibrating on the
solid surface of the AHU duct. This issue also occurs in DPAC. Therefore, the seats were
designed in such way that the metal stand beneath incorporates air conditioning
openings on every seats. There are initiatives taken which has minimize the sound of air
flow in the audience seating area.
Plywood staircase
FCU
UNIT
OPENINGS
SLAB
AIR DUCT FOAM LAYERS
REDUCE AIR
FRICTION AND
ABSORB
SOUND FROM
FCU UNIT
Diagram 2.3.7 and Figure 2.3.9 shows the air-conditioning mechanism below the seats in the auditorium
Diagram 2.3.8 shows the FCU Unit and the connecting pipings to the auditorium seats

37. Internal Noise Source
Squeaky Staircase (Structural borne noise)
It is extremely disturbing when the audience happen to enter and leave in the middle of the
performance, and the squeaky sound from the staircase. The sound is transmitted through
structural-borne, where sound vibrates on the solid hard surface of the plywood. The solution
to reduce the noise can simply done through a selection of softer material like carpet to cover
over the staircase.
Concrete floor
Plywood staircase
Figure 2.3.10, Diagram 2.3.9 and Diagram 2.3.10 shows the staircase as the disturbance that may interrupt the
audience towards the performances
Figure 2.3.10 shows material of staircase Diagram 2.3.9 shows location of staircase
Diagram 2.3.10

38. Internal Noise Source
Performance stage flooring (Structural borne noise)
DPAC is mainly serve for musical production, drama and small scale dance. It is advisable
to consider the probability of sprung floor to provide some degree of bounce and flex
under impact. The sprung floor are suspended on transducers that act like shock
absorber.
The stage is made of plywood, it has sound control which bounces high frequencies,
resonating better sound quality, and absorbing bass energy. Also, plywood are more
durable and economical.
Due to space limit, theatre was built with a shallow apron between the stage and
audience seat. Where the noise of the stage floor might be very loud to the audiences.
Therefore, the stage floor is covered with vinyl sheet to increase slip resistance and
reduce the noise.
Plywood
Vinyl Sheet
Dual density shock dampening
elastomer blocks at
Stage
Apron
Audience
seat
Stage
Apron
Audience
seat
Diagram 2.3.11 Located Flooring Type
Figure 2.3.11 Flooring Type in Auditorium

39. 3.0
CONSTRUCTION
MATERIALS ANALYSIS

40. 1. Ceiling
Materials:
Concrete Slab + Spray Foam
The ceiling is made up of concrete to form a concrete slab. Due to its ability to reflect sound
since it is a hard surface, a layer of sound insulation must be applied in order to reduce the
resultant sound cause by the reflection.
In DPAC, spray foam is used as a layer covering the concrete slab as it is able to reduce the
sound reflection cause by the concrete itself. Therefore, the dampening of sound can be
increased by using spray paints. The spray foam is able to absorb a small amount of sound but
most of the sound are dispersed out from it
Figure 3.1 above and the diagram 3.1 on the right is
showing the location of the ceiling in the auditorium

41. 2. Reflector Panel
Materials:
Plywood
The reflector panels are defined as the panels that are hang up just below the ceiling as a
purpose to reduce the sound reflection and its impact to the receiver (audience).
Since the ceiling with spray foam can only reduce part of the sound waves, the reflector panel
acts to reduce sound reflection by blocking part of the sound waves via absorption. Part of the
sound is then transmitted through the reflector panel and is delivered to the receiver. The
reflector panel can absorb only low frequency sound, while the high frequency sound bounce
on it.
The direct sound can be heard clearer for those who are sitting at the back as the mass
reflection of sound can be reduced by using reflector panels. Thus, the sound are distributed
and reflected equally to the audience.
The diagram 3.3 and the Figure 3.2 above show the reflected ceiling plan with the highlighted reflector panels

42. 3. Acoustic Treated Wall
Materials:
Fibre Board, Rockwool, Concrete
The combination of the materials creates sound insulating wall which it reflects and transmit
part of the sound into the wall. The acoustic treated wall is made up of 3 layers mainly the fibre
board as the layer facing the interior of the auditorium, the rockwool as the middle components,
and a layer of concrete at the other side of the wall.
Acoustic
Treated Wall
Zig-Zag
Steel Panel
Diagram 3.6 shows the components of the Acoustic Treated WallDiagram 3.5 shows location of Acoustic Treated Wall
Figure 3.3 shows the Attachment of Panels to Walls

43. Fibre Board
It is a high density product which is made
up of liquid rocks forming into wool.
It works as either by impeding the sound
transmission through a structure or
absorption of sound at its surface.
Fibre Board makes up 90% of wood and it
is often used as heat-proof or acoustic
materials.
The fibre board is used due to its ability to
absorb or transmit part of the sound into
the wall especially high frequency ranges
Rockwool

44. 4. Zig-Zag Steel Panels
Materials:
Steel
Since it is an auditorium, it is important to diffuse the sound as diffusion of sound minimizes the
coherent reflections that causes distinct echoes. It is also functioning as to make an enclosed
space sound larger.
Acoustic
Treated Wall
Zig-Zag Steel
Panel
The diagram above shows the diffusion of the sound when the sound hits the steel panels.
Diffusion of those sound does not remove much of the energy. Instead, they are diffused and
the reflection of the sound is greatly reduced to provide an ambient and more lively space
Incident Sound
Diffused Sound
Diffused Sound
Diffused Sound
Diffused Sound
The figure 3.4 shows the highlighted zig-zag steel panels
Diagram 3.8 shows the location of zig-zag
steel panels
Diagram 3.9 shows the diffusion of sound waves at the zig-zag
steel panels

45. 5. Cyclorama Wall
Materials:
Fibre Board, Steel Framing
This wall is located on the stage which is used to define the boundary of the stage. It is also a
sound barrier to the backstage or vice versa as this structure is mainly made up of fibre board
at both sides, and the steel framing system which holds the fibre boards.
Due to the white colour of its surface, it creates reflection of light and forms a focus point to the
audience
Acoustic
Treated Wall
Zig-Zag Steel
Panel
Diagram 3.13 above shows the sound waves created from
the backstage. The transmitted wave is weak due to the
ability of the fibreboard to absorb sound waves.
backstage
stage
Diagram 3.12 above shows the Location of
Cyclorama Wall
Figure 3.7 above shows the Cyclorama Wall Diagram 3.11 above shows the materials
of the Cyclorama Wall

46. 6. Flooring
Materials:
Concrete, Plywood
Since the walls are installed with zig-zag steel panels, DPAC use only concrete flooring for the
audience to walk, and plywood lied with vinyl sheet as stage to ensure the safety of the
performers.
Due to the hard surfaces of the concrete flooring together with the plywood stage flooring, the
sound waves might bounce and reflect to the whole theatre. This reflection of sound is reduced
with the installation of the zig-zag steel panels which can diffuse the sound in the auditorium
and the absorption of sound by the audience.
Acoustic
Treated Wall
Zig-Zag Steel
Panel
Plywood flooring
Concrete flooring
Figure 3.5 and the Diagram 3.10 show the location and the materials used as the floor of the auditorium
Dance Vinyl Flooring
This type of flooring has a high slip-resisting property. It is
installed on the plywood flooring which is the stage as to
increase the performers safety. However, it does not have
any effect towards sound absorption.
Figure 3.6 Vinyl Sheet (Dance Anti-Slip Flooring Sheet)

47. 7. Staircase
Materials:
Plywood, Metal Plate
The staircase is made up of plywood fixed to the metal plate which is rarely noticeable from the
eye level. Both the materials have a flat and reflective surface therefore the sound waves are
not absorbed by them.
The plywood has a coated surface, which reflects the light to the audience for walking safely in
the auditorium, while there is also the LED lighting which is hidden underneath the concrete
flooring and near to the metal plate.
Figure 3.8 above shows the plywood staircase
Diagram 3.14 above shows the sectional diagram of the staircase Diagram 3.15 above shows the location of
the plywood staircase

48. 8. Curtain
Duvetyn
Bolton Twill Fabric
Velvet Fabric
There are three types of curtain found in DPAC. Duvetyn, Bolton Twill fabric as well as Velvet
fabric.The main function for these curtains are to hide the lights from entering the auditorium.
This is to prevent disturbance while the performance is going on. It can also absorb sound as
well as decrease excessive echo delay.
Diagram 3.16: Location of different kind of curtains in DPAC
Bolton Twill Fabric
Bolton twill fabric is used as a covering for
the control space entrance. It is cost friendly
and extremely durable. The purpose of using
this curtain is to reduce sound penetration
and to avoid sound from transferring through
the structure. It is indeed a great choice for
theatrical curtain.
Figure 3.9: Bolton Twill fabric in DPAC

49. Velvet Fabric
Duvetyne Fabric
Velvet fabric was placed at the entrance of DPAC. It is very durable and it can reduce
sound penetration and also to avoid sound to transfer through the structure. Due to it’s
soft characteristics, it can absorb sound effectively. Besides that, it can also prevent
lights from entering the theatre.
Figure 3.10 shows the velvet fabric at the entrance to the auditorium Diagram 3.17 shows the location of the velvet fabric
Figure 3.11 shows the duvetyne fabric in both sides of
the stage acting as a stage skirting.
Figure 3.12 shows the texture of duvetyne fabric.
Duvetyne fabric is placed at both sides of the stage. This is to prevent lights from the
backstage to penetrate to the audience or vice versa. It is also to hide the performers
who are preparing for the show. Duvetyne helps to reduce reflection of light and is also
fireproof material. It is one of the most economical masking fabrics. It is ideal for
blocking out unwanted light as it is high opacity.

50. 9. Seat
Materials:
Foam & Fabric Cover, Plywood, Steel
The seat is made up of foam and covered with fabric to maximize the absorption of sound. The
seat must be able to absorb sound waves like a human sits on it. It should be as effective as the
sound absorption of one human being is equal to a seat.
The hand rest which is made up of plywood has not much effect on sound absorption and
sound reflection and therefore this part can be neglected.
The steel stand is an important material to support the seat. It also functions as an air
conditioning system to ventilate the auditorium but this creates noise where this will be further
discussed in the noise intrusion section.
Figure 3.13 shows the components of the seat
Diagram 3.18 shows the seats in the auditorium

51. 10. Door
Auditorium acoustic door are used in DPAC where sound and noise control is in primary
concern. Sound waves can be greatly reduced either from the exterior to the interior of the
auditorium or functioning from the other way round. This is essential in designing an
auditorium so the audience or the performers will not be able to receive the sound waves
that are transmitted from the exterior of the space.
The acoustic door is made up of plywood and rockwool in which the rockwool is a good
sound absorber while blocking unnecessary noise from the exterior of the auditorium.
Materials:
Plywood, Rockwool
Figure 3.16 shows the acoustic door which is the
main entrance to the auditorium
Diagram 3.19 shows the location of the acoustic door
and the normal door of the auditorium
Figure 3.15 above shows the normal door which
is the entrance to the sound lock before the
acoustic door to the auditorium
Figure 3.14 above shows the ‘sound lock’ space in
between the normal door and acoustic door
normal door
acoustic
door
normal door
acoustic door

52. Sound Lock
Sound lock is an important design to an auditorium as to reduce the noise that is coming
from the exterior of the auditorium that might interrupt the performance and the enjoyment
of the audience towards the performance.
Sound lock
auditorium
entrance
Diagram 3.20 and Diagram 3.21 above is important in explaining the design of sound lock
to the transmission of sound from the exterior of the auditorium. As shown in the diagram,
most of the sound is transmitted through the normal door into the ‘sound lock’ space. As
sound has to transfer a distance of air to the acoustic door, part of the sound waves have
been turned into heat energy and dissipates in the air. Since the acoustic door is installed
with absorbing materials, the sound is unable to transfer into the auditorium and therefore
the sound is greatly reduced so the quality of sound system and performance in the
auditorium is enjoyable by the audience
Sound
Transmission
Sound
Reflection and
Absorption
Sound Waves
(Noise) from Exterior
Reflected Sound
Waves
Entrance ‘Sound Lock’
Space
Auditorium
Diagram 3.20
Diagram 3.21

53. 3.2 Calculation of Reverberation Time
Introduction
Reverberation time is defined as the time for the sound pressure level in a room to decrease by
60dB from its original level after the sound is stopped. The reverberant sound in a room will fade
away due to the sound energy bouncing off. This often caused by absorption by multiple
reflections between the surfaces of a room.
It is dependent upon the following variables:
1. The volume of the enclosure (distance)
2. The total surface area
3. The absorption coefficients of the surfaces
Hence, reverberation time can be calculated by the Sabine Formula:
Where:
RT = reverberation time (sec)
V = volume of the room (cu.m)
A = total absorption of room surfaces (sq.m sabins)
Reverberation Time Calculation
Volume of Auditorium
A
B
C
Diagram 3.22
shows plan of
auditorium

54. Estimated Floor Area (m²)
A : 173.46
B : 160.70
C : 29.61
Estimated Volume (m²)
A : 1243.88
B : 1854.64
C : 87.50
Total Volume of Auditorium (m )
= 3186.02m
ABC
3
3
Diagram 3.23 shows section of auditorium

55. Surface Material Area 500Hz
Absorption
coefficient
Abs. units (m²
sabins)
A Flooring ( Stage ) Plywood 128.210 0.050 6.41
B Flooring ( Audience ) concrete 106.000 0.020 2.12
C Staircase Plywood 7.828 0.050 0.40
D Staircase (Metal
Plate)
Steel 8.710 0.080 0.70
E Human / Seat cushion 169.000 0.042 7.10
Total Absorption (A) 16.73
A
A
B
B
C
C
E
ED
Diagram 3.24
shows ceiling plan
of auditorium

56. A
B
C D
BA D
E
F
E
F
G
G
Surface Material Area 500Hz
Absorption
coefficient
Abs. units
(m² sabins)
A Door Plywood +
Rockwool
6.00 0.10 0.60
B Transition Curtain Velvet Fabric 16.80 0.25 4.20
C Interior Curtain Bolton Twill Fabric 4.00 0.10 0.40
D Zig-zag steel panel Steel 215.35 0.88 189.51
E Stage Curtain Duvetyn, 101.00 0.20 40.96
F Acoustic Treated Wall Fibre Board,
Rockwool,
Concrete
358.92 0.75 269.19
G Cyclorama Wall Fibre Board, Steel
Framing
85.00 0.30 25.50
Total Absorption (A) 530.36
C
Diagram 3.25 shows section of auditorium

57. Surface Material Area 500Hz
Absorption
coefficient
Abs. units (m²
sabins)
A Ceiling Concrete Slab
+ Spray Foam
363.70 0.15 54.56
B Reflector Panel Plywood 21.86 0.05 1.09
Total Absorption (A) 55.65
A
B
B
A
3
Diagram 3.26 shows ceiling plan of auditorium

58. Total Abs Unit
= 16.73 + 530.36 + 55.56
= 602.65m² sabins
Total Volume of the Theatre
= 3186.02m
REVERBERATION TIME
= 0.16V / A
= 0.16(3186.02) / 602.65
= 0.85sec
The reverberation time for auditorium is 0.85sec with 3186.02m which falls within the
average range of recommended reverberation time. This shows that the materials used
compromise with volume of the theatre to achieve an adequate reverberation time. The
theatre accommodate both speeches and musical events, therefore the reverberation time is
balanced in between to suit both the function.
3
3
DPAC
Table 3.27 shows where the auditorium lies in the optimum reverberation time in
different types of auditorium and halls.

59. 4.0
SOUND DEFECTS AND
DESIGN ISSUES

60. Squeaky noise produced by staircase
The footstep of people walking on the plywood staircase along the aisle of the theatre
creates low frequency vibrations that transmitted through structure-borne. This low
frequency vibrations tend to vibrate throughout the whole structure which create squeaky
noises that is unpleasing to the audience.
Design Solution & Suggestion
To protect the audience from these unnecessary noises, the impact of noise generation can
be reduced through the use of thick carpeted flooring for the staircase along the aisle as it
acts as an outstanding sound absorber and serving as an acoustical aid. Carpet has a higher
absorption coefficient of 0.50 for 500 Hz as compared to plywood of 0.05 for 500 Hz.
Besides, shock absorbing underlayment also plays an important role in addressing this issue
by further improving the sound absorption quality.
Carpet
Rubber
Plywood
Diagram 4.2 above shows sectional drawing of proposed treated staircase.
Acoustical Defects & Design Issue
FIgure 4.1 above shows plywood staircases Diagram 4.1 above shows squeaky noise produced by
footsteps.

61. Acoustical Defects & Design Issue
Poor Sound Isolation
I. Ducting & Diffusers
Ductings and diffusers are exposed everywhere within the theatre. Excessive high velocity of
air that flows through the diffusers blades generates noise that penetrates into the theatre,
thus affecting the acoustic quality in the theatre.
II. Light Fixtures
The light fixtures behind the zig-zag steel panels serve as a decorative element that
enhances the visual and aesthetic value of the theatre. However, it tends to create a buzzing
and flickering sound generated by the ballast.
Design Suggestion
I. Ducting and diffusers should be covered by the ceiling and not exposed within the theatre.
II. Lighting should undergo frequent inspection and maintenance to ensure it does not
produce internal noise that would affect the acoustic quality of the theatre. Installing an
Figure 4.4 above shows zig zag
steel panels.
Figures 4.5 and Figure 4.6 above show lighting wirings behind
zig-zag steel panel.
Figures 4.2 and Figure 4.3 above show exposed ducting and diffusers.

62. Acoustical Defects & Design Issue
Mechanical Noises
The machines of FCU Air Conditioning System is placed at the space below the seating area,
which generates mechanical noises through discharging low velocity air supply from the
openings below the seats, transferring it along the horizontal surface.
Design Suggestion
Openings should not be placed below the seats to avoid penetration of air flow that
generates noises.
Figure 4.7 above shows
openings below seats
Diagram 4.3 below shows FCU Air Conditioning machines
below seating area.

63. Acoustical Defects & Design Issue
Reflection
The ceiling has a larger surface area of concrete slab with spray foam which reduces the
reflected sound intensity, therefore, several reflecting panels should be added to the
highlighted spaced below which is the center of ceiling to allow better sound spreading to all
the areas within the theatre. This is to ensure that the reflected sound towards the back are
better reinforced.
Figure 4.8 above shows area where reflecting panels should be
added.
Diagram 4.3 below shows reflection diagram when additional reflecting panels are added.
Additional Reflecting Panel
Existing Reflecting Panel
Direct Sound
Reflected Sound

64. 5.0
CONCLUSION

65. As a conclusion of our observations, data collection, and analysis on Damansara Performing
Art Centre (DPAC), we have gained plenty of information on acoustical design in an
auditorium. Besides rules and regulations on designing an auditorium, there is a need for an
architect to design a space with materials that can tackle with the sound effects and issues
in an auditorium that can serve a good acoustic performance to the audiences.
The DPAC is installed with building materials that can solve the issues of most of the
acoustical problems, which results and fulfill the compliance to the reverberation time
required by a small sized hall. The calculation of the reverberation time (RT) in a small size
auditorium, DPAC has a RT value of 0.85s where the RT value is determined by the
absorption coefficient of the materials and any of the thickness of the materials might also
affect the RT value. For a small size auditorium, it is the best to maintain the RT value of this
space to be lower than 1s.
Also, the analysing of several factors which include material properties, absorption
coefficient, sound reflection, diffraction, absorption, diffusion, and echoes, are used to
determine the sound waves transfer in an auditorium. This is important as the quality of
sound that is to be delivered to the audience needs to be determined so that the audience
will be able to get a great experience towards the performances in the auditorium.
Therefore, the study of the auditorium space is very important to an architect as this will
introduce them to design an auditorium that is best fit to the public besides designing just a
simple auditorium. As an architect, it is our job to build a comfortable environment to the
public with suitable design.

66. 6.0
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