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 Reflection
2.2.2 Sound Diffusion
2.2.3 Sound Sound Delay and Echo
2.2.4 Sound Shadow
2.2.5 Echo Flutter
2.2.6 Sound Distribution
2.3 Potential of Noise Intrusion
3.0 CONSTRUCTION MATERIALS ANALYSIS
3.1 Construction Materials Used
3.2 Calculation of Reverberation Time
4.0 SOUND DEFECTS AND DESIGN ISSUES
5.0 CONCLUSION
6.0 REFERENCES
CONTENT
4. 1
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)
2
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.
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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
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12. 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
8
Figure above and the diagram on the right is showing the
location of the ceiling in the auditorium
The diagram above shows the spray foam that reduces the reflection of the sound waves
13. 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.
9
The diagram and the figure above show the reflected ceiling plan with the highlighted reflector panels
The diagram above shows the sound waves reflection at the reflector panels
14. 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
10
Diagram above shows the components of the Acoustic Treated
Wall
Diagram above shows the coverage of the acoustic treated wall
Diagram above shows location of Acoustic Treated Wall
15. 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
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16. 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
12
The figure above shows the highlighted zig-zag steel panels
Diagram above shows the location of
zig-zag steel panels
17. 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 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 above shows the Location of Cyclorama
Wall
13
Figure above shows the Cyclorama Wall Diagram above shows the materials of the
Cyclorama Wall
18. 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
Picture and the diagram above 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.
Vinyl Sheet (Dance Anti-Slip Flooring Sheet)
14
19. 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 but the waves are all
reflected.
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 above shows the plywood staircase
Diagram above shows the sectional diagram of the staircase Diagram above shows the location of the
plywood staircase
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20. 1. Acoustic Treated Wall
Material: Concrete, Rockwool, Fibre Board
Sound reflection and diffusion are a normal process that take place in DPAC
frequently. Acoustically treated wall is a necessary in DPAC in order to
decrease the cause of unwanted sound. It consist of three layers, which are
the fibre board, plywood and also concrete.
Rockwool is an acoustic barrier that can absorbs sound in an efficient way. It
absorbs sound efficiently especially in low frequency ranges. This is due to it
consists of higher density batts that can reduce airflow effectively as well as
decrease in sound transmission. Rockwool is a soft material that combines both
sound absorption and thermal. It also contains fire retardant properties.
On the other hand, fibre board is an absorption materials for high frequency
ranges. It decreases the airborne noise and sound transmission from interior
and exterior.
Figure :Placement of acoustically treated
walls in DPAC
Figure :Construction details of acoustically
treated wall
21. 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.
Figure : 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 : Bolton Twill fabric in DPAC
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22. VELVET FABRIC
DUVETYNE FABRIC
17
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.
Figure shows the velvet fabric at the entrance to the auditorium Diagram shows the location of the velvet fabric
23. 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 shows the components of the seat
Diagram shows the seats in the auditorium
17
24. 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 shows the acoustic door which is the main
entrance to the auditorium
Diagram shows the location of the acoustic door and
the normal door of the auditorium
Figure above shows the normal door which is the
entrance to the sound lock before the acoustic
door to the auditorium
Figure above shows the ‘sound lock’ space in between
the normal door and acoustic door
normal door
acoustic
door
normal door
acoustic door
18
25. 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
The diagram 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
19
27. Sound Propagation
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:
FIgure… Spherical propagation of sound
The diagram below shows the scenario of sound under reflection,, diffusion,
dispersion, diffraction and also other factors of propagation:
28. 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
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… Reflection of sound on the surface of certain medium
Surface
Direct sound Reflected sound
i r
i = r
29. 23
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.
That 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
30. 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… Sound reflection on the suspended side ceiling panels
Diagram.. Sound reflection on the suspended front ceiling panels
Reflective ceiling plan
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... are the “live” areas. 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.
31. Looking at the diagrams above, we can conclude that by introducing the
suspended reflective steel panels lengthens the range of useful ceiling
reflection, reaching a wider range of audience.
Diagram.. Live area with suspended reflective panel
Diagram.. Live area without suspended reflective panel
3375mm
4790mm
32. 25
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 and 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.. 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 ‘Construction of materials used’ (pg…), 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 (refer to pg…).
33. 26
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
= 29.4msec
.. . No delay
Time Delay 2
= (R3 + R4 - D) / 0.34s
= (10.3 + 10.5 - 11.2) / 0.34
= 28.24msec
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 take 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:
.. . No delay
Time delay = (R1 + R2 -D)/0.34
Time delay 30msec - Effective reflective sound
Time delay 40msec - Delay
Sound delay and echo
37. 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
.. . Effective. Also shows that there’s no sound shadow
R4
R3
Time Delay 2
= (R3 + R4 - D) / 0.34s
= (12.0 + 7.0 - 15.0) / 0.34
= 11.76msec
Reflective ceiling plan
Sound delay calculation on section perspective
38. 26
D = 2.0m
H = 3.2m
2H = 6.4m
Calculation
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.
39. 26
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:
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
42. 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).
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2.3 Potential of Noise Intrusion
43. 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.
TNB
DPAC
JALAN PJU 8/8
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44. 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.
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45. 30
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.
Rock wool 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.
46. Internal Noise Source
Ducting & Diffuser (Structural 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.
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47. Internal Noise Source
Air conditioning system (Air 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
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48. 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
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49. Internal Noise Source
LIght fixture (Structural 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.
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50. 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.
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Plywood
Vinyl Sheet
Dual density shock dampening
elastomer blocks at
predetermined interval.
Stage
Apron
Audience
seat
Stage
Apron
Audience
seat
52. What is 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.
Sound Sources in DPAC
1.Speakers
Locations of Speaker
Plan of DPAC
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54. 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
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55. 3.Musical Instruments
Music made by musical instruments are also consider as sound because musics are desirable.
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Plan of DPAC
Section of DPAC
56. Calculation
38
Surface Material Area 500Hz
Absorption
coefficient
Abs. units (m2
sabins)
Flooring ( Stage ) Plywood 128.21 0.05 6.41
Flooring ( Audience ) concrete 98.08 0.02 2.12
Staircase Plywood 7.828 .0.05 0.40
Metal plate steel 8.71 0.08 0.70
Human / Seat cushion 169 0.042 7.10
Total Absorption (A) 16.73
57. Calculation
38
Surface Material Area 500Hz
Absorption
coefficient
Abs. units (m2
sabins)
Acoustic Treated
Wall
Fibre Board,
Rockwool,
Concrete
358.92 0.75 269.19
Zig-zag steel panel Steel 215.35 0.88 189.51
Door Plywood +
Rock Wool
0.1
Curtain Duvetyn,
Bolton Twill
Fabric, Velvet
Fabric
0.2
Total Absorption (A)
58. Calculation
38
Surface Material Area 500Hz
Absorption
coefficient
Abs. units (m2
sabins)
Ceiling Concrete Slab
+ Spray Foam
363.70 0.28 101.84
Reflector Panel Plywood 21.86 0.17 3.72
Total Absorption (A) 102.28
61. 1
Acoustical Defects & Design Issue
It is a norm for acoustical defects to occur 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. Some
of the defects can be solved during the design stage of acoustic room.
Poor Ensemble
62. 1
Acoustical Defects & Design Issue
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 0.17 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
Section drawing of proposed solution for staircase
63. 1
Acoustical Defects & Design Issue
Poor Sound Isolation
I. Ducting & Diffusers
Ductings and diffusers are exposed all over the ceiling 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 of the theatre.
II. Fluorescent light zig-zag steel panels
The lighting system behind the zig-zag steel panels serve as a decorative element that
enhances the visual and aesthetic value of the theatre. However, it tend 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
electronic ballast could also be a solution to this issue.
64. 1
Acoustical Defects & Design Issue
Mechanical Noises
As the machine of FCU Air Conditioning System is placed at the space below the seating
area, it generates mechanical noise through discharging low velocity air supply from the
openings below the seats. This causes the noise to transfer along the horizontal surface.
Design Suggestion
Openings should not be placed below the seatings as it would reduce the penetration of air
flow the generates noises which would affect the acoustic quality of the theatre.
