An analysis report on the acoustic analysis on Permata Pintar Auditorium, UKM

1. BUILDING SCIENCE II BLD60803
Auditorium
- A Case Study on Acoustic Design -
NAME STUDENT ID
CARMEN CHAN SHEN WEN 0326485
CHAN JIA CHIN 0326560
CHEN LIAN LIAN 0333357
CHRISTAL WONG CHING LING 0326715
KHOO SUE LING 0326470
LEE XING SHEN 0327496
LIM JING KAI 0326756
POH JIA YEN 0331197
TANG SOON FOO 0330958

2. 1.0 INTRODUCTION
1.1 Permata Pintar Auditorium
1.2 Architectural Drawings
1.3 Methodology
2.0 ACOUSTICAL ANALYSIS
2.1 Auditorium Design
2.2 Acoustical Components
2.3 Sound Diffusion
2.4 Sound Propagation
2.5 Sound Reflection
2.6 Sound Delay
2.7 Sound Shadow
2.8 Noise Intrusion
2.9 Sound Lock System
2.10 Sound Reinforcement System
3.0 REVERBERATION TIME
4.0 CONCLUSION
5.0 REFERENCES
TABLE OF CONTENTS
1
2
3
7
8
9
17
24
27
28
29
31
32
34
36
39
42
43

3. LIST OF FIGURES
Figure 1.1: Exterior of Permata Pintar Auditorium (GDP Architects, 2015)
Figure 1.3.1: Digital sound level meter (Lutron, 2019)
Figure 1.3.2: Measuring tape (left) & Laser measure (right) (IndiaMart, 2019)
Figure 1.3.3: Digital camera (B&H, 2019)
Figure 1.3.4: Hair dryer (Phillips, 2019)
Figure 2.1.1: Fan shaped form of auditorium. (Tang, 2019)
Figure 2.1.2: Plan showing sound reflections from side walls. (Tang, 2019)
Figure 2.1.3: Arrows show surrounding noises that are being reflected back from the aluminium-cladded
facade of the auditorium. (Chen, 2019)
Figure 2.1.4: Section that shows the different material components used to form the outer and inner part of
the facade. (Chen, 2019)
Figure 2.1.5: Lightweight steel frame structure fixed in between aluminium cladding and hyperion
composite. (Chen, 2019)
Figure 2.1.6: Lightweight steel trusses were used for the construction of the roof that spans three main
sections of the building. (Chen, 2019)
Figure 2.1.7: Walls highlighted (in red) shows the concrete masonry units that were used to build walls of
the auditorium. (Chen, 2019)
Figure 2.1.8: Hard and semi-smooth concrete masonry wall used in the auditorium. (Chen, 2019)
Figure 2.1.9: Concrete block “open” facing (cores perpendicular to fuzz)
Figure 2.1.10: Sound reflecting forestage canopies that are non-adjustable, suspended from the ceiling.
(Chen, 2019)
Figure 2.1.11: Sound reflection forestage canopies as seen from the auditorium. (left and right) (Chen,
2019)
Figure 2.1.12: High Shell - Stage Ceiling > 9 meters high, side walls < 15 meters apart and shell < 9 meters
deep
(Chen, 2019)
Figure 2.1.13: Coupled Stagehouse (With tiered sound reflecting forestage canopies to allow flow of
low-frequency sound energy)
(Chen, 2019)
Figure 2.1.14: Mezzanine floor plan that shows the balcony (in red) of the auditorium. (Chen, 2019)
Figure 2.1.15: Section that shows the slanted concrete slab of the balcony. (Chen, 2019)
Figure 2.1.16: Section of a conventional auditorium with balcony. (Chen, 2019)
Figure 2.1.17: Typical floor plan of an auditorium with a balcony. (Chen, 2019)
Figure 2.1.18: Section (left) and the actual sloped mezzanine balcony in the auditorium (right). (Chen,
2019)
Figure 2.1.19: Blow-up section of the sloped concrete soffit. (Chen, 2019)
Figure 2.1.20: Section diagram showing the basic elements of a mezzanine balcony. (Chen, 2019)
Figure 2.2.1: Loop Pile Carpet in the auditorium. (Khoo, 2019)
Figure 2.2.2: Location of Loop Pile Carpet. (Khoo, 2019)
Figure 2.2.3: Acoustically absorbing surface of carpet. (Iverson, 2007)
Figure 2.2.4 : Safety curtains in the auditorium. (Khoo, 2019)
Figure 2.2.5: Location of curtains in the auditorium. (Khoo, 2019)
Figure 2.2.6: Acoustically absorbing surface of curtains. (Iverson, 2007)
Figure 2.2.7: Seating at Permata Pintar Auditorium. (Khoo, 2019)

4. LIST OF FIGURES
Figure 2.2.8: Arrangement of seating at the Auditorium. (Khoo, 2019)
Figure 2.2.9: Acoustically diffusing surface of Arc One Plus seating. (Iverson, 2007)
Figure 2.2.10: Ceiling of the auditorium. (Poh, 2019)
Figure 2.2.11: Location of plaster ceiling in the auditorium (Poh, 2019).
Figure 2.2.12: Sectional detail of gypsum plaster. (Pyrok, n.d.)
Figure 2.2.13: Underside of mezzanine balcony. (Poh, 2019)
Figure 2.2.14 : Location of walls with cement plaster. (Poh, 2019)
Figure 2.2.15: Axonometric detail of stage wall. (tsib.org, 2017)
Figure 2.2.16: Location of mezzanine balcony & walls with cement plaster. (Poh, 2019)
Figure 2.2.17: Sectional detail of reflective cement plaster on CMU. (Poh, 2019)
Figure 2.2.18: Stage of the auditorium. (Poh, 2019)
Figure 2.2.19: Location of stage flooring. (Poh, 2019)
Figure 2.2.20: Sectional detail of reflective stage floor. (Peace & Quiet Insulation, n.d.)
Figure 2.2.21: Seating base of the auditorium. (Poh, 2019)
Figure 2.2.22 : Location of seatings in the auditorium. (Poh, 2019)
Figure 2.2.23: Sectional detail of absorptive seating base. (Poh, 2019)
Figure 2.2.24: Glass railings at the mezzanine balcony. (Poh, 2019)
Figure 2.2.25 : Location of glass railings in the auditorium. (Poh, 2019)
Figure 2.2.26: Sectional detail of reflective glass railing. (Poh, 2019)
Figure 2.3.1: Hollow-core concrete walls in Permata Pintar auditorium. (Wong, 2019)
Figure 2.3.2: Section of CMU Blocks (Wong, 2019).
Figure 2.3.3: CMU blocks as diffusers surrounding the auditorium for better acoustics experience. (Wong,
2019)
Figure 2.4.1 Plan shows sound distribution readings taken from sound source to the ground floor. (Chan,
2019)
Figure 2.4.2 Plan shows sound distribution readings taken from sound source to the gallery. (Chan, 2019)
Figure 2.5.1 Floor plan showing sound reflections in auditorium. (Lim, 2019)
Figure 2.5.2 Section showing sound reflections in auditorium. (Lim, 2019)
Figure 2.6.1 Section showing sound delay towards the front row. (Lim, 2019)
Figure 2.6.2 Section showing sound delay towards the gallery. (Lim, 2019)
Figure 2.7.1 Section shows direct sound to front row, back row and gallery, comparing the sound intensity.
(Chan, 2019)
Figure 2.7.2 Section shows less indirect sound waves reach seatings under the gallery. (Chan, 2019)
Figure 2.8.1: Chatter from the audience & footsteps. (Chan, 2019)
Figure 2.8.2 Noise from lighting ballast. (Chan, 2019)
Figure 2.8.3: Noise from air-conditioning diffuser. (Chan, 2019)
Figure 2.8.4: The sound of footsteps are louder when walked on timber flooring on stage compared to the
muffled sound on carpet. (Chan, 2019)
Figure 2.8.5: The light ballast makes a constant low buzzing sound. Besides that, air from the air
conditioning creates a low humming sound due to air conditioning duct or diffuser vibrating. (Chan, 2019)
Figure 2.8.6 Section shows exterior noise from bird sounds and location of louvres glass. (Chan, 2019)

5. LIST OF FIGURES
Figure 2.8.7 Section shows location of rear exterior wall. (Chan, 2019)
Figure 2.9.1 Plan shows location of doors to enter and exit into the auditorium. (Chan, 2019)
Figure 2.9.2 Section shows location of doors to enter and exit into the auditorium. (Chan, 2019)
Figure 2.9.3: Doors leading directly to the auditorium hall. The squeaks created by the doors may disrupt
the audiences in the auditorium hall. (Chan, 2019)
Figure 2.9.4: Table shows the higher the STC value, the better the rating and the better the performance.
(Haleybros, 2015.)
Figure 2.9.5: Example section of an acoustical door with STC 42. (Metalec, 2015).
Figure 2.10.1: Position of line array speakers at the auditorium. (Lee, 2019)
Figure 2.10.2: Line Array speakers at the auditorium.(Lee, 2019)
Figure 2.10.3: Position of subwoofers at the auditorium. (Lee, 2019)
Figure 2.10.4: Amate Audio JK12W 12’ Compact Subwoofer. (Amate Audio, 2017)
Figure 2.10.5: Subwoofers at the auditorium. (Lee, 2019)
Figure 2.10.6: Position of stage monitors at the auditorium. (Lee, 2019)
Figure 2.10.7: Amate Audio KEY12A 12’. (Amate Audio, 2017)
Figure 2.10.8: Stage Monitors at the Auditorium. (Lee, 2019)
Figure 2.10.9: Section shows different type of propagation of speakers. (Lee, 2019)
Figure 3.1: Materials of the components. (Chan, 2019)
Figure 3.2: Optimum reverberation time. (Roberts, 2016)

6. 1.0 INTRODUCTION
Permata Pintar Auditorium
Architectural Drawings
Methodology
1

7. 1.1 Permata Pintar Auditorium, UKM
Name : Permata Pintar Auditorium
Location : Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor
Total fixed seats capacity : 600
Year of completion : 2014
Built up area : 2670 m2
Located on a 20.15 acre land in the University Kebangsaan Malaysia campus in Bangi, the
Permata Pintar Auditorium is the newest addition to the campus’ collection of facilities. The
auditorium features 3 interconnected levels, equipped with a lobby, auditorium hall, stage and
back of house facility. It’s auditorium primarily accommodates lectures, convocations, and the
school’s musical theatre programmes.
The dressing rooms, rehearsal area and VIP seatings are located at the back of house. The
overall form of the auditorium is an abstraction of the undulating valley bounding the site. The
auditorium exterior is cladded with natural, earth-coloured materials to accentuate the organic
composition of the building. The aluminium cladding were arranged to form a rhythmic
scale-like skin to form a distinctive contrast with other elements. The distinction between
materials attracts the students’ attention and encourages them to explore the exterior walls.
Figure 1.1: Exterior of Permata Pintar Auditorium (GDP Architects, 2015)
2

8. GROUND FLOOR PLAN
SCALE 1:250
1.2 Architectural Drawings
A A’
B’
B
3

9. FIRST FLOOR PLAN
SCALE 1:250
A A’
B’
B
4

10. SECTIONA-A’
SCALE1:300
5

11. SECTION B-B’
SCALE 1:250
6

12. 1. Digital Sound Level Meter
The sound level meter is used to measure
the sound level in the auditorium. The
acoustic unit of measurement is in decibels,
or dB. The measurement using the A-scale,
reflects the frequency-dependant nature of
human hearing. It is used to measure sound
intensity levels at different locations of the
auditorium to record the Sound Intensity
Level (SIL).
2. Measuring Tape
Measuring tape measures dimensions of the
auditorium for drawing and calculation
purposes. The It is also used to measure the
distance of sound level meter to the sound
source when taking sound levels.
3. Digital Camera
The digital camera is used to capture and
document photos of the auditorium for
analysis. This includes building materials,
areas of noise intrusion or areas
experiencing sound shadow.
4. Hair Dryer
The hair dryer was utilized to mimic a
consistent decibel level of normal human
speech to carry out sound level tests.
Auditorium sound tests should not be
conducted with acoustic enhancements such
as a microphone or speaker.
Figure 1.3.1: Digital sound level meter
(Lutron, 2019)
Figure 1.3.2: Measuring tape (left) & Laser measure
(right) (IndiaMart, 2019)
Figure 1.3.3: Digital camera (B&H, 2019)
Figure 1.3.4: Hair dryer
(Phillips, 2019)
1.3 Methodology
7

13. 2.0 ACOUSTICAL ANALYSIS
Auditorium Design
Acoustical Components
Sound Diffusion
Sound Propagation
Sound Reflection
Sound Delay
Sound Shadow
Noise Intrusion
Sound Lock System
Sound Reinforcement System
8

14. 2.1.1 Form and Shape
The auditorium is designed in a fan shaped form to propagate sound equally throughout the
auditorium hall. However, due to the minimal splay angle of 16.5 degree (the recommended
being 30 - 60 degrees), the form bares close resemble to a regular end stage auditorium.
Therefore, audiences face relatively in the same direction which make layouts such as this
suitable for lectures or slide-based presentations. The stage also utilizes a fan shaped form
to prevent flutter echoes which occurs between parallel walls.
Figure 2.1.1: Fan shaped form of auditorium. (Tang, 2019)
2.1 Auditorium Design
9

15. 2.1.2 Levelling and Arrangement of Seats and Stage
The auditorium has a narrow plan and the seats are arranged in straight stepped rows. The
side rows are angled towards the stage, still being able to see ⅔ of the stage. Sound will travel
in a straight path from the stage and reach every corner of the auditorium by reflection of
sound. The distance between the centre of the stage to the last row of the seat is 22.5m which
is beyond the ideal range of unamplified speech from source to listener. The seats are
staggered such that the audience have unobstructed views and receives direct sound.
However, a deep overhanging balcony creates an area of sound shadow above 6 rows of
seats at the centre.
22.5m
Figure 2.1.2: Plan showing sound reflections from side walls.
(Tang, 2019)
10

16. 2.1.3 Facade - Aluminium Cladding & Hyperion Composite Cladding
Figure 2.1.3: Arrows show surrounding noises that are being reflected back from the aluminium-cladded
facade of the auditorium. (Chen, 2019)
Figure 2.1.4: Section that shows the different material components used
to form the outer and inner part of the facade. (Chen, 2019)
Concrete Masonry Wall
Aluminium cladding; being a hard, reflective and smooth surface material, is in a way a good sound
reflector where sound energy bounces off the material and back to the surroundings as shown in the
topmost figure of the site plan.
However, in this case where lightweight steel-frame is sandwiched in between aluminium cladding on
the exterior and the hyperion composite cladding on the interior surface of the facade, the sound
insulation from surrounding noises can hardly be reduced because of the opening (as shown in the
above blow-up section, in yellow) between the facade shell and the concrete masonry wall that enclosed
the main auditorium.
11

17. 2.1.4 Facade - Composite Construction
Figure 2.1.5: Lightweight steel frame structure fixed in
between aluminium cladding and hyperion composite.
(Chen, 2019)
Lightweight Steel Frame
Aluminium Cladding
Hyperion Composite
Figure 2.1.6: Lightweight steel trusses were used for the construction of the roof that spans three main sections of
the building. (Chen, 2019)
Lightweight steel-framed (LSF) construction has the potential to reach high standards regarding the
functional performance of buildings. However, because lightweight steel-framed buildings have low
mass and the connections between the outer and the inner sheathing of the walls are usually rigid,
provided by steel studs, noise can still penetrate fairly easily despite a slight reduction.
12

18. 2.1.5 Wall Construction
Louvre Block
390mm (L) x 140mm
(W) x 190mm (H)
Solid Block
390mm (L) x 140mm
(W) x 190mm (H)
Figure 2.1.8: Hard and
semi-smooth concrete masonry
wall used in the auditorium. (Chen,
2019)
When absorption of high-frequency sound energy is not critical,
the open area of protective facings need only be greater than
about 10 percent to control reverberation time or noise buildup
within rooms. As a consequence, a wide variety of textures and
forms can be used to satisfy this requirement.
When absorption is used to control echoes, however, protective
facings should have a higher percentage of open area from
numerous, closely spaced openings. To conceal the
sound-absorbing material behind most facings, a protective
cover is used.
Figure 2.1.7: Walls highlighted (in red) shows the concrete masonry units that were used to build walls of the
auditorium. (Chen, 2019)
Figure 2.1.9: Concrete block
“open” facing (Egan, 2007)
13

19. Figure 2.1.12: High Shell - Stage
Ceiling > 9 meters high, side walls < 15
meters apart and shell < 9 meters deep
(Chen, 2019)
Sound-reflecting panels, suspended in front of the proscenium, reflect sound energy from the
stage to the audience and decrease the initial-time delay gap.
These panels are known as forestage canopies, extended the orchestra shell into the
auditorium. This extension can enhance the direct sound needed for intimacy and can also
reflect sound energy from the orchestra pit back toward the pit.
The openings between the panels allow sound energy to flow into upper volume so it can
contribute to the low-frequency reverberation in the main auditorium below.
Figure 2.1.13: Coupled Stagehouse (With tiered sound reflecting
forestage canopies to allow flow of low-frequency sound energy)
(Chen, 2019)
2.1.6 Sound Reflecting Forestage Canopies
Figure 2.1.10: Sound reflecting forestage canopies that are non-adjustable, suspended from the ceiling. (Chen,
2019)
Figure 2.1.11: Sound reflection forestage canopies as seen from the auditorium. (left and right) (Chen, 2019)
14

20. 2.1.7 Mezzanine Balcony - Cantilever Concrete Beam and Slab
Presence of mezzanine gallery helps in reducing the distance to the farthest row of seats and/
or to increase seating capacity.
The overhang is kept shallow (depth is less than twice the opening height) and the soffit is
sloped as shown in the Figures in order to prevent echoes.
Figure 2.1.16: Section of a
conventional auditorium with balcony.
(Chen, 2019)
Figure 2.1.17: Typical floor plan of an auditorium with a
balcony. (Chen, 2019)
Figure 2.1.15: Section that shows the slanted concrete slab of the balcony. (Chen, 2019)
Figure 2.1.14: Mezzanine floor plan that shows the balcony (in red) of the auditorium. (Chen, 2019)
15

21. In order to prevent echoes
and long-delayed reflections
off the balcony face, the
surface of the balcony slab
facing the stage is tilted or
sloped so sound will be
reflected towards nearby
audience.
Figure 2.1.20: Section diagram showing the basic elements of a
mezzanine balcony. (Chen, 2019)
Figure 2.1.18: Section (left) and the actual sloped mezzanine balcony in the auditorium (right). (Chen, 2019)
Figure 2.1.19: Blow-up section of the sloped concrete soffit. (Chen, 2019)
16

22. 2.2.1 Sound Absorption Components
i) Floor - Loop Pile Carpet
Carpeted flooring is implemented throughout the
auditorium flooring except the stage. The main
purpose of this is to completely absorb surface noise
from footsteps, eliminating distractions during events.
Loop Pile carpet is a type of carpet made from uncut
loops of yarn. It is less efficient in absorbing sound
compared to cut pile carpet. At Permata Pintar, the
carpet is glued directly to the concrete floor,
preventing hard contact with the floor and thus
attenuates impact sound.
ii) Stage - Safety Curtains (Fire Resistant)
Safety curtains made out of medium Velour are used
at the stage of Permata Pintar auditorium. Besides
acting as a sound absorber, it is also a fire resistant,
preventing fire starting on stage from spreading to the
rest of the auditorium.
Various sound absorption materials were used throughout the Permata Pintar Auditorium to
provide noise control and to reduce interior noise. The main method for this is by providing
treatment and finishes for the floors and the seating.
Figure 2.2.6: Acoustically absorbing
surface of curtains. (Iverson, 2007)
2.2 Acoustical Components
Figure 2.2.1: Loop Pile Carpet in the
auditorium. (Khoo, 2019)
Figure 2.2.3: Acoustically absorbing
surface of carpet. (Iverson, 2007)
Figure 2.2.2: Location of Loop Pile
Carpet. (Khoo, 2019)
Figure 2.2.5: Location of curtains in the
auditorium. (Khoo, 2019)
Figure 2.2.4 : Safety curtains in the
auditorium. (Khoo, 2019)
Some sound energy
are absorbed &
converted to heat
All sound energy are
absorbed &
converted to heat
17

23. iii) Auditorium - Upholstered Seating
Figure 2.2.9: Acoustically diffusing
surface of Arc One Plus seating.
(Iverson, 2007)
Figure 2.2.7: Seating at Permata Pintar
Auditorium. (Khoo, 2019)
Figure 2.2.8: Arrangement of seating at the
Auditorium. (Khoo, 2019)
The seating in Permata Pintar auditorium are Arc
One Plus Auditorium seatings. They are thickly
upholstered except for the area below the seating.
The fabric upholstery for the seating provides
additional sound control to the auditorium when the
seat is occupied and pushed down for use.
All sound
energy are
diffused
18

24. i) Ceiling - Gypsum Plaster
The forestage canopies of the auditorium are made of
gypsum plaster. Gypsum plaster is a material which
resonates and absorbs low-frequency sound. It
reflects sound for all other frequencies, ensuring
sound transmission from the stage reaches the other
end of the auditorium.
Figure 2.2.12: Sectional detail of gypsum plaster. (Pyrok, n.d.)
Cold Rolled Steel Channel
Gypsum Board
Spray Applied Texture as Necessary to
Provide Required Sound Absorptive Rating
Outside Corner with
Pre-fabricated Molding
Steel Stud Framing
Soffit
2.2.2 Sound Reflection Components
Figure 2.2.10: Ceiling of the auditorium.
(Poh, 2019)
Figure 2.2.11: Location of plaster ceiling in the auditorium (Poh, 2019).
19

25. ii) Wall - Cement Plaster
Cement plaster is used as a finish for the underside of
the mezzanine balcony as well as the walls at the
stage area. Hard cement plaster wall is relatively
smooth. Thus, it has very low sound absorption but
high sound reflection.
CMU
Cement Plaster
Figure 2.2.15: Axonometric detail of stage
wall. (tsib.org, 2017)
Figure 2.2.17: Sectional detail of reflective cement
plaster on CMU. (Poh, 2019)
CMU
Cement Plaster
Most sound waves bounce off
Figure 2.2.13: Underside of mezzanine
balcony. (Poh, 2019)
Figure 2.2.14 : Location of walls with cement plaster.
(Poh, 2019)
Figure 2.2.16: Location of mezzanine balcony & walls with cement plaster. (Poh, 2019)
20

26. iii) Stage - Composite Timber Flooring
The finish for the stage floor and stairs is made of
composite timber flooring. The flooring does not serve
as a good sound absorber due to its hard and smooth
surface. The lack of shock absorbing acoustic
underlays creates some unwanted noise such as
footsteps. Sound waves are reflected when they hit the
surface.
iv) Auditorium - Perforated Plastic Seating Base
The plastic base of the seatings are designed with
indentations. When the tip-up seat is unoccupied, these
indentated facings act as multiple sound depersion
devices to weaken and absorb high-frequency sound
with each individual holes sharing a common volume
(Egan, 2007).
Figure 2.2.20: Sectional detail of reflective stage
floor. (Peace & Quiet Insulation, n.d.)
Composite
Timber
Flooring
Concrete Slab
Most sound
waves
bounce off
Figure 2.2.23: Sectional detail of
absorptive seating base. (Poh, 2019)
Some sound
energy are
absorbed &
converted to heat
Some sound
energy are
transmitted
Some sound
energy are
dispersed
Figure 2.2.18: Stage of the auditorium.
(Poh, 2019)
Figure 2.2.19: Location of stage flooring.
(Poh, 2019)
Figure 2.2.21: Seating base of the auditorium.
(Poh, 2019)
Figure 2.2.22 : Location of seatings in the auditorium.
(Poh, 2019)
21

27. v) Railing - Glass Panels
Glass railings are used at the mezzanine gallery of
the auditorium. The glass panels which are 6mm thick
are able to block direct sound from the stage. This
leads to the decrease in sound intensity level at the
mezzanine gallery as the audience only receive
diffused sound from the stage.
vi) Wall - Zenbes CMU Blocks
Concrete masonry unit (CMU) blocks are modular
building blocks made of concrete (Cavanaugh, Tocci
& Wilkes, 2010). Walls at the seating area are made
of Zenbes CMU blocks. The blocks with hollow cores
are custom made to function as sound trappers and
sound diffuser.
Figure 2.2.26: Sectional detail of reflective glass railing. (Poh, 2019)
Most sound
waves bounce off
Diffused sound
waves reach
the audience
Figure 2.2.24: Glass railings at the mezzanine
balcony. (Poh, 2019)
Figure 2.2.25: Location of glass railings in the auditorium.
(Poh, 2019)
Figure 2.2.27: Location of CMU walls in the auditorium.
(Poh, 2019) 22

28. 2.2.3 Materials Tabulation of Permata Pintar Auditorium, UKM
Location Component Material
Surface
Area (m2
)
125 Hz 500 Hz 2000 Hz
Auditorium
Flooring Loop Pile Carpet 740.43 0.1 0.62 0.63
Wall
Concrete masonry
unit (CMU) blocks
1057.08 0.05 0.31 0.39
Ceiling Gypsum plaster 630.00 0.45 0.80 0.65
Fire Door Solid timber 57.60 0.14 0.06 0.10
Seating
(Occupied)
Fabric upholstered 340.00 0.32 0.74 0.81
Seating
(Unoccupied)
Fabric upholstered
with perforated
plastic base
170.00 0.07 0.26 0.50
Control Room
Double glazed
glass windows
7.10 0.15 0.03 0.02
Railing
6mm glass panels
with steel handrails
31.02 0.10 0.04 0.02
Underside of
Mezzanine
Balcony
Cement plaster 133.36 0.02 0.03 0.05
Stage
Flooring
Composite timber
flooring
196.71 0.05 0.05 0.05
Wall Cement plaster 401.19 0.02 0.03 0.05
Drapery
Safety velour
curtain
140.40 0.05 0.49 0.70
23

29. CMU Blocks - as sound trappers and large surface
reflectors.
The rough surface of unfinished concrete walls diffuse and
reflect sound energy. Due to the nature of concrete, it is
mildly absorptive.
CMU Blocks as a sound reflector and sound diffusers in Permata Pintar Auditorium.
Diffusion materials and treatment is depended on the usage of auditorium, just like how the size
and volume is affected by the usage. CMU block walls surrounding the auditorium with hollow
cores act as sound trappers. The Sound Intensity Level (SIL) were recorded from various
positions in the auditorium. The spatial distribution of the sound were then examined.
Sound diffusion is a method to
1. To distribute sound energy evenly with a diffusion
2. To treat sound abbreviations (such as echos) in the space - to prevent the occurrence of
undesirable acoustical defects.
3. An excellent alternative or complement to sound absorption because they do not remove
sound energy, but effectively reduce distinct echoes and reflections while still leaving a
live sounding space.
Reflection occurs when
sound strikes onto the
wall’s hard surface.
Bouncing of sound
waves causing it to lose
its energy.
Reflection of sound leads
to echo and
reverberation
(Cavanaugh, Tocci &
Wilkes, 2010).
Figure 2.3.1: Hollow-core concrete
walls in Permata Pintar auditorium.
(Wong, 2019)
Figure 2.3.2: Section of CMU Blocks
(Wong, 2019).
2.3 Sound Diffusion
24

30. Reflection Absorption Diffusion
Sound is bounced off a
surface. This occurs on flat,
rigid surfaces like concrete
walls . The sound bouncing
back off the surface creates
echoes.
When sound waves hit the
surface, kinetic energy is
converted into a small
amount of heat energy which
dissipates causing it to
decay faster. Soft materials
found in the auditorium such
as the seats, carpet and
stage curtain act as
absorbents.
When a sound wave hits an
irregular surface, the vibration
breaks up and travels through
diverted paths. This divides the
wave energy out to different
directions, causes the energy
to deplete faster or creates a
more even sound.
Diffusive Space
Perfectly diffusive sound auditorium is one that has certain key acoustic properties which
are the same anywhere in the auditorium. Small sound spaces generally are very poor
diffusion characteristics at low frequencies due to room modes.
Non-diffusive spaces
Auditoriums which are highly non-diffuse are ones where the acoustic absorption is unevenly
distributed around the space, or where two different acoustic volumes are coupled. Listeners
in perimeter seats receive unbalanced reflections. Hence adding diffusion disperse the sound
field evenly for the audience.
Diffusive Space vs Non-Diffusive Spaces
25

31. Suggestions to Optimize Sound Diffusion of Permata Pintar Auditorium Hall
To optimize sound diffusion in a hall or room, the wall and ceiling could be designed in a
zig-zag profile or uneven irregular-shaped units that will be installed along the boundaries.
Sharp-uneven hard surfaces enable to diffuse sounds better, as long as the wavelength
equivalent to the dimensions of irregularity.
Besides that, reflectors should be installed at the front ⅓ portion to the stage in order to
maximize sound from the stage to the audience, while the remaining ⅔ should be diffusers to
control the sound spread and intensity.
26

32. The Sound Intensity Level (SIL) were measured using a sound meter from a constant sound
source. The measurements were taken from 10 points spread out evenly throughout the
auditorium. From the measurements, we observed that sound dispersion from the sound source
to the back of the auditorium have a minimal attenuation in sound intensity levels in exception
of the area on the gallery and below the gallery.
Figure 2.4.1 Plan shows sound distribution readings
taken from sound source to the ground floor. (Chan,
2019)
Figure 2.4.2 Plan shows sound distribution readings
taken from sound source to the gallery. (Chan, 2019)
2.4 Sound Propagation
27

33. Sound reflections happen when incident sound energy is striking to hard surfaces. Reflections
of sound used in acoustic to distribute and reinforce sounds. CMU blocks reflect sound
towards the auditorium.
The auditorium has no specific concentration of sound due to the shape of auditorium. Fan
shaped plan of the auditorium distribute sound to every seatings evenly through reflection of
sound. The distribution of sound allows audiences to receive similar amount of sound from
every seating position in the auditorium except sound shadow area.
2.5 Sound Reflection
Useful Ceiling Reflections
The ceiling design is articulated and inclined gradually from the stage towards the back of the
hall allowing sound propagation in the auditorium to be reflected towards the audience in even
distribution, retaining the sound intensity further with reverberation. The inclined ceiling design
can contribute more useful sound reflections compared to a flat horizontal ceiling thus the
auditorium has wider useful ceiling reflections.
Figure 2.5.1 Floor plan showing sound reflections in auditorium. (Lim, 2019)
Figure 2.5.2 Section showing sound reflections in auditorium. (Lim, 2019)
2.5.1 Sound Reflection
2.5.2 Ceiling Reflection Patterns
28

34. Time Delay = R1 + R2 - D
0.34
= (7.6 + 8.2) - 10.4
0.34
= 15.88msec < 30msec
2.6 Sound Delay
Reflected sound beneficially reinforces the direct sound if the time delay between them is
relatively short, with maximum of 30msec. However, echo occurs when the time delay exceed
40msec for speech and 100msec for music. Echos are probably the most serious of room
acoustical defects thus most of the auditorium designs were to avoid echos.
Time Delay =
R1 + R2 - D
0.34
10.4m
8.2m
7.6m
2.6.1 Sound Reflection Towards Front Row
Figure 2.6.1 Section showing sound delay towards the front row. (Lim, 2019)
29

35. 21.9m
18.5m
4.6m
In conclusion, the calculations proved that time delay for sound reflection and direct sound
does not exceed 30m/s. Hence, sound reflections occurs in auditorium act as reinforcement
to direct sound but not echo.
2.6.2 Sound Reflection Towards Gallery
Figure 2.6.2 Section showing sound delay towards the gallery. (Lim, 2019)
Time Delay = R1 + R2 - D
0.34
= (18.5 + 4.6) - 21.9
0.34
= 3msec < 30msec
30

36. 2.7 Sound Shadow
Seatings on the gallery have a sound intensity level of 40.3dB, a much lower intensity
compared to 45.6dB at the front and 44.5dB at the centre. This is caused by an obstruction of
direct sound waves caused by the glass railing on the gallery, only allowing diffused or
indirect sound waves to propagate to the seatings.
Besides that, seatings under the gallery have a sound intensity level of 40.8dB, compared to
45.6 dB at the front or 44.5dB at the centre. The large gallery caused a sound shadow due to
the depth of the gallery (7.9m) exceeding the height of the gallery (4.1m) thus obstructing the
indirect sound waves reflected from the ceiling. Sound shadow can be alleviated by adding
time-delay sound reinforcement systems.
Figure 2.7.1 Section shows direct sound to front row, back row and gallery, comparing the sound
intensity. (Chan, 2019)
Figure 2.7.2 Section shows less indirect sound waves reach seatings under the gallery. (Chan, 2019)
Sound shadow or acoustic shadow, is an area where sounds that should be audible
cannot be heard or have a decrease in sound intensity. In this case, sound shadow are
formed towards the back of the auditorium below the gallery and on the gallery.
31

37. 2.8 Noise Intrusion
2.8.1 Interior noise intrusion
Interior noise intrusion originates from the operational noise of building services
components or human activity inside the auditorium, which is the ventilation and
air-conditioning systems, footsteps, chatter and the sound of chair creaking.
Figure 2.8.1: Chatter from the
audience & footsteps.
(Chan, 2019)
Figure 2.8.2 Noise from lighting
ballast. (Chan, 2019)
Figure 2.8.3: Noise from
air-conditioning diffuser.
(Chan, 2019)
Figure 2.8.4: The sound of footsteps are louder when
walked on timber flooring on stage compared to the muffled
sound on carpet. (Chan, 2019)
Figure 2.8.5: The light ballast makes a constant low
buzzing sound. Besides that, air from the air
conditioning creates a low humming sound due to air
conditioning duct or diffuser vibrating. (Chan, 2019)
Although there are several aspects of interior noise that are unavoidable such as chatter
among the audience or less significant noise such as footsteps on the stage, operational noise
in the building could be reduced or even prevented. Buzzing sounds from the lights are due to
magnetic ballasts that operate at 60Hz. The solution is to replace the magnetic ballast with
electronic ballast operating between 20Hz to 40Hz. Humming sounds from the air conditioning
can be prevented through frequent maintenance and sound insulation.
Suggestions to Reduce Interior Noise of Permata Pintar Auditorium Hall
32

38. 2.8.2 Exterior noise intrusion
Exterior noise intrusion originates directly from the exterior surroundings. This sounds are
in the form of bird sounds from the nearby trees. The sounds enter directly through the
perforated elements of the auditorium, which are the louvres.
Birds
Exterior noise also enters through the rear exterior wall. The rear exterior wall is the only
barrier between the exterior surrounding and the auditorium. Hence, the rear exterior is not able
to prevent exterior noise from entering the auditorium.
Air-borne
transmitted sound
through louvres
Rear exterior wall
Figure 2.8.6 Section shows exterior noise from bird sounds and location of louvres glass. (Chan, 2019)
Figure 2.8.7 Section shows location of rear exterior wall. (Chan, 2019)
Suggestions to Reduce Exterior Noise of Permata Pintar Auditorium Hall
The louvres are allowing exterior noise to enter. Thus, the louvre windows should be replaced
with acoustical windows which are double or triple glazed with at least 7in gap in between to
isolate the sound. The rear wall needs more sound insulators and reduce the openings for noise
to enter.
33

39. 2.9 Sound Lock Systems
5
5
5
5
1
2
3
4
Sound lock in an auditorium is a vestibule or entranceway that has highly absorptive walls and
ceilings and a carpeted floor; used to reduce transmission of noise into an auditorium.
However, there is a notable absence of vestibules in Permata Pintar Auditorium.
NTS
Ground Floor Plan
+58.90
Doors to enter and exit
the auditorium hall.
Section A-A’
NTS
3
2
AA’
Legend
1. Main Entry
2. Lobby
3. Auditorium Hall
4. Washroom
5. Entry + Exit of Auditorium Hall
5
5
34
Figure 2.9.2 Section shows location of
doors to enter and exit into the
auditorium. (Chan, 2019)
Figure 2.9.1 Plan shows location of doors
to enter and exit into the auditorium.
(Chan, 2019)

40. Problems Detected
Squeak created by the entry and exit door could be heard from the auditorium.
Outside of the auditorium hall, loud noises such as music played loudly from the lobby could be
heard from the auditorium hall.
Suggestions to Improve Sound Locking System of Permata Pintar Auditorium Hall
Suggestions to improve the sound locking system by enclosing the auditorium hall by having
well-sound insulated vestibules before entering the auditorium hall. The vestibules behave as a
sound trapper. Highly-sound insulated vestibules could absorb unnecessary noise to prevent
noise entering into auditorium hall.
Acoustical doors designed to reduce transmission of sound, that is to attenuate sound.
Choosing heavy door panels and assembling the doors carefully to ensure it is tightly sealed to
prevent transmission of sound through air. Choosing acoustical doors with Sound Transmission
Class of 40 to 50s.
Characteristics of The Acoustical Door With STC 42
- Magnetic acoustic seal installed on the door stop
- Compressible acoustic seal installed on the frame
jambs and head (as illustrated), and under the door
- Surface mounted automatic door bottom
- Aluminium threshold
Figure 2.9.3:
Doors leading
directly to the
auditorium hall.
The squeaks
created by the
doors may
disrupt the
audiences in the
auditorium hall.
(Chan, 2019)
Figure 2.9.4: Table shows the higher the STC value, the better the
rating and the better the performance. (Haleybros, 2015.)
Figure 2.9.5: Example section of an
acoustical door with STC 42.
(Metalec, 2015).
35

41. 2.10 Sound Reinforcement System
2.10.1 Introduction to Sound Reinforcement
In simple terms, the role of a sound system is to amplify and adjust the sound quality of an
audio signal, and then provide corresponding output from the speaker system that the listeners
will hear.
1. The process begins with a sound source (such as a human voice), which creates
waves of sound (acoustical energy).
2. These waves are detected by a transducer (microphone), which converts them to
electrical energy.
3. The electrical signal from the microphone is very weak, and must be fed to an
amplifier before anything serious can be done with it.
4. The loudspeaker converts the electrical signal back into sound waves, which are
heard by human ears.
Speaker System
In the auditorium, the speaker system in operation is classified into 3 types: line array,
subwoofer and stage monitor.
2.10.2 Line Array
Using a number of similar loudspeaker elements orientated
in an angled line, the array creates a near-line source of
sound where the distance between each adjacent drivers is
close enough that sound waves constructively interfere
with each other to propagate further. This design creates
sound in a vertical output pattern useful for focusing sound
at large audiences.
Figure 2.10.2: Line Array speakers
at the auditorium.(Lee, 2019)
Figure 2.10.1: Position of line array
speakers at the auditorium. (Lee, 2019)
36

42. 2.10.3 Subwoofer
A speaker specially designed to reproduce a range of
very low frequencies only (the bass). The typical range
for a subwoofer is about 20-200 Hz. A "powered
subwoofer" includes a built-in amplifier to drive the
speaker.
Figure 2.10.4: Amate Audio JK12W 12’
Compact Subwoofer (Amate Audio, 2017)
Figure 2.10.5: Subwoofers at the auditorium.
(Lee, 2019)
2.10.4 Stage Monitor Speakers
These are stage-facing loudspeakers which allow
performers to listen to their own sound or audio
mixes. Without these monitors, the performers will
hear the reverberated sounds which are delayed and
distorted in turn which could, for example, cause the
singer to sing out of time with the band.
Figure 2.10.7: Amate Audio KEY12A 12’
(Amate Audio, 2017)
Figure 2.10.8: Stage Monitors at the
Auditorium. (Lee, 2019)
Figure 2.10.3: Position of subwoofers at
the auditorium. (Lee, 2019)
Figure 2.10.6: Position of stage monitors at
the auditorium. (Lee, 2019)
37

43. Figure 2.10.9: Section shows different type of propagation of speakers. (Lee, 2019)
The speaker system at Permata Pintar Auditorium projects the amplified sound played or
recorded towards the hall as shown in the figure above. The combination and specifications of
the speakers are entry-level and is classified as a basic setup for performance grade stage,
sufficient for a general PA system. The array speakers direct the sound towards the audience
while sounds of lower frequency are bass-boosted by the subwoofers, creating an evenly
distributed sound towards the audience which when recorded is louder in the front and
marginally softer at the back of the hall.
2.10.5 Advantages of Sound Reinforcement
1. Ability to adjust and modify frequencies and intensities of recorded sounds which are
then projected in a controlled environment by the speakers.
2. Amplification of sound intensity to propagate sound waves further in a large space.
3. Able to control the quality of audio output and choice of sounds recorded.
2.10.6 Disadvantages of Sound Reinforcement
1. Sound reinforcement is not a proper solution to prolong reverberation time which is
necessary for certain performances.
2. Audio equipment requires professionals to handle and operate.
3. Technical errors may occur during usage of sound reinforcement.
38

44. REVERBERATION TIME
39

45. No. Component Surface Area (m2
)
500 Hz
Absorption Coefficient Abs Unit (m2
sabins)
1 Carpet Floor 740.43 0.62 459.07
2 CMU Block Wall 1057.08 0.31 327.6948
3 Gypsum Plaster Ceiling 630.00 0.80 508
4 Solid Timber Fire Door 57.60 0.06 3.456
5 Occupied Seating 340.00 0.74 251.60
6 Unoccupied Seating 170.00 0.26 44.2
7 Control Room Glass Window 7.10 0.03 0.213
8 Glass Panel Railing 31.02 0.04 1.2408
9
Underside of Mezzanine
Balcony Cement Plaster
133.36 0.03 4.0008
10 Composite Timber Flooring 196.71 0.05 9.8355
11 Cement Plaster Wall 401.19 0.03 12.0357
12 Safety Velour Curtain 140.40 0.49 68.796
1712.01
3.0 Reverberation Time
Reverberation time is the measure of time required for reflected sound to fade away.
Therefore, it is important to calculate the reverberation time for Permata Pintar Auditorium to
determine its response towards acoustic sound and its suitability as a certain room type based
on its time, in this case an academic auditorium. The reverberation time for the Permata Pintar
Auditorium is calculated using the Sabine’s Formula. To calculate this, the surface area and
absorption coefficient of the components (with reference to the materials tabulation in Chapter
3) are applied using 500 Hz as a standard of measurement.
1
2
3
4
5
6
7
8
9
10 11
12
Figure 3.1: Materials of the components. (Chan, 2019)
40

46. The reverberation time for the Permata Pintar Auditorium is 0.6907 seconds, which shows that
the auditorium is suitable for lecture and conference rooms. Hence, the low reverberation
time deemed it optimal for lectures and talks. The low reverberation time is affected by low
reflective efficiency caused by the less complex trapezoid shape formed by the walls, the rigid
concrete block walls, and the non adjustable ceiling height which is only limited to cater to
certain purposes. There is also a larger percentage of soft absorbent materials compared to the
hard reflective materials. This keeps more sound from being reflected, therefore reducing the
reverberation time of the room.
RT = 0.16V
A
RT = 0.16 (7390.23)
1712.01
= 0.6907 sec
Volume of Auditorium = 7390.23
Reverberation Time using Sabine’s Formula,
Reverberation Time =
0.16 V
A
RT
Figure 3.2 : Optimum reverberation time. (Roberts, 2016)
41

47. CONCLUSION
In conclusion of our case study through our findings, we calculated that Permata Pintar
Auditorium falls within the lecture and conference room category with a reverberation time of
0.69 seconds. This fits their main program which is to serve as a lecture hall for the students of
Permata Pintar Program, although it is not optimized for other forms of use such as plays,
musical or theatrical performances.
Besides that, we noted that the design and form of the auditorium distributes the sound evenly
with only a slight attenuation towards the back row seating. However, there are notable defects
in the design as the seating below the gallery and above the gallery experiences sound
shadow.
Furthermore, another rather serious defect are the exterior noise intrusions. Due to the lack of
vestibules, louvre openings above the stage and lack of sound insulators behind the
auditorium, significant noise could be heard in the auditorium which could affect the quality of
the programs hosted there.
42

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