Project One : A Case Study On Acoustic Design
Building Science II
Auditorium. [Damansara Utama Methodist Church] Tutor : Mr. Edwin Chan Group Members : Tan Min Chuen 0322938 Chang Huey Yi 0322898 Lee Yet Yee 0322328 Esther Oo Pui Ying 0326915 Ng Kwang Zhou 0322802 Teoh Jun Xiang 0322099 Tang Ying Jien 0322357 Lim Woo Leon 0322180
LIST OF FIGURES AND DIAGRAMS Chapter 1 Figure 1.1: Damansara Utama Methodist Church (DUMC) Dream Centre exterior façade. Figure 1.2: Damansara Utama Methodist Church (DUMC) logo. Figure 1.3: Church services held in the Damansara Utama Methodist Church Auditorium. Figure 1.4: Concert event held in the Damansara Utama Methodist Church Auditorium. Figure 1.5: Damansara Utama Methodist Church’s surrounding context.
Chapter 2 Figure 2.1: Digital sound level meter. Figure 2.2: Measuring tape. Figure 2.3: Laser measure. Figure 2.4: DSLR camera. Figure 2.5: JBL portable Bluetooth speaker used on site.
Chapter 3 Table 3.1 Calculation of sound absorption unit Table 3.2: Weighted criteria of auditoriums.
Figure 3.1: seating level of auditorium. Figure 3.2: Example of speaker array. Figure 3.3: Example of a subwoofer. Figure 3.4: Example of a monitor. Figure 3.5: Location of monitors on stage. Figure 3.6: Background noise reading as indicated by digital sound meter. Figure 3.7: Background noise reading as indicated by digital sound meter. Figure 3.8: The HVAC system noise source. Figure 3.9: The construction of the Symphony Square corporate office tower, as viewed from the back of DUMC. Figure 3.10: Source of noise (pink) in respect to DUMC Auditorium’s location (blue) Figure 3.11: View of the upper gallery from ground level. Figure 3.12: The exit doors on the gallery. Figure 3.13: Glass windows on the first floor. Figure 3.14: External aisle present on the first floor. Figure 3.15: Dry wall
I
Figure 3.16: Acoustic fibreglass Figure 3.17: Wooden boards Figure 3.18: Carpet Figure 3.19: Ceramic tiles Figure 3.20: Padded chairs Figure 3.21: Auditorium seatings Figure 3.22: Steel railings Figure 3.23 : Acoustic drapery Figure 3.24: Plasterboard & gypsum plaster ceiling Figure 3.25 : Glass Figure 3.26 : Timber parquet flooring Figure 3.27: Carpeted stage apron Figure 3.28: Stage sets & instruments Figure 3.29 : Location of reflective and absorbent walls present at DUMC Figure 3.30: Timber Wall Panel Figure 3.31: Panels & Groove Figure 3.32: Acoustic Fiberglass Boards (Stairway leading to first floor) Figure 3.33: Acoustic Fibreglass Wall Figure 3.34: Plastered Drywall Figure 3.35 : Needle Punched Carpet Figure 3.36 : Needle Punched Carpet Figure 3.37 : Fixed Folding Theatre Seats Figure 3.38 : Moveable Seats Figure 3.39 : Plasterboard ceilings Figure 3.40 : Tiled gypsum plaster ceilings Figure 3.41: Front view of auditorium stage Figure 3.42: Side view of auditorium stage Figure 3.43: Carpeted apron and stage steps
Diagram 3.1: Optimum 140° wide layout ensures high frequency sounds are able to be discerned. Diagram 3.2: SIL measurement of the auditorium. Diagram 3.3: seating level of auditorium. 
II
Diagram 3.4: Level ground seat arrangement. Note weaker SIL as distance from source increases. Diagram 3.5: Elevated source arrangement reduces SIL loss. Diagram 3.6: Sound reinforcements added into design to aid sound projection. Diagram 3.7: stereophonic system used in DUMC. Diagram 3.8: Position of amplifiers, array speakers and stage monitors and sound propagation. Diagram 3.9: Position and propagation of speaker array. Diagram 3.10: Position and propagation of Subwoofers. Diagram 3.11: Position and propagation of stage monitors. Diagram 3.12: Sound propagation of auditorium. Diagram 3.13: Flat ceiling design Diagram 3.14: Staggered ceiling design Diagram 3.15 Sound delay at position 1 Diagram 3.16 Sound delay at position 2 Diagram 3.17 Sound delay at position 3 Diagram 3.18 Sound delay at position 4 Diagram 3.19 Reverberation time for different spaces Diagram 3.20 Sound shadow area in the auditorium. Diagram 3.21 Sound shadow area in the auditorium. Diagram 3.22: Sound source, path and receiver relationship. Diagram 3.23: The noise sources identified within the auditorium. Diagram 3.24: The HVAC system noise source on ground level. Diagram 3.25: Possible sound paths of the HVAC system. Diagram 3.26: Frequencies at which various types of mechanical and electrical equipment generally control sound spectra. Diagram 3.27: The construction noise source. Diagram 3.28: Transmission of noise from the external environment to the auditorium. Diagram 3.29 : Spatial tabulation of auditorium Diagram 3.30: Timber Wall Panels at Ground Floor Plan Diagram 3.31: Timber Wall Panel Cross Sectional Detail Diagram 3.32: Sound Shadow Diagram 3.33: Acoustic Fibreglass Board at First Floor Plan Diagram 3.34: Sound propagation at an Acoustic Fibreglass Board Diagram 3.35: Acoustic Fibreglass Board Cross Sectional Detail Diagram 3.36: Acoustical Fibreglass Wall at Ground Floor Plan 
III
Diagram 3.37: Acoustic Fibreglass Wall Cross Sectional Detail Figure 3.38: Plastered Drywall at First Floor Plan Diagram 3.39: Sound Reflective Surface Diagram 3.40: Absorbent Acoustic Surface Diagram 3.41 : Carpeted Area on Ground Floor Diagram 3.42 : Carpeted Area on First Floor Diagram 3.43 : Carpet Have High Sound Absorption, Hard Floor Have Low Sound Absorption Diagram 3.44 : Detail Drawing of Floor Components. Diagram 3.45 : Ground Floor Plan Diagram 3.46 : First Floor Plan Diagram 3.47: Location of different ceiling materials Diagram 3.48: Location of different ceiling materials Diagram 3.49: Rigid ceiling system with sound batt insulation and closed cell foam Diagram 3.50: Area of timber parquet flooring Diagram 3.51: Section of stage floor - materiality Diagram 3.52: Location of concrete wall, canvas background, stage curtain and backstage plan Diagram 3.53: Location of concrete wall, canvas background, stage curtain and backstage section
IV
TABLE OF CONTENTS 1. INTRODUCTION 1.1.1 General Information
1
1.1.2 Brief Introduction
1-2
1.1.3 History of DUMC
3
1.1.4 Context and Location
4
2. METHODOLOGY
5
2.1.1 Introduction
5-7
2.1.2 Measuring and recording equipment 3. ACOUSTICAL ANALYSIS 3.1. Auditorium design 3.1.1 Drawings and photos 3.1.2 Shape and form of the auditorium
8-11 12-13
Design and sound coverage Sound Concentration 3.1.3 Levelling of seats and stage
14-16
3.1.4 Sound Reinforcement
17-21
Types of loudspeaker system System components Speaker Arrays Subwoofers Monitors 3.1.5 Sound Propagation
22-25
1. Ceiling Reflector Panel 2. Sound delay and echo Position 1 Position 2 Position 3 Position 4 3.1.6 Reverberation Time
26-27
1. Large volume result in high RT 2. Reverberation time calculation 3.1.7 Sound Defect Sound shadow area 2.
Flutter echo
28
3.1.8 Acoustical Treatment and Component 29-48 Material Tabulation Space Tabulation
29-32 33
Acoustical treatment and components
34-48
-Walls
34-40
-Floorings
41-42
-Seatings
42-43
-Ceilings
44-45
-Stage Flooring
46
-Stage Curtain and Concrete wall
47
3.2 Noise And Noise Intrusion In DUMC 49 3.2.1 Introduction 49
49
3.2.2 Detrimental Effects Of Noise On The Listener Or Environment 49
49
3.2.3 Room Criteria: Background Noise 49-50
49-50
3.2.4 Acoustical Analysis of sound control 50-59
50-59
-Noise source and sound path
49-51
-HVAC system noise source
52-54
-Symphony Square corporate office tower construction
55-56
-Natural Weather Conditions
57-58
2. Absence of sound lock
59
4. CONCLUSION 60
60
5. REFERENCES 61
66-62
1. Introduction to DUMC [Damansara Utama Methodist Church]
Building Science II : Project One
1.1 INTRODUCTION TO DAMANSARA UTAMA METHODIST CHURCH AUDITORIUM
Figure 1.1: Damansara Utama Methodist Church (DUMC) Dream Centre exterior faรงade.
Figure 1.2: Damansara Utama Methodist Church (DUMC) logo.
1.1.1 GENERAL INFORMATION Establishment: Since 1980 Address: Dream Centre, 2 Jalan 13/1, Seksyen 13, 46200 Petaling Jaya, Selangor, Malaysia Contact number: 03-7958 7388 Email address: general@dumc.my Website: http://dumc.my
1.1.2 BRIEF INTRODUCTION Damansara Utama Methodist Church is a cell church based in Petaling Jaya, Malaysia. A cell church is a non-traditional form of church which defines its small groups of Christians (cells) as the basic building blocks of church life.
1
As one of the prominent Methodist churches located in the Klang Valley, the church was established in 1980 by 22 young professionals and their 3 children who moved from SSMC (Sungei Way- Subang Methodist Church). Since then, the church has undergone three memorable decades of progress and development to become the famous church we know today. The Damansara Utama Methodist Church Auditorium is located within the DUMC Dream Centre. The auditorium, which completed its construction since 2016, has a maximum capacity of 2300 people. It functions as a multi-purpose hall, in which church services, concerts and talks are frequently held. However, its main function is to accommodate the large amount of Christians during their services.
Figure 1.3: Church services held in the Damansara Utama Methodist Church Auditorium.
Figure 1.4: Concert event held in the Damansara Utama Methodist Church Auditorium.
2
1.1.3 HISTORY OF DAMANSARA UTAMA METHODIST CHURCH (DUMC)
1980 22 young adults and their families decided to move from Sungei Way-Subang Methodist Church (SSMC) and establish the Damansara Utama Methodist Church. The church started their first service on the 6th of January, 1980, which is the first Sunday of the year. In its first service, there were only 80 people in the congregation in a simple setup with basic amnesties, which is located not far from The Ship in Damansara Utama. Soon, a number of doctors and medical students from University Malaya joined in.
1988 DUMC moves to a two adjacent shop lots in another part of Damansara Utama.
1993 DUMC moves to its first owned premise located in Taman Mayang. The sanctuary could accommodate 500 people.
1996 DUMC starts its first vernacular service, the Chinese Church of DUMC.
1999 DUMC relocated to the former Ruby Cinema in SEA PARK.
2007 DUMC moves to its current premise, the Dream Centre.
2016 The Damansara Utama Methodist Church Auditorium is constructed, which could accommodate up to 2300 people.
3
1.1.4 CONTEXT AND LOCATION
Figure 1.5: Damansara Utama Methodist Church’s surrounding context.
The Damansara Utama Methodist Church is located in Seksyen 13, Petaling Jaya, an industrial and commercial zone. As the construction of the Symphony Square commercial tower is still undergoing behind the church, unwanted sound will transmit from the construction site to the auditorium, which is located within the church building. Residential areas, such as Seksyen 14 and PJS 12 are also present within the context.
4
2. Methodology [Damansara Utama Methodist Church]
Building Science II : Project One
2.1 METHODOLOGY 2.1.1 INTRODUCTION Before the site visit to the auditorium was conducted, we studied a few measuring techniques to familiarise ourselves with on-site measuring techniques. Measuring and recording equipment were prepared to facilitate our on-site measurement and recording exercises.
2.1.2 MEASURING AND RECORDING EQUIPMENT 1. Digital sound level meter
Figure 2.1: Digital sound level meter.
A digital sound level meter is an instrument that gives constant and objective measurements of sound level in a space. The A-scale, which corresponds to the way the human ear responds to the loudness of sound and a weighted sound level value is read on the meter (in dBA). The device was used to measure the sound intensity level (SIL) at different locations of the auditorium to identify: - Sound concentration - Sound shadow - Background noise
5
2. Measuring tape
Figure 2.2: Measuring tape.
A standard measuring tape is a rigid, retractable and lockable measuring tool. It was used to measure the distances between auditorium spaces, which would benefit the generation of the drawings.
3. Laser measure
Figure 2.3: Laser measure.
A laser measure is a simple yet accurate measuring tool to measure the height and width of the exterior and interior of a building. Similar to the measuring tape, it was used to determine the dimensions between spaces, which would benefit the generation of the drawings.
6
4. Digital cameras
Figure 2.4: DSLR camera.
DSLR and digital cameras were prepared to take photographs on site. The photographs will later be used as references when further analysis of the space is conducted.
5. Portable Bluetooth speaker
Figure 2.5: JBL portable Bluetooth speaker used on site.
The portable Bluetooth speaker is used during the site visit to present the acoustic performance within the auditorium. A constant sound in terms of volume and frequency was released at a single point on stage and the sound level readings were taken from various distances in the auditorium. The sound level readings measured help us to identify sound concentration, sound shadows and background noise.
7
3. acoustical analysis [Damansara Utama Methodist Church]
Building Science II : Project One
VISUAL AND PHOTOS
Exterior Facade of Damansara Utama Methodist Church - Dream Centre
Balcony Platform for PA System
Auditorium Ceiling - Gypsum Plaster & Plaster
Aerial View of DUMC’s auditorium from the first floor
8
Stage View of Damansara Utama Methodist Church
Sound Control Room
Performance Stage - Ongoing Service The DUMC Auditorium constitutes of design elements that has created a space with the intention of speech being audible and intelligible throughout. The surfaces of the multipurpose auditorium should fulfill design requirements that reflects and projects the sound to the rear of the space for any ongoing services. The auditorium has a total volume of 28116m³ and surface area of 2371.46m², the hall consists of two levels of seatings, with 1199 padded & theatre seats at the ground floor and 1107 theatre seats on the first floor. The materials of the walls comprises of plastered drywall, acoustical fiberglass wall, acoustical fiberglass panels and timber panels ; Flooring comprises of timber parquet, ceramic tiles and carpet (majority) ; Ceiling comprising of Gypsum plaster and plaster. Overall, these materials has contributed with the reflection and absorption of sound waves, affecting the overall reverberation time.
9
ORTHOGRAPHIC DRAWINGS
Figure 1: Ground Floor Plan
Figure 2: First Floor Plan
10
Figure 3: Section A-A’
11
3.1.2 Shape and Form of Auditorium 1. Design and sound coverage The Fan-shaped hall The fan-shaped hall, originally developed by the ancient Greeks was successful for an outdoor Theatre. DUMC designed the auditorium as a fan-shaped hall auditorium which is suitable for a speech hall rather than a concert hall. By building a fan-shaped hall, the potential for flutter echo is much reduced when compared to a rectangular-shaped hall. It also leaves a low level of delayed sound towards the rear of the hall, where the reverberation time is lower. However, acoustical flaws are also inevitable as the rear auditorium wall is automatically generated as a concave curved surface, which produced a focused echo back to the stage. Extreme width at the rear of the hall tends to leave seats in the centre rear of the stalls with few early reflections. This is particularly the case for reflections from the side.
Sound source without sound reinforcement
Out of coverage area
Diagram 3.1: Optimum 140° wide layout ensures high frequency sounds are able to be discerned.
12
2. Sound Concentration The measurement of the Sound Intensity Level (SIL) from the sound source shows that there is a distinct sound concentration zone accumulated at the stage area of the auditorium. This is obvious as the concave-shaped auditorium provides a feedback where it converges sound into the centre.
45 dB
45 dB
55 dB 55 dB
55 dB 59 dB
43 dB 50 dB
63 dB
43 dB 50 dB
Diagram 3.2: SIL measurement of the auditorium.
13
3.1.3 Levelling of Seats and Stage The levelling or raking of the seating area is of utmost importance to ensure that sound waves reach the ears of all occupants within the auditorium clearly. The auditorium utilised two types of seating configuration which are permanent and temporary to accommodate different occasions. The permanent seats are placed at the levelled terraces on the ground and first floor, while the temporary seats are placed at the ground floor pit.
1st Floor Terrace
Ground Floor Pit
Ground Floor Terrace
Figure 3.1: seating level of auditorium.
Diagram 3.3: seating level of auditorium.
14
On the ground floor pit, given the scenario where the seats are not raised, the sound would not be able to travel all the way to the furthest- most seat as the vibrations would have been absorbed by only the first half, with majority of the sound waves dying out by the time it reaches the second. Thus, SIL will decrease further when it reaches the 1st floor terrace, resulting in little to no volume of sound being heard.
Diagram 3.4: Level ground seat arrangement. Note weaker SIL as distance from source increases. The auditorium solves this issue by raising the stage, elevating it above the seats and allowing the sound source to project directly to all the occupants with maximum SIL and with minimum delayed sound.
Diagram 3.5: Elevated source arrangement reduces SIL loss.
15
Sound reinforcements are also added to aid direct sound projection towards the 1st floor terrace where sound attenuation thus reduces sound delay.
Diagram 3.6: Sound reinforcements added into design to aid sound projection.
16
3.1.4 Sound Reinforcement Reinforcement by loudspeaker system The loudspeakers are positioned higher than it would be in an auditorium with a raked floor. Sound amplification system is used for the following purpose: To reinforce the sound level when the sound source is too weak to be heard. To provide amplified sound for overflow audience. To minimize sound reverberation. To provide artificial reverberation in rooms which are too dead for satisfactory listening. 1. Type of loudspeaker system Stereophonic system The auditorium uses two or more clusters of loudspeakers around the proscenium opening or the sound source.
Figure 4.4.1 Example of stereophonic system.
17
2. System Components Components include subwoofers, array speakers (ceiling mounted) and stage monitors.
Speaker array and subwoofers
Stage monitors
Diagram 3.8: Position of amplifiers, array speakers and stage monitors and sound propagation.
(A) Speaker Arrays There are 3 speaker arrays suspended from the ceiling directly in front of the stage directed to the centre, left and right sides of the hall to ensure a balanced transmission of sound to the entire hall. The speakers are configures in a 9-8-9 configuration whereby there are 9 speakers for each left and right arrays and 8 speakers in the centre array. The speakers are installed in such a manner to avoid reflection from the flat floor which produce inconsistent amplification should the speakers be on ground level.
Figure 3.2: Example of speaker array.
18
Diagram 3.9: Position and propagation of speaker array.
(B) Subwoofers Alternating between the 3 arrayed speakers are subwoofers that boosts the lower frequency range of the sound, typically below 100Hz. There is a total of 4 subwoofers which are also suspended from the ceiling of the stage. Instead of being configures in an array similar to the speakers, the 4 subwoofers are installed as single units as lower frequencies have slower attenuation and can easily reach the audiences. However, the output source of the subwoofers is pointed towards the concrete wall behind it to produce indirect sounds which will be reflected to the audiences via the angled ceiling. This method further reduces the attenuation of lower frequency sounds.
Figure 3.2: Example of sub-woofers.
19
Figure 3.3: Example of a subwoofer.
Diagram 3.10: Position and propagation of Subwoofers.
(C) Monitors Monitor speakers function to provide feedback to the performers on stage which are situated in the blind spot area of the speakers. It is placed on the stage floor facing the performers to ensure that they can hear the sound they produce to help with synchronisation between different instruments during performance.
Figure 3.4: Example of a monitor.
20
Figure 3.5: Location of monitors on stage.
Diagram 3.11: Position and propagation of stage monitors.
21
3.1.5 Sound Propagation In order to increase the efficiency of sound, it is necessary for the sound to be reflected back towards the audience. However, the amount of sound reflected, with added design of these reflections, must be carefully controlled to minimize the echoes.
Reflectors Absorbers Diagram 3.12: Sound propagation of auditorium.
The auditorium of DUMC, incorporates reflectors all around the stage area and also the back of the auditorium which serve to reflect sound effectively back to the audience. Nevertheless, the rest of the auditorium then must be covered with absorbent materials which can minimize the resultant reflected sound, making it almost indiscernible. The extensive use of absorbent materials reduces the reverberation time of the auditorium to counter its large volume. It is also to comply with the function of a speech auditorium.
22
1. Ceiling reflector panels The ceiling reflector panels included in the design forms a staggered ceiling configuration that aids in reflecting sound backwards to the gallery and increasing the volume of sound as it reaches the ears of the occupants. Due to the panels being hard surfaces, it reflects almost all incident sound energy striking them and distributes sound evenly throughout the auditorium. The increments of these sound levels are extremely important for the occupants at the last row. Useful ceiling reflections
Diagram 3.13: Flat ceiling design
Compared to the flat ceiling design, the staggered ceiling design offers more useful sound reflections.
Useful ceiling reflections
Diagram 3.14: Staggered ceiling design
23
2. Sound delay and echo DUMC is a multipurpose hall that caters for both speech and music, hence, the sound transmission in DUMC should not exceed the time delay for both speech and music. A time delay of 40msec for speech and 100msec for music is deemed as an echo as a sound distinct from that travelling directly from source to listener will be perceived. (A) Position 1
Diagram 3.15 Sound delay at position 1
Time Delay =
1đ?‘œ.81+12.61−7.18 0.34
= 47.76 ms
The time delay for this position is 47.76ms, where an echo will be heard during a speech. This is due to the high ceiling the elongates the travel path of the sound.
(B) Position 2
Diagram 3.16 Sound delay at position 2
24
Time Delay =
12.73+16.34−18.11 0.34
= 32.34 ms
The time delay for this position is 32.34ms, where the direct sound is reinforced by the reflected sound, no echo is heard.
(C) Position 3
Diagram 3.17 Sound delay at position 3 Time Delay =
26.92+3.23−26.8 0.34
= 3.35 ms
The time delay for this position is 3.35ms, where the direct sound is reinforced by the reflected sound, no echo is heard.
(D) Position 4
Diagram 4. xx Sound delay at position 3
Diagram 3.18 Sound delay at position 4 25
Time Delay =
22.12+19.46−11.34 0.34
= 88.94 ms
The time delay for this position is 88.94ms, where an echo will be heard during a speech. This severe sound defect is treated by applying sound absorbent materials at the edge of the auditorium, hence, drastically reducing sound intensity level of the echo.
3.1.6 REVERBERATION TIME DUMC is a large auditorium with a volume of 28,116 m3, the auditorium function as a multipurpose hall for the church. The ideal reverberation time for such a large multipurpose auditorium will be 1.6-1.8.
Diagram 3.19 Reverberation time for different spaces fposition 4
1. Large volume result in high RT Due to the large volume of the auditorium, the reverberation time of the auditorium will be high according to Sabine’s Formula. This phenomenon has led to a heavy use of sound absorption material within the auditorium itself, yet the reverberation time for the auditorium is still approximately 1.81s which considered high for a multipurpose hall. It will affect the experience of the audience during a speech as the intelligibility of the spoken word will be affected.
26
2. Reverberation time calculation 500Hz Material
Effective Surface Area (m²)
Sound Absorption Coefficient
Absorption Units (m²sabins)
1. Plastered Drywall
1211.72
0.03
36.35
2. Acoustic Fire Glass Board
731.34
0.80
585.07
3. Wood Boards
344.58
0.10
34.46
4. Brick Wall
561.70
0.01
5.62
5. Carpet
2129.89
0.50
1064.95
6. Ceramic Tiles
20.96
0.01
0.21
7.Timber Parquet
220.61
0.20
44.122
8. Gypsum plaster ceiling panel (12mm)
241.77
0.06
14.5
9. Plaster ceiling
2381.34
0.06
142.88
10. Solid Timber Double Door
45.36
0.06
2.72
11.Concrete Column
16.68
0.02
0.33
12. Padded Chairs (Unoccupied)
230.75
0.15
34.61
13. Auditorium Seats (Unoccupied)
763.65
0.59
450.56
14. Heavy Cloth
179.69
0.40
71.88
TOTAL ABSORPTION (A)
2488.26
Table 1 Calculation of sound absorption unit According to Sabine’s Formula, RT=
0.16Ă—đ?‘‰ đ??´
Reverberation time for the auditorium is, RT=
0.16Ă—28116 2488.26
= 1.81s 27
3.1.7 SOUND DEFECT 1. Sound shadow
Diagram 3.20 Sound shadow area in the auditorium. The gallery has created a sound shadow area at the space underneath, where sound wave least propagates to. Resulting in a lower sound intensity level at the area. However, the sound shadow area is very shallow, as some indirect sound waves area able to propagate to the area, hence, it doesn’t require periphery audio device at the back of the seating area. Wooden boards are installed on the wall at the edge of the sound shadow area, providing a reflective surface that creates more indirect sound waves, increasing the sound intensity level.
Diagram 3.21 Sound shadow area in the auditorium. 2. Flutter echo As conceived from the plan, there is no parallel walls in the auditorium, thus, no sign of flutter echo is captured.
28
3.1.8 ACOUSTICAL TREATMENT AND COMPONENTS 1. Material tabulation HOUSE Component
Materials
Surface Finishes
Coefficient
Dry wall with plaster finish
Paint
0.03
2. Acoustic Fibreglass Board
Fibreglass core, Perforated CoPolymer
Fabric Wrap
0.80
3. Wood Boards
Strips of wooden panels
Wood Polish
0.10
1. Carpet
5mm thick needle punch carpet
0.50
2. Ceramic Tiles
Ceramic tile with smooth surface
0.01
Plaster finish rectangular column
0.10
2. Concrete
Painted concrete cylindrical column
0.02
1. Padded Chairs
Padded chair with metal frame
0.15
Thick cushion seats - Unoccupied
0.59
Occupied
0.68
Material Walls
Flooring
Structure
Seatings
1. Dry wall
1. Plaster
2. Auditorium Seats
Railing
1. Steel
Doors
1. Timber
Description
Painted steel railings with steel cables
Paint
Solid timber double door
Paint
500 HZ
0.06
Wood hollow core door Ceiling
1. Gypsum Plaster
2. Plaster Acoustic Drapery Others -Control Room -Baby Room
1. Heavy Cloth
1. Glass
Gypsum plaster tiles, unperforated with air space
0.06
Plaster on laths with airspace
0.06
Medium velour, 50% gather, over solid backing
0.40
4mm thick fixed glass window
0.10
Table 3.2: Material tabulation - house
29
Figure 3.15: Dry wall
Figure 3.16: Acoustic fibreglass
Figure 3.17: Wooden boards
Figure 3.18: Carpet
Figure 3.19: Ceramic tiles
Figure 3.20: Padded chairs
30
Figure 3.21: Auditorium seatings
Figure 3.22: Steel railings
Figure 3.23 : Acoustic drapery
Figure 3.24: Plasterboard & gypsum plaster ceiling
 
Figure 3.25 : Glass
31
STAGE Component
Materials Material
Walls
1.Concrete wall
2.Canvas background Apron Absorber
Description Smooth painted concrete, 150mm thick
Surface Finishes
Coefficient
Paint
0.01
500 HZ
Thin tensile canvas backdrop
1.Carpet
5mm thick needle punch carpet
0.05
Flooring
1. Timber parquet
wooden platform with void beneath
Acoustic Drapery
1. Heavy Cloth
Medium velour, 50% gather, over solid backing
0.40
Furniture
Stage sets and instruments
Proscenium opening with average stage set
0.30
Wood Polish
0.20
Table 3.3: Material tabulation - stage
Figure 3.26 : Timber parquet flooring
Figure 3.27: Carpeted stage apron
Figure 3.28: Stage sets & instruments
32
2. Space tabulation
Diagram 3.29 : Spatial tabulation of auditorium
33
3. Acoustical treatment and components (A) Walls
Figure 3.29 : Location of reflective and absorbent walls present at DUMC
The walls of the auditorium are thoroughly covered with sound absorbent materials to reduce the overall reverberation. These materials reduce the formation of echoes by absorbing sound waves. The acoustic material typically visible to the audience is devoted to a different task altogether: absorbing or dampening the sound waves that emanate from stage in front of them. Most of the time, the idea behind the application of these materials is to keep the sounds from echoing off of the walls of an enclosed space, a phenomenon that would likely produce a very aurally confusing experience for the audience if left unchecked. The main type of material with the intention of absorbing sound is acoustic fibreglass ; Reflective materials are mainly plastered drywall, concrete columns and timber parquet.
• 34
• Timber wall panels
Diagram 3.30: Timber Wall Panels at Ground Floor Plan
Figure 3.30: Timber Wall Panel
Figure 3.31: Panels & Groove
Timber wall panels are located at the back wall (Figure 1.2) of the ground floor, just below the upper levels balcony. These timber wall panels includes horizontal perforation/grooves (Figure 1.4) which mainly reflects any sound waves propagated towards it. By having a cavity, mineral fibre insulation and grooves, this allows the timber wall panels to absorb additional low-mid range frequency, though minimal.
35
Diagram 3.31: Timber Wall Panel Cross Sectional Detail
Diagram 3.32: Sound Shadow
These panels are located at the sound shadow area as the depth and shape of the auditorium is not maximised for an optimum distribution of sound, this causes an acoustical issue which affects the amount of sound received by the audience seated in the back rows (Figure 1.5). To increase the timber acoustic panel effectiveness, the groove width can be increased and add thicker porous absorber behind panels. Cavity depth can be increased to trap more low frequency sound. A 50mm thick of absorber, mineral fiber insulation are in-line with the panel to increase sound absorption. The cavity depth and absorbent mineral fiber material affects the sound absorption quality.  36
• Acoustic Fibreglass Board and Walls
Acoustic fibreglass Board
Diagram 3.33: Acoustic Fibreglass Board at First Floor Plan
Figure 3.32: Acoustic Fiberglass Boards (Stairway leading to first floor)
37
Diagram 3.34: Sound propagation at an Acoustic Fibreglass Board
Diagram 3.35: Acoustic Fibreglass Board Cross Sectional Detail
The rear walls of the auditorium at the first floor are covered in acoustic fibreglass boards of different angles and sizes which absorbs the midrange sound waves coming from the stage (Figure 2.2), These materials reduce the formation of echoes by absorbing sound waves. It functions as the sound absorber to also reduce the noise produced by the HVAC at the exterior. A weaved fabric is wrapped around the fibreglass panels (Figure 2.3), which benefits by allowing the sound waves to dissipate through the porous membrane before being trapped and dampened. 39
Acoustic fibreglass Walls
Diagram 3.36: Acoustical Fibreglass Wall at Ground Floor Plan
Diagram 3.37: Acoustic Fibreglass Wall Cross Sectional Detail
Figure 3.33: Acoustic Fibreglass Wall
The acoustic fibreglass wall includes an air space gap (Figure 2.5). This air space gap has a mechanism similar to a cavity absorber, it works well with low frequency range which is appropriate for tha auditorium as the hall as bass reliant music are mostly played. When the incident sound energy which is already dampened by the first absorption of the panel entering the air gap, the sound waves are reflected back and trapped (Figure 3.2), subsequently being attenuated, thus reducing the reverberation time.  39
• Plastered Drywall
Figure 3.38: Plastered Drywall at First Floor Plan
Diagram 3.39: Sound Reflective Surface
Diagram 3.40: Absorbent Acoustic Surface
Figure 3.34: Plastered Drywall
Plastered dry walls are installed on the first floor of the auditorium and at the side of the auditorium. Due to the low sound absorption of its material properties, it reflects sound waves propagated towards it (Figure 3.1), producing echoes. Overall, increasing the collection of the reflected sounds in the auditorium. Flutter echoes are prevented as the walls of the auditorium are not parallel to one another. 40
(B) FLOORING
Figure 3.35 : Needle Punched Carpet
Figure 3.36 : Needle Punched Carpet
Diagram 3.41 : Carpeted Area on Ground Floor
Diagram 3.42 : Carpeted Area on First Floor Majority of the floor in DUMC auditorium is covered in a layer of carpet. The needle punched carpet that is utilised is created by having barbed needles punched into a matted layer of fiber, that form a mat of surface fibre.
Needle punched carpet is sound absorbent,
dampening impact and sounds that are a result of the dense foot traffic. It is also porous and absorbs sound energy and reduces reflections and echoes.
33 41
Diagram 3.43 : Carpet Have High Sound Absorption, Hard Floor Have Low Sound Absorption
Diagram 3.44 : Detail Drawing of Floor Components. Between the carpet and existing concrete floor, a thin floor underlayment is used to provide forth er cushioning from footsteps and impacts, and prevent the transmission of floor vibration. The underlayment is comprised of two layers, a flexible solid mass barrier, a soft foam portion that prevents the vibrations and is to be faced towards the ground.
(C) SEATINGS The auditorium feature 2 styles of seating, fixed folding theatre seats as well as moveable seats.
Figure 3.37 : Fixed Folding Theatre Seats
Figure 3.38 : Moveable Seats
42 33
Diagram 3.45 : Ground Floor Plan
Diagram 3.46 : First Floor Plan Other than offering acoustical taming throughout the room surfaces, added sound control is accomplished with the help of the padded seats. It adds to the acoustical absorption of an empty auditorium and allows the space to achieve a similar quality of sound whether the auditorium is ďŹ lled to partial or maximum capacity. This can only be achieved if the material is a padded fabric. A solid, hard material changes the acoustic performance of the auditorium depending on the number of occupants and the reected sound vibrations.
43
(D) CeilingsÂ


Figure 3.39 : Plasterboard ceilings
Figure 3.40 : Tiled gypsum plaster ceilings
The design of ceiling is an important factor for acoustical treatment where the ceiling system must have the ability to break impact noise vibrations; reflect the sound waves produced from the stage and absorb airborne noises that enter the space at each ceiling wall connection. In addition, the material used also influences the acoustical properties of the ceiling.
Diagram 3.47: Location of different ceiling materials
Majority of the ceiling in the auditorium is made of plaster while some parts are made of tiled gypsum plaster. Plaster is a material that absorbs low frequencies, at the same time, an effective sound reflector for other frequencies. 
44
Diagram 3.48: Location of different ceiling materials The smooth and seamless surface of the plaster ceiling aids in creating a better reflection of sound waves, ensuring the coverage of sound propagation where the audience at different areas of seating are able to hear the sound produced from stage.
Diagram 3.49: Rigid ceiling system with sound batt insulation and closed cell foam However, the rigid ceiling system has a much greater area of direct contact between the finish material and the structure above. Hence, to improve the acoustical qualities of the ceiling, resilient channels with sound clips should be attached to the structure system, perpendicular to the joist or beams. Moreover, the addition of sound batt insulation between the joist will assist in the absorption of the airborne and flanking transmission. A second layer of gypsum board can be attached to achieve additional reduction as the mass and damping ratings are increased. 
45
(E) Stage Flooring
Figure 3.41: Front view of auditorium stage
Figure 3.42: Side view of auditorium stage
The mass of the flooring system at the stage is the main factor towards noise control. Noises with high frequency vibration like sound produced by the musical instruments and low frequency vibrations which include footfalls of people walking on the stage as well as sound emitted from the sound monitors. Hence, the materiality of the stage plays an important role in reducing the airborne and impact noise transmissions to an adequate level.
Diagram 3.50: Area of timber parquet flooring
Diagram 3.51: Section of stage floor materiality
Timber parquet flooring is used as the finishing surface for the stage as it is resilient in withstanding foot traffic as well as creating a longer reverberation time due to its hard and acoustically reflective surface. The timber flooring is layered over concrete slabs where it provides ample airborne sound insulation between the two habitable spaces as the required level of impact sound insulation is unable to be achieved by utilising only one of the materials. In addition, timber floorings are not as exceptional in providing airborne sound insulation compared to concrete slabs. Hence, sound reduction can be achieved with the addition of concrete underlayment which increase the solidity of stage floor and reduce the hollow percussive sound produced from footfalls. 
46
Stage Apron & Steps
Figure 3.43: Carpeted apron and stage steps The main stage apron is covered with carpet finish which absorbs reflected sound from the auditorium. However, the carpet finish used at the stage apron does not have a major impact towards the sound absorption level as the surface area of the carpeted apron is insignificant compared to the carpeted floorings. The carpeted aprons function more towards aesthetic and decorative purposes. Steps on the stage are carpeted as well to achieve a silent footfall when ascending up and down the steps. (F) Stage Curtain & Concrete Wall
Diagram 3.52: Location of concrete wall, canvas background, stage curtain and backstage - plan
47
Diagram 3.53: Location of concrete wall, canvas background, stage curtain and backstage - section At the stage, curtains located at the backstage helps in controlling the reverberation by absorbing excess sound and eliminating acoustical reflections. Behind the stage curtain is a layer of canvas background followed by a concrete wall where there is an air gap between the curtain and wall. The air gap in between aids in noise isolation while the drapery is used to absorb sound which enables the reduction of reverberation time and prevention of echoes. The concrete walls on both sides of the backstage reflects sound waves produced from the noises, thus, capturing the sound within the backstage without transferring to the auditorium.
48
3.2 NOISE AND NOISE INTRUSION IN DAMANSARA UTAMA METHODIST CHURCH AUDITORIUM 3.2.1 INTRODUCTION The Damansara Utama Methodist Church (DUMC) Auditorium experiences noise intrusions, which is characterised by recipients as undesirable and unwanted sound.
3.2.2 DETRIMENTAL EFFECTS OF NOISE ON THE LISTENER OR ENVIRONMENT As DUMC Auditorium is a multi-purpose auditorium which functions to host activities such as church sermons, concerts as well as talks, a desirable acoustical environment is essential for all these activities to take place. However, noise intrusions are present. Some of the disadvantages of these noise intrusions include: Hindering concentration and knowledge retention Creating distractions, which will eventually lead to inefficiency and inattention when a particular work is conducted Causing interference with desirable sounds such as music or speech, which delays productivity due to the annoyance created
3.2.3 ROOM CRITERIA: BACKGROUND NOISE Room criteria measures have been developed to evaluate existing background noise levels in enclosed areas, such as rooms, as well as to specify required background levels for enclosed areas to be constructed. The simplest noise criteria is determined by measuring or specifying a maximum A-scale weighted level (dBA). Occupancy
Max dBA
Small auditoriums (≤500 seats)
35-39
Large auditoriums, theatres and churches (> 500 seats)
30-35
Table 3.2: Weighted criteria of auditoriums.
49
On-site measurement:
Figure 3.6: Background noise reading as indicated by digital sound meter.
Figure 3.7: Background noise reading as indicated by digital sound meter.
During the site visit conducted, the background noise measured using the digital sound level meter (38 to 41 dBA) is higher than the weighted criteria of large auditoriums (30-35 dBA). This indicates that the selected case study has an undesirable background noise level which is caused by noise intrusions.
3.2.4 ACOUSTIAL ANALYSIS OF SOUND CONTROL The analysis of noise in the auditorium can be viewed from the standpoint of a source, path and receiver relationship. Sound source
Sound path
Sound receiver
Diagram 3.22: Sound source, path and receiver relationship.
50
1. Noise sources and sound path Noise sources which can be identified when using the auditorium include the HVAC system at the left side of the auditorium stage, the Symphony Square corporate office tower construction at the back of the auditorium as well as natural weather conditions such as thunder.
Diagram 3.23: The noise sources identified within the auditorium.
51
(A) HVAC system noise source The noise produced by the HVAC system, which is identified at the left side of the auditorium stage, is characterised as an interior noise. This is because the noise, which occurs within the building itself, is produced by ventilation system machineries.
Diagram 3.24: The HVAC system noise source on ground level.
Figure 3.8: The HVAC system noise source.
52
Although the source of the noise produced by the HVAC system can be easily identified, the actual system components which contribute to the noise remains unknown as they are concealed by walls near the backstage. However, airborne and structure-borne sound transmission allows the sound to be transmitted to the receiver through the mediums.
Diagram 3.25: Possible sound paths of the HVAC system.
i. Possible sound paths of the HVAC system Airborne sound transmission -
Sound which travels through the air from the source Able to travel with or against the direction of airflow Sound which travels through supply ductworks, return ductworks, or an open plenum
-
Structure-borne sound Sound which travels through the vibration of solid parts of the building’s structure, such as walls, floors, or ceilings Breakout sound
-
Sound that breaks out through the walls of the supply or return ductwork
53
ii. Main HVAC noise sources -
Fans (for air circulation) Axial Centrifugal Propeller
-
Compressors (that convert gas to liquid) Piston Rotary Scroll Centrifugal Pumps (to circulate liquids)
-
Diffusers and ductwork (to distribute air) Turbulent aerodynamic noise “Break-out� noise
Diagram 3.26: Frequencies at which various types of mechanical and electrical equipment generally control sound spectra.
iii. Noise control approaches for HVAC systems To effectively curb noise problems posed by HVAC systems, a few approaches can be implemented, such as: Planning location of HVAC systems at a certain distance from the receivers Resilient mounting & connected services Flexible connections to equipment to lower fluid velocities Internal duct lining and attenuators Routing of ductwork and piping Enclosing ductwork and piping 54
(B) Symphony Square corporate office tower construction The noise produced by the construction of the Symphony Square corporate office tower, which is identified at the back of the auditorium, is characterised as an outdoor noise. This is because the noise produced by the construction equipment and machineries originates from the exterior of the building.
Diagram 3.27: The construction noise source on ground level.
Figure 3.9: The construction of the Symphony Square corporate office tower, as viewed from the back of DUMC. As the auditorium is located near the back of the building, noise which originates from the construction site is able to intrude the space easily.
55
Figure 3.10: Source of noise (pink) in respect to DUMC Auditorium’s location (blue).
i. Possible sound path of the construction Noise produced by the construction equipment and machineries undergoes airborne transmission, where the sound is transmitted through the air from the source. The unwanted sound (noise) is then transmitted from the air to the back façade of the church building The sound energy that is transmitted directly through the structure is reradiated from building elements such as walls and panels, and eventually reaches the recipient as airborne sound.
56
(C) Natural weather conditions Noises created by natural weather conditions, such as thunder, can be identified within the auditorium. These noises are outdoor noises, as their sources originate outside of the building. The noises created by natural weather conditions are transmitted from above the auditorium.
Figure 3.11: View of the upper gallery from ground level.
Noise from the exterior environment is able to enter the auditorium via the exit doors at the gallery as they lack sound proofing treatments.
Figure 3.12: The exit doors at the gallery.
57
The first floor level is fenestrated using normal glass windows with low sound reduction index. As such, airborne sound transmission allows the unwanted sound to be transmitted from the external environment into the first floor easily. An external aisle, which is present on the first floor right after the exit doors, allows this sound to be transmitted into the auditorium via the exit doors.
Figure 3.13: Glass windows on the first floor.
Figure 3.14: External aisle present on the first floor.
Diagram 3.28: Transmission of noise from the external environment to the auditorium.
58
2. Absence of sound lock Sound locks, which function to keep noise out of an enclosed space, is absent in the auditorium. As such, the absence of the system does not enhance the sound insulation property of the auditorium, allowing noise to transmit into the space.
59
4. conclusion [Damansara Utama Methodist Church]
Building Science II : Project One
4.0 CONCLUSION To conclude our findings, Damansara Utama Methodist Church Auditorium is an auditorium which is not very suitable to host live and instrumental performances as they depend heavily on electronic audio reinforcements to overcome its shortcomings mentioned in Chapter 3. Although the extensive use of absorbent materials makes it suitable for speech, there are still inevitable acoustical defects not just within, but also in its surrounding context. Through our observation and analysis, noise intrusion proved to be a major problem faced by the auditorium, especially when it is used for a multitude of functions. As such, the management should take appropriate measures to deal with this problem and to provide a comfortable acoustical environment for users.
60
5. references [Damansara Utama Methodist Church]
Building Science II : Project One
5.0 REFERENCE
Acoustical Surfaces. (2013). AMBIENT OR BACKGROUND NOISE LEVEL. Retrieved from http://www.acousticalsurfaces.ae/101_10.htm Barron, & Michael. (2009). The-fan shaped hall. In Auditorium Acoustics and Architectural Design, Second Edition (2nd ed., p. 95). New York, NY: Taylor & Francis. Colleran, N. (October, 2012). Setting the Stage for Acoustics First. Retrieved from http:// www.acousticsfirst.com/article-setting-the-stage-for-acoustics-first-productions-mag.htm DUMC. (2018). About DUMC. Retrieved from http://dumc.my/about-dumc/our-history/ DUMC. (2018). About DUMC. Retrieved from https://www.facebook.com/pg/dumcMY/ about/?ref=page_internal Healey, R. (May, 2014). Investigations into the sound absorbing properties of gypsum wall board. Retrieved from https://asa.scitation.org/doi/abs/10.1121/1.4877192 Lai, Y.X. (July 26, 2017). Building Science II Project 1: Auditorium Acoustic Design. Retrieved from https://issuu.com/yikxinlai/docs/new_bolded_dumc_slide Lee, S. (March 19, 2015). Damansara Utama Methodist Church. Retrieved from http:// www.church.com.my/damansara-utama-methodist-church.html Liew, Q. (December 20, 2017). Auditorium: SHANTANAND Temple of Fine Art Case Study. Retrieved from https://www.slideshare.net/QuinnLiew/auditorium-shantanand-temple-of-fineart-case-study Mominzaki. (2014, April 7). Auditorium Acoustics. Retrieved from https://www.slideshare.net/ mominzaki/auditorium-acoustics-33230112 PYROK, Inc. (2018). Acoustement Plaster 20. Retrieved from http://www.acoustement.com/ acoustement-plaster-20/#toggle-id-2 Scherff USA. (2011). Installation Detail-Alpha. Retrieved from http://www.scherffusa.com/ installation/acoustic_plaster_alpha_rondo_quadro.htm Swamy, R.N. (November 21, 2015). Noise control. Retrieved from https:// www.slideshare.net/narasimhaswamy/noise-control-55355735 Tan, Y. (December 20, 2017). Auditorium Case Study on Acoustic Design. Retrieved from https://www.slideshare.net/yincytwincy/building-science- p01?ref=http://yincyt.blogspot.my/p/ building-science.html The ARC. (2018). Acoustics: Room Criteria. Retrieved from https://web.iit.edu/sites/web/files/ departments/academic- affairs/Academic%20Resource%20Center/pdfs/Workshop__Acoustic.pdf Ueno, K. & Tachibana, H. (August, 2010). A consideration on acoustic properties on concerthall stages. Retrieved from https://www.acoustics.asn.au/conference_proceedings/ICA2010/ cdrom- ISRA2010/Papers/O1b.pdf  
61
Vibro-acoustics. (2018). Chillers. Retrieved from http://noisecontrol.vibro- acoustics.com/ application-solutions/chillers Auditoriums | Meeting Rooms | Sound Design. (n.d.). Retrieved from https:// soundmanagementgroup.com/applications/education/auditoriums/ The Science Of Auditorium Design. (2017, January 20). Retrieved from https:// www.ethos3.com/2015/08/the-science-of-auditorium-design/ SMC Australia Pty Ltd. (n.d.). Acoustic Polyester Panel with Fireproof Sound-Absorbing Facing. Retrieved from http://www.megasorber.com/soundproofing-products/soundabsorbers/fireproof-faced-acoustic-polyester-wool ACOUSTICAL FUNDAMENTALS. (2015, November 26). Retrieved from http:// proaudioencyclopedia.com/acoustical-fundamentals/ Sound Absorbing Acoustic Panels and Superchunk Bass Traps. (n.d.). Retrieved from http:// www.facstaff.bucknell.edu/esantane/movies/Acoustic.html
62