Building Science II_Experimental Theatre

BUILDING SCIENCE II (BLD61303) Auditorium : A Case Study on Acoustic Design

EXPERIMENTAL THEATRE, UNIVERSITY MALAYA

Daren Lai Kam Fei

0332570

Esther Wong Jia En

0332188

Gavin Tio Kang Hui

0333373

Ng Zien Loon

0328565

Priscilla Huong Yunn

0332599

Wendy Lau Jia Yee

0333538

Yong Ping Ping

0332585

Tutor : Ar. Edwin Chan

CONTENT LIST 1.0 Introduction 1.1 1.2 1.3 1.4

2.0

3.0

Page 1 Overview of Experimental Theatre History of Experimental Theatre Context and location Drawings 1.4.1 Ground Floor Plan 1.4.2 Mezzanine Floor Plan 1.4.3 Section A-A’ 1.4.4 Section B-B’

Methodology 2.1 Introduction 2.2 Measuring and Recording Equipment Sound source and Noise Intrusion 3.1 Sound Source in Experimental Theatre 3.1.1 Introduction

Page 7

Page 9

3.2

Noise Intrusion 3.2.1 Introduction 3.2.2 Effects of Noise 3.2.3 Noise Analysis 3.2.4 Existing Noise Sources in Experimental Theatre 3.2.4.1 Outdoor Noise - External Environment 3.2.4.2 Outdoor Noise - Human Activities 3.2.4.3 Indoor Noise - Human Activities and Movement (Air-borne Noise) 3.2.4.4 Indoor Noise - Machineries and Equipments

3.3 3.4

Background Noise Noise Control 3.4.1 Noise Control in Experimental Theatre 3.4.1.1 Space Organisation 3.4.1.2 Sound Absorption 3.4.1.3 Sound Insulation 3.4.1.4 Sound Lock

3.5

Sound Reinforcement 3.5.1 Introduction 3.5.2 System Reinforcement 3.5.2.1 Subwoofers 3.5.2.2 Line Arrays 3.5.2.3 Stage Monitors 3.5.2.4 Two-Way Wall Speakers 3.5.3 Advantages and Disadvantages of Sound Reinforcement System in Experimental Theatre

4.0

Time Delay 4.1 Introduction 4.2 Calculations of Sound Delay and Echo

Page 33

5.0

Acoustical Analysis 5.1 Auditorium Design 5.1.1 Shape of Auditorium 5.2 Ceiling 5.2.1 Planar Relationship between Ceiling and Ground Floor 5.2.2 Multi-Angled Ceiling 5.2.3 Ceiling as Sound Diffuser to Mezzanine Floor 5.2.4 Chamfered Ceiling Corner 5.2.5 Ground Floor Rear Ceiling 5.2.6 Useful Ceiling Reflection and Sound Diffuser 5.3 Wall 5.3.1 Timber Panel with 150mm Air Gap 5.3.2 60° Slanted Side Walls 5.4 Railing 5.5 Seating

Page 38

6.0

Acoustical Treatment and Components 6.1 Material Tabulation of Experimental Theatre 6.2 Materials of Ceiling 6.2.1 Plaster Ceiling 6.3 Materials of Walls 6.3.1 Drywalls 6.3.2 Timber Panels 6.4 Materials of Floors 6.4.1 Pile Carpeted Floor 6.5 Materials of Seatings 6.6 Materials of Sound Absorption Panels

Page 50

7.0

Sound Propagation Analysis 7.1 Ambient Sound Analysis 7.2 Sound Propagation Analysis

Page 59

8.0

Reverberation Time 8.1 Introduction 8.2 Calculation of Reverberation Time 8.2.1 Division of Floor Area 8.2.2 Volume of Experimental Theatre, V 8.2.3 Total Room Absorption, AT 8.2.3.1 Absorption of Floor Surfaces, A1 8.2.3.2 Absorption of Wall Surfaces, A2 8.2.3.3 Absorption of Other Surfaces, A3 8.2.3.4 Total Room Absorption, AT 8.3.4 Total Reverberation Time

Page 73

9.0 Conclusion

Page 81

10.0 References

Page 83

topic one

INTRODUCTION 1.1 1.2 1.3 1.4

OVERVIEW OF EXPERIMENTAL THEATRE HISTORY OF EXPERIMENTAL THEATRE CONTEXT AND LOCATION DRAWINGS 1.4.1 Ground Floor Plan 1.4.2 Mezzanine Floor Plan 1.4.3 Section A-A’ 1.4.4 Section B-B’

01

1.0 INTRODUCTION

1.1

Overview of Experimental Theatre

OVERVIEW OF EXPERIMENTAL THEATRE

Figure 1.0 : View of the auditorium seating of the E.T.

Name of Auditorium Address Type Of Auditorium Architect Architecture Style Year of Construction Built up area Capacity

Figure 1.1 : View of the auditorium stage of the E.T.

: Experimental Theatre, University of Malaya : 825, Lingkungan Budi, 50603 Kuala Lumpur, Wilayah Persekutuan Kuala Lumpur : Performing Arts Theatre : Dato’ Kington Loo of BEP Architects : Brutalism and Modernism : 1965-1966 : 5621m3 : 435 pax

The Experimental Theatre (E.T.) is a small gem located in the heart of University of Malaya, functioning as a performing arts theatre designed for a range of experiences such as stage performances, conferences, seminars, presentations and product launches. The E.T. is well-known and adequately equipped with the newest upgrades since its renovation in 2011, hence it is also sought after by outside parties to host events by private and corporate functions.

The present layout of the E.T is based on the original concept of Richard Wagner, by incorporating modern innovations and systems into the auditorium. One of the interesting features on stage is a proscenium stage, with a ramp leading to the basement rooms that serve as a green room (waiting area or touch-up lounge for the performers). There is also a hydraulic platform located in front of the stage, serving as an extension of the stage when raised, and an orchestra pit when lowered. A structure of grids and rigging can be found hidden above the stage, used to accommodate modern sound and lighting systems. As for the auditorium, it consists of tiered stalls and a gallery (mezzanine oor or raised seating platform).

02

1.0 INTRODUCTION

1.2

History, Context and Location

HISTORY OF EXPERIMENTAL THEATRE

The E.T. was constructed during the 1960s together with the Dewan Tunku Canselor (D.T.C.), both which were the works of Dato’ Kington Loo of BEP Architects. It was designed under the strong influence of Brutalism and Modernism, with the building constructed mainly from a bare concrete structure using egg-crate reinforced concrete and béton brut (architectural concrete left unfinished or roughly-finished after pouring and left exposed visually) imprints.

On 29 June 2001, a pre-dawn fire scorched the D.T.C. but fortunately the E.T. was left unscathed.

Later on, renovation works on the E.T. were undertaken circa 2001, but never progressed beyond the modification of the ultrastructure was left abandoned for the next ten years. It was not until early 2009 that the E.T. was declared a National Heritage, and plans to restore the E.T. finally resumed which lasted until 2011 before it was reopened to the public.

Figure 1.2 : E.T. in October 2009 before renovation.

1.3

Figure 1.3 : E.T. in March 2011 after renovation.

CONTEXT AND LOCATION

The Experimental Theatre is located within the campus of University Malaya, Kuala Lumpur. It is located next to other university facilities such as Dewan Tunku Canselor (DTC), The Cube Cultural Centre, and research centres. It is surrounded by the main vehicular access road which having a high traffic flow during rush hour. There are also some car parks allocated along the building edges which the surrounding greenery and vegetation maintained as an buffer zone of vehicular noise level.

Figure 1.4 : Site context of Experimental Theatre 03

1.0 INTRODUCTION

1.4

Drawings

DRAWINGS

1.4.1 GROUND FLOOR PLAN

B

2

6 1

Figure 1.5 : Diagram showing Ground Floor Plan.

A

A’ 4

5

3

B’

Ground Floor Plan

1:500

1. Entrance (University Students)

3. Performance Stage

5. Ramp (Towards Basement)

2. Male & Female Toilet

4. Back Stage

6. VIP Entrance Hallway

04

1.0 INTRODUCTION

1.4

Drawings

DRAWINGS

1.4.1 MEZZANINE FLOOR PLAN

B 3 2

5

4

1 A

A’

B’

Mezzanine Floor Plan

1:500

1. Lift Lobby (Entrance)

3. Backstage Control Room

5. Staircase (From VIP Entrance

2. Male & Female Toilet

4. Balcony

Hallway)

05

1.0 INTRODUCTION

Drawings

1.4.5 SECTIONS

2 1

1

3 4

Section A-A’

1:500

1. Back Stage

3. House

2. Balcony

4. Basement

5 3

6

1 4

Section B-B’

2

1:500

1. Performance Stage

3. House

5. Backstage Control Room

2. Basement

4. Orchestra Pit

6. VIP Entrance Hallway

06

topic two

METHODOLOGY 2.1 2.2

INTRODUCTION MEASURING AND RECORDING EQUIPMENT

07

2.0 METHODOLOGY

2.1

Measuring and Recording Equipment

INTRODUCTION

Before going to site visit, we loaned the measuring tool from university for measuring the dimensions and the sound intensity levels at our chosen auditorium. We made a prior arrangement from the staff from university to ensure an unoccupied theatre for the accuracy of reading. Data collected and recorded on site are then analysed of its acoustic intensity and properties.

2.2

MEASURING AND RECORDING EQUIPMENT

1. Digital Sound Level Meter Digital Sound Level Meter, a meter calibrated to measure intensity of sound level under unit of measurement is in db short for decibels. The acoustic intensity measurement within the auditorium to determine the sound concentration and background noise level.

Figure 2.0 : Digital sound level meter.

2. DSLR Camera DSLR Camera was used to capture photographs of the building materials and conditions of the experiential theatre. Photography taken for further investigation and evaluation on acoustical analysis.

Figure 2.1 : DSLR camera.

3. Smartphone Smartphone was used as an alternative way for taking photography of exterior and interior of the auditorium. It also used to produce a constant frequency of white noise on the auditorium stage for the sound meter to be taken at various points for analysis purpose.

Figure 2.2 : Smartphone.

4. Measuring Tape The measuring tape was used to determine the dimension of the auditorium for drawings of plans and sections. It only be used to measure reachable areas for distance that within five metres.

Figure 2.3 : Measuring tape.

5. Laser Rangefinder (80m handheld) Laser rangefinder was used to take measurement accurately for distance that beyond 5 metres due to the limitation of measuring tape such as height and width of the buildings, stage and ceiling within the building. It is also used to determine the angle of the ceiling in auditorium.

Figure 2.4 : Laser rangefinder.

08

topic three

SOUND SOURCE AND NOISE INTRUSION 3.0 3.1 3.2

3.3 3.4 3.5

Sound source and Noise Intrusion Sound Source in Experimental Theatre 3.1.1 Introduction Noise Intrusion 3.2.1 Introduction 3.2.2 Effects of Noise 3.2.3 Noise Analysis 3.2.4 Existing Noise Sources in Experimental Theatre Background Noise Noise Control 3.4.1 Noise Control in Experimental Theatre Sound Reinforcement 3.5.1 Introduction 3.5.2 System Reinforcement 3.5.3 Advantages and Disadvantages of Sound Reinforcement System in Experimental Theatre

09

3.0 SOUND SOURCE AND NOISE INTRUSION

3.1

Introduction

SOUND SOURCES IN EXPERIMENTAL THEATRE

3.1.1 INTRODUCTION Sound is a result of vibrating air that transmit through an elastic medium such as air, water or solid. It could be generated by musical instruments, human vocal chord, running engines, vibrating loudspeaker diaphragm and so on. Sound and noise are dierent. Noise, on the contrary, is an unpleasant and less desired sound which has more irregular vibration quality.

1.

Speaker

Figure 3.0: Line array used in the auditorium (A)

Figure 3.1: Two way speaker used in the auditorium (B)

(B)

(B)

(B) (B)

(A)

(A)

Figure 3.2: Plan of Experimental Theatre showing location of speakers

10

3.0 SOUND SOURCE AND NOISE INTRUSION

3.1

Introduction

SOUND SOURCES IN EXPERIMENTAL THEATRE

2.

Human vocal cord (Performers) Human vocals of performers are also considered as sound source as the sound is pleasant.

Figure 3.3 : Plan of Experimental Theatre indicating location of human vocal source

Figure 3.4: Section of Experimental Theatre indicating location of human vocal source.

11

3.0 SOUND SOURCE AND NOISE INTRUSION

3.1

Introduction

SOUND SOURCES IN EXPERIMENTAL THEATRE

3.

Musical instruments Music produced by musical instruments are considered as sound source as the sound is desirable.

Figure 3.5: Plan of Experimental Theatre showing location of music source

Figure 3.6 : Section of Experimental Theatre showing location of music source

12

3.0 SOUND SOURCE AND NOISE INTRUSION

3.2

Effects of Noise, Noise Analysis

NOISE INTRUSION

3.2.1 INTRODUCTION Noise is a sound or sounds, especially when it is unwanted, unpleasant, or loud. Noise can be produced by many sources such as man's vocal cord, a running engine, a vibrating loudspeaker diaphragm, an operating machine tool, and so on.The difference between sound and noise depends upon the listener and the circumstances.

In an auditorium design, noise levels should be reduced to acceptable levels in order to prevent adverse outcomes of the noise exposure which will degrade the quality of a performance or and an event. Therefore, to deal with noise, firstly, sources of noise have to be identify and various solutions can be applied to prevent excessive exposure of noise occurs.

3.2.2 EFFECTS OF NOISE The Experimental Theatre of University Malaya use for different type of activities such as stage performance, conferences, seminars, presentations and product launches. Noise pollution in an auditorium may lead to several issues to the users, the performers, and further affect the quality of events and performances housed. ● ● ● ●

Noise during events or performances will distract users and performers attention.

Noise during presentation or speech may cause misinformation between presenters and audiences.

Noise may lead to psychological variables which built up performers’ anxiety and stress that affect quality of performance.

Noise will generally cause annoyance which affect user experiences in the auditorium.

Therefore, an auditorium which is a place to hear and, moreover, a place to listen to and learn.

The outer beauty of an auditorium is recognized by how it looks, but the inner more lasting beauty of the auditorium is truly known by how it sounds. An desirable acoustical environment is vital in providing audiences a good show experience as well as giving performers to carry out a smooth performance.

3.2.3 NOISE ANALYSIS The analysis of noise for noise control action can be translated into a relationship of a source and receiver, connect by a path or medium.

Sound sources can be divided into three categories: ● ● ●

Occupants activity Operation of building machineries and equipments Environmental sound produced outside of a building

13

3.0 SOUND SOURCE AND NOISE INTRUSION

Noise Analysis

Noise source of building can be divided into two groups: 1.

Outdoor/ exterior noise ● Noises produced by transportation such as road traffic, railway, and aircraft. ● Opening and closing of the doors ● Mechanical equipment such as compressors, cooling towers and construction equipments.

2.

Indoor/ interior noise ● Human behaviour and movement ● Machines and electrical appliances ● Seating, flooring and door may produce noise

These noise (or sound in general) can be transmitted in two ways: 1.

Airborne The noise sources is transmitted through the air to the receiver via the path through openings such as open doors, cracks and electric fixtures.

2.

Structure-borne Sound energy from a sources vibrate through the building structure and transmitted from one space to another space of the building,

In noise control, the sound receiver can be a building or a room in a building as well as a person.

Actions can be taken to reduce noise based on this relationship of sound transmission from the source to receiver.

14

3.0 SOUND SOURCE AND NOISE INTRUSION

Existing Noise Sources

3.2.4 EXISTING NOISE SOURCES IN EXPERIMENTAL THEATRE 3.2.4.1 Outdoor Noise - External Environment Experimental theatre is located adjacent to Lingkungan Budi, a one-way road which is one of the main road. It is mainly congested during peak hours.

The vehicles passing by the road causes transportation noise in the building. This noise is transmitted through airborne as well as structure-borne transmission, In this case, the building itself acts as a receive of noise.

The other side of the auditorium is the school compound surrounded by greenery, which acts as a partial sound absorber that aid in reduction of the background noise.

Figure 3.7 : Location plan of Experimental Theatre

Figure 3.8: TraďŹƒc condition of Lingkungan Budi during normal hour.

15

3.0 SOUND SOURCE AND NOISE INTRUSION

Existing Noise Sources

3.2.4 EXISTING NOISE SOURCES IN EXPERIMENTAL THEATRE Airborne noise is transmitted along a continuous air paths such as openings and cracks around doors, which can be identiďŹ ed in the auditorium. The glass door at the entrance becomes a noise source as the gap between the door panels is permeable to the external noise. The service roller shutter door located next to the stage is not completely sealed, thus causes sound intrusion.

Figure 3.9 : Glass entrance door.

Figure 3.10: Service roller shutter door to the left of the stage.

Figure 3.11: Gap between the roller shutter door and adjacent wall.

Figure 3.12: Plan of Experimental Theatre indicating position of service roller shutters and glass door.

16

3.0 SOUND SOURCE AND NOISE INTRUSION

Existing Noise Sources

3.2.4.2 Outdoor Noise - Human Activities Noise generated by activities can be transmitted into the auditorium as there is an absence of buer zone between between the main entrances and the auditorium.

Activities such as having conversation that happen at the lobby can be heard at the back of the auditorium. Regular cleaning routine is also one of the noise contribution.

Figure 3.13 : Glass entrance door.

Figure 3.14 : Glass entrance door.

Figure 3.15 : Plan of Experimental Theatre indicating location of human activities happening.

17

3.0 SOUND SOURCE AND NOISE INTRUSION

Existing Noise Sources

3.2.4.3 Indoor Noise - Human Activities and Movement (Air-borne Noise) Indoor noise is generated by impact of the physical contact with a surface. Specific noise sources generated by human movement can be identified in the auditorium: ● ● ● ● ●

Auditorium chairs Timber ramp at the gallery/balcony level Door hinge Door slam stopper Temporary timber staircase

The noise generated is a low but noticeable creaking sound might be extremely disturbing when the audience happens to enter or leave in the middle of a performance.

Figure 3.16: Door slam stopper of entrance door (A)

Figure 3.17: Auditorium seats.

Figure 3.18: Temporary steps on both sides of stage (B)

Figure 3.19: Timber ramps (C)

(A)

(A) (C)

(B)

(B)

Figure 3.20: Plan of Experimental Theatre indicating location of indoor noise source

18

3.0 SOUND SOURCE AND NOISE INTRUSION

Existing Noise Sources

3.2.4.4 Indoor Noise - Machineries and Equipments The fixtures employed for lighting such as spotlights and stage lights might produce buzzing sound. There are fluorescent lamp in the acoustic timber panel where the buzzing sound would be heard if someone is sitting near the panel.

Light fixtures producing buzzing noise indicate improper dimming or electromagnetic interference from other devices causes vibration in the light bulb which will produce the sound.

Figure 3.21: Light equipment (spotlight) for stage performance. (A)

Figure 3.23: Light equipment above the stage. (C)

19

Figure 3.22 : Light equipment at the mezzanine floor. (B)

Figure 3.24: Light equipment on the gallery. (D)

3.0 SOUND SOURCE AND NOISE INTRUSION

Existing Noise Sources

3.2.4.4 Interior Noise - Machineries and Equipments

(B)

(B) (A)

(D)

(D)

(C)

Figure 3.25: Plan indicating placement of machineries and equipment.

Interior noise is also generated by the HVAC system. It is the type of sound transmitted through structural borne in which sound is vibrating on the solid surface of the AHU duct. However, our readings are not aected as the HVAC system is not operating during the recording session.

Figure 3.26: Diusers of air conditioning and mechanical air intake openings.

20

3.0 SOUND SOURCE AND NOISE INTRUSION

Existing Noise Sources

3.3 Background noise Quality acoustical characteristics are important in auditorium spaces so that performances and presentations can be clearly heard and understood. For performance spaces and general performance spaces, recommended noise criteria (NC) rating ranges from NC-20 to NC-30; recommended sound transmission class (STC) rating ranges from STC 40 to STC 50.

Background noise is estimated to be at a level of 35db due to the noise sources as shown in chapter 3.2.5.

Experimental Theatre with an occupancy of 435 seats and octave band center frequency of 500Hz, the noise match the NC of an auditorium, which is around the range of 30s.

This indicate that the selected case study has an desirable background noise level.

Figure 3.27: Graph shows the noise criteria (NC) curve.

21

3.0 SOUND SOURCE AND NOISE INTRUSION

3.4

Noise Control

NOISE CONTROL

Improve the sound quality inside an auditorium by reducing the noise is known as noise control.

Noise control through sound transmission relationship: ● Control the source ● Block the path ● Enclose the receiver Methods of noise control ● Elimination of noise source. ● Substitute noisy machinery or equipment with quieter alternatives. ● Architectural and structural design. ● Building layout. ● Sound absorption. ● Sound insulation.

22

3.0 SOUND SOURCE AND NOISE INTRUSION

Noise control

3.4.1 NOISE CONTROL IN EXPERIMENTAL THEATRE 1.

2.

3.

4.

Building layout Sound absorption Sound insulation Sound lock

3.4.1.1 Space Organisation The auditorium is surrounded by hallways on three sides, isolating the auditorium from the external environment. This reduce the airborne noise entering the auditorium, to achieve eďŹƒcient acoustics design.

A. B.

1.5 metres wide hallway dividing the auditorium from the servicing area of the auditorium, diminishing the machinery noise entering the auditorium.

Both 7 metres wide hallway disconnect the auditorium from the vehicular road, these hallways lessen the noise produce by vehicular from the road reaching the auditorium.

Figure 3.28: 1.5 metre hallway (A)

Figure 3.29: 7 metre hallway (B)

(B) (C) (A)

Figure 3.30: 7 metre hallway (C)

Figure 3.31: Plan of Experimental Theatre indicating hallways.

23

3.0 SOUND SOURCE AND NOISE INTRUSION

Noise control

3.4.1.2 Sound Absorption The principle of sound absorption is applied in noise control in Experimental Theatre. Medium pile carpet is used to cover the hard concrete floor of the auditorium to efficiently control noise from footsteps and other impacts. Extensively use of carpet in the auditorium creates more comfortable environment, as the carpet dampens noise and reduces sound transmissions. This fuzzy, porous structure of the carpet and soft furnishing allows the sound waves to penetrate into the pile, rather than being reflect back into the room. The individual fibres, tufts and underlay of the medium pile carpet have different frequencies at which they absorb wide range of sound waves.

Figure 3.32: Pile carpet used as floor cover

Multiple layers of materials are overlay the floor of the auditorium stage to reduce the noise produced. Concrete floor is covered with 20mm polished timber flooring with linoleum vinyl sheet on it. These materials reduce footstep noise produced during performance on stage.

Figure 3.33: auditorium stage flooring

24

3.0 SOUND SOURCE AND NOISE INTRUSION

Noise control

Sound Absorption The thick, heavy velour fabrics curtains surrounding the auditorium stage help control the reverberation by absorbing excess noise and eliminating the acoustic reection. Other than attenuating the chatter and noise in the room, it also prevent noise penetration from the backstage and the exterior environment. The pleated nature of the curtain (meaning it does not lay at), exposes a more sound-absorbing surface, thus improving the low frequency sound attenuation.

Figure 3.34: Velour curtain

Figure 3.35: Plan of Experimental Theatre indicating location of velour curtains.

25

3.0 SOUND SOURCE AND NOISE INTRUSION

Noise control

3.4.1.3 Sound Insulation Sound insulation is a kind of measure to prevent sound waves from permeating. The best way to insulate the solid-borne sound is to use the unconnected structure. In Experimental Theatre, double walls are used to create air cavity and this method is known as the “mass-air-mass� system. Large cavity is incorporated in this system. By increasing the air cavity, the sound is least likely to permeate through, thus increases the insulating properties.

Experimental Theatre has two pockets of air cavity on each side of the auditorium between its wall with a gap of 150mm.

Figure 3.36: Plan of Experimental Theatre indicating the position of walls with air cavity.

26

3.0 SOUND SOURCE AND NOISE INTRUSION

Noise control

3.4.1.4 Sound lock Sound lock acts as a barrier between the auditorium to the hallway. As shown in figure (), most of the sound is transmitted through the normal door into the “sound lock” space. As sound has to transfer a distance of air to the acoustic door, part of the sound waves have been turned into heat energy and dissipates in the air. The acoustic door is installed with absorbing materials, thus sound is unable to transfer into the auditorium. Quality of sound system and performance in the auditorium is enjoyable as outside noise is greatly reduced.

Figure 3.37: Plan of Experimental Theatre indicating sound lock area.

27

3.0 SOUND SOURCE AND NOISE INTRUSION

Sound reinforcement

3.5 Sound Reinforcement 3.5.1 Introduction The distance between the centre of the stage to the edge of the auditorium is about 18m long.

The distance for an auditorium to function efficiently without sound reinforcement is about 15m, therefore Experimental Theatre required sound reinforcement system to ensure the sound of the performers or speakers on stage can deliver to every audiences in the auditorium. The sound reinforcement system components can be found in the auditorium are: ● ● ● ●

Subwoofers Line array Stage Monitors Two way wall speaker

3.5.2 System component 3.5.2.1 Subwoofers Experimental Theatre consists of two subwoofers located on each sides on the stage. Subwoofer is a loudspeaker that handles the lower frequencies or bass or sub bass from 20Hz to 80Hz. Low frequency produced by subwoofer has slow attenuation, therefore a single unit on each side of the stage is sufficient to deliver the sound to the audiences.

Besides, the subwoofer displaced on both sides of the stage allow a wider and balance sound distribution. The placement of the subwoofer against the wall will further enhance the bass output.

Figure 3.39: Plan indicating position of subwoofers

Figure 3.38: Subwoofer

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3.0 SOUND SOURCE AND NOISE INTRUSION

Sound reinforcement

3.5.2.2 Line array The Experimental Theatre consists of two main line arrays suspended from the ceiling on the left and right sides of the auditorium. Each line array have two identical speakers mounted vertically on each other. The line array consist of retractable mechanism for height adjusting.

This line array system allow much more consistent sound levels from the front to the back of the auditorium. In addition, the line array set on higher level in the auditorium to ease the control of the vertical coverage of the low frequencies emitted from it. This system also reduce sound sent to the ceiling which will cause unwanted reections back to the listeners. It also reduce the amount of sound leaks onto the stage and decrease the sound being regenerated through open mics on stage.

Position of the line array in Experimental Theatre allow balanced propagation from both sides, however it causes a higher concentration of sound toward the centre of the auditorium.

Figure 3.40: Line array suspended from ceiling.

Figure 3.41: Plan indicating location of two main line arrays.

Figure 3.42: Section of Experimental Theatre indicating line array.

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3.0 SOUND SOURCE AND NOISE INTRUSION

Sound reinforcement

3.5.2.3 Stage monitor Stage monitor system which known as performer-facing loudspeakers, it is a loudspeaker which place on the floor of stage the driver points upward at an angle facing the performers. This enable the performers to hear themselves during performance and not rely on the reverberated reflections bouncing from the rear wall of the auditorium which delayed and distorted, causing the performers to throw out their timing.

Experimental Theatre is equipped with 4 stage monitors on the floor of the stage with another 2 mounted on the wall on each side of the stage to ensure the sound span over the 14 metres great depth of the stage as well as its large volume of space.

Figure 3.43: Stage monitor (A)

Figure 3.44: Stage monitor (B)

(A)

(A)

(A)

(B)

(A)

(B)

Figure 3.45: Plan indicating position of stage monitors.

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3.0 SOUND SOURCE AND NOISE INTRUSION

Sound reinforcement

3.5.2.4 Two-way wall speaker Four evenly spread two-way wall speakers mounted on the low ceiling below the mezzanine floor.

This help to amplify the sound clearly from the stage to the sound shadow area at the back of the auditorium. This will prevent significant delay of sound transmission.

Figure 3.46 : Two way wall speaker

Figure 3.47 : Plan indicating position of two way wall speakers

Figure 3.48: Section indicating position of two way wall speaker.

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3.0 SOUND SOURCE AND NOISE INTRUSION

Sound reinforcement

3.5.3 Advantages and Disadvantages of sound reinforcement system in Experimental Theatre

Advantages ● ● ● ● ●

Speakers and microphones help to reinforce and amplify sound intensity across a longer distance and wide coverage.

Able to adjust the tones in the voice or music to enhance understanding or enjoyment.

Speakers such as line array can minimise the sound being sent to the ceiling and prevent unwanted sound reflection to the audiences.

Sound reinforcement system can easily cut through background noise such as chatter, vehicular and machineries.

Sound reinforcement system able to minimise the the spread of sound to areas that are not intended to cover such as floor, wall, or ceiling.

Disadvantages ● ●

● ●

●

Placement of speakers on the left and right side of the auditorium may cause unbalanced sound distribution in the middle of auditorium.

Poor set up or controlled sound system may cause duplicating sound produced by performer and speaker at two seperate time. Therefore, the ideal differences between this two sources should not more than 1/30 seconds.

Poor sound reinforcement system may also cause the sound produced by system to have excessive low frequencies or high frequencies that reduce the quality of performances.

Placement of subwoofers against the wall in the Experimental Theatre may boost the bass but the ideal placement should be 8 to 12 inches from the wall to ensure a better bass quality.

If there is no enough height of the line array speakers, vertical pattern control can be lost, allowing the low and mid frequencies to project to the ceiling and stage, causing unwanted reflections.

32

topic four

TIME DELAY 4.1 Introduction 4.2 Calculations of Sound Delay and Echo

33

4.0 TIME DELAY

4.1

Introduction

INTRODUCTION

Sound delay occurs when the distance of the reflected sound is longer than the direct sound. If the reflected sound reaches the audience at a slower rate than the direct sound, an overlap in sound which known as echo will be heard. The time difference between when the listener hears the direct sound and when the reflection is heard is referred to as the echo delay time. This delay time depends on the distances between the listener, the sound source and the reflecting surface, with greater distances resulting in longer delay times.

Reflected sound beneficially reinforces the direct sound if the time delay between them is relatively short with the maximum of 30 milliseconds (msec). Any distinct repetition will be heard as echo when its delay time is beyond 30 msec.

Sound delay is affected by following variables: ● ●

Distance travelled by direct sound Distance travelled by reflected sound

To identify whether echo is heard in Experimental Theatre, Time delay formula is used:

Time delay =

R1 = Distance travelled by reflected sound (m) R2 = Distance travelled by reflected sound (m) D = Distance travelled by direct sound (m)

34

4.0 TIME DELAY

4.2

Calculation of sound delay and echo

Calculation of Sound Delay and Echo

Figure 4.0: Plan indicating distance travelled by direct and reected sound

Sound delay and Echo 1 Time delay = (R1 + R2 ) - D 0.34 = ( 15.3 + 15.3 ) - 13.8 0.34 = 49.4 ms

The time delay for this position is 49.4ms, where the direct sound is not reinforced by the reected sound. Echo is heard.

35

4.0 TIME DELAY

Calculation of sound delay and echo

Figure 4.1: Plan indicating distance travelled by direct and reflected sound

Sound delay and Echo 1 Time delay = (R1 + R2 ) - D 0.34 = ( 17.2 + 17.4 ) - 20.5 0.34 = 41.5 ms The time delay for this position is 41.5ms, where the direct sound is not reinforced by the reflected sound. Echo is heard.

Figure 4.2: Section indicating distance travelled by direct and reflected sound

Sound delay and Echo 3 Time delay = (R1 + R2 ) - D 0.34 = ( 7.5 + 7.7 ) - 5.1 0.34 = 29.7 ms The time delay for this position is 29.7ms, where the direct sound is reinforced by the reflected sound. No echo is heard.

36

4.0 TIME DELAY

Calculation of sound delay and echo

Figure 4.3: Section indicating distance travelled by direct and reflected sound

Sound delay and Echo 4 Time delay = (R1 + R2 ) - D 0.34 = ( 16.4 + 1.0 ) - 16.5 0.34 = 2.6 ms The time delay for this position is 2.6ms, where the direct sound is reinforced by the reflected sound. No echo is heard.

Figure 4.4: Section indicating distance travelled by direct and reflected sound

Users seating at mezzanine floor will not receive sound echo without the aid of sound reinforcement as direct sound is blocked by the glass railing.

37

topic five

ACOUSTICAL ANALYSIS 5.1 Auditorium Design 5.1.1 Shape of Auditorium 5.2 Ceiling 5.2.1 Planar Relationship between Ceiling and Ground Floor 5.2.2 Multi-Angled Ceiling 5.2.3 Ceiling as Sound Diffuser to Mezzanine Floor 5.2.4 Chamfered Ceiling Corner 5.2.5 Ground Floor Rear Ceiling 5.2.6 Useful Ceiling Reflection and Sound Diffuser 5.3 Wall 5.3.1 Timber Panel with 150mm Air Gap 5.3.2 60° Slanted Side Walls 5.4 Railing 5.5 Seating

38

5.0 ACOUSTICAL ANALYSIS

5.1

Auditorium Design

5.1.1

Shape of Auditorium

Auditorium design

The form of experimental theatre is a fan shape with the rear corner of auditorium being trimmed by the side walls

A fan-shaped auditorium is desirable to ensure a free flow of direct sound waves to the audience provided the distance is less than 23 metres, which is applicable to Experimental Theatre.

Direct sound waves lessen the diffused early sound field, hence, smaller seat-to-seat variations in acoustical quality and a systematic variation in acoustical characteristics from the front to the rear of the hall.

22.4 m

Sound source

Direct sound wave

Figure 5.0. Fan-shaped Experimental Theatre.

Trimming of fan-shaped auditorium creates side walls that reflect sound at an angle where human directional hearing sensitivity is the highest. The angle of reflection is closer to normal in relative to the reflected sound wave in fan-shaped auditorium.

Figure 5.1: Side walls reflect sound at an angle where human directional hearing sensitivity is the highest.

As a result, the fan-shaped auditorium together with its trimmed corner direct sound to the back central part of the auditorium to counter the undesired sound shadow at the area beneath mezzanine floor.

Figure 5.2: Shape of auditorium is useful to counter the area of sound shadow.

39

5.0 ACOUSTICAL ANALYSIS

5.2

Ceiling

5.2.1

Planar Relationship between Ceiling and Floor

Ceiling

Reduce Flutter Echo The ceiling is designed with multiple planes of different angles, intentionally made non-parallel with the ground surface to prevent flutter echo. It is arrayed in a jagged arrangement that reflects incident sound in different directions.

Figure 5.3: Non-parallel ceiling and floor surface prevent flutter echo.

5.2.2

Multi-Angled Ceiling

Diffused sound The multi-angled ceiling panel created sharp edges that operate as sound diffusers. The edges that present at two discrete points along the ceiling span disperse the sound evenly throughout the auditorium.

Figure 5.4: Sound diffusion at edges of multi-angled ceiling panels.

Concentration of sound waves can be caused by concave ceiling, which should be avoided. The multi-angled ceiling formed several gentle concave shapes at Experimental Theatre.

However, the curvature is not significant enough to concentrate sound waves at certain points

Figure 5.5: Gentle concave shape observed at the ceiling of Experimental Theatre.

40

5.0 ACOUSTICAL ANALYSIS

5.2.3

Ceiling

Ceiling as sound diffuser to mezzanine floor

Sound Diffuser Ceiling panels are generally angled at smooth angles until the panel right above the front edge of the mezzanine floor. It has a relatively sharper angle of deflection facing the stage that connects both levels of ceiling at an approximate angle of 135°. With the sharp protruding edge above the mezzanine floor, it disperses the direct sound from stage onto mezzanine seatings.

135°

Figure 5.6: Sound diffusion to mezzanine floor.

Figure 5.8: Lower ceiling at mezzanine floor.

Figure 5.7: Sharp angle on ceiling.

Less Attenuation The decrease in ceiling level above mezzanine floor promotes better acoustical quality on the level. The reflected sound from ceiling will experience less attenuation before being received by the audience.

3.6m 4.2m

Figure 5.9: Lower ceiling at mezzanine floor reduces sound attenuation.

41

5.0 ACOUSTICAL ANALYSIS

5.2.4

Ceiling

Chamfered Ceiling Corner

Reflected Sound Instead of joining ceiling panels to walls perpendicularly, the edge is being chamfered to avoid sharp 90° angle. With the extended slanted ceiling panels, direct sound is only being reflected once before travelling back to ground floor. Hence, less sound energy is lost.

Figure 5.10: Lower ceiling at mezzanine floor.

Figure 5.12: Direct sound is being reflected twice

Figure 5.11: Direct sound is being reflected once

5.2.5 Ground Floor Rear Ceiling

Reduce Sound Shadow The depth of the mezzanine should be less than twice the height of the mezzanine floor from ground level beneath it. Ideally, the depth should not be more than the height, if not acoustical shadow can be created underneath.

Ratio of depth to height of the mezzanine floor is less than 1:2, hence the sound shadow effect below the mezzanine floor is minimized.

Figure 5.13: Lower ceiling at mezzanine floor.

42

5.0 ACOUSTICAL ANALYSIS

Ceiling

5.2.5 Ground Floor Rear Ceiling

Reduce Sound Shadow The depth of the mezzanine should be less than twice the height of the mezzanine floor from ground level beneath it. Ideally, the depth should not be more than the height, if not acoustical shadow can be created underneath.

4.2m

Ratio of depth to height of the mezzanine floor is less than 1:2, hence the sound shadow effect below the mezzanine floor is minimized.

2.3m

Ratio of depth to height = 1 : 1.83 Figure 5.14: Section indicating height and depth of mezzanine floor.

The hard surface at the edge of the timber panel of mezzanine parapet acts as a sound diffuser to reflect sound to the front part of the sound shadow area.

Figure 5.15: Section indicating sound diffuse and reflect to sound shadow area.

Figure 5.16: Lower ceiling at mezzanine floor.

Figure 5.17: Sound shadow area under mezzanine floor.

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5.0 ACOUSTICAL ANALYSIS

5.2.6

Ceiling

Useful Ceiling Reflection and Sound Diffuser

The useful ceiling reflection is the span whereby the ceiling is used to reflect sound to the audience to for sound reinforcement. The angle of ceiling is specially designed so that the sound reflection span will cover all of the seatings.

Figure 5.18: Ceiling of Experimental Theatre.

Useful Ceiling Reflection

Sound diffuser

Figure 5.19: Section indicating useful ceiling reflection and sound diffuser.

44

5.0 ACOUSTICAL ANALYSIS

5.3

Wall

5.3.1

Timber Panel with 150mm Air Gap

Wall

The side walls of the auditorium are furnished with collections of timber panels with 150mm air gap. Each plywood panel spans 1.1 metres long and is tilted by 6° away from the surface of the wall. The panels cover up most of the surface area of the side walls, articulating the original true walls with at parallel surface.

Figure 5.20: Plan highlighting position of acoustic timber panels

Figure 5.21: Timber panels of Experimental Theatre

Figure 5.20: Top part of the acoustical timber panel is covered with deteriorated raw timber panel

Figure 5.22: Timber panels of Experimental Theatre

45

5.0 ACOUSTICAL ANALYSIS

Wall

Prevent Flutter Echo Flutter echoes are high frequency sounds that persist locally due to multiple reflections between parallel planes. This acoustical defect is common in shoebox-shaped auditorium (similar to the rear part of the Experimental Theatre) where two sets of parallel planar wall can be found in general. Parallel wall cannot be left untreated for more than 7.5 metres to minimize flutter echo.

The timber panels with 150mm air gap are practical and efficient in reducing the effect by reflecting the incidence sound from a point source into different non-parallel directions.

Timber panel with 150mm air gap

Figure 5.23: Parallel planar wall highlighted in Experimental Theatre

Sound Diffuser The acoustical timber panels are designed with sharp edges of acute angle, approximately 75°. Functioning as sound diffusers, the sharp corners are capable to scatter and spread out sound energy. They help in diffusing high frequency sound with short wavelength by breaking and dispersing reflected sound throughout the auditorium.

Figure 5.23: Parallel planar wall highlighted in Experimental Theatre

46

5.0 ACOUSTICAL ANALYSIS

5.3.2

Wall

60° Slanted Side Walls

Reduce Sound Shadow Effect With the side walls which are slanted at an angle of 60°, the angle of incidence of direct sound from stage is increased.

The reflected sound wave from side walls are concentrating to the rear area of auditorium which is meanwhile also the sound shadow area. The area below mezzanine floor is being shaded from the reflected sound wave from ceiling. The side walls have treated the effect by adjusting the angle of reflection in relation to the distance of side walls from stage, dimension of side wall and angle of the side wall.

5.3.3

Figure 5.27: Angle of incidence with slanted side wall

Curved Rear Wall

To Avoid Long Sound Delay Due to the fan shape design of the auditorium, the presence of curved rear wall would promote the occurrence of sound concentration.

Also, sound reflection from rear wall would create long sound delay to the audience at the front of auditorium. Hence, sound absorptive material s added onto the surface of the particular wall.

Figure 5.29: Curved Rear Wall

Figure 5.28: Slanted side wall

Figure 5.31: Curved Rear Wall in Experimental Theatre

47

5.0 ACOUSTICAL ANALYSIS

5.4

Railing

Railing

Concave Mezzanine Railing The front of mezzanine floor parapet should be designed to avoid reflections that could affect sound quality in the seating areas in the front of the hall at ground level. However, the hard surface of glass railing and plywood are highly reflective. The effect is further enhanced when the plan view of mezzanine floor is in a concave shape, promoting the effect of sound delay.

Figure 5.32: Curved Rear Wall

Improper Height of Glass Panel In order to maintain visual permeability from mezzanine floor to stage, glass railing is used.

However, the height of glass panels are higher than all the three seating in mezzanine floor. It barricades direct sound from stage, causing mezzanine floor to only receive reflected sound from ceiling.

Figure 5.35: Section showing direction of sound reflected from glass railing

Figure 5.33: Railing in Experimental Theatre

Figure 5.34: Railing in Experimental Theatre

48

5.0 ACOUSTICAL ANALYSIS

5.5

Seating

Seating

For better sight line as also for good listening conditions, the successive rows of seats are raised over the preceding ones with the result that the floor level rises towards the rear.

The elevation is based on the principle that each listener shall be elevated in respect to the person in front so that the listener’s head is approximately 12cm above the path of sound which would pass over the head of the person in front. However, with a staggered seating position, it is possible to reduce the separation of height to a minimum span of 8cm. In our case, the ET has a staggered arrangement with a height separation of 11cm, which falls within the acceptable range of between 8 to 12cm. Hence, direct sound will pass through the gap between the seatings.

11cm

Figure 5.38: Call-out Section showing seat-to-seat height

Alternate seating arrangement allows sound waves to travel across different rows through the gap between audiences. Hence, the acoustic experience of the audience can be improved.

Figure 5.38: Alternate seating arrangement allowing sound travel between seats

Figure 5.38: Alternate seating on ground floor

49

topic six

ACOUSTICAL TREATMENT AND COMPONENTS 6.1 Material Tabulation of Experimental Theatre 6.2 Materials of Ceiling 6.2.1 Plaster Ceiling 6.3 Materials of Walls 6.3.1 Drywalls 6.3.2 Timber Panels 6.4 Materials of Floors 6.4.1 Pile Carpeted Floor 6.5 Materials of Seatings 6.6 Materials of Sound Absorption Panels

50

6.0 ACOUSTICAL TREATMENT AND COMPONENTS

Material tabulation of Experimental Theatre

6.0

ACOUSTICAL TREATMENT AND COMPONENTS

6.1

MATERIAL TABULATION OF EXPERIMENTAL THEATRE Absorption Coefficient

Location

Component

Material

Description

Finishes 125Hz

500Hz

2000Hz

Brick

Brick wall plastered on both sides

Emulsion paint, white

0.05

0.02

0.05

Timber

H.W. timber panels (12mm plywood panels)

NIL

0.18

0.42

0.83

Concrete

Cement render

Polished

0.02

0.02

0.05

Timber

Timber parquet

Varnish

0.02

0.20

0.10

Aluminium

Aluminium grill skirting

Antique copper, gold faux texture

-

-

-

Timber

Hardwood timber parquet

Varnish

0.20

0.10

0.05

Marmoleum vinyl

Vinyl sheet covered over H.W timber on concrete floor

NIL

0.02

0.04

0.05

Velour

Velour acoustic curtain (medium fabrics)

NIL

0.05

0.40

0.60

Walls

Floors

Stage

Aprons

Stage curtain

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6.0 ACOUSTICAL TREATMENT AND COMPONENTS

6.1

Material Tabulation of Experimental Theatre

MATERIALS TABULATION OF EXPERIMENTAL THEATRE

Absorption Coefficient Location

Component

Material

Description

Finishes 125Hz

500Hz

2000Hz

Timber

12mm thickness plywood acoustic timber panel

NIL

0.18

0.42

0.83

Gypsum

2 layers of 15mm gypsum board on steel studs with 150mm air gap filled with 50mm rockwool

Emulsion paint, white

0.08

0.05

0.02

Acoustic fibreglass panels

Fibreglass (72 kg/m3) with a facing of stretched fabric

Stretched fabric

0.10

0.50

0.70

Concrete

600mm diameter round concrete column

Emulsion paint, white

0.01

0.01

0.02

Floors

Carpet

10mm thickness short pile carpet over concrete floor

NIL

0.08

0.30

0.75

Ceiling

Plaster

12mm thickness GRC plaster

Emulsion paint, white

0.20

0.18

0.15

Polyureth ane foam

Upholstered tin-up foam seating

NIL

0.33

0.64

0.77

Plastic

Molded one piece plastic component

-

-

-

Glass

1.4mm thickness glass window panel

0.30

0.10

0.05

Timber

Hardwood timber

0.18

0.10

0.08

Timber

Hardwood timber flush double door

0.14

0.06

0.10

Walls

Column

House

Seating

Control booth

Doors

52

NIL

NIL

NIL

Varnish

6.0 ACOUSTICAL TREATMENT AND COMPONENTS

Material of ceiling

6.2 Material of ceiling 6.2.1 Plaster ceiling (12mm thickness GRC plaster) Hard and smooth surface causes the reflection of sound to be more effective. Thus, the inclined flat surface of the ceiling helps directing the sound back to the seating area.

Figure 6.1:Inclined flat surface ceiling in auditorium

Figure 6.2: Inclined flat surface ceiling in auditorium

Figure 6.3: Inclined flat surface ceiling in auditorium

Figure 6.4 Inclined flat surface ceiling in auditorium

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6.0 ACOUSTICAL TREATMENT AND COMPONENTS

Material of wall

6.3 Material of walls 6.3.1 Dry Wall (2 layers of 15mm gypsum board on steel studs with 150mm air gap filled with 50mm rockwool) The wall of the auditorium is an acoustically treated wall. Consisting of 3 layers, which are gypsum board, rockwool and bricks. Rockwool is a soft material that combines both thermal and sound absorption by inducing resonance with soundwaves.

Figure 6.5: Dry wall in auditorium

Figure 6.6: Dry wall in auditorium

12mm plywood panels 110mm brick wall

15mm gypsum boards 150mm air gap with 59mm rock wool

Steel studs Figure 6.7: Sectional detail of wall with the drywall highlighted

Figure 6.8: Dry wall highlighted on ground floor

Figure 6.9: Dry wall highlighted on mezzanine floor 54

6.0 ACOUSTICAL TREATMENT AND COMPONENTS

Material of walls

6.3 Material of walls 6.3.2 Timber Panels with 150mm air gap (12mm thickness plywood acoustic timber panel) Side walls must avoid parallelism because standing waves with a highly non-uniform nodes and antinodes can be formed between such walls. This can be avoided by tilting or splaying of the wall surfaces. In the Experimental Theatre’s case, the timber panels are used to provide dispersion as it has smooth and hard surface while being angled advantageously to reflect sound to the seating area. This will prevent the chance of incident and reflected waves from interfering with each other while the absorptive characteristics also reduces flutter echo.

Figure 4.11. Timber panels in auditorium

Figure 4.11. Timber panels in auditorium

12mm plywood panels 110mm brick wall

15mm gypsum boards 150mm air gap with 59mm rock wool

Steel studs Figure 6.10: Sectional detail of wall with the timber panel highlighted

Figure 6.11: Timber panels highlighted on ground floor

Figure 6.12: Timber panels highlighted on mezzanine floor 55

6.0 ACOUSTICAL TREATMENT AND COMPONENTS

Material of floors

6.4 Material of floors 6.4.1 Pile carpeted floor 10mm thickness short pile carpet over concrete floor Concrete floor of the auditorium is covered with a layer of pile carpet as concrete is a highly reflective material. The pile carpet is used to absorb impact noise created by walking footsteps and sound of items falling. Pile carpets have high sound absorption coefficient because of the fibres, pile tufts and underlays have different resonant frequencies which absorb the sound waves.

Figure 6.13: Pile carpeted floor in auditorium

Figure 6.15: Pile carpeted floor in auditorium

Figure 6.14: Pile carpeted floor in auditorium

Figure 6.16: Pile carpeted floor in auditorium

56

Figure 6.17: Pile carpeted floor in auditorium

6.0 ACOUSTICAL TREATMENT AND COMPONENTS

Material of seating

6.5 Material of seating (Upholstered tin-up foam seating with Molded one piece plastic component) The seat is made of polyurethane foam and covered with fabric to maximize the absorption of sound. It is effective in absorbing high sounds with high frequency as compared to lower frequency sounds.

The plastic hand rest has not much effect on sound absorption and reflection, thus can be neglected. The stand holding the seat is made of steel which is a strong material in a sense of stability but when connections to the cushions are loose, it generates squeaking sounds and thus, unwanted noises.

Figure 6.18: Seating in auditorium

Figure 6.19: Seating in auditorium

Figure 6.21: Seatings highlighted on ground floor

Figure 6.20: Seating in auditorium

Figure 6.22: Seatings highlighted on mezzanine floor

57

6.0 ACOUSTICAL TREATMENT AND COMPONENTS

Material of Sound Absorption Panels

6.6 Material of Sound Absorption Panels (150mm fibreglass panel with 200mm air gap) The core construction of the sound absorption wall panels is dimensionally stable glass fiberboard laminated with a molded glass fiber, all covered with a specially formulated fiberglass mat. In the auditorium, the sound absorption panels are located at the back for both ground floor and mezzanine level. Sound absorption panels trap sound energy and prevent it from reflecting off of the surfaces they cover. The panels are used to eliminate echoes and reflections that muddle or color amplified music and speech. These wall panels will also reduce reverberation levels in a room, which can sometimes provide ambient noise reduction.

Figure 6.23: Sound absorption panels in auditorium

Figure 6.24: Sound absorption panels in auditorium

Wall

Panel

Acoustic felt 200mm air gap Isolating mineral wool

Figure 6.25: Sectional details of sound absorption panels

Figure 6.26: Sound absorption panels highlighted on ground floor 58

Figure 6.27: Sound absorption panels highlighted on mezzanine floor

topic seven

SOUND PROPAGATION ANALYSIS 7.1

Ambient Sound Analysis

59

7.0 SOUND PROPAGATION ANALYSIS

Ambient sound analysis

7.0

SOUND PROPAGATION ANALYSIS

7.1

AMBIENT SOUND ANALYSIS

Ambient sound readings were measured with only background noise. Since it is an enclosed area, all the readings should be the same. However, there are some factors causing variation in the reading taken.

Figure 7.0: Ground floor recorded sound level

Figure 7.1: Mezzanine floor recorded sound level

60

7.0 SOUND PROPAGATION ANALYSIS

7.1

Ambient sound analysis

AMBIENT SOUND ANALYSIS

Figure 7.2: Ambient Sound Data

Figure 7.3: Main vehicular path outside auditorium

Figure 7.4: Main vehicular path outside auditorium

The area recorded the highest sound level due to the presence of main vehicular path. The area induce most noise in the morning (school time) and in the evening (class dismissal time).

61

7.0 SOUND PROPAGATION ANALYSIS

7.1

Ambient sound analysis

AMBIENT SOUND ANALYSIS

Figure 7.5: Ambient Sound Data

Figure 7.6: Glass door with gap between adjacent fin walls

Figure 7.7: View of foyer

The wall between vehicular path and indoor foyer is able to cancel out 19db of noise. The thick concrete fins have higher ability in canceling out sound compared to glass doors and curtain windows whereby there are gaps between them with the adjacent attaching walls.

62

7.0 SOUND PROPAGATION ANALYSIS

7.1

Ambient sound analysis

AMBIENT SOUND ANALYSIS

Figure 7.8: Ambient Sound Data

Figure 7.9: View of corridor entering from foyer

Figure 7.10: View of corridor exiting from auditorium

The corridor has no door and is more enclosed than the one adjacent to the vehicular path hence being recorded less noise.

63

7.0 SOUND PROPAGATION ANALYSIS

7.1

Ambient sound analysis

AMBIENT SOUND ANALYSIS

Figure 7.11: Ambient Sound Data

Figure 7.12: Trees as buffer between corridor and carpark

Figure 7.13: View from carpark

The area has less noise due to the presence of softscape that absorbs sound and it is further away from main vehicular road but closer to the carpark

64

7.0 SOUND PROPAGATION ANALYSIS

7.1

Ambient sound analysis

AMBIENT SOUND ANALYSIS

Figure 7.14: Ambient Sound Data

Figure 7.15: Workers cleaning the floor

There was a worker cleaning the floor with pressure washer causing the auditorium perimeter corridor and the seating closer to front door to receive more noise.

Figure 7.16: Pressure washer as main noise source

65

7.0 SOUND PROPAGATION ANALYSIS

7.1

Ambient sound analysis

AMBIENT SOUND ANALYSIS

Figure 7.17: Ambient Sound Data

Figure 7.18: Corridor flanked which mainly flanked by solid walls or closed opening

There is no proper sound insulation to barricades the sound from the exterior environment, hence the glass door is only able to cancel out 4db of noise.

Figure 7.19: Glass door

66

7.0 SOUND PROPAGATION ANALYSIS

7.1

Ambient sound analysis

AMBIENT SOUND ANALYSIS

Figure 7.20: Ambient Sound Data

Figure 7.21: Gap between railing and stage

Figure 7.22: The span of gap

There is a gap between railing and stage, resulting intrusion of noise from basement into the auditorium.

67

7.0 SOUND PROPAGATION ANALYSIS

7.2

Sound propagation analysis

SOUND PROPAGATION ANALYSIS

In general, the position further from sound source will receive less sound due to acoustic attenuation. In addition, there are seat-to-seat variations caused by several factors.

Figure 7.23: Ground floor recorded sound level

Figure 7.24: Mezzanine floor recorded sound level

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7.0 SOUND PROPAGATION ANALYSIS

7.2

Sound propagation analysis

SOUND PROPAGATION ANALYSIS

Figure 7.25: Noise intrusion from adjacent sound control room

Figure 7.26: View of corridor exiting from auditorium

Figure 7.27: The back door in auditorium which is loosely closed

The back door on the left cannot be tightly closed, so there is more noise intrusion from the corridor.

69

7.0 SOUND PROPAGATION ANALYSIS

7.2

Sound propagation analysis

SOUND PROPAGATION ANALYSIS

Figure 7.28: Noise intrusion from adjacent sound control room

Figure 7.29: Timber panels span along both sides of wall

Due to the presence of timber panels with 150mm air gap, on average the sound recorded along the edge of the wall is higher than the middle of the auditorium.

Figure 7.30: Timber Panels with 150mm air gap

70

7.0 SOUND PROPAGATION ANALYSIS

7.2

Sound propagation analysis

SOUND PROPAGATION ANALYSIS

Figure 7.31: Noise intrusion from adjacent sound control room

Figure 7.32: Sound Control Room

There is no barrier between the sound control room on mezzanine floor, causing noise intrusion that affects experience of audience on mezzanine floor.

Figure 7.33: Adjacent office with grill door

71

7.0 SOUND PROPAGATION ANALYSIS

7.2

Sound propagation analysis

SOUND PROPAGATION ANALYSIS

Figure 7.34: Noise intrusion from adjacent vehicular path

The area on the right is closer to the main vehicular path, hence being recorded higher reading than left area on the left of the same row

72

topic eight

REVERBERATION TIME 8.0 8.1 8.2

Reverberation Time Introduction Calculation of Reverberation Time 8.2.1 Division of Floor Area 8.2.2 Volume of Experimental Theatre, V 8.2.3 Total Room Absorption, AT 8.3.4 Total Reverberation Time

73

8.0 REVERBERATION TIME

8.1

Introduction, Calculation of reverberation time

INTRODUCTION

Reverberation time is the time needed for the original sound pressure level in a room or space to decay by 60 dB after the sound source is abruptly ended. It’s a measure of time required for the sound to “fade away” or decay in an enclosed space. Sound in a room will repeatedly bounce off surfaces such as the floor, walls, ceiling, windows or tables and being absorbed.

Reverberation time (RT) is affected by following variables: ● ● ●

Volume of the enclosure (distance) The total surface area The absorption coefficient of the surfaces

To calculate the RT of Experimental Theatre, Sabine Formula is used.

RT = Reverberation time (sec) V = Volume of the room (m³) AT = Total absorption of room surface (m² sabins)

8.2

CALCULATION OF REVERBERATION TIME

8.2.1 DIVISION OF FLOOR AREA

Figure 4.1: Plan showing division of floor area for calculation.

Figure 4.2: Section showing division of floor area for calculation.

74

8.0 REVERBERATION TIME

Volume of Experimental Theatre, Total room absorption, AT

8.2.2 VOLUME OF EXPERIMENTAL THEATRE, V

Divisions

Wall Area, A

Floor Width, W

Volume = A x W

A

74.7 m²

27.5 m

2054.3 m³

B

24.1 m²

24.0 m

578.4 m³

C

29.8 m²

16.6 m

494.7 m³

D

131.6 m²

27.5 m

3619.0 m³

Total Volume of Experimental Theatre

6746.4 m³

8.2.3 TOTAL ROOM ABSORPTION, AT Total Room Absorption is calculated by the addition of the absorptions provided by each surface in Experimental Theatre. The surfaces are divided into 3 types, floor materials (A1), wall materials (A2), and others (A3).

Sound absorption coefficient of materials varies at different frequency. For this case study, 500 Hz is taken as the standard of measurement, as most musical performances are found to be under this category of frequency. This is true for the Experimental Theatre which functions as a performing art space.

75

8.0 REVERBERATION TIME

Absorption of Floor Surfaces, A1

8.2.3.1 Absorption of Floor Surfaces, A1

A

B C Figure 4.3: Floor materials on ground floor.

A

Figure 4.4: Floor materials on first floor.

Component

Material

Surface Area, S

Absorption Coefficient, ∝

Absorption of Surface, A

A

Carpet flooring

674.9 m²

0.30

202.5 m² sabins

B

Marmoleum vinyl sheet over hardwood timber flooring on concrete

251.3 m²

0.04

10.1 m² sabins

C

Hardwood timber parquet on concrete

197.0 m²

0.07

13.8 m² sabins

Total Absorption of Floor Surfaces, A1 ( Source of Absorption Coefficient: AcousticTraffic )

76

226.4 m² sabins

8.0 REVERBERATION TIME

Absorption of wall surfaces, A2

8.2.3.2 Absorption of Wall Surfaces, A2

c

A

Figure 4.5: Wall materials on the side wall of Experimental Theatre.

B

Figure 4.6: Wall materials on back wall of Experimental Theatre.

Component

Material

Surface Area, S

Absorption Coefficient, ∝

Absorption of Surface, A

A

Acoustic timber wall panel

104.7 m²

0.42

44.0 m² sabins

B

Acoustic fibreglass panel

42.0 m²

0.50

21.0 m² sabins

C

Drywall with 100mm cavity

22.3 m²

0.05

1.1 m² sabins

Total Absorption of Wall Surfaces, A2 ( Source of Absorption Coefficient: AcousticTraffic )

77

66.1 m² sabins

8.0 REVERBERATION TIME

Absorption of other surfaces, A3

8.2.3.3 Absorption of Other Surfaces, A3

Figure 4.7. Plaster ceiling

Figure 4.8. Timber door

Figure 4.9. Curtain with dedium fabric

Figure 4.10. Glass window at sound control room

Figure 4.11: Unoccupied polyurethane auditorium seats

Figure 4.12: Glass railing on mezzanine oor

Figure 4.11. Other materials labelled on section.

Figure 4.13: Painted concrete column under mezzanine oor 78

8.0 REVERBERATION TIME

Total room absorption, AT

Component

Material

Surface Area, S

Absorption Coefficient, ∝

Absorption of Surface, A

A

Plaster ceiling

563.8 m²

0.18

101.5 m² sabins

B

Timber doors

10.3 m²

0.06

0.6 m² sabins

C

Curtains (dedium fabrics)

372.9 m²

0.40

149.2 m² sabins

D

Glass windows

9.0

0.04

0.4 m² sabins

E

Polyurethane auditorium seats (unoccupied)

208.8

0.64

133.6 m² sabins

F

Glass railing

21.9

0.04

0.9 m² sabins

G

Painted concrete columns

3.6

0.01

0.04 m² sabins

Total Absorption of Other Surfaces, A3 ( Source of Absorption Coefficient: Acoustic Traffic )

8.2.3.4 Total Room Absorption, AT AT = A1 + A2 + A3 = 226.4 m² sabins + 66.1 m² sabins + 386.2 m² sabins = 678.7 m² sabins

79

386.2 m² sabins

8.0 REVERBERATION TIME

Total reverberation time, Conclusion

8.2.4 Total Reverberation Time Using Sabine Formula: V = 6746.4 m³ AT = 678.7 m² sabins

0.16 (6746.4) RT =

678.7

= 1.59 s

E.T.

R.B. Newman, "Acoustics" in J.H. Callender (ed.), Time-Saver Standards for Architectural Design Data, McGraw-Hill, New York, 1974, p. 696

Conclusion: Reverberation time of this Experimental Theatre is 1.59 seconds which falls under the mid range of multi purpose hall. This theatre can cater for general purposes such as speech and music.

According to the reading obtained, it might occur some loss of articulation during the delivery of speech. However, it can perform well for musical performance, but not for concert hall.

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topic nine

CONCLUSION 9.0 Conclusion

81

9.0 CONCLUSION

9.0

Conclusion

CONCLUSION

Figure 9.0: Soundproof Glass Door

Figure 9.1: Convoluted Acoustic Foam Panel

Soundproof glass door should be used to cancel out noise from surrounding context.

Convoluted acoustic foam panels should be applied to cover up the gap between the front stage and railing to inhibit sound intrusion from basement.

Figure 9.2: Lower Glass Railing

Figure 9.3: Ceiling with curvature

Either the glass railing should be adjusted lower or the seatings on mezzanine oor should be elevated higher to receive more direct sound from stage while maintaining visual permeability.

Ceiling should be plastered to create curvature on the ceiling to allow sound to bounce back to musician and for smoother sound diusion and

82

topic ten

REFERENCES 10.0 Reference List

83

10.0 REFERENCES

References

Reference List ASA Lay Language Papers 167th Acoustical Society of America Meeting. (n.d.). Retrieved 2019, from https://acoustics.org/pressroom/httpdocs/167th/2pAAa7_Kocyigit.html.

Comparitive Examples of Noise Levels. (n.d.). Retrieved 2019, from https://www.industrialnoisecontrol.com/comparative-noise-examples.htm.

Published Articles. (n.d.). Retrieved 2019, from http://www.acousticsciences.com/media/articles/auditorium-acoustics-101-quieter-better.

Norvasuo, M. (n.d.). The amphitheatre and fan shaped forms: Acoustic forms in Aalto's auditorium designs.

Retrieved 2019, from https://www.academia.edu/5469220/The_amphitheatre_and_fan_shaped_forms_Acoustic_forms_in_Aaltos _auditorium_designs.

Bradley, J. S. (1987, May 1). Comparison of a fan‐shaped and a rectangular hall. Retrieved 2019, from https://asa.scitation.org/doi/abs/10.1121/1.2024101. http://theatreprojects.com/files/pdf/Resources_IdeasInfo_typesandformsoftheatre.pdf Carpet effective, presents sound-absorption solution. (n.d.). Retrieved 2019, from http://m.engineeringnews.co.za/article/carpet-effective-presents-sound-absorption-solution-2015-07-17/re p_id:4433.

What are the advantages and disadvantages of sound systems? (n.d.). Retrieved 2019, from https://www.quora.com/What-are-the-advantages-and-disadvantages-of-sound-systems.

Full-Range. (n.d.). Retrieved 2019, from https://www.astralsound.com/full-range.htm.

Advantages of a Public Address System. (2019, March 14). Retrieved 2019, from https://cescomplete.com/2017/11/20/advantages-public-address-system/.

Mellor, D. (n.d.). Retrieved 2019, from https://www.soundonsound.com/techniques/stage-monitoring-monitor-mixing.

Vaijayanthi, & Davis, S. K. (2017, April 5). Point Source, Line Arrays or Column Speakers: What's Best for Your Church? –. Retrieved 2019, from https://pro.harman.com/insights/enterprise/hospitality/house-of-worship/point-source-line-arrays-or-colum n-speakers-whats-best-for-your-church/.

Staff, E. H. (2014, June 21). The Importance of Subwoofers in Your Home Audio System. Retrieved 2019, from https://www.electronichouse.com/home-audio/the-importance-of-subwoofers-in-your-home-audio-system /.

Carpet effective, presents sound-absorption solution. (n.d.). Retrieved 2019, from http://m.engineeringnews.co.za/article/carpet-effective-presents-sound-absorption-solution-2015-07-17/re p_id:4433.

Sound Insulation. (n.d.). Retrieved 2019, from https://www.sciencedirect.com/topics/engineering/sound-insulation.

Julita. (2016, June 8). Difference Between. Retrieved from http://www.differencebetween.net/language/words-language/difference-between-sound-and-noise/.

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