Connexion Conference & Event Centre
Auditorium Building Science II (BLD 61003)
Tutor: Mr. Azim Sulaiman Group Members: 1. Charlotte Chin Ya-Le 2. Nurul Rihana 3. Natalie Chen KheMin 4. Lin Shan En 5. Peh Ellyn 6. Sak Kar Wai 7. Neo On E 8. Ho Yen Liang 9. Ahmad Nabil bin Jimi
0326940 0326468 0327110 0331085 0326812 0326525 0326727 0326660 0327780
Acknowledgement Our group would like to express our gratitude to the individuals who actively assisted the group on ďŹ nishing this project of Building Science II (BLD60803). All effort and assistance given is highly appreciated. This project would not have been successful without the cooperation, understanding and communication of the group. The respected individuals are as follow: First and foremost, UOA Group, UOA Development Bhd that manages and built Connexion Conference & Event Centre (CCEC) for allowing us to conduct our architectural research on the prestigious auditorium. The approval and guided tour of our site visit is much appreciated. The HR Manager of CCEC, Ms. Aida Azmi, Mr. Harriz Kamal, and Ms. Ani Fauzani, the staffs of CCEC, have given us guidance and help on understanding the auditorium in detail. Apart from that, we would like to extend our gratitude to our tutor, Mr. Azim Sulaiman who educated us, giving us guidance throughout this assignment. Last but not least, the people who made this documentation successful, our group members who poured in effort and hardwork.
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Content 1.
Introduction / 4 1.1 Introduction of CCEC / 5 1.2 Historical Background / 6
2.
Methodology / 7 2.1 Measuring & Recording Equipments / 8 2.2 Data Collection and Documentation Method / 9
3.
Auditorium Design and Acoustics Analysis / 10 3.1 Auditorium Design / 11 3.1.1 Form and Layout 3.1.2 Materials and Finishing 3.2 Sound Propagation / 26 3.2.1 Sound Concentration 3.2.2 Sound Reection 3.2.3 Sound Delay & Echo 3.2.4 Flutter Echo 3.3 Sound Reinforcement / 35 3.3.1 Full-range speakers and Power AmpliďŹ ers 3.3.2 Two Way Ceiling Speakers 3.4 Noise Intrusion / 38 3.4.1 Noise Source 3.4.2 Background Noise 3.4.3 Noise Control 3.5 Reverberation Time / 48 3.5.1 Tabulation of Materials and Absorption Units 3.5.2 Calculation of Reverberation Time
4.
Conclusion / 53
5.
References / 54
3
1.0 Introduction 1.1 Introduction to CCEC 1.2 Historical Background
4
1.1 Introduction to CCEC
Figure 1.1: Overall view of auditorium
Connexion Nexus Auditorium Connexion Nexus or as it is now renamed, Connexion Conference & Event Centre (CCEC) is firmly making a name for themselves among the event scene in the Klang Valley. Their ballrooms and meeting rooms are popular because of the flexibility of their space. They have a state of the art Auditorium that comes with a top class AV system and a three tier seating arrangement Event type : Annual General Meeting (AGM), Business Presentation, Concert, Conference, Convention, Press Conference, Product Launch, Product Talk, Seminar, Training Session
Basic information Name of Auditorium Location
: Connexion@Nexus Auditorium : 7, Jalan Kerinchi, Bangsar South City, 59200 Kuala Lumpur, Malaysia
Type of Auditorium Year of Construction
: Multi-purpose Auditorium : 2012
Total volume
: 2014 3 : 2265.14 m
Total seats
: 298 fixed seats
Year of Completion
5
1.2 Historical Background
The idea behind the development of Connexion@Nexus was to provide an opportunity for the community to come together in a strategically nestled location between Bangsar, Kuala Lumpur city centre and Petaling Jaya for all kinds of activities including business, social and leisure. An entire floor within Connexion@Nexus (located at Level 3A) is dedicated to function rooms, ballrooms, a gazebo, as well an auditorium , which became the choice of our case study. Serving as multi-purpose auditorium, a variety of events are held here, including Annual General Meeting (AGM), business presentations, concerts, movie screenings, conferences, conventions, press conferences, product launches, product talks, seminars and training sessions.
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2.0 Methodology 2.1 Measuring and Recording Equipments 2.2 Data Collection and Documentation Method
7
2.1 Measuring and Recording Equipments
1.
Figure 2.1: Laser Measuring Device
The laser measuring tool helps in certain situation to obtain measurements that could not be acquired easily by normal measuring methods. The tool is mostly used during site visit to measure ceiling heights and elements that are of unreachable height. This measuring tool can measure up to a maximum of 80 metres. It is also easy to handle, lightweight and has high precision. 2.
Figure 2.2: Pocket measuring tape
Sound Level Meter
A sound level meter is a measuring instrument used to assess noise and the decibel (dB) of sound by measuring sound pressure. The sound level meter is used to measure the sound intensity at various locations in the auditorium to determine the sound concentration and background noise level 4.
Figure 2.4: Sample of smartphone
Pocket measuring tape
Measuring tapes of 7.5 metres is used as the primary measuring tool during the site visit to the auditorium. Measuring tape can be used and brought around easily. This tool gives relatively accurate measurements in centimetres. Primarily used to measure distance that are accessible.
3.
Figure 2.3: Sound Level Meter
Bosch GLM 100 Digital Laser Measuring Device
Smartphone for video playing providing a constant tune
Recordings from sound level meter requires a constant tune to have a constant variable in our ďŹ ndings when measuring the sound concentration in different points and angles of the auditorium. The constant tune is played for 30 seconds at 432 Hertz at each interval during the measurement.
5. Butter paper with oor plans and other paper materials Butter papers and A4 paper materials are used to record down the measurements through sketches and annotations on diagrams or plans. Figure 2.5: Butter paper with oor plans
8
2.2 Data Collection and Documentation Method
Photographs Photos are documented for visual references and representation without encountering the actual object. They are easy to ďŹ le and also used for further analysis of acoustic materials and as illustrations. Figure 2.6: Photographs
Annotated diagrams Annotated diagrams should be recorded with clear indications for better understanding. Recording data verbally and diagrammatically requires only a pen and a paper. Figure 2.7: Annotated Diagrams
Drawings or sketches Sketches are produced during our site visit to understand the interior of the auditorium. Different colour of pens are also used to differentiate the lines that are drawn on papers. The interplay of different line weights are distinguished to communicate depth, proximity and importance. Figure 2.8: Drawings or sketches
Online research Online source is considered the primary source for researching of contents. The research process includes ďŹ nding documentation that are accurately cited, and analysis of the auditorium in order to come up with contents that are well explained and described. Figure 2.9: Online research
Book research Books and journals are borrowed from the Taylor’s University Library in order to understand the architectural analysis of the auditorium in terms of acoustics. Figure 2.10: Book research
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3.0 Auditorium Design & Acoustic Analysis 3.1 Auditorium Design 3.2 Sound Propagation 3.3 Sound Reinforcement 3.4 Noise Intrusion 3.5 Reverberation Time
10
3.1 Auditorium Design 3.1.1 Form & Layout Auditorium Drawings
Diagram 3.1 : Auditorium plan (n.t.s)
Diagram 3.2 : Auditorium section (n.t.s)
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3.1 Auditorium Design 3.1.1 Form & Layout Volume obtained from digital model: 2265.14 m3
Diagram 3.3: Axonometric of auditorium
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3.1 Auditorium Design & Drawings 3.1.1 Form & Layout Shape & Massing
Diagram 3.4: Expected sound path from plan
The auditorium has an overall curvilinear shape with concave walls lining the left and right of the space. This conďŹ guration hints to a poor acoustical design as concave shape tends to concentrate the reected sound to the centre of auditorium, leading to an uneven distribution of sound intensity in the auditorium.
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3.1 Auditorium Design & Drawings 3.1.1 Form & Layout Levelling of Stage The levelling of the seating arrangements is important as it affects the sound intensity distributed throughout the auditorium.
Diagram 3.5 : Ground Level Seat arrangement have a lower sound intensity level as the distance between the source and the receiver increases
Diagram 3.6 : Elevated sound source arrangement allows the sound to be projected further and more uniformly throughout the space
Connexion Conference & Event Center Auditorium
Diagram 3.7 : Elevated audience seatings conďŹ guration
The seating arrangements in Connexion Conference and Event Center Auditorium implemented the most effective conďŹ guration among the three stated here. Elevating the audience seatings allows the sound to be distributed more evenly as it is uninterrupted by any objects that might absorb or reect the sound.
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3.1 Auditorium Design & Drawings 3.1.1 Form & Layout Seating Arrangement
Diagram 3.8: Seating arrangement of Auditorium
The seating arrangement of Connexion Conference and Event Center is fanned out in order to ensure a maximum number of seat ďŹ tted into the space and also to obtain an optimum view of the stage from every seat. Moreover, the seating arrangements are able to achieve an effective and high quality acoustics throughout the space. The angle of the configuration highly affects the quality of the sound as sound waves travel in a spherical order. It has been noted that the auditorium is spanned out at an 140° which ensures all the seats to be in the sound coverage from the stage.
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3.1 Auditorium Design & Drawings 3.1.1 Form & Layout Layout
Diagram 3.9 : House
Diagram 3.10 : Stage
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3.1 Auditorium Design & Drawings 3.1.2 Materials & Finishing Tabulation of House Materials and Absorption Units
Table 3.1: Tabulation of Hall Materials
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3.1 Auditorium Design & Drawings 3.1.2 Materials & Finishing Tabulation of Stage Materials and Absorption Units
0.75
0.08
Table 3.2 : Tabulation of Stage Materials
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3.1 Auditorium Design & Drawings 3.1.2 Materials & Finishing House Material Board Sound Absorbent Materials
Thin Carpet
Medium Pile Carpet
Upholstery Fabric
Heavy Velour Curtain
Sound Absorbent & Sound Reflective Material
Acoustic Fabric Sound Reflective Materials
Gypsum Plasterboard Ceiling
Timber Veneer
Tinted Glass
Steel Railings
Figure 3.1 : House Materials
Stage Material Board Sound Absorbent Materials
Heavy Velour Curtain
Acoustic Fabric
Sound Reflective Materials
Timber Parquet Flooring Figure 3.2 : Stage Materials
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3.1 Auditorium Design Acoustical Treatment Materials Analysis Wall
Figure 3.3: Acoustic Panels on the Concave Walls
Acoustic Panel
Diagram 3.11: Location Indication of Acoustic Panels
The auditorium is built with a concave shaped wall, as a result sound travel towards concave surfaces will naturally concentrate to the center of its projection, which is the audiences’ seating area. To reduce the sound concentration on the center, 25mm acoustic panels are applied on both sides of the concave surface, and also on the rear flat walls of the auditorium.
The outer fabric layer of the acoustic panels are functioned to allow reflection of high frequency sound and in between the fabric, there is a 25mm air gap to absorb low frequency sound and reduce sound reverberation. The air in the cells provide resistance to the sound waves which then loses energy in the form of heat. When the sound propagates through the seating area, the acoustic panels on the rear wall helps to absorb the sound and avoid sound reflection which causes echo.
Sound Reflection Sound Dissipation
Diagram 3.12: Wall Section of House
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3.1 Auditorium Design Acoustical Treatment Materials Analysis Floor
Figure 3.4: Medium Pile Carpet Flooring
Medium Pile Carpet
Diagram 3.13 : Location Indication of Medium Pile Carpets
The flooring used for the house of the auditorium is covered with medium pile carpets. The carpeted floor is used to reduce impact sound, caused by the sound of footsteps, slammed door or if someone drops something on the floor during a speech. Carpet flooring is highly effective in noise control by absorbing airborne sound, reducing surface noise generation and reducing impact-sound transmission to room spaces below.
Diagram 3.14 : Floor Section Details of the House
The carpet has an additional underlay, which is a rubber layer, offering further sound resistance to the absorption carried out by the surface carpet. Both combinations help reduce the airborne noise more effectively, sound absorption will be lower if the carpet backing is too impermeable.
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3.1 Auditorium Design Acoustical Treatment Materials Analysis Floor
Figure 3.5: Timber Parquet Tiles on Stage Surface
Stage (Timber Parquet)
Diagram 3.15: Location Indication of Stage Flooring
The stage of the auditorium is covered with timber parquet tiles on a concrete slab, whereas under the slab is air cavity. When sound energy is transmitted through the floor surface, sound reflection occurs between both hard surfaces of the concrete slab and the timber parquet tiles. Sound energy is absorbed and loss as it reflects multiple times in between the hard objects. Some of the sound energy is also transmitted through the concrete slab and trapped in the air cavity below.
Diagram 3.16 : Sectional Details of Stage Flooring
Sound Dissipation
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3.1 Auditorium Design Acoustical Treatment Materials Analysis Floor
Figure 3.6: Thin Carpet on the Concavs
Thin Felt Carpet over Concrete Floor
Diagram 3.17: Location Indication of Acoustic Panels
Thin felt carpet is used on the flooring of the control room. Although thin carpet does not reduce impact sound as strong as the medium pile carpet, sound energy wouldn’t escape from the control room into the house of the auditorium as the STC value of both combination of glass and wall is high.
Seating
Figure 3.7: Upholstered Tip-Up Seatings
Upholstered Tip-Up Seatings
Diagram 3.18 : Location Indication of Seatings
The upholstered material applied on the seatings offer additional sound insulation and to maintain and control the acoustical quality of the auditorium. It helps maintain a similar acoustic quality whether the capacity of the hall is partially or fully filled.
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3.1 Auditorium Design Acoustical Treatment Materials Analysis Curtain
Figure 3.8: Heavyweight Velour Curtains on stage
Heavyweight Velour
Diagram 3.19: Location Indication of Curtains
The Velour curtains hung on the stage, are essentially sound absorbers used for control of reverberation or unwanted echo on stage. The highly porous material act as thousands of tiny sound traps, attenuating the chatter noise from the audience in the room. The pleated shape of the curtain, will cause the fabric to be “gathered,” such that it loops in and out (i.e. does not lay flat). The pleating is able to expose more sound-absorbing surface, thus increasing effective surface area and improving low frequency sound attenuation.
Diagram 3.20 : Location Indication of Acoustic Panels
Diagram 3.21 : Pleated Shape of Curtain act as Sound Trap
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3.1 Auditorium Design Acoustical Treatment Materials Analysis Ceiling
Figure 3.9: Gypsum Plasterboard Staggered Ceiling
Gypsum Plaster Ceiling
Gypsum plaster board ceiling is composed of materials with high stiffness and hard surface. This contributes to its low sound absorption coeďŹƒcient, making it a good sound reector. Its lightweight characteristics makes it a favourable choice of material commonly used in lecture halls and auditoriums.
Diagram 3.22: Location Indication of Gypsum Plasterboard Ceiling
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3.2 Sound propagation 3.2.1 Sound Concentration Form & Shape of Auditorium: The Concave Shape Hall
46.1
46.2
41.55
47.3
38.2
44.7
48.45
35.85
45.65
52.75
53.75
46.6
Diagram 3.23 : Low SIL measurement in the centre of auditorium
Although concave walls have the tendency to converge sound to the centre of the auditorium, which will create a distinct sound concentration zone in the middle, this is not found in Connexion Conference & Event Centre Auditorium due to the acoustic panel lining the concave walls acting as a low frequency absorber. It is evident that steps have been taken to reduce the impact of sound concentrated area. Referring the measurement of Sound Intensity Level (SIL) from the sound source (stage), the sound intensity level in the middle of the auditorium is found the lowest compared to other spots. This is because the acoustic panel is a high frequency reflector at the same time. Thus the sound intensity is higher at the side of the auditorium immediately off the reflective surface. Towards the center the intensity of reflected sound decrease.
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3.2 Sound propagation 3.2.1 Sound Concentration Form & Shape of Auditorium: The Concave Shape Hall
Diagram 3.24 : Concave walls tend to converge reected sound to the centre of auditorium (without acoustical treatment)
Diagram 3.25: Concave walls lined with low frequency sound absorber (acoustic panel) to reduce impact of sound concentrated area (with acoustical treatment)
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3.2 Sound propagation 3.2.1 Sound Concentration Form & Shape of Auditorium: The Concave Shape Hall
Diagram 3.26 : Acoustic panels which are also high frequency sound reflector reflects sound thus the SIL measurements at the side of the auditorium is higher
Diagram 3.27: Towards the center the intensity of reflected sound decrease, thus lowest SIL measurement at the center of auditorium
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3.2 Sound propagation 3.2.1 Sound Concentration Distance & Sound Attenuation
46.1
46.2
41.55
47.3
38.2
44.7
48.45
35.85
45.65
52.75
53.75
46.6
Diagram 3.28 : Decrease of SIL level towards the end of auditorium
We observed decrease of SIL level towards the end of the auditorium. However the sound attenuation is not signiďŹ cant as this is an enclosed space. An anomaly is observed at the back of the auditorium due to reection of sound by smooth & hard material which will be further elaborated in 3.3.2.
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3.2 Sound propagation 3.2.2 Sound Reflection Effective Ceiling Reflection
C
Direct Sound
B
Sound Reflection
A Diagram 3.29 : Longitudinal section showing the the sound reflection of the auditorium affected by the ceiling design
As shown above, the tilting of auditorium ceiling reflects sound effectively back to the audience to respond to sound attenuation towards the back of auditorium.
46.2
C
41.55
47.3
38.2
B
44.7
48.45
35.85
A
45.65
46.1
52.75
53.75
SIL measurement higher than position A due to effective ceiling reflection
46.6
Diagram 3.30 : SIL measurement showing how staggering of ceiling succeeded in reflecting sound to position B and position C
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3.2 Sound propagation 3.2.2 Sound Reflection Wall Reflection at the Back
C
Direct Sound
B
Sound Reflection
A Diagram 3.31 : Longitudinal section showing the the sound reflection of the auditorium aided by wall at the back of auditorium
Due to the timber panels framing the control room at the center back of the auditorium and the glass panel , it is noticeable that the seatings in front of the control room have a higher sound intensity level compared to the sides due to the sound reflected by the timber panel.
46.2
C
41.55
47.3
38.2
B
44.7
48.45
35.85
A
45.65
46.1
52.75
53.75
SIL measurement higher than position B due to effective wall reflection
46.6
Diagram 3.32 : SIL measurement showing how reflective material at the back of the auditorium reflects sound to position C
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3.2 Sound propagation 3.2.3 Sound Delay & Echo
An echo is distinctly different from a reverberation as it is a constant repetition of the original sound. The nature of the programme influences the desired sound delay period, and thus, the definition of its echo. Generally, in an auditorium designed for speeches, any sound delay above 40 m/s will be considered as an echo, while an auditorium designed for music will consider any sound delay above 100 m/s as an echo. In this analysis, only reflective surfaces will be treated as sources of sound delay.
D = Direct sound R = Reflected sound
R2
R1
D
Diagram 3.33 : Direct and reflected sound from sound source to Position 1
Sound delay at Position 1: 6.28 + 6.51 - 6.30 0.34
= 19.09 m/s
Time delay of 19.09 m/s is acceptable for a speech-oriented auditorium.
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3.2 Sound propagation 3.2.3 Sound Delay & Echo
R2 R1
D
Diagram 3.34: Direct and reflected sound from sound source to Position 2
Sound delay at Position 2: 7.98 + 6.94 - 11.90 0.34
= 8.88 m/s
Time delay of 8.88 m/s is low, showing direct sound is reinforced by the reflected sound.
R2 R1
D
Diagram 3.35 : Direct and reflected sound from sound source to Position 3
Sound delay at Position 3: 12.28 + 6.33 - 17.28 = 3.91 m/s 0.34 Time delay of 3.91 m/s towards the back of auditorium. Time delay is lowest when the distance of direct sound from sound source to sound recipient is furthest. In conclusion, Connexion Conference & Event Centre Auditorium does not suffer from echo as the sound delay is always under 40 m/s.
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3.2 Sound Propagation 3.2.4 Flutter Echo Parallel walls at the front of the stage Parallel walls only at both side of the stage, which results to flutter echo only present on the front portion of the stage.
Figure 3.10: Parallel walls indicated in front of the stage
Diagram 3.36: Plan showing parallel walls that causes flutter echo and only occur at the frontage of the stage
Non-parallel alignment of ceiling compared to floor The alignment of ceiling compared with the floor are non-parallel, which prevents flutter echo. The uneven alignment of ceilings break up flutter echoes by reflecting the sound waves in different directions and angles so that the repetitive reflections are eliminated.
Diagram 3.37: Non-parallel alignment of ceiling compared to floor
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3.3 Sound Reinforcement The sound reinforcement system in the auditorium consist of main speakers and smaller speakers on the ceilings to deliver and amplify the sound from the performers to the audience by providing a better clarity using loudspeaker system. Speakers should be efficient, able to handle high power, have a flat frequency and should have minimum distortion. Loudspeaker system helps to: ● Minimize sound reverberation time ● Provide amplified sound to the audience across the auditorium ● Control tone and frequency of speakers
Diagram 3.38: Common loudspeaker driver types and audio frequencies they reproduce
Diagram 3.39 : Position of full-range speakers and amplifier
Diagram 3.40: Position of ceiling speakers
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3.3 Sound Reinforcement
Figure 3.11 : Position of speakers in Auditorium
Diagram 3.41: Sound reinforcement systems around the auditorium
3.3.1 Two Way Ceiling Speakers
Figure 3.12 : Two Way Ceiling Speakers
There are total of 12 ceiling speakers located throughout the ceiling of the auditorium. The speakers are enclosures that incorporate just a woofer and a tweeter are referred to as a Two-Way Speaker. It functions for both events and emergency announcement purposes.
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3.3 Sound Reinforcement 3.3.2 Full-range speakers and Power Amplifiers
Figure 3.13 : Power amplifiers of HK E 435 A Figure 3.14 : Full- range speakers of HK EA600
There are 4 full-range speakers located both at the sides and at the top of the stage. These are the speakers that deliver most of the sound to the audience or listeners. The speakers are located at the top center of the stage, to achieve a consistent wide coverage to project sound across the listeners in the auditorium. The concave shape of the stage also allowed the speakers to adjust the two side speakers inward so they're pointed towards the listener more specifically, at a point directly behind the listener's head. A power amplifier is any device that uses a small amount of energy and converts it to a larger amount of energy, which is barely noticeable. The amplifier added at the top of the auditorium just to handle musical peaks with greater ease and less strain, which results in better overall sound clarity.
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3.4
Noise
In an auditorium , noise is an unwanted and undesirable sound. It can impact the quality of a performance or an event with disruption and unpleasantness to the hearing experience High-frequency noises low-frequency noises.
are
also
more
disturbing
than
Hence as a rule , the noises of mechanical/electrical such as fan, motor and pump, are more disturbing than noises of natural origin such as wind ,rain and waterfall. 3.4.1 Noise source
Sound Source
Sound Path
Sound Receiver
Figure 3.15: Path of sound transmission
The analysis of noise for noise control segregated into a relationship of source and receiver , connected by a path.
Sound sources can be divided into three categories :1.User activity 2.Operation of building’s mechanical & electrical services 3.Environmental sounds from outside of building
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3.4
Noise
3.4.1 Noise source Internal noise: User activity The interior noise is generated through the impact of the physical contact with a surface. The noise sources that can be identiďŹ ed in the auditorium are the squeaking sound of the auditorium chairs, timber staircase leading to the stage and the sound of the door slammer when someone enters or exits the auditorium. Even though the noise generated is low, but these noticeable sounds might cause general annoyance or interruption during a performance.
Figure 3.16: Door slam stopper
Figure 3.17: Timber staircase
Figure 3.18: Auditorium chairs
Door slam stopper Timber staircase Auditorium chairs
Diagram 3.42: Source of interior impact noise
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3.4
Noise
3.4.1 Noise source Internal noise: Operation of building’s mechanical & electrical services Sound from speaker installed on the ceiling is constantly emitting static noises when it is turned on . Air conditioning between the ceiling alcove and a few ventilation ducts can be heard when the auditorium is quiet. These are airborne transmitted sound - sound energy that transmit along continuous air paths which form the background noise in the auditorium. Background noise will further be discussed under 3.4.2.
Diagram 3.43 : Noise source from speakers, ventilation ducts & air conditioning
Figure 3.19 Air-conditioning
Figure 3.20 : Ceiling with ventilation ducts & speakers
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3.4
Noise
3.4.1 Noise source External noise: Environmental sounds from outside of building Vehicular noises The location of the auditorium is located next to the drop off of the building and also faces the the main road. The vehicles passing by the road causes transportation noise that can be heard in the corridor outside the auditorium.
Figure 3.21 : Auditorium facing the main road
Figure 3.22: Corridor outside auditorium
Human noises People can be heard talking outside at the waiting area/reception area.
Diagram 3.44 : Human noise source outside the auditorium
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3.4
Noise
3.4.2 Background noise Quality acoustical characteristics are important in auditorium spaces to allow performances or presentations during an even to be heard clearly without any interference of noise. For presentation and performance spaces in general, recommended noise criteria (NC) rating ranges from NC - 20 to NC - 30 and recommended sound transmission class (STC) rating ranges from STC 40 - STC 50.
Table 3.3: Recommended NC ranges for indoor activity area (mbrdesigngroup, 2013)
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3.4
Noise
3.4.2 Background noise Background noise is estimated to be at the level of 33.4 dB due to the noise sources. The auditorium, which has the octave band of 432 Hz, has a noise criteria range of NC 25, which matches the recommended noise criteria of an auditorium.
Table 3.4; Table 3.5: Background noise reading at 33.4 dB, has a Noise Criteria of NC 25 (falls between 20-30), which is desirable for good listening condition
This NC value contributes to good listening condition, due to eďŹƒcient noise control: 1. sound absorption for interior noise 2. sound lock and sound insulation for exterior noise
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3.4
Noise
3.4.3 Noise Control Sound Absorption - Internal Noise
Medium Pile Carpet Acoustic Fabric Upholstery Fabric Velour Curtain and Acoustic Fabric
Diagram 3.45 : Location of sound absorption material
Figure 3.23 : Medium Pile Carpet
Figure 3.26: Acoustic Fabrics
Figure 3.24: Acoustic Fabric
Figure 3.25: Upholstery Fabric
Figure 3.27: Heavy Velour Curtains
The whole auditorium is covered with soft, uneven materials which are used to reduce interior noise by using the principle of sound absorption, making the auditorium distraction free during a performance or an event. Heavy velour curtains and acoustic fabrics can also be found around the perimeter of the stage. During an event, these curtains and fabrics are used to reduce the level of noise from the backstage and also the exterior environment by absorbing low frequency sounds. Medium pile carpet also reduce impact noise. 44
3.4
Noise
3.4.3 Noise Control Sound Lock - Exterior Noise
43.9 dB 43.9 dB
46.5 dB
52.3 dB
56.6 dB Diagram 3.46 : Sound lock area of the sides of the auditorium
A sound lock is an entranceway that has highly absorptive walls and ceilings and a carpeted floor; used to reduce transmission of noise from the area outside into an auditorium. There are two sound lock areas that can be seen from the diagram above. The first sound lock area is found at the main entrance of auditorium. This is designed to block the sound of people’s movement and interaction at the foyer and also the sound of traffic as the auditorium is located next to the main road. With the presence of this sound lock, it reduces both the transmission of structure - borne and air - borne noise that can reach the auditorium, making the auditorium a distraction free space during an event.
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3.4
Noise
3.4.3 Noise Control Sound Lock - Exterior Noise
Figure 3.28 : The sound lock area that is located at the main entrance
The second lock area is located at the side entrance of the auditorium, which consist of a curved hallway that is connected from the back of the auditorium and leads directly to the loading bay entrance, which allows user to leave during an ongoing event without disruption. The exterior sound such as construction noises and birds chirping can also be blocked from entering the auditorium.
Figure 3.29: The curved hallway that is located at the side entrance of the auditorium
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3.4
Noise
3.4.3 Noise Control Sound Insulation - Exterior Noise
200mm Concrete wall
Diagram 3.47: The sound lock area that is located at the main entrance
Table 3.6: STC Ratings of different thickness concrete wall https://www.ccanz.org.nz/page/Noise-Transmission.aspx
Table 3.7: STC reference table
The concrete wall of the auditorium which separate the exterior corridor and internal space has a thickness of 200mm, with a STC (Sound Transmission Class) of 58. With a STC exceeding 50, loud noises from vehicles and talking human cannot be transmitted into the auditorium, insulating the exterior noise. High STC rating of concrete wall blocks airborne noise from transmitting into the auditorium, when further aided with sound lock, contribute to low background noise in auditorium.
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3.5
Reverberation Time
3.5.1 Purpose of Reverberation Time Reverberation is a phenomenon where the produced sound is reflected, causing a large number of reflections to build up and then decay as the sound is absorbed by the surfaces of objects in the space. The length taken for the sound to decay, or the reverberation time, plays a vital role in determining the use of the space as it would affect the acoustical quality of the room. It is defined by the time taken, in seconds, for a sound to lose 60dB from its original sound pressure level. Generally, a hall used for musical performances such as orchestras requires a higher reverberation time so that the music would remain longer in the hall, making the performance more ‘lively’. However, for speeches and talks, the reverberation time should be shorter to maintain the intelligibility of the voice of the presenter.
Table 3.8 : Reverberation Time in Seconds
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3.5
Reverberation Time
3.5.2 Calculation of Reverberation Time Reverberation time of a room can be calculated using the formula:
RT = 0.16 V / A, where V is the volume of the space, and A is the total sound absorption by the room surfaces. From the formula, it is known that reverberation time is affected by two factors: capacity of the room and the capability of the materials used in absorbing sound. Generally, materials with lower sound absorption coefficients would reflect sound better, allowing sound to remain in the hall for a longer period of time. Whereas a hall with a higher volume would provide longer period of time for sound to echo through the space before it loses 60dB of its sound pressure level. The following page is a table of materials used in the auditorium with their respective sound absorption coefficients. These coefficients are then multiplied with their respective surface areas to obtain the absorption unit of each material in the auditorium.
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Reverberation Time
3.5.2 Calculation of Reverberation Time
Table 3.9: Calculation Reverberation Time
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Reverberation Time
3.5.2 Calculation of Reverberation Time Since reverberation time would affect audiences’ experience in an event, the following calculation of RT is done by assuming full occupation of audience in the auditorium.
RT = 0.16 V / A From the previous table, the total absorption unit of room surfaces of the auditorium, A = 7 + 85.16 + 2.81 + 167.57 + 15.84 + 26.8 + 142.38 + 132 + 0.21 = 579.77 m² sabins The volume, V of the auditorium is 2265.14m³ Therefore, RT = 0.16(2265.14) / 579.77 = 0.625s
Table 3.10 Indication of CCEC Auditorium in Reverberation Time classification table
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Discussion Despite being classified as an auditorium, the calculated RT of the hall is only 0.625s, which falls in the range of classrooms and conference rooms, suitable for speeches and talks. This is due to the abundant use of sound absorbers in a small room volume. Although acoustically ‘dead’, the hall serves as an excellent event space for talks and conferences, which justifies the design decision of the hall in relation to its location -- in the heart of Bangsar, a bustling city centre renowned for many business activities. And hence, its primary use for events like business presentation, product launch, press conference and Annual General Meetings (AGM).
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Conclusion In summary, the auditorium, or should it be called the conference room of CCEC, has achieved excellence in design with some compromises on the flexibility of its usage. The adoption of a concave form allows higher housing capacity for audience, and issues arising from the configuration such as concentration of sound at the centre, is resolved with the use of sound absorptive materials lining the curved walls. Brilliant arrangement of seats captures most of the sound as they are spread in 140 •, receiving sound which propagates in a spherical manner. Ceilings are also well tilted to effectively reflect sound from the stage to the back of the auditorium. Lost of sound pressure level towards the center of the hall is solved with the addition of speakers at the centre above the stage. The selection of materials for flooring, such as the medium pile carpet on rubber layer for the house, significantly reduces impact noise generated from footsteps and dropped objects which would interrupt an ongoing event. Whereas the use of timber parquet panels on concrete slab above air cavity for stage flooring helps double the reduction of sound energy of impact noise. Sound lock areas flanking the hall from the main entrance on the right and side entrance on the left effectively reduce sound intrusion from the exterior thanks to the soft, uneven materials that with high STCs that absorb and isolate noise. The only drawback of the hall is the excessive use of acoustic panels that line the concave wall, resulting in reduced reverberation time, thus making the hall acoustically dead, which limits its versatility as an auditorium.
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Reference
Books Appleton, I. (2008). Buildings for the performing arts. 2nd ed. Oxford: Architectural, pp.65-160. Cavanaugh, W. (2009). Architectural Acoustics: Principles and Practice, 2nd Edition. John Wiley & Sons. Hardy, H. (2006). Building type basics for performing arts facilities. Hoboken, N.J.: John wiley & Sons. Raimond, J. (1934). The coefficient of differential galactic absorption. [Groningen].
Website Acousticalsolutions.com. (2019). [online] Available at: https://acousticalsolutions.com/wp-content/uploads/2015/01/as-studio-54-acoust ic-panels-data-sheet.pdf AcousticsFREQ.com. (2019). Sound-Absorbing Drapery: Theory & Application. [online] Available at: http://acousticsfreq.com/sound-control-acoustic-curtain/ Creamer Media's Engineering News. (2019). Carpet effective, presents sound-absorption solution. [online] Available at: https://www.engineeringnews.co.za/article/carpet-effective-presents-sound-absorp tion-solution [Accessed 13 May 2019]. Homecarpetone.com. (2019). Why Carpets are Extremely Effective at Sound Absorption. [online] Available at: https://homecarpetone.com/blog/2013/12/6/Fuzz_Buzz_Flooring/Why_Carpets_ar e_Extremely_Effective_at_Sound_Absorption/ar/18/ Lifewire. (2019). When It Comes to Your Speakers, Power Has Little to Do With Volume. [online] Available at: https://www.lifewire.com/amp-power-speaker-efficiency-3135077 [Accessed 13 May 2019]. Mbr-design-group.com. (2019). [online] Available at: http://www.mbr-design-group.com/tech/notes/NC%20Table.pdf Webb, D. (2019). First reflection, Flutter echo, Comb Filtering. [online] Webblab.sk. Available at: http://webblab.sk/home-studio/8-first-reflection-flutter-echo-comb-filtering
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