BUILDING SCIENCE II PLENARY THEATRE
TUTOR: AR.EDWIN GROUP MEMBERS: Foo Shi-ko………………………………............. Wong Carol………………………………………. Rozanna farah Ibram………………………….... Winnie Ang Wei Yi………………………………. Tang Ju Yi………………………………………... Nicole Ann Choong Yin…………………………. Jacinta Kabrina Majalap………………………… Neoh Jia Wen…………………………………….
0318262 0317742 0317967 0317885 0317735 0323148 0311339 0318228
CONTENT Introduction………………………………………………………………...........
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1.0 Aim and Objective…………………………………………………………..
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2.0 Technical Drawings & Pictures……………………………………………..
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3.0 Precedent Study 3.1 Research Methodology 3.1.1 Site Condition……………………………………………... 3.1.2 Measuring Device…………………………………………. 3.1.3 Acoustic Analysis Calculation Method…………………… 3.2 Data Collection, Calculation and Analysis 3.2.1 Sound Reflection………………………………………….. - uniform reflection, sound dispersion - tilted ceiling (acoustic ray bouncing diagrams) 3.2.2 Direct and Indirect Sound Path…………………………… - time delay 3.2.3 Sound Diffusion…………………………………………… 3.2.4 Sound Absorption…………………………………………. - building materials absorption coefficient 3.2.5 Reverberation……………………………………………... - reverberation time (RT) 3.2.6 Acoustical Defects in Auditorium………………………… - echo (flutter echo) - long-delayed reflection - sound shadow - sound concentration 3.2.7 Noise Sources……………………………………………... - measurement of sound - sound source (interior/ exterior noises, occupant activity, M&E operation, environmental sound) - sound path (sound transmission: airborne and structure-borne) - sound receiver (SI, SRI, transmission coefficient) 3.2.8 Noise Control…………………………………………….... - Action - Design Consideration
8 8 8
10
12 15 16 19 21
25
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CONTENT 3.2.9 Acoustical Design Considerations………………………… - type of auditoria & their usage - shapes & volumes - sound reinforcement tools
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4.0 Conclusion and Recommendation…………………………………………...
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5.0 References…………….……………………………………………………..
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6.0 Appendix…………………………………………………………………….
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INTRODUCTION
The Plenary Theatre is located in the Kuala Lumpur Convention Center, (KLCC). Opened in 2003, it comprises of world class facilities such as the Plenary Hall, Plenary Theatre, exhibition and conference halls. KLCC hosts an array of events such as exhibitions, conferences, corporate meetings and entertainment events. Located in the heart of the city, the Plenary Theatre overlooks vistas of KLCC park and Petronas Twin Towers making it a perfect venue for small conferences and seminars.
Owner: KLCC Properties Sdn Bhd Completed: June 2003 Seating capacity: 500 seats Room volume: 16660.45m3
1
1.0 AIM AND OBJECTIVE The objective of this report is to learn how the acoustics of a local auditorium is interpreted and studied through an in-depth case study on acoustic design. The aim of the project is to understand the significance of materials used and the application of materials inside the auditorium. This report is also an analysis of sound study and the architecture that encourages it.
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2.0 TECHNICAL DRAWINGS AND PICTURES
3
2.0 PICTURES
7
3.0 PRECEDENT STUDIES 3.1 Research Methodology 3.1.1 Site Condition The KL Plenary Theatre is an intimate auditorium fit for an audience of 500. The tiered seating and advanced audio visual and lighting system makes this venue suited for corporate event lectures and speeches. It also takes into account sound buffers for the comfort of the audience. Double walls are used in the interpreter rooms and bathroom to ensure current events are not disrupted.
Plenary theatre
Diagram 3.1.1.1 Building plan of Kuala Lumpur Convention Centre 8
3.0 PRECEDENT STUDIES 3.1 Research Methodology 3.1.2 Measuring Device Through observation during the site visit and referring to photos we gathered the data and checked the legibility of the data through the drawings and info available online. Due to strict regulations, we could not take any pictures of the theatre.
3.1.3 Acoustic Analysis Calculation Method Reverberation Time (RT) The reverberation time is the time taken for sound to fade away. The lower the value, the faster sound is dissolved. We observed how the materials used affected the sound pressure levels and applied it to the given formula.
RT =
0.16v A
V= volume of space A= total absorption of room surfaces
Time delay Time delay= Sound from its source is reflected and heard in a delayed time. The average time delay for speeches are usually 40msec, whereas music has a longer delay of 100msec
Time delay=
R1+ R2 - D 0.34
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3.0 PRECEDENT STUDIES 3.2 Data Collection, Calculation and Analysis 3.2.1 Sound Reflection Sound waves hit every side of the enclosure continuously until the sound energy reduces to zero. The amount of waves reflected depends on the smoothness, size, and softness of the materials of enclosure. The angle of incidence of sound rays is equal to that of the reflected rays only if the surface of the reflector is flat. But when it is curved, the angles are different.
The first step in the analysis was to check the inclination angles and positions of the ceiling’s reflective surfaces. Properly tilted ceilings can contribute more useful sound reflections.
Diagram 3.2.1.1 Ray diagram of listener at front rows from stage
Diagram 3.2.1.2 Ray diagram of listener at middle rows from stage
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3.0 PRECEDENT STUDIES 3.2.1 Sound Reflection
Diagram 3.2.1.3 Ray diagram of listener at back rows from stage
Useful ceiling reflection
Useful ceiling reflection
Diagram 3.2.1.4 Diagram of useful and not useful ceiling panels
Based on these results, it can be concluded that only some of the ceiling panel provides proper sound reflections in the theater. Ceiling panels in the middle do not play much role in sound reflections due to its incline direction.
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3.0 PRECEDENT STUDIES 3.2 Data Collection, Calculation and Analysis 3.2.2
Direct and Indirect Sound Path
Reflected sound beneficially reinforces the direct sound if the time delay between them Is relatively short, that is a maximum of 30 msec. A time delay of 40 msec for a space for speech is perceived as a sound distinct from travelling directly from source to listener. It is deem as an echo which obscure the perception and understanding of speech. The analysis was performed at three positions at the audience’s seats : front, middle and back.
R2
R1 1st reflected sound
D First Reflected Sound ( To Ceiling ) Time Delay = = =
R1 + R2 - D 0.34 9.5m + 10m - 7m 0.34 36.76 msec
L D S
R2 R1
1st reflected sound
First Reflected Sound ( To Wall ) Time Delay = = =
R1 + R2 - D 0.34 19.9m + 32.2m - 23m 0.34 85.5 msec
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3.0 PRECEDENT STUDIES 3.2.2
Direct and Indirect Sound Path
R1 1st reflected sound
R2 D
First Reflected Sound ( To Ceiling ) Time Delay = = =
R1 + R2 - D 0.34 9.5m + 15m - 16m 0.34 25 msec
S D L R1 R2 1st reflected sound
First Reflected Sound ( To Wall ) Time Delay = = =
R1 + R2 - D 0.34 20m + 19m - 16.46m 0.34 66.2 msec 13
3.0 PRECEDENT STUDIES 3.2.2
Direct and Indirect Sound Path
R2
R1 1st reflected sound D
First Reflected Sound ( To Ceiling ) Time Delay = = =
R1 + R2 - D 0.34 27m + 5.5m - 27.4m 0.34 15 msec
R2 R1 L 1st reflected sound D
S
First Reflected Sound ( To Wall ) Time Delay = = =
R1 + R2 - D 0.34 35m + 20m - 36m 0.34 55.8 msec
The late reflections and echoes are the most problematic part on auditorium acoustics. Based on the analysis diagram, the time delay in this theater is too long for its function. Nonetheless, this problem is solved when the architect eliminate the delay reflection using carpets, thick curtain and other high absorption coefficient materials.
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3.0 PRECEDENT STUDIES 3.2.3 Sound Diffusion Sound Diffusion in simple terms is the scattering of sound energy. When sound bounces off hard flat surfaces, the energy remains very much intact yielding discrete echoes. These echoes will produce destructive effects like comb filtering, standing waves and flutter echoes which degrade speech intelligibility and music clarity. Installing sound diffusers can deal with this problem. Diffusers interrupt discrete echoes by scattering or diffusing sound energy over a wide area without removing it from the room. This maintains sound clarity and improves speech intelligibility.
Problem Repetitive reflections from hard parallel surfaces produce flutter echoes that are perceived as degrade sound quality and speech intelligibility. Absorptive surfaces are often used to control this annoying problem, with the unfortunate side effect of making the room too “dead�.
Solution Acoustic timber wall panel acts as the diffuser that controls flutter echo by sound diffusion, maintaining the natural ambiance of the room. When adjacent panels are spaced and mounted with an air cavity, low frequency absorption can also be achieved. 15
3.0 PRECEDENT STUDIES 3.2.4 Sound Absorption Sound Absorption is the change in sound energy into some other form, usually heat when it passes through a material or strikes a surface. Soft, porous materials and fabrics, and people absorb a considerable amount of sound energy when it impinges on them. Sound absorption is a major factor in producing good room acoustics, especially when controlling reverberation. 3.2.4.1 Building Materials Absorption Coefficient Material are neither perfect reflectors or absorbers. When sound energy arrives at a surface, part of it is reflected or absorbed. The term used to define a material sound absorption is its coefficient of absorption (α). An absorption coefficient of 1.0 indicates 100% absorption of sound energy. Therefore, the larger the absorption coefficient (α), the more effective sound absorber the material is. Note that absorption coefficient (α) varies with the sound frequency Hz.
Material
Picture
Absorption Coefficient 125 Hz
Ceiling
Gypsum plasterboard
0.3
500 Hz
2000 Hz
0.15
0.05
Double layers of gypsum plasterboards are used for the ceiling applications of the auditorium. They are widely acclaimed for their high quality and unique features. They are lightweight for easy installation. Besides, they have good sound insulation and thermal conductivity.These plasterboards are offered in different surface designs at reasonable price in varied customized options. 16
3.0 PRECEDENT STUDIES 3.2.4 Sound Absorption Material
Wall
Floor
Picture
Absorption Coefficient 125 Hz
500 Hz
2000 Hz
Acoustic Timber Wall Panel Its high sound absorption effect for all spectrum of noise. It has hard surface and easy to maintain over time.
0.18
0.42
0.83
Glass Acoustically treated glass windows to control room and interpretation room located directly opposite stage for unobscured view. However, glass windows could be a path of unwanted noise transmission.
0.30
0.10
0.05
Carpet Carpet absorbs sound but can also attenuate impact sound since it prevents hard contact with floor surface. Its absorptivity is good in high frequencies, and is based on the thickness. It is usually made of synthetic materials but also made from wool, cotton or other fibers.
0.15
0.50
0.70
Plywood The reason for using plywood instead of plain wood for stage is its resistance to cracking, shrinkage, twisting/warping, and its general high degree of strength. It is preferred because of its long-lasting and good resistance to damage.
0.40
0.20
0.05
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3.0 PRECEDENT STUDIES 3.2.4 Sound Absorption Material
Picture
Absorption Coefficient 125 Hz
500 Hz
2000 Hz
Furniture
Chair The cushion, backrest and the rear of seat back are designed with woven fabric stretched over a thick, breathable, open-cell foam padding. Legs are moulded aluminium epoxy finish for aesthetic improvement as well as cleaning and maintenance.
0.37
0.68
0.77
Wall
Rigging Platform Fly Bar The upper part of the stage house where scenery, drappery, equipment can be suspended out of the view of audience.
0.15
0.06
0.04
Curtain Drapes and curtains are designed for audience chamber to adjust acoustics. Reflective surfaces can be covered with curtains.
0.10
0.40
0.50
Rigging Platform Fly Bar
Gypsum plasterboard
Glass
Acoustic timber wall panel Stage
Cushioned chair Carpet
Plywood
Curtain
Diagram 3.2.4.1 Diagram showing the material in Plenary Theatre 18
3.0 PRECEDENT STUDIES 3.2.5
Reverberation
Reverberation time (RT) is the continuing presence of an audible sound after the source of the sound has been stopped or gradually dies away caused by rapid multiple reflections between the surfaces of a room. Both speech and music are influenced by reverberation, with longer reverberation desirable for music and shorter reverberation desirable for speech. It is commonly understood that an environment good for speech is poor for music, and vice versa. Reverberant enhancement is fundamentally important to tonal beauty for musical instruments and vocal music, but reverberation had a garbling effect on speech intelligibility.
Reverberation time depends on : 1.The volume of enclosure 2.The total surface area 3.The absorption coefficient of the materials Area ( m2 )
Absorption Coefficient
Absorption Units
Thick carpet
1179.6
0.5
589.8
Plywood
319.8
0.2
63.96
1499.4
0.15
224.91
Glass
38.8
0.14
5.432
Acoustic Timber wall panel
364.3
0.42
153.048
Floor
Ceiling Gypsum Plaster Board
Wall Left
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3.0 PRECEDENT STUDIES 3.2.5
Reverberation
Right Acoustic Timber wall panel
403.2
0.42
169.344
Glass
42
0.14
5.88
Acoustic Timber wall panel
272
0.42
114.24
410
0.4
164
500 people
0.45
224
Back
Front Curtain
Other Cushioned pews, unoccupied
4119.2
1715.614
Total volume: 16660.45 m3 16660.45 RT = 0.16
X
1715.614
=
1.55 sec
On the basis of the presented results, we can see that the reverberation time is 1.55 seconds and have exceeded the normal RT of theatre for speech which is a maximum of 1 second. It can be concluded that the reverberation time obtained is slightly longer for the function of the room. Nevertheless it is still considered as favourable because large rooms usually has longer RT. After an appropriate analysis, it was found that the usage of the auditorium is not limited to speech only . It can be served as a multipurpose auditorium. 20
3.0 PRECEDENT STUDIES 3.2.6
Acoustical Defects in Auditorium
Acoustical conditions in a big space, such as room, ball or auditorium and etcetera, are achieved when there is clarity of sound in every part of the occupied space.The primary goal for speech is to have words understood by listener. This is referred to and is measured as speech intelligibility. Speech includes both the spoken word and the sung word. It is well accepted that music listeners usually want to hear the words, whether spoken or sung. When people complain that they cannot hear, even though the loudness may be quite high, it means that they cannot understand the words. For this, the sound should rise to achieve suitable intensity everywhere with no echoes or near echoes or distortion of the original sound; with correct reverberation time. Below are a list of acoustical defects: ●
Flutter Echo
●
Long-delayed reflection
●
Sound shadow
●
Sound concentration (Sound Foci)
Flutter echo There are certain paths for sound that produce a repeating loop. Every time the wavefront passes the engineer or artist, it is heard as the sound is intended, but with a twist. Just as when you "click" the individual prongs on a comb in quick succession, the quickly repeating sound of the wavefront continuously passing the listener produces a distinctive "zinging" tone. This is known as flutter echo and is due to our brain's desire to interpret air pressure fluctuations at some frequency as a particular tone. For this is exactly what is occurring as the wavefront continuously passes your ear at some rapid rate.
Diagram 3.2.6.1 Flutter echo 21
3.0 PRECEDENT STUDIES 3.2.6
Acoustical Defects in Auditorium
Parallel wall
Splay wall
Diagram 3.2.6.2 Flutter in the Plenary Theatre (Plan View) are avoided through elimination of parallel walls. The flutter paths are most commonly located along lines between parallel surfaces. Speakers or recorded sound sources located between parallel surfaces are constantly sending sonic wavefronts into the repeating loops of these flutter paths.
Flutter echo effect is easy to avoid, by defining the property of the phenomenon of the formation between the surfaces parallel to one another. Plenary Theatre is designed so that both side wall are in splay orientations to prevent flutter echo. Typically, 5 ° is a quantity sufficient to prevent flutter echo. The existing premises used absorbent materials to get rid of the echo. It is repeated enough that one of the reflective surface is lined with absorbent material or absorbent.
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3.0 PRECEDENT STUDIES 3.2.6
Acoustical Defects in Auditorium
Long-delayed reflection Long-delayed reflection are those that arrive at the listener's ear within a time delay following the direct signal between 1/40th second and 1/4 second. These reflections should be relatively indistinct and quiet, about 15 dB below the speech signal range. For Plenary Theatre which mainly for speech event, it is crucial to prevent long-delayed reflection for understanding speech. Listener will get confused if there are reflection of sound delayed. To prevent this, the architect eliminate all late reflections by absorbing them through adding absorption materials.
Sound shadow A phenomenon caused by the absorption or obstruction of a sound wave by an object in its path. The effect produced is perceived as a reduction in loudness depending on the observer's position with respect to the sound source and obstructing object and is greatest when the three are aligned.
Diagram 3.2.6.3 The blue part indicating the sound shadow produced in the Plenary Theatre. (Plan View) From the diagram, we can see that people sitting at the sound shadow might face problems where he or she could barely hear the speech clearly if there is no sound reinforcement. 23
3.0 PRECEDENT STUDIES 3.2.6
Acoustical Defects in Auditorium
Sound concentration (Sound Foci) The form and shape of the Plenary theatre make sound waves to concentrate in some particular areas creating a sound of large quality. These spots are known as sound concentration or sound foci. This particular defect could be removed by: â—?
Geometrical design shapes of the interior faces.
â—?
Providing highly absorbent materials on critical areas (curved spaces)
Diagram 3.2.6.4 Most concentration of sound are being directed onto the centre part of the Theatre (Plan View)
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3.0 PRECEDENT STUDIES 3.2.7 Noise Sources 3.2.7.1 Noise Definition Noises are considered as undesirable sound. It may be disruptive to the theatre user as speeches are being presented on stage or within the space. Besides the loudness of a noise, it can be the frequency, continuity, occurrence, mood of user and origin of the noise that dictates its level of disruptiveness. Usually, the “hum” of mechanical and electrical components of a building affects users more than noises created naturally such as; wind, rain, and rustling leaves. The frequency of the noise is also another factor whereby high frequency noise is much more annoying than lower frequency noise.
Different levels of noise cause a variety of side effects on human, prolonged noise at lower levels causes psychological disturbance while higher levels may cause hearing loss. For every space with a given purpose an acceptable amount of background noise is required to be fulfilled by the architectural design and acoustic engineering. The plenary theatre is a speech auditorium; the ambiance noise should be kept at a standard of 25 to 30 dBA, the lowest level of noise is allowed within the space.
3.2.7.2 Measurement of noise Sound is measured by its frequency-weighted sound levels whereby different frequency is detected by the microphone of a sound level meter. Sound level meter is an instrument that translates constant and objective measurement of sound into readable data. Due to the limitation of the human ear, these measurement tools adjusts to the frequencies humans are able to hear while the frequencies that exceeds these limitations are disregarded.
There are two standard frequency-weightings on the sound level meter: C scale and A scale. C scale is called the ‘flat’ frequency weighting as all the sound energy is accumulated and translate into a general value, units in dBC. While the A scale corresponds to the human ear capabilities of hearing the loudness of sounds and filters out the lower frequencies, units in dBA. 25
3.0 PRECEDENT STUDIES 3.2.7 Noise Sources
Measurement Devices The problem with measuring sound is to get an accurate reading with the fluctuation in the sound levels. Several ways such as increasing the response setting, taking several readings, follow and measure the fluctuations. The resulting data would show the following: LAS – slow – A scale weighted sound level LAF – fast – A scale weighted sound level LCS – slow – C scale weighted sound level LCF – fast – C scale weighted sound level Lmax – maximum Lmin – minimum Ln – percentiles, noise level exceeding n% of measurement time.
Figure 3.2.7.1 Sound Level Meter
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3.0 PRECEDENT STUDIES 3.2.7 Noise Source 3.2.7.1 Acoustic Study In order to prevent noises from the interior and exterior interfering with the activity within the theatre, it is crucial to study the relationship of the sources of the sound, the path travelled by the sound and its receiver.
SOURCE
PATH
RECEIVER
3.2.7.2 Noise Source
NOISE Catwalk
NOISE NOISE Prefunction Control Room ROOM ACOUSTIC Theatre
NOISE
Stage
Figure 3.2.7.2 Noise Source
Noise in the theatre can be categorized into three: occupant activity, operation of the building, and environmental noises produced from the exterior of the building. The occupant activity can be the people conversing, walking around, clapping, crying babies, toilet flushing, interpreting speeches and such. Next is the noise produced by the building mechanical and electrical services, such as the air conditioning, hoist system, the nearby operations of elevators and escalators. Finally, the environmental noise is produced by the activities outside the building including: wind, rustling of leaves, traffic, trains, rain and constructions.
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3.0 PRECEDENT STUDIES 3.2.7 Noise Source
3.2.7.3 Electrical services & appliances Various levels of noise are produced by the building services such as : HVAC, plumbing, power generators and lightings. Some of these equipments are fastened with silencers and anti-vibration parts to reduce the noise production. Most of these machines are located some distance away from the theatre, however the HVAC is accessible almost in every room in the Convention Center.
The HVAC posed three ways of distributing noise: airborne, structure-borne, duct-borne. Airborne noise can be countered with noise barriers in the walls, ceilings, floorings and other types of barrier. Next the structure-borne noise can reduced by including special vibration isolators proposed by the MEP engineers within the design. Duct linings, sound attenuators and isolators installed in the ducts as well as analysis of the HVAC operations to distinguish significant locations that produces high noise levels. The velocity of airflow in the ducts are controlled to avoid hissing sounds. All of these operations are monitored to accommodate the noise requirement of Plenary theatre.
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3.0 PRECEDENT STUDIES 3.2.7 Noise Source
Sound source
Brand/Type
Elevator
Escalator
Speaker system
Fujitec Passenger lift
Units (s)
Wattage (W)
Voltage (V)
2
Fujitec
2
Meyer CQ2 FOH
2
Meyer UPA-1P down fill cluster
2
Noise Level (dBa)
50 220/380
45
1240
85–134 165–264
35
Meyer USW-1P 3
House Delay speakers
· AC
Meyer UPMs
12
230
115 / 230
Quad Arena 12” ceiling speakers
10
200
70/100
Quad Arena 8” ceiling speakers
12
120
70/100
KLCC District Cooling Centre (DCC)
3500
30
24
Figure 3.2.7.3 Noise Level of M&E
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3.0 PRECEDENT STUDIES 3.2.7 Noise Source Noise Path There are two paths which sound can travel through: airborne and structure-borne. Sound travels through the air in a continuous open air paths such as: windows, air ducts and grilles, shafts and door, as well as the cracks along the door. As for structure-borne sound, it travels through solid parts of the building (walls, panels, partitions, floors and ceilings) as vibration energy and reradiated to receiver through airborne sound energy. Other than that, there is impact noise where the noises are produced upon physical impact such as: footsteps, knocking, slamming doors and windows.
Noise Receiver In this case instead of the human receiving the noise, the buildings and the rooms within the buildings are considered as the receiver.
Figure 3.2.7.4 Jalan Pinang Traffic
Figure3.2.7.5 Space in between KLCC and Mandarin Oriental
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3.0 PRECEDENT STUDIES 3.2.8 Noise Control
To better tackle the issue of noise it is best to understand how noise can be reduced. There are two main ways noise can be reduced: sound absorption and sound insulation. The absorption of direct, reflected and reverberated noise in the receiving room can be absorbed to an extent by the materials used in the room. After a room is treated with sound absorptive components the difference can be calculated as:
Reduction of noise level (dB) = 10 log (
A2 ) A1
A1 – total amount of sound absorption before A2 – total amount of sound absorption after
Insulating noise is defined as reducing the energy that is travelling into an adjoining airspace. There are several principal ways to control airborne and impact noise:
Mass: Heavyweight structures transmits less energy for every distance covered. Completeness: The structure or space needs to be airtight sealed from exterior noises. Stiffness: The stiffness of the material properties affects the amount of energy travel through them respectively. In reducing the energy, the more flexible and elastic a material is the more it buffers the amount of sound energy. However in contrast a stiff material will lose more insulation capability allowing more noise to pass through.
Actions to Reduce Noise The audience are required to switch off their mobile phones and other electronic devices as well as to refrain from making noises during the speech. Staffs working around the venue are required to work at a quieter pace as well as operating on quieter devices or operate with a silencer.
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3.0 PRECEDENT STUDIES 3.2.8 Noise Control
Noise Reduction in Design The location and orientation of the building is located in the middle of Kuala Lumpur, the Convention Center is situated next to the KLCC Park, 49 acres of greenery. Acting as a major city buffer absorbing most of the noise within the city. The theatre side facing the park experience least noise pollution from the surroundings than the rest.
Figure 3.2.8.5 Site plan showing noise being buffered by the greenery in KLCC park.
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3.0 PRECEDENT STUDIES 3.2.8 Noise Control Noise from rain hitting the roof would mostly be reflected off as the roof is made of metal that reflects sound waves fairly easily as well as insulation materials are made of rockwool fibre for noise and thermal insulation. The fiber also helps to insulate the heat from outside. While the noise that managed to penetrate the roof is diffused and reflected on the gypsum plasterboard used as the acoustical ceiling panels as well as the catwalk ceiling with different components that assist in the diffusing the noise.
Roof
Catwalk
Figure 3.2.8.6 Rain impact noise diffusion
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3.0 PRECEDENT STUDIES 3.2.8 Noise Control
Noise Barriers A noise barrier is a wall, screen, building, or other impervious structure that breaks the line-of sight between a source and a receiver. The more a barrier penetrates through the line-of sight between a source and a receiver, the greater the barrier attenuation.
The KLCC was designed and build – contract with Sunway Construction Bhd and were responsible in consulting on the acoustics for the spaces. The designers of the theatre took several steps required to build a speech theatre and insulate and reduce as much noise as possible, while keeping the project’s aesthetics and cost efficiency. Firstly, surrounding the theatre are rooms and facilities serving several purposes. Each space produces different levels of sound therefore the walls used for the interpreting room, wet closets, hallways, elevators are of various sound insulation capabilities.
Doubled walls
Air Concrete wall Timber panel
Washroom
Theatre
Figure 3.2.8.7 Washroom decoupled wall 34
3.0 PRECEDENT STUDIES 3.2.8 Noise Control
Concrete wall Timber paneling
Lounge
Theatre
Figure 3.2.8.8 Interpretation Lounge wall
Standard double pane glass Air pocket Soundproofing glass
Theatre
Interpretation room
Wall
Figure 3.2.8.9 Interpretation Room glass panel
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3.0 PRECEDENT STUDIES 3.2.8 Noise Control
Figure 3.2.8.10 Interpretation room of Plenary Theatre Furthermore, design solution to combat the noise from the pre function area where people would gather or linger outside of the theatre is through separating the spaces between 2 doors and an air buffering room. The doors work when both are closed and noise from the pre function area is reflected and diffused at the first door then proceeded to be disperse within the space in between and further diffused and reflected at the second door closing the theatre space. It also function as a buffer zone which one door would diffuse the sound from travelling directly into theatre whenever there is audience or workers going out during the speech.
Pre-function corridor
Theatre Figure 3.2.8.11 Double Door 36
3.0 PRECEDENT STUDIES 3.2.8 Noise Control
Sound Reduction Index (SRI) Sound Reduction Index is the measurement of insulation for direct transmission of sound travelling through air, measured in decibels, dB. 1 ) T T - Transmission coefficient SRI = 10 log (
Transmission coefficient is the insulation measurement within a partition, the amount of sound energy passing through it. It is calculated as the proportion of the energy before and after passing through the partition.
T=
Transmitted sound energy Incident sound energy
SRI of composite partition It is calculated as overall transmission coefficient and the surface area of individual components. TO = [(T1.A1) + (T2.A2) + (Tn.An)] / (A1 + A2 + A3) TO – overall transmission coefficient T1 – transmission coefficient of one component A1 – area of component
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3.0 PRECEDENT STUDIES 3.2.9 Acoustical Design Consideration 3.2.9.1 Geometry The Plenary Theatre functions as a conference hall for speech presentation. Therefore, the acoustic requirements are critical in promoting speech intelligibility and audience interaction. Overall, the geometry of the Plenary Theatre is described as a combination of slight fan-shaped and rectangular shape, where the stage is located at the narrower front area and the audience seatings becomes wider and maintained at a fixed width towards the rear.
This is because a whole rectangular geometry is only suitable for relatively small speech hall. The addition of slight fan shape will emphasize wall reflections.
rectangular-shaped
fan-shaped
Diagram 3.2.9.1 Fan-shaped geometry aid in sound reflection.
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3.0 PRECEDENT STUDIES 3.2.9 Acoustical Design Consideration Fan-shaped geometry ●
Side walls are splayed from the stage to accomodate larger seating capacity.
●
It provides good visibility.
●
The splayed wall can usefully reflect sound energy to the rear of the hall.
●
Generally, it is more suitable to be used for speech performance.
Rectangular-shaped geometry ●
The side walls ensure short reflection times.
Auditorium
Stage
Diagram 3.2.9.2 Fan-shaped geometry aid in sound reflection. Plenary theatre is well served by arranging the seating in a moderate fan plan or semicircular amphitheater plan to bring the audience closer to the stage than an axial plan would.
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3.0 PRECEDENT STUDIES 3.2.9 Acoustical Design Consideration 3.2.9.2 Sound reinforcement by reflectors The sound source is closely surrounded with large sound-reflective surface in order to supply additional reflected sound energy to every portion of the audience area. In the Plenary Theatre, There are 2 large acoustic timber side wall panels at the front portion of the auditorium helps in the reflection of sound.
Diagram 3.2.9.3 Large acoustic timber wall panels as reflectors
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3.0 PRECEDENT STUDIES 3.2.9 Acoustical Design Consideration The Plenary Theatre is a large and has a fairly high ceiling. In order to avoid excessive delay between reflected and direct sound, suspended reflectors (Gypsum plaster boards) are employed at a lower level. Monumental designs with high ceilings, useful in assuring adequate reverberation from high volume in concert halls, are not practical in speech theatre where the goal of high intelligibility demand less reverberance and strong reinforcement. This goal is best met with low ceilings, or at least ceilings that have a significant quantity of lower surfaces that reflect sound quickly to audience no later than 40 msec after the direct sound from the speaker.
Diagram 3.2.9.4 Gypsum Plaster boards installed on the ceiling
12m
6m
Diagram 3.2.9.5 The height of the ceiling will affect the acoustic of Plenary Theatre 42
3.0 PRECEDENT STUDIES 3.2.9 Acoustical Design Consideration The rear of the Plenary Theatre has a concave surface which helps to strengthen sound reflection. However, this might result in localising the reflections to the neglect of other areas of seating.
Concave Shaped
Diagram 3.2.9.6 Slight concave shape for sound reflection.
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3.0 PRECEDENT STUDIES 3.2.9 Acoustical Design Consideration 3.2.9.3 Sound reinforcement by loud speakers The installation of sound reinforcement systems aims to provide uniform coverage over the entire seating. The localization of a sound source by the listener occurs upon hearing the first sound from the source. This requires placement of the loudspeakers in such a way that the reproduced sound arrives at the listener’s ears from a similar direction as the listener sees the talker. In this arrangement, the listener will localize the sound as arriving from the direction of the original source, not from the loudspeaker.
Advantages of sound amplification system: ●
To reinforce the sound level when the sound source is too weak to be heard
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To provide amplified sound for overflow audience
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To minimize sound reverberation
The sound reinforcement systems provided in the Plenary theatre: ●
High quality speaker system
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House delay speakers
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LCR balanced line inputs
The loudspeaker system: Stereophonic System There are 2 cluster of loud speakers around the sound source.
Diagram 3.2.9.7 loud speakers location
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3.0 PRECEDENT STUDIES 3.2.9 Acoustical Design Consideration
Diagram 3.2.9.8 2 cluster of loud speakers In such a large room like Plenary Theatre, sound reflections from the room boundaries can arrive at the listener after direct sound with very long-delays. The hearing mechanism cannot integrate such long-delayed reflections with the direct sound, which is generally harmful to the intelligibility and clarity of sound. Therefore, in large rooms, better results are generally obtained through the use of loudspeakers that radiate sound within a narrow angle aimed toward the listening area. This high directivity tends to reduce the quantity and loudness of harmful sound reflections from the room boundaries. 45
4.0 CONCLUSION An acoustic environment that is ideal for one type of activity can be unsatisfactory for another. Although Plenary Theatre might seem to command the most interest and research for listening places within the architectural acoustic profession, the reality is that most of the time, it also serve nearly every sort of activity, including concerts. A good multipurpose auditorium design should be able to handle these differences by incorporating acoustic adjustability.
Effective control of acoustical environment in buildings involves at least a conceptual understanding of the basic properties of sound, how it is propagated throughout the spaces, and how it is influenced by various building materials and construction systems. Just as with the numerous other disciplines involved in the overall building environment, the solutions to acoustic problem require no small amount of experienced judgement and just plain common sense. After all, people do not respond to just one aspect of their environment. Acoustic, therefore, is rarely the most important aspect, but it is significantly part of the environment and its effective control will help produce a good building. However, we can conclude that a lot of acoustical improvement still can be applied in Plenary Theatre for a better acoustic environment.
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5.0 REFERENCE 1.
Plenary Theatre - Kuala Lumpur Convention Centre. (n.d.). Retrieved April 29, 2017, from http://www.bing.com/cr?IG=0B09E828F6D441F8BD3E6F70909ED223&CID=18 44FF1BDC8F6E000000F568DD1F6FBA&rd=1&h=seGGIJlBr-9vZWx3uahQGjF qeBH4-ZSzyC_efDp0Fvk&v=1&r=http%3a%2f%2fwww.klccconventioncentre.co m%2fPlenary_Theatre-%40-Overview.aspx&p=DevEx,5063.1
2.
Wybrane aspekty analizy i kształtowania akustyki pomieszczeń. (n.d.). Retrieved April 29, 2017, from https://brasil.cel.agh.edu.pl/~14sapyzik/index0743.html?page_id=69
3.
Northwood, T. D. (1977). Architectural acoustics. Stroudsburg, PA: Dowden, Hutchinson & Ross.
4.
Upham, J. B. (1853). Acoustic architecture. New Haven: B.L. Hamlan.
5.
Acoustic Basics. (n.d.). Retrieved April 29, 2017, from http://www.asc-studio-acoustics.com/acoustic-basics/
6.
(n.d.). Retrieved April 29, 2017, from https://www.sfu.ca/sonic-studio/handbook/Sound_Shadow.html
7.
Heyl, P. R., & Chrisler, V. L. (1938). Architectural acoustics. Washington: United States Department of Commerce, National Bureau of Standards.
8.
Program in Architectural Acoustics. (n.d.). Retrieved April 29, 2017, from http://www.bing.com/cr?IG=466A11BAC0D74466851DEEF7536625A4&CID=2 57AF4A393B062F31140FED0922063B8&rd=1&h=KBFhf1HFFU_3SB-9jFGdY 2brRediDFFgMuJo5VLBCis&v=1&r=http%3a%2f%2fsymphony.arch.rpi.edu%2f &p=DevEx,5082.1
9.
Reveberatioin time. (n.d.). Retrieved April 29, 2017, from http://hyperphysics.phy-astr.gsu.edu/hbase/Acoustic/revtim.html
10.
Auditorium Soundproofing with Sound Panels - Soundproofing by Netwell Noise Control. (n.d.). Retrieved April 29, 2017, from http://www.controlnoise.com/auditorium-soundproofing/
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6.0 APPENDIX
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