Building science 2 report (1)
- 1. 1 9. BAKHT JALAL KHAN 0326850 TUTOR: MR AZIM SULAIMAN
- 2. TOPIC PAGE 1.0 INTRODUCTION 1.1 ACKNOWLEDGEMENT 1.2 AIMS & OBJECTIVES 1.3 SITE INFORMATION 1.4 HISTORICAL BACKGROUND 1.5 PHOTOS 1.6 DRAWINGS 3 4 4 4 5 5 6 2.0 METHODOLOGY 2.1 MEASURING INSTRUMENTS 2.2 DATA COLLECTION METHODS 8 9 10 3.0 ACOUSTICAL ANALYSIS 3.1 AUDITORIUM DESIGN ANALYSIS 3.2 MATERIAL AND PROPERTIES 3.3 ACOUSTIC TREATMENT AND COMPONENTS 3.4 SOUND PROPAGATION AND RELATED PHENOMENA 3.5 NOISE INTRUSION 11 12 14 17 21 30 4.0 REVERBERATION TIME 32 5.0 CONCLUSION 35 6.0 REFERENCES 38 CONTENT 2
- 4. 1.1 ACKNOWLEDGEMENT Multiple parties are credited for the completion of this project. It is thanks to Mr Azim Sulaiman for providing us with the neccessary information through his tutorials that we were able to understand what is needed for the completion of the report, as well as answering some of our questions through tutorials. Also credited for our project completion is Ar. Edwin, who through his lectures gave us a clear understanding on the fundamentals of acoustics design and its related calculations. A special thanks to Ms. Premila of Nexus School for arranging with us the date for site visit and making this possible. Coordinated teamwork and encouragement between the group members are also crucial to the completion of the project. 1.2 AIM & OBJECTIVE The main objective of this project is to gain a clear understanding on the application of acoustic designs in an actual theatre/auditorium. Acoustic design is one of the architectural and engineering techniques to control the behaviour of sound in an enclosed space. The purpose is to improve sound distribution in the enclosed space by enhancing the desired sound suited for the program. It is also for the purpose of us to truly understand sound wave movement under certain conditions and the importance of such. 1.3 SITE INFORMATION Name of theatre: Nexus International School Theatre Location: No. 1 Jalan Diplomatik 3/6 Presint 15, 62050 Putrajaya, Malaysia Theatre type: Multi-purpose theatre Total volume: 14578.15m3 Year of construction: 2008 Total seats: 580 fixed 4
- 5. 1.4 HISTORICAL BACKGROUND Nexus International School Malaysia established in 2008, Nexus International School is the first international boarding school based in Putrajaya, Malaysia. A member of Taylor’s Education Group (TEG), Neus International School has the backing of a company that offers well-known educational excellence. Surrounded by a lush tropical environment the school is still within easy reach of Kuala Lumpur City Centre (KLCC). The school’s Performing Arts Department is furnished with a fully equipped theatre. Plans for the theatre were included in the initial building design how it was kept running at an incomplete state for a number of years whereby it was awaiting further financial requirements to advance. An estimate of one million ringgit was allocated on the installment of sound improving technology in the year 2017. This was followed by an estimate of two hundred thousand ringgit for light technology, making it fully equipped. The theatre itself is suited for a mixed acoustical purpose (Speech & Music). 1.5 PHOTOS 5
- 9. 2.1 MEASURING INSTRUMENTS Digital Sound Level Meter 9 The sound meter was used to measure the sound levels at a particular point within the theatre. The unit of measure is decibels (dB). It is commonly in the form of a hand- held instrument with a microphone and the diaphragm of the microphone responds to changes in air pressure caused by sound waves. Measuring Devices Measurment tapes were used to obtain the measurements of the theatre and to measure the distance of the sound level meter from the sound source when sound levels data were taken. Smart Phones Individual members each had a smart phone to capture personal photos that mostly relates to the topic that they previously choose to focus on. Digital Camera A digital camera was used to document the existing context within our theatre and to aid our after-visit analysis as well as evidence of our visit to the theatre.
- 10. 2.2 DATA COLLECTION METHOD To ensure that the site visit could be carried out smoothly and without problems, formal arrangements were made with the authority in charge of the theatre to make sure that the theatre would be unoccupied and available for us to use and conducting our analysis. We documented as many details as possible during the site visit with the help of the aforementioned tools along with all the neccessary measurements required to assist our analysis. 10
- 12. 3.1 AUDITORIUM DESIGN ANALYSIS 3.1.1 Sloped Floor • Sloped floor design allow more direct angle of incidence which in turn allow less absorption. It provide a proper sightline from the audience to the stage. It is very important for public speaker as their audience grows, they will need to consider about the visuality and hearability of the audience and sloped floor design will affect these aspect. 3.1.2 Form And Massing • Rectangular Shaped Auditorium • The form of the auditorium is in a rectilinear shape with several angular and parallel at the side of the auditorium. This results in poor acoustic design as parallel wall leads to flatter echoes issue which consist of noticeable small echoes that will affect the quality of auditorium. The sound will be more concentrated in the middle and the front. Plan of the theatre 12 Slope floor allow more direct soundwave
- 13. 3.1.3 Ceiling • Ceiling Reflector direct sound energy from stage to the seating area. Ceiling reflector is exponentially important in rectangular-shaped design auditorium due to rectangular- shaped designs usually lack reflection, where the ceiling reflector will increase early reflections. 3.1.5 Arrangement Of Seats • The seats in the auditorium is arranged in fan shape to ensure a maximum number of seats are fitted and obtain an greater sightline to stage from every seat. As spherical wavefront will be formed when sound emit from the source, this layout helps to achieve the most effective acoustic quality as all seats fall within the angle of the existing sound projecting area. Diagram highlighting the position of seats in the theatre 13 Reflection of soundwave on the ceiling
- 14. 3.2 MATERIALS & PROPERTIES OF THE THEATRE In Absorptive Materials there are 3 types of Sound Absorptive Materials which are fibrous, panel resonators and volume resonators. The Absorptive Materials transform the sound energy into heat energy when sound passes through a material or hits a surface. Commonly Fibrous and Panel Resonators are used in buildings. Fibrous Materials (Porous) absorbs sound energy by pumping air through the material. It uses a frictional drag of air moving into the tiny spaces between the fibres. This is done as the cells provide resistance to the sound waves (energy). But this absorptive material depends on its thickness, porosity, density and air resistance to airflow. Painting cannot be used as a finish for this material as it prevents this porosity. Panel Resonators are built within a membrane for e.g. Thin Plywood or Linoleum in front of a sealed airspace containing absorbent materials. They are often used when low frequency absorption is required. Middle and high frequency absorption is unwanted or provided by another treatment. Volume Resonators (Cavity) is an air cavity within a massive enclosure connected to the surroundings by a narrow neck opening. The sound causes the air in the neck to vibrate and the air mass behind causes the entire construction to resonate at a particular frequency. Absorption is not always proportional to the thickness of the material. It depends on the type of material and the installation method of it. In Nexus School Theatre’s case, it uses Materials consisting of Fibrous Materiality and Panel Resonators for acoustic treatment. 14
- 15. MATERIAL NOISE REDUCTION COEFFICIENT Stage Floors House 125 2000500Photo Material Description CoefficientMaterials Surface finishes ComponentArea Tara flex Black rubberised stage flooring Curtain Fabric Red folded fabric Soft Soft 0.02 0.04 0.05 0.1 0.4 0.5 Floors Carpet Green needle punch carpet Soft 0.1 0.5 0.6 Furniture Plastic Blue and grey plastic shells bolted onto metal frames Hard 0.07 0.14 0.14 Walls 1. Cork Panels Cork boards on battens 0.15 0.65 0.35Smooth Black ceramic tiles cladded 2 Ceramic Tiles 0.01 0.01 0.02Rough Cloth panel walls framed 3 Cloth 0.46 1.0 1.0Soft Wall insulation 4 Rockwool 0.15 0.9 0.9 Ceiling Timber Panels Timber board on suspended galvanised iron ceiling joists and runners 0.1 0.74 0.61 Doors Smooth Timber Acoustic timber door with steel framing 0.35 0.44 0.54Smooth Drapery Red folded heavy fabric Fabric 0.1 0.4 0.5Soft 15
- 16. MATERIAL NOISE REDUCTION COEFFICIENT Control Room Walls (Internal) 125 2000500Photo Material Description CoefficientMaterials Surface finishes ComponentArea Fabric Clothed wall Floors Concrete Floor slab Soft Smooth 0.46 1.0 1.0 0.01 0.02 0.02 16
- 17. 3.3 ACOUSTIC TREATMENT The Nexus School Theatre is designed to suit for Mixed Acoustical Purpose (Speech and Music). 3.3.1 Stage Flooring - Tara Flex In the past, the stage flooring was initially comprised of Timber but to improve the sound control of the theatre, it is replaced by Tara Flex material. A soft rubberised flooring material used as a sound and shock absorbent with a slip resistant property. The impact sounds of people walking, running and performing on the stage will be absorbed by the material. Drapery The curtains are comprised of cloth materiality, which act as sound absorbers but acoustically transparent. They are installed within the stage and 2 exitways on the door openings. They are placed within the exits to reduce the sound energy of the stage performance from travelling through the openings and externally. These curtains are more heavy, dense and fuzzier than carpets. They form an air space between itself and the wall. Its folded feature provides the curtain a larger surface area, to absorb the sound energy emitted to them. 17
- 18. Flooring - Carpet The Carpet is used as a sound absorbent material for the house’s flooring. Their soft fabric is needle punched, which creates a lot of tiny air pockets to trap air. Softening the sound impact of people walking and absorbing the sound transmitted from the stage. 3.3.2 Walls Cork Panels (Acoustic Panelling) The Cork Panels are battened to the theatre’s walls above the floor level to act as Acoustic Panels. These panels will absorb the sound energy travelled to them. Consisting of little holes, which acts as air pockets, trapping the air within them. The sound (energy) will be dispersed from these panels. They are also built above the floor level to prevent them from being damaged and connecting the sound from the walls to the floor. Therefore these panels act as sound insulation to prevent the sound from travelling through the wall by sound absorption means. 18
- 19. Rockwool Panels The walls of the theatre are structurally made out of Rockwool, a mineral fibre. The Rockwool wall consist of a sponge built between 2 wooden panels attached to a concrete slab. The spongy mineral fibre creates a lot of tiny air pockets, which absorbs the sound energy travelled through them. Preventing the sound from going through the walls externally. It disperses the sound energy, giving the time for it to decay. Fabric Walls Cloth panels are framed and attached to certain parts of the house walls and the control room’s interior. They act as sound absorbers to absorb the direct sound energy travelling from the stage. The control room’s interior walls are filled with this material in order to provide the room’s privacy by reducing the noise transmittance from the stage into the space. 19
- 20. 3.3.3 Ceiling- Timber Panels The ceiling panels are comprised of timber, employing the same principles as the walls as sound travels upwards. By principles is that when sound is travelled upwards, the panels absorb the sound and reflected them back towards the audience. It is also used for aesthetic purposes. 3.3.4 Acoustic Doors The doors are comprised of timber panels with steel framing and double seals. Timber is used to reflect the sound waves emitted by the stage performance. Double seals are used to seal the air gaps of the doors to prevent the sound from travelling through these gaps. 20
- 21. 3.4 SOUND SOURCES & PROPAGATION 3.4.1 SOUND SOURCE Sound source are subjects producing sound waves into the environment within the range of frequencies than can be perceived by the human ear. Sound Source A The sound amplification system in the theatre is the main sound source. The stage is the main performing area where the sound is produced and transmitted towards the audience. The purpose of this system is used to strengthen the sound level when the sound is too weak to be heard, to provide amplified sound for overfull audience and to minimize sound reverberation. There are total of 8 speakers hanging top of the front stage and total of 4 speakers positioned individually on the stage area. Position of speakers shown on plan Position of speakers shown in photo 21
- 22. Loudspeakers are adjusted and controlled through a processor in a control room located above the audience seating. The speaker’s volume have been adjusted before performances show starts. The top speakers produce higher volume of sound to make sure it is transmitted to the audience seating at the back area of the theatre. The bottom speakers on front stage produce sounds of a lower volume which directed to the audience seating in front which is located nearer to the sound source. Section of the functioning speakers SPECIFICATION A PRODUCT BRAND Yamaha CM10V Floor Monitor Speaker DIMENSION ( w x h x d ) 560mm x 353mm x 277mm FREQUENCY RANGE 71Hz – 20kHz WEIGHT 13.3 kg POWER RATING 125w (noise)/ 250w(pgm)/ 500w(peak) PLACEMENT Floor 22
- 23. SPECIFICATION B PRODUCT BRAND Yamaha C112VA Full Range Speaker DIMENSION ( w x h x d ) 416mm x 620mm x 329mm FREQUENCY RANGE 68Hz – 16kHz WEIGHT 21.8 kg POWER RATING 175w (noise)/ 350w(pgm)/ 700w(peak) PLACEMENT Ceiling SPECIFICATION C PRODUCT BRAND Yamaha IF2112/64 DIMENSION ( w x h x d ) 378mm x 695mm x 454mm FREQUENCY RANGE 55Hz – 20kHz WEIGHT 21.8 kg POWER RATING 300w (noise)/ 700w(pgm)/ 1400w(peak) PLACEMENT Ceiling 23
- 24. Sound Source B The sound source of this is the least evident and originates from the audience themselves. Audience’s in and out movement from the theatre, adjusting of seats and small chatters contribute to sounds in the auditorium and can be kept minimum by announcement and reminders before and during intermissions Sound Source : Audience 24
- 25. 3.4.2 SOUND CONCENTRATION The sound concentration zone of the auditorium can be determined through the measurement of the sound intensity level (SIL) from the sound source. There is a distinct sound concentration at the front & middle of the auditorium. SIL measurement in auditorium without any sound SIL measurement in auditorium with spotlight cooling fan on only 47dB 44dB 42dB 45dB 40dB 36dB 32dB 30dB 29dB 25dB STAGE 25
- 26. Therefore, the sound concentration zone is created through the auditorium’s diamond form. Due to the direction of the front ceiling timber panel, this reflects the sound to the front and middle part of the auditorium as the back ceiling timber panel has no acoustic value. SIL measurement in auditorium with music on. Sound Reflection Diagram. The design of the auditorium reflects the sound path towards the middle & front area 68dB 75dB 78dB 69dB 70dB 26
- 27. 3.4.3 SOUND REFLECTION The surface of the auditorium has been altered with the right materials to reflect and absorb the right amount of sound reflected to the audience for the better acoustic quality. Smooth surfaces reflects waves coherently while rough surface would reflect the waves in many different directions. Porous surface will absorb sound waves. Timber perforated acoustics panels are placed on the sides and back of the auditorium to absorb the sound waves. Carpet is used to cover the floor of auditorium to help in absorbing the sound waves while preventing internal noises. Timber panels on the ceiling of the auditorium are added to reflect the sound waves. But only the front panels has acoustic property while the back panel does not. On the wall of the auditorium, ceramic tiles are placed from floor to 750mm height to reflect the sound waves to audience and preventing the sound waves to be absorbed by the carpet flooring. Diagram of auditorium with absorbers & reflectors placing Sound propagation at front row 2, proving sufficient sound reflected 27
- 28. Sound propagation at middle row 7, proving more than sufficient sound reflected Sound propagation at back row 13, proving lack of sound reflected 28
- 29. 3.4.4 SOUND ECHOES & SOUND DELAY Echoes are the distinctive repetition of a sound. Reverb is when the reflected sound wave reaches the audience ear in less than 0.1 seconds after original sound wave. In theatre design, the longest acceptance delay time for speech is 40ms and a delay time of 100ms for music & performance. Time delay = (5.6m+5.7m-4m)/0.34s = 21.5ms A time delay of 21.5ms towards front row 2 is acceptable for speech orientated auditorium Time delay = (8m+5.6m-8.3m)/0.34s = 15.6ms A time delay of 10.6ms towards back row 13 is acceptable for speech orientated auditorium Time delay = (11.4m+6.7m-14.5m)/0.34s = 10.6ms A time delay of 15.6ms towards middle row 7 is acceptable for speech orientated auditorium In conclusion, the sound delay in the NEXUS auditorium is still within control even in different seatings. This also shows that the auditorium is suitable for speech usage but not very good for musical purposes. Echo is not a problem in the auditorium as it is handled properly through certain design strategies. 29
- 30. 3.5 NOISE INTRUSION Sound in general can be described as a vibration that travels through a medium to a person’s ear. However, the term ‘noise’ is often considered to be a disturbance which brings unpleasantness. The degree of desirable depends on various qualities including the frequency, continuity, volume, time of occurrence, place and even the personal state of mind of the listener. 3.5.1 EXTERNAL NOISES There are multiple origins of noise at the external of Nexus International School Auditorium which are vehicular noise along the main road, the sound produced by the opening and closing of doors, the sound of conversation taking place outside the auditorium, potential noise from the soccer field and also potential noise coming from the musical classrooms just outside the main entrance of the auditorium. The noise produced from the musical classroom just outside the auditorium can enter visa the doors. However, there is a sound lock within the inner and outer door at the main entrance of the auditorium. This serves to trap the sound waves within the sound lock and prevent them from interfering with the event inside, bringing the noise level from the outside down to less then 25dB for the seats nearby the door. Besides, there is an exterior alley running along the sides of auditorium that many occupants such as crews and price receivers used to get to the front or the back of the auditorium without creating disturbance to the audience. However, any noise from the walkway can be heard in the auditorium due to the lack of sound proofing on the doors and sound locks. Thus, the seats closer to the doors are exposed to roughly 50dB of noise disturbance. Door dampers are attached on each end, however the noise of opening and closing of the doors are not reduced because of its excessive weight. Sound lock within the inner and outer doors 30
- 31. 3.5.2 INTERNAL NOISES Not only from the external, there are also noise sources from the interior of the auditorium such as the footsteps on carpeted floor and on the stage as well as the spotlights. The carpeted floor reduces echo, however the noise of footsteps can not be reduced as the flooring material used is timber. On the stage of the auditorium, which is paved with a layer of timber veneer for aesthetics, causes incessant thudding sounds when stepped on. The air gap below its concrete platform which is used for amplifying the subwoofers below the stage is contributing to the noise of the footfalls. The air-conditioners in this auditorium do not produce noise. Instead, it is the Ellipsoidal Reflector Spotlights that are producing loud noises as the spotlights are equipped with cooling fans to prevent overheating. Entrance to the side alleys The walkway of the side of the auditorium Carpeted floor Tara Flex flooring stageEllipsoidal Reflector Spotlight 31
- 33. 4.0 REVERBERATION TIME CALCULATION Sabine Formula: RT = 0.16V/A Where. RT: Reverberation Time (sec) V: Volume of the room A: Total Absorption of Room Surface 1 STAGE Floor A = 115.43m2 α = 0.04 Aα = 4.617m2 Curtain A = 139.92m2 α = 0.4 Aα = 55.968m2 Note A : Area α : Absorption Coefficient Aα : Absorption Surface 2 HOUSE Floor A = 2090.93m2 α = 0.5 Aα = 1045.465m2 Furniture A = 1611.55m2 α = 0.14 Aα = 225.617m2 Wall a. Cork Panel A = 222.46m2 α = 0.65 Aα = 144.6m2 b. Rockwool A = 111.83m2 α = 0.9 Aα = 100.647m2 Ceiling (Timber Panel) a. A = 1121.66m2 α = 0.74 Aα = 830.03m2 b. A = 1121.66m2 α = 0.1 Aα = 112.17m2 Door A = 18.6m2 α = 0.44 Aα = 8.185m2 Drapery A = 5.04m2 α = 0.4 Aα = 2.016m2 33
- 34. CALCULATIONS ∑ Stage = 4.617 + 55.968 = 60.59m2 ∑ House = 1045.47 + 225.62 + 144.6 + 100.65 + 830.03 + 112.17 + 8.185 + 2.016 = 2468.74m2 V = 14578.15m3 A = ∑ Stage + ∑ House = 60.59m2 + 2468.74m2 = 2529.33m2 RT = 0.16V/A = 0.16 (14578.15)/2529.33 = 0.92 seconds The Nexus International School Theatre has a reverberation time of 0.92 seconds, making it more suitable as a space for speech and lectures but making it not optimal for a music performance, resulting in the addition of speakers to aid in that regard. 34
- 36. 5.1 RECOMMENDATIONS 36 Maintenance Scheduled maintenance should be done, to fix loose screws, greasing door hinge and the handle to minimise unwanted noise that would affect of disrupt the acoustic experience in the theatre. Lights Consideration to start using less quiet fans to cool down the lights would be a good step towards preventing internal noise intrusion, especially since the lights wo u l d b e sw i t c h e d o n constantly. Replacing old panels According to the person we interviewed, he said the old panels loses its function overtime and replacing it regularly would help to improve the acoustical issue. Reduce absorbent The Nexus International School Theatre would benefit from reducing the amount of absorbent materials as it would be able to increase the reverberation time of the theatre, making it more s u i t a b l e f o r a m u s i c performance.
- 37. 5.2 CONCLUSION Overall, this project is an eye opener to us and it is a huge learning experience for the nine of us. It lets us understand the performance of acoustic design is dependant on the function of the auditorium, and utilising said design to make the users feel comfortable. The layout of the space as well as materials of the structure such as walls, floors, chairs, curtains, ceilings etc. can affect the acoustic inside and can even efficiently affect the sound from the outside. Based on our analysis and calculations, Nexus Theatre has a considerably low reverberation time, with a similarly short sound delay, making it a suitable space for giving speeches or talks, but much less suitable for something like a musical performance, as it lacks the richness of sound for the audience in this theatre. With that said, the speakers somewhat make up for this problem. To conclude this case study, we very much understand about how the acoustic design such as architectural layout and materials used can play a very large role to control the desired sound and unwanted noise caused by various sources, and how it affects the people using the theatre. This project has benefit us as future architects to design a more effetive and comfortable space for people in the future, especially for something underappreciated such as acoustics. 37
- 39. 6.0 REFERENCES • Absorption Coefficient Chart. (n.d.). Retrieved from https://www.acoustic-supplies.com/ absorption-coefficient-chart/ • Acoustic performance. (n.d.). Retrieved from https://www.woodsolutions.com.au/articles/ acoustic-performance • Acoustic properties of wood. (2014, January 09). Retrieved from https://www.woodproducts.fi/ content/acoustic-properties-wood • Door & Window Solutions. (n.d.). Retrieved from https://acousticalsolutions.com/product- category/doors-windows/ • Grondzik, W.T.& Kwok, A.G. (2015). Mechanical and electrical equipment for buildings. New Jersey: John Wiley & Sons. • Superior sound proofing, acoustics engineered. (n.d.). Retrieved from http:// www.rockwoolasia.com/advice/benefits-of-rockwool/acoustics/ 39