Building Science II

BUILDING SCIENCE II BLD 60803

Project 1: Auditorium: A case study on Acoustic Design

Tutor : Mr. Edwin Chai Phey Chiat Chow Wei Qi Goretty Lee Pey Shy Joslyn Siew Zi Tong Koh Jing Fan Ong Yi Teng (Crystal) Serene Lim Jia Yi Toh Yi Lin Yap Shu Won

0334480 0331447 0326837 0334488 0330792 0326486 0334258 0327984 0331392

CONTENT 1.0 INTRODUCTION 1.1 Aim and Objectives 1.2 General information 1.3 Historical Background of DPAC 1.4 Context and Location 1.5 Floor Plan 1.6 Reflected Ceiling Plan 1.7 Section 2.0 ACOUSTIC DESIGN ANALYSIS 2.1 Sound Source 2.2 Sound Propagation 2.2.1 Sound Distribution 2.2.2 Sound Reflection 2.2.3 Sound Diffraction 2.2.4 Sound Delay and Echo 2.2.5 Sound Shadow 2.2.6 Echo Flutter 2.3 Potential of Noise Intrusion 3.0 CONSTRUCTION MATERIALS ANALYSIS 3.1 Construction Materials Used 3.2 Calculation ( Reverberation Time ) 4.0 SOUND DEFECTS AND DESIGN ISSUES 5.0 CONCLUSION 6.0 REFERENCES

1.0 INTRODUCTION

1.1 Aim and Objectives We are required to conduct a case study on a local auditorium in a group of eight and produce a report towards the acoustical analysis study in the auditorium.

The aim of the project is to allow students to understand the acoustical theories in a chosen auditorium. The objectives of this project include: • To analyze the acoustic characteristics of an auditorium • To determine the use of the construction materials in an auditorium that affect the transfer of sound • To determine the acoustic qualities of an auditorium and ways to improve them • To allow exploration and understand the design of an auditorium to the public

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1.2 General Information Name of Auditorium : Damansara Performing Arts Centre Address : H-01, DPAC, Empire Damansara, Jalan PJU 8/8, Damansara Perdana, 47820 Petaling Jaya, Selangor, Malaysia.

Chosen Auditorium : Proscenium Theatre Total seats : Max. 200 pax Stage : 11.25m (width) x 7.25m (depth)

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1.3 Historical Background of DPAC

Built in 2013, Damansara Performing Arts Center (DPAC) was the end-result of its Artistic Director, Wong Jyh Shyong’s hard work and dedication towards a better platform to enable local dance artists to have more engagement with international artists. The establishment of DPAC was also missioned to accommodate the sheer growing numbers of arts practitioners in Damansara and neighbour districts.

DPAC is dedicated in promoting arts through learning, practising and appreciating arts in Malaysia. It aims to enhance public awareness on how art-forms are able to enrich people’s lives and shape a better world. DPAC has a proscenium theatre, a black box, an experimental theatre, an indoor theatre-foyer and several dance studios. These are all state-of-the-art facilities to ensure professional practices could be carried out regardless of the forms of the arts performed.

DPAC does not contain itself in a standalone building. It is located inside the car park in an office building. Since it was an add-on to the building, several modifications had to be made to facilitate the construction of DPAC. A column of the building had to be removed to accommodate more seats and to remove view disturbance. As a result of this, metal truss then replaced the removed column and supported the rood. To enhance sound insulation, the area of the rooms had to be extended and the interior was finished with industrial metal containers and plates. All of these modifications had resulted in two changing rooms, one at the back stage and another on the level above.

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1.4 Context and Location Menara Gamuda

DPAC Empire City PJ Trade Centre

LDP way

High

Empire Damansara

Metropolitan Square Condo

Damansara Performing Arts Centre (DPAC) is located within Empire Damansara, Damansara Perdana, a mixed development that satisďŹ es both business and lifestyle needs. It is located in a prime location in Petaling Jaya and can be accessible easily from different directions through many major highways.

It is sits comfortable more than 150 meters from Lebuhraya Damansara - Puchong highway which is one of the main road connecting between Damansara and Puchong and it is mainly congested during peaks hours including lunch time, increasing the sound travelling distance and therefore reducing the noise.

However, DPAC is facing to the northwest of a large contour area of vegetation, which as a partial sound absorber that helps in aiding the reduction of background sound. When one is inside DPAC, you could hardly hear any noises from the busy road.

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1.5 Floor Plan

Scale 1:200

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1.6 Reflected Ceiling Plan

Scale 1:150

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1.7 Section

Scale 1:200

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2.0 ACOUSTIC DESIGN ANALYSIS

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2.1 Sound Sources in DPAC Sound

Sounds are vibrating waves that could be produced by musical instruments, human vocal cord, running engine, vibrating loudspeaker diaphragm and so on. Sound can be propagated through a medium such as air, water or even solid. Difference between sound and noise is noise are unpleasant, loud and disturbing.

1.Speakers

Plan of DPAC

Locations of Speaker 9

Section of DPAC

Locations of Speaker

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2.Human Vocal Chord(Performers such as Acapellas) Human vocals of performers are also consider as sound source as they are well-trained before go on stage to perform.

Plan of DPAC

Section of DPAC

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3.Musical Instruments Music made by musical instruments are also consider as sound because musics are desirable.

Plan of DPAC

Section of DPAC

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2.2 Sound Propagation Propagation of sound can be simply defined as a sequence of waves of pressure traveling through a compressible media. In the event of propagating, the sound waves can be reflected, refracted, or attenuated by the medium. Sound propagates outwards from a point source in a spherical wavefront as shown below:

Diagram 2.2.1 shows spherical propagation of sound

The diagram below shows the scenario of sound under reflection, diffusion, dispersion, diffraction and also other factors of propagation:

Diagram 2.2.2 Scenario of sound propagation

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2.2.1 Sound reflection When sound travels in a given medium, it strikes the surface of another medium and bounces back in some other direction, this phenomenon is called the reflection of sound.In the case of this theatre, sound sources from the stage reflects on the reflective panels to the audience.

Reflected sound

Direct sound

i

r i=

r

Surface Diagram 2.2.3 shows reflection of sound on the surface of certain medium

It is important to make sure to obtain an early reflection (99%) as it is used to reinforce direct sounds (1%). However, we have to be careful to reduce late reflection as it will contribute to echoes.

Audience seating layout affected by sound reflection Vertical reflective panel

2100mm

Direct Sound Reflected Sound

Diagram 2.2.4 set back of audience seating

Seats are set back from the stage at a distance to accommodate the shown reflected sound without being interrupted by the vertical reflective panel. The front seats are strategically located to receive the smallest angle of reflected sound from the sound source.

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Sound reflection analysis on plan The walls of the DPAC theatre are not symmetrical on plan view, this results in a messy reflection of sound waves that leads to various different directions. This leads to a difference in sound distribution on both sides of the audience.

There is no intention in leading the reflected sound towards certain direction that might potentially help with the overall quality of sound propagation. However, on the positive side, a wider range in the audience can be covered

Diagram 2.2.5 Sound reflection on plan view

This side of the theatre has a wider reflected range due to the angled walls.

This side of the theatre has more concentrated sound distribution. However, the reflected sound only reaches a small range of audience before it loses energy.

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Sound reflection analysis on section

Suspended front reflective panel

Suspended side reflective panel

In order to create a wider area of useful reflective ceiling and also effectively reflect sound to the audience, sound reflecting panels are placed suspended from the ceiling.

Diagram 2.2.6 Reflective ceiling plan with indication of suspended reflective panel

Vertical panel is placed attached to the ceiling in between the audience and stage to prevent the stage lighting to affect the audience experience.

This degrades the efficiency of sound reflection.

Diagram 2.2.7 Sound reflection on the suspended front ceiling panels

Diagram 2.2.8 Sound reflection on the suspended side ceiling panels

The grey area shown in the diagram 2.2.7 is the “live” area. This shows a slight defect as the center-to-back of the audience seemingly receives less of the reinforced reflected sound.

However as shown in the previous analysis on plan,the reflected sound mostly leads towards said area so it makes up for this defect.

The suspended side reflective panels reflect the sound waves towards the walls to later be diffused for a more even sound distribution.

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4790mm

Diagram 2.2.9 Live area with suspended reflective panel

3375mm

Diagram 2.2.10 Live area without suspended reflective panel

Looking at the diagrams above, we can conclude that by introducing the suspended reflective steel panels it lengthens the range of useful ceiling reflection, reaching a wider range of audience.

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2.2.2 Sound diffusion Sound diffusion is a method of spreading out sound energy with a desired element, a diffuser, for better sound in a certain space (Calder, 2018), These “diffusers” are usually in the form of corners, edges, scattering and irregularities of elements. These “diffusers” helps to diffuse high frequency sound with short wavelength which breaks and disperse throughout the theatre. In the case of DPAC, there are a few prominent “diffusers”: 1.

Zig zag reflective steel panels 2.

Lightings 3.

Cornerings 4.

Stairs Below shows the diffusion of sound on the zig zag reflective steel panels. The rest of the “diffusers” act according to the same method of diffusion:

Direct sound Diffused sound Diagram 2.2.11 shows corrugated Surface of The Steel Panel Diffuse The Sound Evenly to The Audience

2 3

3

1

1

4

4

4 3

Diagram 2.2.12 Sound diffusion on section view

Direct Sound

Diffusion of Sound

3

1

1

Sound source Diagram 2.2.13 Sound diffusion on plan view

Referring to the part ‘Construction of materials used’ in this report , it is shown that the zig-zag reflective steel panels covers a majority of the walls surrounding the audience in the theatre. Hence, a wide portion of the sound that are reflected by the panels are diffused, resulting in a considerable evenly distributed sound around the theatre. Furthermore, the other “diffusers” are also positioned in various spots around the theatre as shown in the above diagram. Therefore, the diffusion of sound in DPAC is effective. This can be shown in the sound distribution data collected.

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2.2.3 Sound delay and echo Sound delay is simply a repetition of a same sound at a later time (techtalk, 2019). These are usually the resultant of reflection of sound. However, depending on the time taken of the reflected sound to reach the listener, it will result in either a effectively reinforced sound or would end up as an echo. This can be calculated by the following formula:

Time delay = (R1 + R2 -D)/0.34 Time delay Time delay

30msec - Effective reflective sound 40msec - Delay

Sound delay calculation on plan perspective

R1

R3

D

R4

R2 Sound Source Direct Sound Reflected Sound Listener

R1 = 10.2m R2 = 11.0m R3 = 10.3m R4 = 10.5m D = 11.2m Diagram 2.2.14 Sound delay calculation of center-back position in audience

Calculation Time Delay 1 = (R1 + R2 - D) / 0.34s = (10.2 + 11.0 - 11.2) / 0.34 = 29.4msec ...

No delay

Time Delay 2 = (R3 + R4 - D) / 0.34s = (10.3 + 10.5 - 11.2) / 0.34 = 28.24msec ...

No delay

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R1

D R2

Sound Source Direct Sound Reected Sound Listener

R1 = 10.6m R2 = 18.2m D = 14.0m Diagram 2.2.15 Sound delay calculation of left-back corner position in audience

Calculation Time Delay = (R1 + R2 - D) / 0.34s = (10.6 + 18.2 - 14.0) / 0.34 = 42.35msec ...

Sound delay

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R1

D

R2

Sound Source Direct Sound Reected Sound Listener

R1 = 10.6m R2 = 17.6m D = 14.0m Diagram 2.2.16 Sound delay calculation of right-back corner position in audience

Calculation Time Delay = (R1 + R2 - D) / 0.34s = (10.6 + 17.6 - 14.0) / 0.34 = 41.76msec ...

Sound delay

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R1

D

R2

Sound Source Direct Sound Reflected Sound Listener

R1 = 11.0m R2 = 12.0m D = 16.2m Diagram 2.2.17 Sound delay calculation of back position in audience

Calculation Time Delay = (R1 + R2 - D) / 0.34s = (11.0 + 12.0 -16.2) / 0.34 = 20msec ...

Effective

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Sound delay calculation on section perspective

Diagram 2.2.18 Reflected ceiling plan with indication of ceiling and reflective panel

R2

R1

D

Diagram 2.2.19 Time delay calculation in section view reflected on the suspended reflective panel R1 = 8.0m R2 = 6.0m D = 8.4m

Calculation Time Delay = (R1 + R2 - D) / 0.34s = (8.0 + 6.0 - 8.4) / 0.34 = 16.47msec . . . Effective

Direct Sound Reflected Sound

R4 R2 R3

R1 D

Diagram 2.2.20 Time delay calculation in section view reflected on the suspended reflective panel and ceiling

Calculation R1 = 13.6m R2 = 3.9m R3 = 12.0m R4 = 7.0m D = 15.0m

Direct Sound Reflected Sound

Time Delay 1 = (R1 + R2 - D) / 0.34s = (13.6 + 3.9 - 15.0) / 0.34 = 7.35msec ...

Time Delay 2 = (R3 + R4 - D) / 0.34s = (12.0 + 7.0 - 15.0) / 0.34 = 11.76msec

Effective. Also shows that there’s no sound shadow

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2.2.4 Sound shadow The previous calculation shows that there is no sound shadow below the deck. To further prove this aspect, the calculation below will show that the dimensions respects the theory shown:

D

2H

D H

Diagram 2.2.21 Sound shadow calculation

Calculation D = 2.0m H = 3.2m 2H = 6.4m ... ...

D

2H

No sound shadow

Conclusion The time delay calculations shows alternate results. Therefore, it shows that the theater has a seemingly poor sound delay performance.

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2.2.5 Echo Flutter Echo flutter is an energy that’s trapped between two parallel surfaces, resulting in a repetition of the same ‘track’ in a span of only a few milliseconds (Foley, 2014). It is important for a theatre like DPAC to eliminate as much echo as possible. However, the theatre itself exists in a rather right angled form, which directly promotes the existence of echo flutter.

Below shows how DPAC have used simple solutions to overcome this defect:

d = 17.2m

Diagram 2.2.22 Indicating angled wall and distance between stage backdrop and back wall

The walls on one side is slightly slanted at an 85 degree angle, which disrupts the originally parallel walls on both sides of the theatre. Hence, flutter echo fails to occur

The distance from the backdrop of the stage towards the wall at the back of the audience that is supposingly parallel are far enough apart to minimise the effect of echo flutter.

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44.9dB

30.5dB

44.1dB

46.6dB

47.1.1dB 45.4dB

45.6dB

34.5dB

35.5dB

35.8dB

35.2dB

35.3dB

Diagram 2.2.25 Sound distribution of Huawei smartphone music with highest volume in the seating area

33.2dB

34.0dB

Sound source

Analysis According to diagram 2.2.23, the noise is considerably distributed evenly with difference of not more than 1dB at different position. The position siding the entrance has a higher reading due to it being under a deck (refer to section) where there are functioning equipments that emits noise. The recording in diagram 2.2.24 has a more uctuated reading due to the inconsistent delivery of sound amplitude during a speech whereas in diagram 2.2.25 Is more consistent and accurate. Overall, the sound distribution is considerably evenly distributed and at the same time shows that the sound propagation strategies applied is in an acceptable range but with potential for better improvements.

Diagram 2.2.24 Sound distribution of normal speech level the seating area taken from the stage

45.7dB

30.4dB

Diagram 2.2.23 Sound distribution of noise (air-borne, structure-borne, inside noise) in the seating area

31.6dB

30.1dB

32.0dB

30.9dB

30.1dB

Sound source

The readings from the digital sound level meter is recorded in different positions in the seatings of the theatre with a constant sound source from the stage. We have recorded different scenarios of sound including: silent (without air conditioning system running), Normal speech level and Huawei smartphone music with highest volume, to analyse a more accurate data.

2.2.6 Sound distribution

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2.3 Potential of Noise Intrusion Noise is unwanted sound judged to be unpleasant, loud or disruptive to hearing.

From a physics standpoint, noise is indistinguishable from sound, as both are vibrations through a medium, such as air or water.

For noise intrusion, two main groups can be identified: 1.

External noise sources There are multiple noise sources from the outside of the auditorium. It can be produced by the road traffic, opening on closing of the doors, human sounds and human chatters.

2.

Internal noise sources Some of the noises comes from the electrical appliances. The acoustics door, flooring and stages also produce some noises. Besides, the audience from the seats also creates various noises such as chatters, sneezing, body movement, etc. There are some preventions were made to minimize the noise intrusion in the auditorium hall.

There are two ways in which noise (or sound in general) can be transmitted in acoustics hall: 1. Air-borne Sound Transmission The noise is transmitted through the air from its sources. Along the continues air paths through opening,such as open doors, cracks around doors and electrical fixtures.

2. Structure-borne Sound Transmission Sound energy from a sources sets into vibration solid parts of the building structure, it is transmitted directly through the structure is radiated from building structure.

Levels of Noises Produce Both Psychological and Physiological Effects: 65 dBA: up to this level of noise may create annoyance, but its result is only physiological (bodily fatigue). Above this level, psychological effects such as mental and nervous effects, may occur.

90 dBA: many years of exposure to such noise levels would normally cause permanent hearing loss.

100 dBA: with short period of exposure to this level, the aural acuity may be impaired temporarily, and prolonged exposure is likely to cause irreparable damage to the auditory organ.

120 dBA: causes pain.

150 dBA: causes instantaneous loss of hearing (deafness).

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External Noise Source Vehicles (Air borne noise) DPAC is located inside Empire Damansara, Petaling Jaya. It is sits comfortable more than 150 meters from Lebuhraya Damansara - Puchong highway which is one of the main road connecting between Damansara and Puchong and it is mainly congested during peaks hours including lunch time, increasing the sound travelling distance and therefore reducing the noise.

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

However, DPAC is facing to the northwest of a large contour area of vegetation, which as a partial sound absorber that helps in aiding the reduction of background sound. When one is inside DPAC, you could hardly hear any noises from the busy road as it is quite far from the main road too.

Diagram 2.3.5 shows position of DPAC beside a roadside

Diagram 2.3.5 shows site context of DPAC

DPAC TNB

JALAN PJU 8/8 Figure 2.3.5 shows position of DPAC beside a roadside

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External Noise Source Entrances (Air borne noise) Sound intrusion can be identiďŹ ed when there is opening and closing the door or even the sound of human talking taking place outside the theatre. However, there is a sound lock which prevent from interfering the audience that sit near to the door and it serves as a function to trap the sound waves in sound lock with the outer door.

Figure 2.3.1 Door to enter the Sound Lock area

Diagram 2.3.1 Doors and Sound Lock Area

Figure 2.3.2 Door to enter the Auditorium

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External Noise Source Backstage door (Air borne noise) There is a backstage door acting as an entrances for the performances which also lead to the basement parking lot and loading bay. It is also another sound intrusion could be founded.

However, the backstage door is designed with the combination of 25mm rockwool core inďŹ ll which can absorb and minimize the noise from entering into theatre.

Rockwool is one of the effective acoustics insulation solution as they provide airborne sound absorption which can remarkably improve the acoustics which due to its high density, non directional ďŹ bres that trap the sound waves and absorb vibration.

Diagram 2.3.2 Location of the Backstage Door

Figure 2.3.3 and Figure 2.3.4 above are showing the backstage door that causes the external noise source

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Internal Noise Source Light fixture (Air borne noise) Light fixture as lighting system might produce some buzzing sound. There are LED strip was kept inside by the internal steel panel where the buzzing noise would be heard if someone are sitting right beside the steel panel.

LED strip are making the buzzing noise is due to improper dimming or electromagnetic interference from others devices causes vibration in the light bulb which will produce some buzzing sound.

The solution was fix the dimmer that compatible the LED strip to ensure there are no more humming sound produced.

Diagram 2.3.4 The Location of the Light Fixtures

Diagram 2.3.5 The Location of the Light Fixtures

31 Figure 2.3.5 The Fixtures csn be Identified behind Steel Panels

Internal Noise Source Ducting & Diffuser (Air borne noise) Ducting and diffuser supply positive pressure distribution systems and negative pressure ducting for exhausting air from rooms. It is one type of sound intrusion that could be identiďŹ ed due to the high pressure of air distribution.

In DPAC, Centralized Air Conditioning with delivery duct is used, such as Fan Coil Unit, diffuser and ducting. Fan Coil Unit with low noise and diffuser with low regeneration noise is one of the selection for acoustics hall. Ducting with internal lining of rockwool and thermalrock with tissue facing to ensure acceptable indoor air quality as good as thermal comfort.

Figure 2.3.6 shows the ducting above the stage

Figure 2.3.7 shows the ducting at the back stage

Diagram 2.3.6 shows the location of ducting and diffuser

Figure 2.3.8 shows the ducting at the right side of the auditorium

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Internal Noise Source Air conditioning system (Structural borne noise) In any indoor room, the noise of a functioning air-conditioning unit is inevitable. It is the type of sound transmitted through structural borne in which sound is vibrating on the solid surface of the AHU duct. This issue also occurs in DPAC. Therefore, the seats were designed in such way that the metal stand beneath incorporates air conditioning openings on every seats. There are initiatives taken which has minimize the sound of air ow in the audience seating area.

OPENINGS SLAB

AIRPlywood DUCT

FCU UNIT

FOAM LAYERS staircase

REDUCE AIR FRICTION AND ABSORB SOUND FROM FCU UNIT

Diagram 2.3.7 and Figure 2.3.9 shows the air-conditioning mechanism below the seats in the auditorium

Diagram 2.3.8 shows the FCU Unit and the connecting pipings to the auditorium seats

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Internal Noise Source Squeaky Staircase (Structural borne noise) It is extremely disturbing when the audience happen to enter and leave in the middle of the performance, and the squeaky sound from the staircase. The sound is transmitted through structural-borne, where sound vibrates on the solid hard surface of the plywood. The solution to reduce the noise can simply done through a selection of softer material like carpet to cover over the staircase.

r

oo

 te e r nc

Co

od o lyw

se

ca air

st

P

Figure 2.3.10 shows material of staircase

Diagram 2.3.9 shows location of staircase

Diagram 2.3.10

Figure 2.3.10, Diagram 2.3.9 and Diagram 2.3.10 shows the staircase as the disturbance that may interrupt the audience towards the performances

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Internal Noise Source Performance stage flooring (Structural borne noise) DPAC is mainly serve for musical production, drama and small scale dance. It is advisable to consider the probability of sprung floor to provide some degree of bounce and flex under impact. The sprung floor are suspended on transducers that act like shock absorber.

The stage is made of plywood, it has sound control which bounces high frequencies, resonating better sound quality, and absorbing bass energy. Also, plywood are more durable and economical.

Due to space limit, theatre was built with a shallow apron between the stage and audience seat. Where the noise of the stage floor might be very loud to the audiences.

Therefore, the stage floor is covered with vinyl sheet to increase slip resistance and reduce the noise.

Stage Apron Audience seat

Audience seat

Stage Apron

Diagram 2.3.11 Located Flooring Type Figure 2.3.11 Flooring Type in Auditorium

Vinyl Sheet

Plywood

Dual density shock dampening elastomer blocks at predetermined interval.

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Diagram 2.3.12 Plywood Flooring and Vinyl Sheet

3.0 CONSTRUCTION MATERIALS ANALYSIS

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1.

Ceiling

Materials: Concrete Slab + Spray Foam The ceiling is made up of concrete to form a concrete slab. Due to its ability to reflect sound since it is a hard surface, a layer of sound insulation must be applied in order to reduce the resultant sound cause by the reflection.

In DPAC, spray foam is used as a layer covering the concrete slab as it is able to reduce the sound reflection cause by the concrete itself. Therefore, the dampening of sound can be increased by using spray paints. The spray foam is able to absorb a small amount of sound but most of the sound are dispersed out from it

Figure 3.1 above and the diagram 3.1 on the right is showing the location of the ceiling in the auditorium

The diagram 3.2 above shows the spray foam that reduces the reflection of the sound waves

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2. Reflector Panel Materials: Plywood The reflector panels are defined as the panels that are hang up just below the ceiling as a purpose to reduce the sound reflection and its impact to the receiver (audience).

Since the ceiling with spray foam can only reduce part of the sound waves, the reflector panel acts to reduce sound reflection by blocking part of the sound waves via absorption. Part of the sound is then transmitted through the reflector panel and is delivered to the receiver. The reflector panel can absorb only low frequency sound, while the high frequency sound bounce on it.

The direct sound can be heard clearer for those who are sitting at the back as the mass reflection of sound can be reduced by using reflector panels. Thus, the sound are distributed and reflected equally to the audience.

The diagram 3.3 and the Figure 3.2 above show the reflected ceiling plan with the highlighted reflector panels

The diagram 3.4 above shows the sound waves reflection at the reflector panels

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3. Acoustic Treated Wall Materials: Fibre Board, Rockwool, Concrete The combination of the materials creates sound insulating wall which it reects and transmit part of the sound into the wall. The acoustic treated wall is made up of 3 layers mainly the ďŹ bre board as the layer facing the interior of the auditorium, the rockwool as the middle components, and a layer of concrete at the other side of the wall.

Acoustic Treated Wall

Zig-Zag Steel Panel

Figure 3.3 shows the Attachment of Panels to Walls

Diagram 3.5 shows location of Acoustic Treated Wall

Diagram 3.7 above shows the coverage of the acoustic treated wall

Diagram 3.6 shows the components of the Acoustic Treated Wall

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Fibre Board

Rockwool

Fibre Board makes up 90% of wood and it is often used as heat-proof or acoustic materials.

The ďŹ bre board is used due to its ability to absorb or transmit part of the sound into the wall especially high frequency ranges

It is a high density product which is made up of liquid rocks forming into wool.

It works as either by impeding the sound transmission through a structure or absorption of sound at its surface.

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4. Zig-Zag Steel Panels Materials: Steel Since it is an auditorium, it is important to diffuse the sound as diffusion of sound minimizes the coherent reections that causes distinct echoes. It is also functioning as to make an enclosed space sound larger.

Acoustic Treated Wall

Zig-Zag Steel Panel

The figure 3.4 shows the highlighted zig-zag steel panels

Incident Sound

Diffused Sound

Diffused Sound

Diagram 3.8 shows the location of zig-zag steel panels

Diffused Sound Diffused Sound

Diagram 3.9 shows the diffusion of sound waves at the zig-zag steel panels

The diagram above shows the diffusion of the sound when the sound hits the steel panels.

Diffusion of those sound does not remove much of the energy. Instead, they are diffused and the reection of the sound is greatly reduced to provide an ambient and more lively space 41

5. Cyclorama Wall Materials: Fibre Board, Steel Framing This wall is located on the stage which is used to define the boundary of the stage. It is also a sound barrier to the backstage or vice versa as this structure is mainly made up of fibre board at both sides, and the steel framing system which holds the fibre boards.

Due to the white colour of its surface, it creates reflection of light and forms a focus point to the audience

Acoustic Treated Wall

Figure 3.7 above shows the Cyclorama Wall

Zig-Zag Steel Panel

Diagram 3.11 above shows the materials of the Cyclorama Wall

stage

backstage

Diagram 3.12 above shows the Location of Cyclorama Wall

Diagram 3.13 above shows the sound waves created from the backstage. The transmitted wave is weak due to the ability of the fibreboard to absorb sound waves.

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6. Flooring Materials: Concrete, Plywood Since the walls are installed with zig-zag steel panels, DPAC use only concrete flooring for the audience to walk, and plywood lied with vinyl sheet as stage to ensure the safety of the performers.

Due to the hard surfaces of the concrete flooring together with the plywood stage flooring, the sound waves might bounce and reflect to the whole theatre. This reflection of sound is reduced with the installation of the zig-zag steel panels which can diffuse the sound in the auditorium and the absorption of sound by the audience.

Acoustic Treated Wall

Zig-Zag Steel Panel

Plywood flooring

Concrete flooring

Figure 3.5 and the Diagram 3.10 show the location and the materials used as the floor of the auditorium

Dance Vinyl Flooring This type of flooring has a high slip-resisting property. It is installed on the plywood flooring which is the stage as to increase the performers safety. However, it does not have any effect towards sound absorption.

Figure 3.6 Vinyl Sheet (Dance Anti-Slip Flooring Sheet)

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7. Staircase Materials: Plywood, Metal Plate The staircase is made up of plywood fixed to the metal plate which is rarely noticeable from the eye level. Both the materials have a flat and reflective surface therefore the sound waves are not absorbed by them.

The plywood has a coated surface, which reflects the light to the audience for walking safely in the auditorium, while there is also the LED lighting which is hidden underneath the concrete flooring and near to the metal plate.

Figure 3.8 above shows the plywood staircase

Diagram 3.14 above shows the sectional diagram of the staircase

Diagram 3.15 above shows the location of the plywood staircase

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8. Curtain

Duvetyn Bolton Twill Fabric Velvet Fabric

Diagram 3.16: Location of different kind of curtains in DPAC

There are three types of curtain found in DPAC. Duvetyn, Bolton Twill fabric as well as Velvet fabric.The main function for these curtains are to hide the lights from entering the auditorium.

This is to prevent disturbance while the performance is going on. It can also absorb sound as well as decrease excessive echo delay.

Bolton Twill Fabric Bolton twill fabric is used as a covering for the control space entrance. It is cost friendly and extremely durable. The purpose of using this curtain is to reduce sound penetration and to avoid sound from transferring through the structure. It is indeed a great choice for theatrical curtain.

Figure 3.9: Bolton Twill fabric in DPAC

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Velvet Fabric

Figure 3.10 shows the velvet fabric at the entrance to the auditorium

Diagram 3.17 shows the location of the velvet fabric

Velvet fabric was placed at the entrance of DPAC. It is very durable and it can reduce sound penetration and also to avoid sound to transfer through the structure. Due to it’s soft characteristics, it can absorb sound effectively. Besides that, it can also prevent lights from entering the theatre.

Duvetyne Fabric

Figure 3.11 shows the duvetyne fabric in both sides of the stage acting as a stage skirting.

Figure 3.12 shows the texture of duvetyne fabric.

Duvetyne fabric is placed at both sides of the stage. This is to prevent lights from the backstage to penetrate to the audience or vice versa. It is also to hide the performers who are preparing for the show. Duvetyne helps to reduce reection of light and is also ďŹ reproof material. It is one of the most economical masking fabrics. It is ideal for blocking out unwanted light as it is high opacity.

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9. Seat Materials: Foam & Fabric Cover, Plywood, Steel The seat is made up of foam and covered with fabric to maximize the absorption of sound. The seat must be able to absorb sound waves like a human sits on it. It should be as effective as the sound absorption of one human being is equal to a seat.

The hand rest which is made up of plywood has not much effect on sound absorption and sound reection and therefore this part can be neglected.

The steel stand is an important material to support the seat. It also functions as an air conditioning system to ventilate the auditorium but this creates noise where this will be further discussed in the noise intrusion section.

Figure 3.13 shows the components of the seat

Diagram 3.18 shows the seats in the auditorium

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10. Door Materials: Plywood, Rockwool Auditorium acoustic door are used in DPAC where sound and noise control is in primary concern. Sound waves can be greatly reduced either from the exterior to the interior of the auditorium or functioning from the other way round. This is essential in designing an auditorium so the audience or the performers will not be able to receive the sound waves that are transmitted from the exterior of the space.

The acoustic door is made up of plywood and rockwool in which the rockwool is a good sound absorber while blocking unnecessary noise from the exterior of the auditorium.

normal door

Figure 3.15 above shows the normal door which is the entrance to the sound lock before the acoustic door to the auditorium

Diagram 3.19 shows the location of the acoustic door and the normal door of the auditorium

normal door

acoustic door

acoustic door

Figure 3.14 above shows the ‘sound lock’ space in between the normal door and acoustic door

Figure 3.16 shows the acoustic door which is the main entrance to the auditorium

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Sound Lock Sound lock is an important design to an auditorium as to reduce the noise that is coming from the exterior of the auditorium that might interrupt the performance and the enjoyment of the audience towards the performance.

auditorium

Sound lock

entrance Diagram 3.20

Entrance

‘Sound Lock’ Space

Auditorium

Sound Waves (Noise) from Exterior

Sound Transmission Sound Reflection and Absorption Reflected Sound Waves

Diagram 3.21

Diagram 3.20 and Diagram 3.21 above is important in explaining the design of sound lock to the transmission of sound from the exterior of the auditorium. As shown in the diagram, most of the sound is transmitted through the normal door into the ‘sound lock’ space. As sound has to transfer a distance of air to the acoustic door, part of the sound waves have been turned into heat energy and dissipates in the air. Since the acoustic door is installed with absorbing materials, the sound is unable to transfer into the auditorium and therefore the sound is greatly reduced so the quality of sound system and performance in the auditorium is enjoyable by the audience 49

3.2 Calculation of Reverberation Time Introduction Reverberation time is defined as the time for the sound pressure level in a room to decrease by 60dB from its original level after the sound is stopped. The reverberant sound in a room will fade away due to the sound energy bouncing off. This often caused by absorption by multiple reflections between the surfaces of a room.

It is dependent upon the following variables: 1. The volume of the enclosure (distance) 2. The total surface area 3. The absorption coefficients of the surfaces Hence, reverberation time can be calculated by the Sabine Formula:

Where: RT = reverberation time (sec) V = volume of the room (cu.m) A = total absorption of room surfaces (sq.m sabins)

Reverberation Time Calculation Volume of Auditorium

A

B

C

Diagram 3.22 shows plan of auditorium

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C

B

A

Diagram 3.23 shows section of auditorium

Estimated Floor Area (m²) A : 173.46 B : 160.70 C : 29.61 Estimated Volume (m²) A : 1243.88 B : 1854.64 C : 87.50 Total Volume of Auditorium (m ) = 3186.02m 3 3

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A

C E B

Diagram 3.24 shows ceiling plan of auditorium

A

B

Surface

C

D

Material

E

Area

500Hz Absorption coefficient

Abs. units (m² sabins)

A

Flooring ( Stage )

Plywood

128.210

0.050

6.41

B

Flooring ( Audience )

concrete

106.000

0.020

2.12

C

Staircase

Plywood

7.828

0.050

0.40

D

Staircase (Metal Plate)

Steel

8.710

0.080

0.70

E

Human / Seat

cushion

169.000

0.042

7.10

Total Absorption (A)

16.73 52

F A

C

E

D

B

E

G

Diagram 3.25 shows section of auditorium

A

B

Surface

F

C

Material

D

G

Area

500Hz Absorption coefficient

Abs. units (m² sabins)

A

Door

Plywood + Rockwool

6.00

0.10

0.60

B

Transition Curtain

Velvet Fabric

16.80

0.25

4.20

C

Interior Curtain

Bolton Twill Fabric

4.00

0.10

0.40

D

Zig-zag steel panel

Steel

215.35

0.88

189.51

E

Stage Curtain

Duvetyn,

101.00

0.20

40.96

F

Acoustic Treated Wall

Fibre Board, Rockwool, Concrete

358.92

0.75

269.19

G

Cyclorama Wall

Fibre Board, Steel Framing

85.00

0.30

25.50

Total Absorption (A)

530.36

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A A B

B Diagram 3.26 shows ceiling plan of auditorium

Surface

Material

Area

500Hz

Absorption coefficient

Abs. units (m² sabins)

A

Ceiling

Concrete Slab + Spray Foam

363.70

0.15

54.56

B

Reflector Panel

Plywood

21.86

0.05

1.09

Total Absorption (A)

55.65

3

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Total Abs Unit = 16.73 + 530.36 + 55.56 = 602.65m² sabins Total Volume of the Theatre 3 = 3186.02m

REVERBERATION TIME

= 0.16V / A = 0.16(3186.02) / 602.65 = 0.85sec

DPAC

Table 3.27 shows where the auditorium lies in the optimum reverberation time in different types of auditorium and halls.

3

The reverberation time for auditorium is 0.85sec with 3186.02m which falls within the average range of recommended reverberation time. This shows that the materials used compromise with volume of the theatre to achieve an adequate reverberation time. The theatre accommodate both speeches and musical events, therefore the reverberation time is balanced in between to suit both the function.

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4.0 SOUND DEFECTS AND DESIGN ISSUES

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Acoustical Defects & Design Issue Squeaky noise produced by staircase The footstep of people walking on the plywood staircase along the aisle of the theatre creates low frequency vibrations that transmitted through structure-borne. This low frequency vibrations tend to vibrate throughout the whole structure which create squeaky noises that is unpleasing to the audience.

FIgure 4.1 above shows plywood staircases

Diagram 4.1 above shows squeaky noise produced by footsteps.

Design Solution & Suggestion To protect the audience from these unnecessary noises, the impact of noise generation can be reduced through the use of thick carpeted ooring for the staircase along the aisle as it acts as an outstanding sound absorber and serving as an acoustical aid. Carpet has a higher absorption coefďŹ cient of 0.50 for 500 Hz as compared to plywood of 0.05 for 500 Hz. Besides, shock absorbing underlayment also plays an important role in addressing this issue by further improving the sound absorption quality.

Carpet Rubber Plywood

Diagram 4.2 above shows sectional drawing of proposed treated staircase.

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Acoustical Defects & Design Issue Poor Sound Isolation I. Ducting & Diffusers Ductings and diffusers are exposed everywhere within the theatre. Excessive high velocity of air that flows through the diffusers blades generates noise that penetrates into the theatre, thus affecting the acoustic quality in the theatre.

Figures 4.2 and Figure 4.3 above show exposed ducting and diffusers.

II. Light Fixtures The light fixtures behind the zig-zag steel panels serve as a decorative element that enhances the visual and aesthetic value of the theatre. However, it tends to create a buzzing and flickering sound generated by the ballast.

Figure 4.4 above shows zig zag steel panels.

Figures 4.5 and Figure 4.6 above show lighting wirings behind zig-zag steel panel.

Design Suggestion I. Ducting and diffusers should be covered by the ceiling and not exposed within the theatre.

II. Lighting should undergo frequent inspection and maintenance to ensure it does not produce internal noise that would affect the acoustic quality of the theatre. Installing an

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Acoustical Defects & Design Issue Mechanical Noises The machines of FCU Air Conditioning System is placed at the space below the seating area, which generates mechanical noises through discharging low velocity air supply from the openings below the seats, transferring it along the horizontal surface.

Diagram 4.3 below shows FCU Air Conditioning machines below seating area.

Figure 4.7 above shows openings below seats

Design Suggestion Openings should not be placed below the seats to avoid penetration of air ow that generates noises.

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Acoustical Defects & Design Issue Reflection The ceiling has a larger surface area of concrete slab with spray foam which reduces the reflected sound intensity, therefore, several reflecting panels should be added to the highlighted spaced below which is the center of ceiling to allow better sound spreading to all the areas within the theatre. This is to ensure that the reflected sound towards the back are better reinforced.

Figure 4.8 above shows area where reflecting panels should be added.

Additional Reflecting Panel

Direct Sound

Existing Reflecting Panel

Reflected Sound

Diagram 4.3 below shows reflection diagram when additional reflecting panels are added.

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5.0 CONCLUSION

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As a conclusion of our observations, data collection, and analysis on Damansara Performing Art Centre (DPAC), we have gained plenty of information on acoustical design in an auditorium. Besides rules and regulations on designing an auditorium, there is a need for an architect to design a space with materials that can tackle with the sound effects and issues in an auditorium that can serve a good acoustic performance to the audiences.

The DPAC is installed with building materials that can solve the issues of most of the acoustical problems, which results and fulfill the compliance to the reverberation time required by a small sized hall. The calculation of the reverberation time (RT) in a small size auditorium, DPAC has a RT value of 0.85s where the RT value is determined by the absorption coefficient of the materials and any of the thickness of the materials might also affect the RT value. For a small size auditorium, it is the best to maintain the RT value of this space to be lower than 1s.

Also, the analysing of several factors which include material properties, absorption coefficient, sound reflection, diffraction, absorption, diffusion, and echoes, are used to determine the sound waves transfer in an auditorium. This is important as the quality of sound that is to be delivered to the audience needs to be determined so that the audience will be able to get a great experience towards the performances in the auditorium.

Therefore, the study of the auditorium space is very important to an architect as this will introduce them to design an auditorium that is best fit to the public besides designing just a simple auditorium. As an architect, it is our job to build a comfortable environment to the public with suitable design.

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