Report

SCHOOL OF ARCHITECTURE, BUILDING AND DESIGN BACHELOR OF SCIENCE (HONS) IN ARCHITECTURE

Building Science II [BLD 61303]

Project 1 Case Study on Acoustic Design

Prepared by : Chong Jia Yi Ee Yun Shan Lee Ning Lee Zi Ying Lim Zia Huei

0320869 0319990 0320125 0320435 0321031 0320303 0319926 0320195

Ong Shi Hui Rachael Cheong Kah Yen Teo Kuo Chien Tutor : Mr. Azim Sulaiman

TABLE OF CONTENTS

1

INTRODUCTION 1.1 Aim and Objectives 1.1 Aim and 1.2Objectives Site Information and Historical Background 1.2 Site Information and Historical Background 2 ARCHITECTURAL DRAWINGS 2.1 Floor Plan .1 Floor Plan 2.2 Reflected Ceiling Plan 2.2 Reflected Ceiling Plan 2.3 Sections 23 ections 3 ACOUSTICS PHENOMENA 3.1 Introduction of Acoustics 3.2 Acoustics in Architectural 3.1 Architectural Acoustics 3.3 Issues of Acoustic Design Strategies 3.2 Issues3.4 of Acoustic Acoustic Design Design Strategies for an Auditorium 3.3 Acoustic Design for an Auditorium 4 METHODOLOGY 4.1 Measuring Equipments 4.1Measuring 4.2Equipments Method of Data Collection 4.2Method of Data Collection

5

ACOUSTICAL ANALYSIS 5.1 Material Absorption Coefficient-hazel Material Absorption Coefficient-hazel 5.2 Identification of Existing Sound Source/ Noise Identification of Existing Sound Source/ Noise - fish 6 ANALYSIS AND FINDINGS 6.1 Sound propagation 6.2 Different Phenomena in Sound

7

ACOUSTICAL DEFECTS AND DESIGN ISSUES

8

CONCLUSION

7.1 Poor Ensemble 7.2 Sound shadow 7.3 Poor Sound Isolation 7.4 Mechanical Noises

AUDITORIUM VIEW

Figure 1 : View of auditorium from stage

Figure 2 : View of stage

1 INTRODUCTION

1.1 Aim and Objectives The aim and objectives of this report is to showcase our analysis and understanding on the acoustic theory in a particular auditorium. Learning outcome are as followed: To study and understand the influences of the auditorium layout towards the public address system in a auditorium hall To study the characteristic and elements of the acoustic features of an auditorium hall and understand the function of the specific feature.

1.2 Site 1

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Name of Auditorium Location

: Damansara Performing Arts Centre : H-01, DPAC, Empire Damansara, Jalan PJU 8/8, Damansara Perdana, 47820 Petaling Jaya, Selangor, Malaysia.

T y p e o f A u d i t o r i u m : M u l t i p u r p o s e A u d i t o r i u m T o t a l S e a t : M a x i m u m 2 0 0 s e a t c a p a c i t y Stage Size : 11.25m (width) x 7.25m (depth) 1.2.2 Historical Background In the year of 2013, DPAC Dance Company (DDC) was formed along with the establishment of Damansara Performing Art Center (DPAC), under the guidance and direction of Artistic Director, Wong Jyh Shyonh. The aim of the company was to present an in-house dance production with the engagement of local artists and collaborative projects between Malaysian and international dance artist. Damansara Performing Arts Centre (DPAC) taking form of a new arts space to meet the growing needs of arts practitioner and arts aficionados in the Damansara district since then.

Dedication of Damansara Performing Arts Centre (DPAC) is strong in promoting arts through learning, practising, and appreciating arts in Malaysia. Since the establishment of the company, DPAC aims to further enhance public awareness on the importance of art-forms that enrich lives while shaping today’s world. DPAC has a proscenium theatre, a black box, an experimental theatre, an indoor theater-foyer and several dance studios. All facilities are all state-of-the-art equipped to cater professional practices of different performing arts practitioners in various forms.

Damansara Performing Arts Centre are not a standalone building, but was fitted into the site between the carpark and office building. Multiple modification are was made to accommodate the auditorium. A column was removed to accommodate more seats and avoid view disturbance, metal truss are used to replace the column and to hold up the roof. Room were extended to increase the sound insulation,and industrial metal containers and plates are used for interior finishes. These multiple modification can accommodate up to 200 people with two changing rooms, with one at the back stage and one on the level above.

2 ARCHITECTURAL DRAWINGS

2.1 Floor Plan Scale 1 :150

2 ARCHITECTURAL DRAWINGS

2.2 Ceiling Plan Scale 1 :150

2 ARCHITECTURAL DRAWINGS

2.3 Section Scale 1 : 150

3 ACOUSTIC PHENOMENA

3.1 Introduction of Acoustics Acoustic is a study of vibration in the air, which produces frequency that can be detected by human’s ears, where sound is formed. There are two basic characteristics of acoustics which include intensity and frequency.

Intensity knows as loudness, is measured in decibels, abbreviated dB. The level of 1 decibel is the lowest noise an average person’s ear. Frequency is the number of times per second a sound vibration occurs, 1 vibration per second is a hertz (abbreviated Hz). Humans hear vibrations the range from 20 per second(low frequency) to 10000 per second(high frequency).

3.2 Acoustics in Architecture Acoustics is the term used to describe the “science of sounds”. It deals with the study of all mechanical waves in matters such as gases, liquids and solids. “Sound”, however, can be defined as vibration in an elastic medium like gases, liquids (air, water) or any solid, physical object that can return to its normal state after being deflected. Sound can be reflected, absorbed, transmitted and diffracted. It is comparatively different to “noise”, though the two are often associated and mistaken for one another by the public. The difference is in its meaning; “sound” is any sort of vibration that can be deemed desirable, or pleasant, “noise”, on the other hand, is undesirable and often disturbing. Whilst it is often considered to be a hindrance, noise in its own service, is important. For example, the sounds of fire alarms or loud music can be deemed irritable, but can also be beneficial in certain cases when it can be controlled. Understanding these differences and knowing how to utilize building materials, system designs and technologies are key factors behind any successful acoustical design.

While the science behind sound is well understood, using that knowledge to create an efficient acoustical performance within a specific building or room is a complex practice. There is no single “solution” or “formula” that can be universally applied to any building design as each built environment offers its own unique set of acoustical parameters.

3.2.1 Sound Intensity Level (SIL) Sound energy is conveyed to our ears by means of a wave motion through some elastic medium (gas, liquid, or solid). At any given point in the medium, the energy content of the wave disturbance varies as well as the square of the amplitude of the wave motion. That said, if the amplitude of the oscillation is doubled, the energy of the wave motion is quadrupled. The common method in gauging this energy transport is to measure the rate at which energy is passing a certain point. This concept is dubbed as “sound intensity”. Consider an area that is normal to the direction of the sound waves. If the area is a unit, namely one square meter, the quantity of sound energy expressed in Joules that passes through the unit area in one second defines the sound intensity. The time rate of energy transfer is then referred to as its "power" – written in the unit: “Watt” (1W is equal to 1 Joule/s). In simpler terms, this means that the sound intensity is the power per square meter. Normally, sound intensity is measured as a relative ratio to some standard intensity. The response of the human ear to sound waves closely follows a logarithmic function of the form “R = k logI", where “R” is the response to a sound that has an intensity of “I”, and “k” is the constant of proportionality. Thus, we define the relative sound intensity level as SL(dB) = 10log I Io The unit of SL is called a “decibel” (abbreviated as dB). “I” is the intensity of the sound expressed in watts per meter and “Io” is the reference intensity defined to be 10-12 W/m2. This value of “Io” is the threshold (minimum sound intensity) of hearing at 1 kHz, for a young person under the best circumstances. Notice that “I/Io” is a unit-less ratio; the intensities need only to be expressed in the same units, not necessarily W/m2.

3 ACOUSTIC PHENOMENA

3.2.2 Reverberation, Attenuation, Echoes and Sound Shadows Sound reverberation is the persistence of sound reflection after the source of the sound has ceased.

Reverberation can have both a positive and a negative effect in architectural design. For example, specifying highly reflective ceiling panels directly above the stage area in an auditorium will help direct the sound toward specific seating areas, thus enhancing the room’s acoustical performance. However, that same reflective performance will become a negative factor if said highly reflective walls and ceiling materials are installed in the rear of the auditorium. That’s because the sound reflections from the rear of the room take too long to reach the audience, resulting in a distracting echo effect. When sound travels through a medium, its intensity diminishes with distance. In idealized materials, sound pressure (signal amplitude) is only reduced by the spreading of the wave. Natural materials, however, all produce an effect which further weakens the sound. This further weakening results from scattering and absorption. Scattering is the reflection of the sound in directions other than its original direction of propagation. Absorption is the conversion of the sound energy to other forms of energy. The combined effect of scattering and absorption is called attenuation. An acoustic shadow or sound shadow is an area through which sound waves fail to propagate, due to topographical obstructions or disruption of the waves via phenomena such as wind currents, buildings, or sound barriers. A short distance acoustic shadow occurs behind a building or a sound barrier. The sound from a source is shielded by the obstruction. Due to diffraction around the object, it will not be completely silent in the sound shadow. The amplitude of the sound can be reduced considerably however, depending on the additional distance the sound must travel between source and receiver. Sound reflection occurs when sound waves bounce off smooth, hard wall, ceiling and floor surfaces.

Concave surfaces tend to concentrate or focus reflected sound in one area. Convex surfaces do just the opposite; they tend to disperse sound in multiple directions.

3.3 Issues of Acoustic Design Strategies Acoustical conditions in an enclosed space is achieved when there is clarity of sound in every part of the occupied space. For this to occur, the sound should rise to a suitable intensity everywhere with no echoes or distortion of the original sound, and with a correct reverberation time. Thus, these acoustical defects in buildings are important to recognize, diagnose and rectify. Acoustical reflectors or diffusers are implemented to evenly distribute the sound and to avoid areas where the sound quality is either weak, too excessive or cannot be heard clearly. Acoustic diffusion or sound reflection helps to provide a wider sound coverage for speech & music, and are often used to improve speech intelligibility and clarity in theatres, assembly halls, auditoriums, recording studios and classrooms. In addition to this, reflectors and diffusers are used to effectively reduce interfering reflections in any one direction by distributing the sound more evenly across the space.

3 ACOUSTIC PHENOMENA

3.4 Acoustic Design for an Auditorium 3.4.1 Selection of the site The proposed site for the auditorium should be as far away as possible from noisy places, like railway tracks, roads with heavy traffic, airports, and industrial vicinities.

3.4.2 Volume The size of the auditorium should remain optimum: small halls leads to irregular distribution of sound because of the formation of standing waves. On the other hand, overly large halls create a weaker intensity and longer reverberation time which may result in serious hearing issues.

3.4.3 Shape and Form One of the most important parameters to be considered for an acoustically efficient auditorium design is the shape and form. Reflections are mainly created due to the presence of side walls and roof of the auditorium; thus, great planning is a must to ensure the reduction of echoes. In the case of parallel walls, splayed side walls are preferred. Curved surface on walls, ceilings or floors are also ideal when the aim is to produce a concentration of sound in a specific region.

3.4.4 Use of Absorbents When the construction of an auditorium is completed; there are still certain inaccuracies that require further improvements to achieve a better acoustical design. Hence, the use of absorbents is essential and a common strategy in amphitheater design. They are often used at the rear wall of the amphitheater, as well as the ceiling, as the reflection sound that occurs around these areas are of no benefit.

3.4.5 Reverberation Reverberation time must be controlled to be a perfect balance (e.g. 0.5 seconds for auditoriums, 1.2 seconds for concert hall and 2 seconds for theatres). The proper use of absorbent materials, the capacity of audience, presence of open windows, types of furniture used, are all examples of important components that affect the reverberation time.

3.4.6 Echelon Effect In an auditorium, any set of hand railings, staircases or any regular spacing of reflected surfaces may produce a musical note due to regular succession of echoes of the original sound. This disturbs the quality of the original sounds produced.

3 ACOUSTIC DESIGN ANALYSIS

3. 1 Shape and Massing The auditorium is a basic rectangular shape with a slight angle inward to the stage from the view at the entrance.

The seating space right in front of the entrance form an extra capacity to fit more audience but with that odd location of seat it became a sound shadow area where direct and reflected sound can hardly approach.

Sound shadow

Diagram 1 : The shape of auditorium

3 ACOUSTIC DESIGN ANALYSIS

3. 2 Levelling of Seats In order to ensure that sound waves reach the ears of every occupants within the auditorium clearly, the designer should take in consider the levelling of the seating area.

Diagram 2 : Seats arranged in single level.

When the seats are arranged in a single level, the sound waves could not travel to the furthermost seat. The sound energy will be absorbed by the sound absorbers along the way such as people and cushioned seats. Hence, the sound waves will die out by the time it reached the second.

Diagram 3 : Elevated seats arrangement.

By raising the level of seats, the listener can receive the direct sound without blocking by absorbers.

3 ACOUSTIC DESIGN ANALYSIS

3. 3 Arrangement of seat The arrangement of seats in DPAC are efficient as sound able to transmit to all parts of the theatre. The distance between the sound sources (stage) and the back seats are within the range of 15m, the optimum distance for human voice to be heard clearly. Moreover, theatre seats are placed within a 140-degree angle of sound projection. This allowed the high frequency sound to be discern. The row of the seats at the side of the theatre are tilted to face the stage for allow visual intimacy as well as acoustical consideration as the sound travel in spherical order. Therefore the arrangement of seats of DPAC are considered well configured except for the seats that fall into sound shadow zone.

Sound shadow

Diagram 4 : Plan showing the efficiency of seats arrangement in aspect of dimension and position

4 METHODOLOGY

4.1 Equipment 4.1.1

Digital Sound Level Meter

Figure 3 : Digital sound level meter

The digital sound level meter is used to measure the sound level from a particular point within the auditorium.

The unit is measured in decibels (dBA).

4.1.2

Photography Device

Figure 4 : Digital camera

Figure 5 : Smartphone

Digital camera and Smartphone are used to capture photos of the build material of the auditorium, equipment installed in the auditorium (speaker, lighting, air-conditioning system, ceiling‌ etc), finishing material of the auditorium, position of sound source as a mean of evidence for our analysis.

4 METHODOLOGY

4.1.3

Measuring Devices

Figure 6 : Measuring tape

Figure 7 : Laser distance measurer

Measuring tape and laser distance measurer are used to measure the dimension of the auditorium for drawing purposes and to measure the distance of the sound source to the digital sound level meter for calculation purposes.

4.2 Data Collection Method Prior arrangement were made before the visit to ensure the auditorium are unoccupied to conduct a more accurate analysis without disturbance. Architectural drawings are obtain prior to the site visit, measurement of the auditorium are checked to ensure an accurate result. In order to obtain a more accurate analysis, all recordings are obtained in 3 decimals points. Every recording are taken 2 times and the average recording are used. Measurement of the auditorium were taken for drawing and calculation purposes.

5 ACOUSTICAL ANALYSIS

5.1 Material and Absorption Coefficient 5.1.1 Wall Acoustically treated wall

10mm Plaster 25mm Fibreboard 100mm Rockwool 25mm Fiberboard 250mm Concrete 10mm Plaster

Diagram 5 : The placement of acoustically treated wall

Diagram 6 : Detail of the wall

The wall of DPAC is an acoustically treated wall. It consists of three layers, which are fibre board, rock wool and concrete. The wall of DPAC is designed to absorb sound because most of the materials used are high reflection.

Rockwool is a soft material that combine with both thermal and sound absorption. It also has fire retardant properties. Fibreboard is easy to work with and quick to install. It is dense but breathes to allow the sound transfer through it. Fibreboard makes the wall more effective absorber as it absorbs high frequencies than rock wool.

Zig-zag steel panels

Diagram 7 : The placement of steel panels

Figure 8 : Zig-zag steel panels

Zig-zag steel panels are installed to serve as acoustical and aesthetic purpose which hiding the lighting wires. It create sound diffusion that improve the liveliness of the theatre. However, excessive placement of it would trap noise in theatre which will affect the auditory response of the audience.

5 ACOUSTICAL ANALYSIS

5.1.2 Ceiling

Figure 9 : Ceiling Concrete

Diagram 8 : The placement of ceiling

Spray form

Diagram 9 : Detail of ceiling

The material of ceiling in DPAC is concrete. Concrete is a strong reflection material. Sound consideration is important for a theatre. The used of concrete will create excessive sound reflection due to the hard surface of the concrete. Thus, a layer of spray form has been applied on the surface of the ceiling to decrease the sound reflection.

Reflector Panel

Diagram 10 : The placement of reflector panels

Figure 10 : Reflector panels

Plywood reflector panel is a suspended panel that are used in DPAC. It hanged by steel and attached to the concrete slab above. The function of panel is to disperse sound evenly across audience. Plywood reflector panel installed at the front and side. It covered partially to avoid redundant sound reflection. The placement and the material of panel brings a huge impact to the theatre. Due to the placement of the panel, it improves the sound distribution in the theatre.

5 ACOUSTICAL ANALYSIS

5.1.3 Flooring

Figure 11 : Vinyl sheet

Diagram 11 : The placement of flooring

Figure 12 : Vinyl sheet

Concrete is mostly used for flooring in DPAC. Plywood and vinyl sheet are only applied on the stage. The plywood has good strength and durability. It is economical as compared to solid wood. One of the reason of using plywood is to balance the material used. The wall is covered with steel panels and plywood can gives a warm feeling in theatre. This theatre is a multipurpose theatre. It is not only for orchestra, but also other performance such as ballet. The plywood flooring is applied with a layer of vinyl sheet to increase slip resistance. Black vinyl sheet on the flooring would not affect the attention of audience during the shows.

5.1.4 Staircase

Concrete Plywood Metal Plate

Diagram 12 : The placement of flooring

Figure 13 : Staircase

Diagram 13 : Detail of staircase

The material of staircase is plywood and metal. Plywood is used at the tread for aesthetic purpose and more noticeable because it is different material with flooring. Due to hard surface, it creates sound reflection. When walking on the plywood stair, it would create noise and disturb the audience during the show. The metal plate is placed at the riser. The function is to reflect the sound.

5 ACOUSTICAL ANALYSIS

5.1.5 Curtain

Diagram 14 : The placement of curtain

Duvetyn Duvetyne is a brushed matte finish that used in the front curtain of DPAC. It is a bit lighter and used as masking throughout the theatre. Moreover, it looks like velour but does not work as well as velour. It allows pinholes of light to show through if there is a very high concentration of light behind it.

Velour fabric Velour fabric is installed at the entrance of Damansara Performance Art Centre(DPAC). It is extremely durable.

The purpose is to reduce sound penetration and avoid sound transfer through the structure. It is a sound absorption material because of its soft characteristic. Also, the curtain is attractive and act as a welcoming element.

Bolton twill fabric Bolton twill fabric is used as covering the service room entrance. It is cheaper and lighter which easier to work with. Due to the complex pattern, surface dust and dirt are less visible, it always a good choice for theatrical curtain. Light may leak through but it does not matter because of the function is to hide the door.

Figure 14 : Duvetyne

Figure 15 : Velour fabric

Figure 16 : Bolton twill fabric

5 ACOUSTICAL ANALYSIS

5.1.6 Seat

Cushion

Plywood

Metal Stand

Diagram 15 : The placement of audience seats

Figure 17 : Audience seats

Figure 18 : Component of audience seats

Upholstered tip-up seats The seats used in DPAC’s audience area are upholstered tip-up seats which made of plywood and red cushion.

Red cushions enhance the visual beauty of the theatre. The purpose of using cushion is to provide comfortable sitting area for audience. It is a great porous absorber in the theatre. Besides, the metal stands are installed in every seat as a supporting structure and air conditioning outlet.

5.1.7 Door

10mm Plywood 25mm Rockwool 10mm Plywood

Diagram 16 : The placement of doors

Diagram 17 : Detail of acoustic door

Plywood is used at the outer door of the entrance. Sound are able to penetrates through the door . So, acoustic door is built to reduce sound penetration. Acoustic doors are constructed by plywood and rock wool. Rock wool is one of the material that are used for the acoustically treated wall. The function is to absorb unnecessary sound.

Other than that, double door system is applied to reduce the noise from the exterior and block the sound from inside.

5 ACOUSTICAL ANALYSIS AREA

COMPONENT

MATERIALS PHOTO

Exterior

Curtain

Entrance Door Interior: Sitting area

Seat

-

COLOUR

SURFACE FINISHES

MATERIAL

DESCRIPTION

Velour fabric

Exterior curtain, Entrance door curtain

Red

Soft

Plywood

Entrance door

Brown

+ Rockwool Entrance door Fabric Upholster ed

Plywood

COEFFICIENT 125 Hz

500 Hz

2000 Hz

0.03 0.25

0.5

Smooth

0.1

0.05

0.04

Brown

Smooth

-

0.1

-

Empty

Red

Soft

0.49

0.8

0.82

Fully Occupied

Red

Soft

0.6

0.88

0.93

Empty

Brown

Smooth

0.32

0.42

0.43

Fully Occupied

Brown

Smooth

0.5

0.76

0.86

Flooring

Concrete

-

Grey

Rough

0.1

0.1

0.2

Staircase

Steel

The riser is steel

Dark grey

Hard

-

0.08

-

Plywood

The tread is plywood

Brown

Smooth

0.05 0.05

0.05

Reflector Panel

Plywood

Suspended on the front and side ceiling

Black

Smooth

0.05 0.05

0.05

Zig-Zag Steel Panel

Steel

Steel panel is covering the wall

Black

Smooth

-

0.88

-

5 ACOUSTICAL ANALYSIS

AREA

COMPONENT

COLOUR

PHOTO

MATERIAL

DESCRIPTION

-

Concrete + Rock wool + Fibreboar d

250mm: concrete 100mm: rockwool 10mm: Fibreboard

Grey

Curtain

Bolton twill fabric

Covered the service room’s door

Upper floor slab

Concrete

SURFACE FINISHES

COEFFICIENT 125 Hz

500 Hz

2000 Hz

Smooth

-

0.55

-

Black

Soft

-

0.1

-

Concrete slab + Spray form

Grey

Rough

-

0.15

-

Plywood

Back panel

Brown

Smooth

Curtain

Duvetyn

Layering of curtain

Black

Soft

Proscenium

Plywood

A frame separating stage and auditorium

Dark grey

Smooth

0.05 0.05

0.05

Flooring

Plywood + Vinyl sheet

Vinyl sheet is applied on the plywood flooring

Grey

Uneven

0.02 0.03

0.03

Acoustically treated wall

Interior: Stage area

MATERIALS

Cyclorama

-

0.05 0.05

-

0.2

0.05

-

5 ACOUSTICAL ANALYSIS

5.2 Identification of Existing Sound Source/ Noise 5.2.1 Sound and noise The term sound and noise can be defined as an " undesired or disagreeable sound" or any other disturbance. From the acoustics point of view, it’s constitute as the same as a phenomenon of atmospheric pressure fluctuations which means an atmospheric pressure. Sound or noise is the result of pressure variations, or oscillations, in an elastic medium such as air, water or even solids which generated by a vibrating surface, or turbulent fluid flow.

5.2.2 External Noises I. Air borne noise - Environmental sound The quietness of a theatre is degraded when outside noise gets inside. The theatre is located right beside a roadside which could cause some unpleasant noise and disturbance whenever there's a heavy traffic during a peak hour ( Vehicle noise from Jln pju 8/8 ). Even just the sound of a motorcyclist engine could be listen through the door from the sound system affecting the audience who seats nearby the section.

Sungai buloh Damansara perdana

TNB

Jln pju 8/8

Kepong LDP Toll

Jalan PJU 8/8

DPAC

DPAC Mon’t Kiara

Mutiara Damansar

Sound system room

The curve

Entrance

LDP

Figure 19 : Position of DPAC beside a roadside

Diagram 18 : Site context

Diagram 19 : Floor plan, Noises from roadside coming from sound system room

II. Air borne noise - Entrance door There multiple origins of noise, like the sound produced by opening and closing the door or even the sound of talking taking place outside the theatre. However, there is a sound lock which prevent the noise from interfering the audience that seats near to the door. The sound lock within the inner and outer door at the main entrance of the theatre serves as a function to trap the sound waves as a result to bring down the noise level to less than 40 bB. The addition of acoustic absorbent linings to the sound locks can also further enhance the sound insulation

Sound lock

Diagram 20 : Floor plan, sound lock

Figure 20 : The inner door of the entrance, Double door system

Figure 21 : The outer door of the entrance

5 ACOUSTICAL ANALYSIS

III. Air borne noise - Back door ( to basement carpark ) There's is a back door behind the stage acting as an entrance for the performers which also leads to a basement parking lots, this is also another sound intrusion could be found in the theatre. However, with the solution of designing the door with the combination of a rock wool core, this could prevent the vehicular noises from entering t h e t h e a t r e w h i c h t h e n s o l v e t h e i s s u e s .

Rock wool is one of the most effective acoustic insulation solution because they provide airborne sound absorption which can dramatically improve the acoustics which due to its high density, non directional fibres that trap the sound waves and absorb vibration.

Backstage

Loading bay / basment carpark

Sound source

Diagram 21 : Floor plan, Noises from Loading bay / Basement carpark

Plywood Wood conglomerate Rockwool Backstage Reflected Absorb & Reflected

Diagram 22 : Sound absorption and reflection shown in door detail section

5.2.3 Internal Noises I. Air borne noise - FCU air conditioning

There are many factors that could affect on designing a comfortable theatre to provide comfort to building occupants. Temperature is one of the element. One may feel very cold in an empty room, but when it’s fill up with people, it can heat up real quick. Therefore, the seats were designed in such way that the metal stand beneath incorporates air conditioning openings on every seats, for a more convenient way to control the temperature of the theatre.

Entrance

Seating area

Front Stage

FCU Air Conditioning

Diagram 23 : FCU air conditioning below the seating area shown in section.

5 ACOUSTICAL ANALYSIS

Internal Noises I. Air borne noise - FCU air conditioning ( Continued )

To achieve such result, it requires a Centralised Air-Conditioning with delivery ducts. A fan coil unit (FCU) is a very simple and flexible device that consist a heating and cooling heat exchanger. It’s is a part of an HVAC system which has a low noise unit. The noise output level can be as low as NR25.

MAX. NOISE RATING LEVEL

APPLICATION

NR 25

Concert halls, broadcasting and recording studios, churches

NR 30

Private dwellings, hospitals, theaters, cinemas, conference rooms

NR 35

Libraries, museums, hospitals, operating theatres and wards,

NR 40

Halls, restaurants, night clubs, shops

NR 45

Department stores, supermarkets, canteens

NR 50

Typing pools, offices with business machines

NR 60

Light engineering works

NR 70

Foundries, heavy engineering works

Table 1 : Maximum noise rating level on different application

Figure 22 : Images showing the openings for air conditioning

Openings

Foam layer reduce air friction and absorb sound from FCU

Figure 23 : Treated AHU duct beneath the seats

AHU duct FCU unit

Diagram 24 : Detail section of the seat

5 ACOUSTICAL ANALYSIS

Internal Noises II. Air borne noise - Ducting and diffuser

Backstage Ducting

Backstage Ducting & Diffuser

Seating area Ducting & Diffuser

Front stage Diffuser

`

Figure 24 : Images showing the internal noise source coming from ducting and diffuser.

Recommended specification Elements

Examples and details

Centralized Air Conditioning with delivery ducts

Fan Coil Unit (FCU)

Selection of fan with low noise

Silencer

Silencer are used to reduce airborne noise which could maximum insertion loss (noise reduction), low static pressure drop

Diffuser

Selection of diffusers with low regeneration noise

Ducting

With Internal lining of Rockwool and thermalrock with tissue facing or GI sheets

Remark FCU might require acoustics box up if it’s installed within a sensitive room to reduce noise.

Excessive air or high velocity of air flows thru diffusers blades will generate noise.

Air speed and volume per diffuser are essential

Table 2 : Recommended specification on Centralized Air Conditioning with delivery ducts

5 ACOUSTICAL ANALYSIS

Internal Noises III. Structural borne noise - Squeaky stairs It’s extremely disturbing when the audience happens to enter and leave in the middle of the performance, and the squeaky sound from the stairs and even the footsteps on the a floor can be heard clearly. The noises are transmitted through a structural borne, resulting from an impact or the vibration against it. The structural fabric can lead to the sound being radiated from an adjacent vibrating surface such as the solid hard surface layer of the thread on stairs which made of plywood and the concrete flooring. The solution to reduce the noise can simply done through a selection of softer material like carpets to cover over the stairs.

Plywood Concrete

Stairs Floor

Figure 25 : Showing the overall view of the flooring material on the seating area

Figure 26 : Stairs (Plywood) Floor (concrete)

IV. Structural borne noise - Stage flooring system.

Marley “Vinyl” flooring

Figure 27 : Showing the material of the stage and the depthness of the stage

5 ACOUSTICAL ANALYSIS

Internal Noises IV. Structural borne noise - Stage flooring system ( Continued ) The theatre is mainly serve for a small scale dance, drama and musical production. It is always advisable to consider the possibility of sprung floor as they provided some degree of bounce and flex under impact. Performers need this to absorb shock and protect their joints from inanity. Especially when performing jumps.

The stage is made of plywood as plywood is a great choice for sound control as it bounces high frequencies, resonating better sound quality, and absorbing bass energy. Besides, plywood is ideal for social dancing, because it is less liable to wrap and shrink and has more durability and economical.

But due to space limit the theatre was built with a shallow apron causing the distance between audience and the stage to be closer where the sound of footfalls of a jump might be very loud to the audience. Therefore, the stage is covered with Marley “vinyl” which mainly increase slip resistance for the performers but it also helps to reduce noise.

Stage

Marley “Vinyl” performance floor Plywood

Apron

Dual density shock dampening elastomer blocks at predetermined intervals

Audience

Diagram 25 : Sprung floor system

Figure 28 : Distance away from audience to stage

Audience

Apron

Stage

Diagram 26 : Distance between audience and the stage in section view

5 ACOUSTICAL ANALYSIS

Internal Noises V. Light fixture as a source of noise

Internal noise also includes the light fixtures as some might produce the buzzing noise, one might not have any impact to the environment but too much light can cause serious impact on producing noise. For example, the inner side on each of the steel panel on the wall is covered by LED strip on the sides where the buzzing noise could be heard if one were seating right beside the steel panel.

The reason why the LEDs are making the buzzing noise is due to improper dimming or electromagnetic interference from other devices which causes vibrations in the light bulb. The solution is to fix the dimmer you are using that is compatible with the LEDs to ensure there's no humming sound.

Area affected

Steel panel

Figure 29 : Images showing the steel panel beside the seats.

Diagram 27 : Showing the affected area by the buzzing noise of LED lights on the steel panel.

6 ANALYSIS AND FINDINGS

6.1 Sound propagation and concentration The reading of the sound is taken from different position of the stage as the sound propagation are varied, outputting a constant 255Hz sound at 60dB, which is a normal speech level. The findings shows that the layout and the use of material of DPAC are not appropriate as: a) it produce unpleasant sound at certain area, b) Uneven sound distribution

6.1.1 Sound concentration According to the reading of sound at different zone of the theatre, we found that the front seats of the stage receive relatively less sound compared to other zone due to the absorbent material of the front stage and the inefficient placement of reflective wall and ceiling panel (refer to diagram 28 )

Diagram 28 : SIL readings of the theatre

The concentration of sound at the centre back which is VIP seats of the theatre due to the excessive reflective material placed near the corner.

Diagram 29 : The concentration of sound

6 ANALYSIS AND FINDINGS 6.1.2 Sound reflection There are 3 types of reflections that we usually hear in a auditorium: early reflection, late reflection and reverberation. Early reflection are desirable to amplify sound so the sound could be hear more clearly. As the reflected sound arriving from the sides are more contributed to the overall reverberance of the room, the steel wall panel of the auditorium plays more important role to amplify the direct sound in a natural way. While the late reflection will create echoes that affect the clarity of the sound sources.

Diagram 30 : The sound propagation from the centre of stage

Vertical reflective panel

Diagram 31 : The sound propagation from the back of the stage

Note that the sound reflection from the centre of stage are relatively lesser, result to varied sound level when performer walking around stage. It is caused by the ineffective placement of vertical reflective panel above the stage. The ceiling panel should be placed further from the stage so that it would reflect the sound from the centre stage more productively.

The reflective sound also failed to convey uniformly to all of the audience as it concentrated at the VIP seats.

It is due to the flat ceiling reflective panel that are ineffective and not well configured.

6 ANALYSIS AND FINDINGS

Diagram 32 : Sound path of speaker on the ground

C A

B Diagram 33 : Sound path of speaker on top

The position of the speaker above the stage are much more ideal than the speaker placed on ground as transmit the sound more directly and evenly to all part of the theatre. Position of the speaker A and B are not appropriate as: a) Face directly to the audience, hence the sound convey unevenly b) Produce structure-borne noise due to the larger area of contact to the floor

Figure 30 : Position of speaker on two sides of the stage

Figure 31 : Position of speaker above the stage

6 ANALYSIS AND FINDINGS 6.1.3 Sound absorption As it is an art and performance theatre, the less the absorption of the sound, the livelier the acoustic theatre is.

Therefore, the strategy of sound absorption is minimal, mostly absorption of sound are provided by the audience and the acoustic wall.

The acoustic wall panel which are absorptive are placed behind of the zig zag steel sound reflector to prevent the occurrence of echo in between the wall and panel as the wall absorbed partial of the reflected sound.

Diagram 34 : Plan showing the reflective and absorbance material used

Diagram 35 : Section showing the reflective and absorbance material used

Notice that the choice of the material at its stage are varying from the audience seats, the sound absorbance drapery are installed, provide a tunable acoustical control ( sound reflective level ) at the stage. For instance, the drapery are closed while scene changing, so that the noise produced by the crews behind the drapery are reduced. It also eliminate the echoes and noise produced from the backstage to transmit to the audience seats.

6 ANALYSIS AND FINDINGS 6.1.4 Sound diffusion

Corrugated surface of the steel panel diffuse the sound evenly to the aud

Diagram 36 : Sound diffusion ray explained in the plan

Diffusers which scatter sound are critical in acoustical theatre design to improve the sound quality in frequencies throughout the middle and high range of the spectrum,. It keeps sound waves from grouping, so there are no hot spots or nulls in a room, making the instrumental or any sound source sounds more natural as the human ear is used to reflections and reverb trails from a single sound source arriving at the inner ear at multiple intervals. Moreover, diffusion allows reverb to decay more naturally while still preserving the sound energy as well as addressing issues with resonance.

Zig zag steel panel that place all over the wall of the theatre are the only method of DPAC to provide sound diffusion. It cover about 90% of the theatre. It making the theatre space more lively and create illusion of the larger space. However, as it placed in front of the acoustic wall, some of the noise are dispersed before it being absorb by the wall, affecting the acoustical quality of the space.

Figure 32 : Coverage of the steel panel

6 ANALYSIS AND FINDINGS

Diagram 37 : Sound diffusion to front rows

The front rows of the theatre receive more direct sound that reflected and diffusion sound because of the placement of the steel panel and the sound absorption of the drapery at the front stage.

Diagram 38 : Sound diffusion to centre rows

Diagram 39 : Sound diffusion to VIP seats

The seats located at the side of the theatre received more diffusion sound as it is nearer to the steel panels on the wall. Therefore, the diagrams above well explained why the SIL reading at centre-front of the theatre are relatively lower than other zone of the theatre (referring diagram 39)

6 ANALYSIS AND FINDINGS

6.2 Different Phenomena in Sound 6.2.1. Echo and Sound Delay Echo and reverberation are two distinctly different things. Echo happens when the sound waves of a sound or series of sounds reflect from a surface back to the listener. Different functions of the spaces have different desired sound delay period, and thus different perceptions of echo.

For this analysis, only reflective surfaces will be treated as effective sources of sound delay. For space used for speech, time delay above 40m sec will be deemed as an echo. In other hand, as for auditorium for music purpose, s o u n d d e l a y a b o v e 1 0 0 m s e c i s d e e m e d a s a n e c h o .

Diagram 6.1.1.1 SIL readings of the theatre 6.1.1 Sound concentration According to the reading of sound at different zone of the theatre, we found that the front seats of the stage receive relatively less sound compared to other zone due to the absorbent material of the front stage and the inefficient placement of reflective wall and ceiling panel (refer to diagram 6.1.3.2 )

Diagram 40 : 40m sec sound delay is acceptable for a performance-oriented auditorium.

6 ANALYSIS AND FINDINGS

Diagram 41 : 11.2m sec and 8.8msec are quite short for a performance-oriented auditorium.

Diagram 42 : 29.1m sec is acceptable for performance-oriented auditorium.

6 ANALYSIS AND FINDINGS

Diagram 43 : 42.94msec is acceptable for performance-oriented auditorium.

Diagram 44 : 12.65msec is quite low for performance-oriented auditorium.

6 ANALYSIS AND FINDINGS

Diagram 45 : 14.7msec is quite low for performance-oriented auditorium.

After the calculations, we can conclude that echo doesn’t exist in this auditorium if it is used for performance and music purposes. However, it does exist if it used as speech-oriented auditorium.

6.2.2. Flutter Echo Flutter echo is a rapid succession of noticeable small echoes that is created when a short burst of sound is produced between parallel sound-reflective surfaces.

DPAC does not create flutter echo as the walls of the auditorium are non-parallel. Besides that, the curtains have absorbed the sounds reflected on it

Diagram 46 : Flutter echo doesn’t exist in this auditorium.

6 ANALYSIS AND FINDINGS 6.2.3. Reverberation Reverberation is different from echo. Reverberation is said as a sound that echoes, but the echoes that create reverberation are extremely complex. It also defined as prolongation of a sound and is produced when a sound or signal is reflected causing a large number of reflections to build up and then decay as the sound is absorbed by the surfaces of objects in the space which could include furniture, people, and air.

To differentiate echo and reverberation, the better way is to see the number of repetitions of sound per millisecond. A reverberation is perceived when the reflected sound wave reaches our ear in less than 0.1 second a f t e r t h e o r i g i n a l s o u n d w a v e .

A desirable reverberation time depends on the types of space as the graph below:

Table 3 : Desirable reverberation time depending on function of the space.

Source: https://acousticalsolutions.com/wp-content/uploads/2015/04/reverb_time_chart_525.jpg

6 ANALYSIS AND FINDINGS The reverberation is influenced by the size and shape of the room that the sound echoes in.

Diagram 47 : The Reverberation time of DPAC.

In this case, the room of DPAC provides lesser reflective surfaces compared to cathedral by just looking at the shape as it was squarish in shape. However, the material of the finishing of the room whether the floorings or the walls provide more hard surfaces. The harder the surface, and the more surface angles and lengths of the room, the longer repetition of echoes occur, resulting in a longer tail or reverberation time.

The original sound wave and reflected sound wave tend to combine as one very prolonged sound wave. DPAC used the auditorium as music and performance hall, hence, the longer reverberation time or decay can be used to enhance harmonic structure in their performances. Generally, the construction of a music hall attempts to produce a reverberation time that lasts anywhere from 1.2 to 3 seconds or longer. The characteristics include an audible cluster of initial reflections followed by a full body and a decay that ends with a roll off of highf r e q u e n c y c o n t e n t .

7 ACOUSTICAL DEFECTS AND DESIGN ISSUES Acoustical defects can be found in a theatre if it is not designed in an appropriate way to its function or due to the later stage development of the theatre. Sometimes, these defects can be solved just by a few tips in an acoustic room at the design stage.

7.1 Poor Ensemble

Diagram 48 : The spots of sound in DPAC (Situation 1)

Diagram 49 : The spots of sound in DPAC (Situation 2)

Diagram 50 : The spots of sound in DPAC (Situation 3)

7 ACOUSTICAL DEFECTS AND DESIGN ISSUES From the first diagram, the play of sound reflection and the propagation of the sound make the design of the auditorium seems reasonable. But in the second diagram, when the speaker is moving forward, the sound will concentrate at the back of the auditorium, the front and the VIP zone will start to suffer from the dead spot as there is no reflected sound from the ceiling applied. In the third diagram, the poor sound ensemble is strongly highlighted when the speaker is moving backward to the stage. Only minimum part of the ceiling reflector is functional at this position.

This becomes a weak point of DPAC from being a great auditorium if there is a large team of classical orchestra or choir team performing on stage. This is because the sound from the back of the stage is hardly heard or received by the audience.

7.2 Sound shadow

Diagram 51 : Sound Shadow in DPAC

Sound shadow area is also one of the defects found in DPAC theatre. In the diagram, the seating area below the control stage overhung is determined as a sound shadow area. At the sound shadow area, the reflected sound that is supposingly transfer to that particular area has been blocked by the stage above.

This defect can be easily solved by lifting the stage higher to prevent the blockage of sound to the area.

7.3 Poor Sound Isolation

Figure 33 : Noise Sources in DPAC

In the theatre, lights, HVAC ducting and diffusers are placed out-and-out everywhere in the theatre. A lot of internal noises are produced and created an unpleasant environment. The lights and cooling system that are probably enhance the visual effects and comfort level has totally affected the sound effects in the theatre.

The ducting system and the diffusers should be covered by a ceiling. Whereas, the lightings should undergo periodic inspection and maintenance to prevent the internal noises in the theatre.

7 ACOUSTICAL DEFECTS AND DESIGN ISSUES 7.4 Mechanical Noises

Entrance

Seating area

Front Stage

FCU Air Conditioning

Diagram 52 : Mechanical Noise transfer diagram of DPAC

The openings under the chair to allow the air flow from the FCU also created a minimal mechanical noises in the theatre. Besides that, the machines of FCU Air Conditioning system are placed under the seating area and sit on the ground. This causes the noises from the machines to transfer along the horizontal surfaces.

The installation of floated floor can be considered as it will prevent the mechanical noises from entering the theatre and isolate the mechanical noises within the space below the seating area.

8 CONCLUSION

To sum up a conclusion from our accumulated findings and subsequent analysis, Damasara Art Performing Centre, DPAC is an auditorium that is not suitable for any large live performances which are unassisted and unamplified. It depends on electronic audio suites to overcome its shortcomings and yet still not a guarantee to its ability to serve as an acoustically efficient auditorium. Many events are still held within its hall despite its issues. Though it has been known as a “multipurpose� auditorium, its suboptimal layout, poor ensemble of sound, poor isolation of interior sound and the presence of numerous sources of unnecessary noises make it does not deserve this title. Its overall approach and operation strongly suggests a focus towards speech-related events or smaller group of stage play only.

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