Acoustic study (assignment 2)

PART A: PRECEDENCE STUDY I. DEWAN FILHARMONIK PETRONAS (Done by: Le Ngan) The basic acoustic criteria must have a low ambient noise level from the internal and external sources, provide a reasonable level of acoustic gain and appropriate reverberation time. A good acoustic system also avoids artifacts such as echoes. So that, the conditions in any auditorium designs are considerably affected by purely architectural considerations like shape, layout of boundary surfaces, and selecting the material, size and volume of the space, seating capacity, hall type.

The layout seating arrangement, seating capacity and volume Dewan Filharmonik PETRONAS (DFP) is a concert hall that was officially opened on 17 August 1998. This hall specifically designed for symphonic performances of the highest quality. Volume, height and proportion of the DFP is a triple-volume concert hall, consisting of three seating levels Stalls, Circle and Upper Circle. The ground level consists of the first tier of seating area and the stage. Two tiers of seating area marked as the second and third level of the seating areas. The hall has a capacity for 885 people, which includes box seating at Stalls level and 20 luxurious corporate suites at Circle and Upper Circle levels.

Planning layout The layout plan of the DFP is inspired from the traditional shoe-box shape. The shoebox shape is considered as the best acoustic plan as it assures total enclosure of the internal area.

Balcony - Following fig 10, the convex surface of the balcony’s shape and the wall panel surfaces of the concert hall diffuse or absorb the sounds. In short, the shape of the enclosed wall determines the reflection mode of the sound. When a balcony is provided, the sound reflection pressure level becomes poor due to lack of effective reflection from walls and ceilings. Furthermore, the reverberation time becomes shorter due to the smaller volume per audience.

Ceiling - The main design that contributes to the acoustic inside this hall is the movable ceiling, also call as acoustic canopy where they go 7 meters - up and down. The acoustic canopy system has 7 panels which are made by concrete. The function of this system is the volume node of the hall as a variable volume system.

Following the need of each show, the acoustic canopy will move. When they need to increase the volume of sound, the ceiling may go lower down, or the opposite site.

The angle of seating (and how it influences the acoustic experience) The sound treatments in fact are essential in order to ensure a balance distribution of sound at each seating levels. The reason on adopting a sloping seating level is to overcome poor sound distribution due to the poroustype absorption provided by seats and audiences. Therefore, in order to overcome this, the seating level is built as a sloping level, specifically to prevent sound absorption by the seats and. In addition, the circulation spaces in-between of seating rows are of optimum dimensions, assuring good resonance.

The selection of material, size, hall type Auditorium - The gently arched perforated metal ceiling allows sound to travel to an upper ceiling. Wall, ceilings and balconies are specifically designed to reflect sound to the audience and the musicians while at the same time eliminating the echoing effect. The hall sits on resilient pads and is surrounded by two concrete wall

separated by an isolation joint to eliminate external noise. Therefore, the air-conditioning is virtually silent. Every element in the hall, every material and finishing, has been designed and selected to create a flexible performing environment that complements a variety of orchestral performances Stage - The stage is made of tongue-and-groove timber which is specifically designed for flexibility.

The walls surrounding the stage are acoustically treated to be sound reflective or absorbent , depending on the desired use. In addition, the walls are of convex shapes, assuring good sound distribution within the concert hall.

Disadvantage Balcony – The function of designing a balcony is to increase the audience capacity. However, the acoustics under the balcony becomes worse because of the direct sound is attenuated due to long distance propagation over the audience. Hence the sound pressure levels are poor due to lack of effective reflection from wall and ceilings. Furthermore, the reverberation time becomes shorter due to the smaller volume per audience; costly to obtain the good reflective materials Advantage Floor – Since the floor with seating capacity gives large absorption compared to others, direct sound is simultaneously being attenuated as it propagates over the absorbing surface. This is due to the absorption of porous-type provided by chairs and audiences, which efficient at high frequencies. The existence of spaces between the rows of seating capacity would cause resonance in low-frequency sounds that would produce a good attenuation.

Sound Reflecting Panels - Movable of a sound reflects via walls and ceiling whereby it’s normally installed to the stage as an orchestra shell. The sound that reflects walls and ceiling would provide a sound energy and distribute the sound to be absorbed to the back stage. The sound distribution then will be reflected back to the players hence produce a pleasant listening conditions for the audience.

Since the reflecting panels are heavy, a compound laminated layer of plywood and damping rubber sheet is preferable in order to reduce its weight.

II. Albi Grand Theater (Done by: Xixi)

Building area: 10200 ㎥ Program: 900 seats auditorium Material: wall & ceiling-concrete, covered with bricks Floor- concrete, covered with black carpet

Stage- timber Dimension: Stage- 10m*16m*0.5m

Auditorium- 12m*16m Ceiling height- 12m Size and Volume of shape Shaped shape

Ceiling shape and sound reflection

For greater seating capacity, the side walls should be splayed from the stage, at this case, the angle of side wall is 35°, it allow greater seating area relatively close to the stage, can usefully reflect sound energy to the rear of the hall Here have some ceiling reflectors, also called clouds, are used to direct sound energy from the stage to the seating area. And to avoid potential flutter echo, a smooth ceiling should not be parallel to the floor. The recommended ceiling height in auditoria design is between 8m and 12.5m for useful sound reflection by the ceiling, at here, the ceiling height is 12m, so the sound reflection at this hall is useful.

Seating capacity This theater have 900 seats, the volume is pretty big, it is a very important factor since it is affecting the acoustic character of the auditorium, in auditorium most of the sound absorption is provided by the audience, so higher seating capacity mean more sound will be absorbed.

Layout seating arrangement

“multiple-aisle” seating layout

End Stage

This theatre use multiple-aisle layout, it will have a maximum of 14-16 chairs per row with access to an aisleway at both ends. The form is “end stage”, it is well suited to lecture, film or slide presentations, but not very conducive to close relationship between performer and spectator.

The angle of seating The angle of seating is 20°, sloping floor is desirable especially for large hall, for the audience it improves sight lines, the listener receives more direct sound than would be available on a flat floor. Sloping floor is desirable in hall where audience sound absorption must be minimized, for safety the slop should not exceed about 35°.

Material In generally, surfaces that close to the stage should be reflective. The sound absorbing materials should be placed in the rear parts of the hall, if necessary. To prevent delayed reflections from rear wall, it can be treated with a sound absorbing material or can be diffusively reflective.

For the stage, at this case there use timber material, it is good for acoustics due to its reflective nature, and the floor covered with carpet, the background noise can be cleaned. As the echoes are caught and captured, greater clarity to original sound is restored.

Hall type

Example of shoe-box style concert hall

Type of this hall is shoe-box style concert hall, the main purpose of a concert hall is to convey sound from musicians to listeners and to reverberate the music for more pleasant experience in the audience area. The term "shoe-box" refers to the shoebox shape of the hall. It provides sufficient sound reflection from its sides producing a rich sound, have very good acoustics.

Disadvantage The end stage is not conducive to a close relationship between performer and spectator. In some large-space auditorium seating layouts many seats are beyond a point where un-reinforced speech would be intelligible. for the material, here did not use enough sound absorbing materials, it may cause echoes.

Advantage The advantages of end stage are that large number of people can watch and that it fits well the shape of many buildings. The actors can make their entrance from the wings enabling quick changes and suprise entrances.

The floor carpet have high abrasion resistance, make up for the shortcomings of other materials. The ceiling reflector provide for acoustical intimacy, clarity, and strength of room sound. Suspended ceiling reflector panels can provide the correct “ceiling shaping� for useful early reflections that improve these acoustical characteristics.

III. Shantanand Auditorium, Temple of Fine Art (Done By : Febbie Fransiska) Building volume : 8769 m3 Auditorium size : 30.7 m (L) x 20,1 m (W) x 9 m (H) Stage shape : Trapezoidal Capacity : 618 seats Type of Space : Community Auditorium

Ground Floor Plan The seating arrangement on the Ground Floor is combined arrangement of multiple-aisle which the arrangement will have maximum 14 – 16 chairs per row and continental which some the quantity of chairs per row can accommodate more seating within the same space compare to multiple-aisle.

First Floor Plan The setting arrangement on the First Floor is multiple-aisle with more seats on some rows. Multiple-aisle is limited to 7 or 8 rows.

Reflected Ceiling Plan Types of Form This auditorium’s form is combined as well. For the ground floor the form is Wide Fan and for the first floor is End Stage.

Material Seating Area - Ceiling : Gypsum Board with Ceiling Grid - Walls : Acoustic Rough Plaster to Solid Back, Timber Acoustic Panel and Fiberglass Absorption Panel - Floor : Wooden Floor on Joist and Pile Carpet Bounded to Closed-cell underlay - Furniture : Fabric Upholstered Tip-Up Seats Stage Area - Walls : Acoustic Absorption Panel and Smooth Painted Concrete - Floor : Rubber Sheet over Timber Floor and Painted Smooth Concrete - Stage Deck : Steel Decking Stage and Seating Area - Ceiling : Gypsum Plaster with Ceiling Grid and Ventilation Grille Seating Furniture

Seating Material and Angle of Seating Ceiling Design The auditorium ceiling used gypsum plaster with ceiling grid. The gypsum board comes with extra thickness 40 mm to resist panel vibration, due to its mass it can lower the absorption frequency and higher the reflections frequency. The height of the ceiling is around 9 m which is hard to transmit sound. Therefore the suspended ceiling provides short delay of sound transmitting and lower down the volume of the auditorium. The angle of the ceiling helps to reflect sounds to the seating area and avoid room echoes.

Wall Design The auditorium used hard and soft acoustic wall. For hard acoustic wall, the auditorium used timber acoustic panels. It’s not only for aesthetic purposes, but also to absorb sound. There are air gaps in between each panel to

absorb unwanted level frequency through panel vibration. The backing of the timber acoustic panel is smooth plaster wall. Rough plaster is layered above smooth concrete solid backing to prevent vibration and reflect sound effectively in four columns in this room.

For soft acoustic wall, it used fiberglass acoustic panels. It used to control echoes and sound foci from the rear wall and balcony faces.

Floor Acoustic joist strips are use through conventional timber joist floors. The strip is supplied in 20 m self-adhesive rolls that are easily placed on the top of the joists. It is used to improve the acoustic performance and reduce the impact sound level.

Advantages General Seating Arrangement.

Continental : Accommodate more seating within the same space if it’s carefully planned.

Theatre Form End Stage : Well suited to lecture, film and slide presentations.

Wide Fan : Brings distant spectators closer to the performer.

Disadvantages General Seating Arrangement Multiple-aisle : Limited to 7 or 8 rows.

Continental : Require wider row spacing, wider aisles and strategic exit doors.

Theatre Form End Stage : Not very conducive to close relationship between performer and spectator.

Wide Fan : Limits space usage to primarily speech related activities.

IV.COMPARATIVE TABLE (Done by: Privena.A) Case Study

Malaysian Philharmonic Orchestra, Malaysia

Albi Grand Theater, France

Plan layout design

- inspired from the traditional shoe-box shape

- use multiple-aisle layout have a maximum of 14-16 chairs per row with access to an aisle-way at both ends - The form is “end stage”

-20 Corporate Suites with attached lounges

Size and Volume

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Seating Capacity and Design

Ceiling Design

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a triple-volume concert hall three seating levels – Stalls, Circle and Upper Circle.

885 people a sloping seating level of 20° resilient pads

Ceiling reflectors, also called clouds, are used to direct sound energy from the stage to the seating area.

- Concave surface gently arched perforated metal ceiling allows sound to travel to an upper ceiling.

- seven movable panels in this upper ceiling

Shantanand Auditorium (Temple of Fine Art) - Trapezoidal (a mixture of shoe-box and rectangular) - Wide shallow plan - Seating straight steeped row - Separated with side angle block

 10200 ㎡  Dimension: Stage: 10m*16m*0.5m  Auditorium12m*16m  Ceiling height- 12m  900 seats  angle of seating is 20°

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angle of seating is 12° auditorium seats are placed in 140° to the sound projection

Ceiling reflectors, also called clouds, are used to direct sound energy from the stage to the seating area.

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Gypsum board ceiling comes with thk 40 mm to resist panel vibration. It can lower the absorption frequency and higher the reflections frequency.

The angle of the ceiling helps to reflect sounds to the seating area and avoid room echoes.

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Building volume : 8769 m3 Capacity : 618 seats

Wall Design

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Floor Design

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Movable acoustically absorptive wall panels which are of convex-shape The movable acoustically absorptive walls with a zig-zag profile around the stage are acting as an orchestra shell

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sloping floor

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Wall- Sound Reflecting Panels Ceiling- gently arched perforated metal ceiling Floor- teak wood timber Stage- teak wood timber

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Materials

side walls should be splayed from the stage angle of side wall is 35

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sloping floor is desirable for safety the slop should not exceed about 35°.

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Wall and ceilingconcrete is covered with bricks Floor- concrete, covered with black carpet Stage- teak wood timber

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Used hard and soft acoustic wall.

Timber acoustic panels absorb unwanted level frequency through panel vibration. The backing prevent vibration and reflect sound effectively.

Fiberglass acoustic panels to control echoes and sound foci from the rear wall and balcony faces.

Sloping floor.

Acoustic joist strips through conventional timber joist floors.

Improve the acoustic performance and reduce the impact sound level.

Walls : Acoustic Rough Plaster to Solid Back, Timber Acoustic Panel and Fiberglass Absorption Panel Ceiling : Gypsum Board with Ceiling Grid Floor : Wooden Floor on Joist and Pile Carpet Bounded to Closed-cell underlay

PART B: NEW CONCERT HALL DESIGN PROPOSAL Introduction In general, sound affects the occupants of a building in two distinct ways. First is by the quality of the sound generated within the building; concert/musical hall for instance whilst the second way is in regards with disturbance or annoyance of loud noise (noise is a term used to describe unwanted sound). Despite much recent research and studies done previously, factors that concerning the quality of sounds are still ambiguous yet imperfectly understood. Occurrence of prolonged, over vibrant or flutter noise in a building surroundings may result to permanent damage of ear.

Acoustical problems in buildings could be avoided if such acoustic requirements being rectified and plan at preliminary design process. The major requirement of designing a concert hall is associated with decibel consideration and good acoustical design, which depends on its actual purpose/function.

A good design of a concert hall can be successfully achieved by defining sources of noise; adopted with architectural requirements and develop both combinations with acoustical necessity in the building. In order to acquire good acoustics, design aspects such as layout plan, shape and form as well as the needs of using good reflective materials are necessary as these elements are the essential design requirements. This process participates wider expertise to address these acoustical needs and generally, ideas and contribution from architects, mechanical and electrical engineers and acoustic consultants are specifically imperative.

I. FORM AND LAYOUT DESIGN PROPOSAL

Layout Plan (Done by : Febbie Fransiska)

SECTION A (Done by Xixi)

SECTION B (Done by Xixi)

3-D PERSPECTIVE VIEWS (Ngan & Privena)

The wall panel surfaces of the concert hall diffuse or absorbs the sounds. In short, the shape of the enclosed wall determines the reflection mode of the sound.

Due to the height of the concert hall which is of 13m height, so that the needs of using various reflective sound absorption materials are necessary.

Ceiling reflectors, also called clouds, are used to direct sound energy from the stage to the seating area. Concave surface gently arched perforated metal ceiling allows sound to travel to an upper ceiling.

Type of this hall is shoe-box style concert hall, the main purpose of a concert hall is to convey sound from musicians to listeners and to reverberate the music for more pleasant experience in the audience area. The term "shoe-box" refers to the shoebox shape of the hall. It provides sufficient sound reflection from its sides producing a rich sound, have very good acoustics.

This theatre have a wide shallow plan. The seating layout plan is straight steeped row, separated with side angle block. It is well suited to lecture, film or slide presentations, but not very conducive to close relationship between performer and spectator.

The angle of seating is 20°, sloping floor is desirable especially for large hall, for the audience it improves sight lines, the listener receives more direct sound than would be available on a flat floor. Sloping floor is desirable in hall where audience sound absorption must be minimized, for safety the slop should not exceed about 35°.

In

generally, surfaces that close to the stage should be reflective. The sound absorbing materials should be placed in the rear parts of the hall, if necessary. To prevent delayed reflections from rear wall, it can be treated with a sound absorbing material or can be diffusively reflective. . The walls surrounding the stage are

acoustically treated to be sound reflective or absorbent. In addition, the walls are of zig-zag shapes with different layers, assuring good sound distribution within the concert hall.

For the stage, at this case there use teak timber material, it is good for acoustics due to its reflective nature and flexibility. As the echoes are caught and captured, greater clarity to original sound is restored.

II. MATERIALS (Done by Xixi) Seat The audience will play a major role in sound absorption.

Therefore, the seats need to simulate the same amount of absorption as a real person sitting on it. So the material of the seat needs a good sound absorption.

The seat’s filling use elastic polyurethane foam, the upholstery fabrics is velour. It is elastic fabrics which do not change the shape. Furthermore, have high abrasion resistance and easy maintenance and upkeep.

Wall Wood can truly enhance the visual beauty of a concert hall, and proper use can improve concert hall acoustics. So for the wall finish, we design to use dense wooden, for example TEAK TIMBER(1000mm*200mm*20mm), also make some panel( same material but different Texture), it reflects sound, and can easily be made into surfaces that channel sound reflections. This property is utilized in musical instruments and concert halls.

Floor For the floor we use Douglas Fir floor (1200mm x 240mm x 20mm), this Softwood floor has been used because of its durability and its ability to absorb sound. This reduced ambient noise caused by movement of people within the auditorium. It also is able to handle the expected heavy traffic without requiring much maintenance.

Ceiling For ceiling it is where sounds can be reflected back to the ground. This causes distinct echoes and can be very disorientating for the performer, as well as being detrimental to concert hall acoustics. In such areas, panel absorption can be installed to minimise the echoes and control reverberation.

So here we design to use cork panel(400mm*400mm*15mm).

In order to provide useful sound reflection, half of the ceiling we use Gray color Oak (1300mm x 120mm x 15mm )

Stage TEAK TIMBER(1200mm x 300mm x 20mm) is use at stage floor, this hardwood material give the stage a beautiful finish that compliments staging and lighting very well, also it provide useful sound reflection.

We installed velour curtains on the preparation.When the stage is curtains can absorb sound very well

stage, to conceal stage preparing,the velour and reduce noise.

III. REVERBERATION TIME (Ngan, Febbie & Privena) Materials

Area(m2)

Absorptions of Surface as (m2)

1803

Absorption Coefficient (500Hz) 0.25

Teak Timber (1000mm*200mm*20mm) Douglas Fir floor (1200mm*240mm*20mm) Gray color Oak (1300mm*120mm*15mm )

165

0.06

9.9

628

0.05

31.4

Velour curtains Upholstered Tip-Up Theatre Seat Total

49 186

0.55 0.15

26.95 27.9

450.75

546.9

RT = 0.16 V (Metric units)/ A =0.16x 21160.23 /546.9 =6.2

IV. CONCLUSION Based on the formula RT= 0.16V/A, RT is proportional to the volume of the space and inversely proportional to the amount of sound absorbing material within a space. For instance, a small classroom with a suspended acoustic ceiling and carpet will have a short RT, whereas a large multipurpose room with a drywall ceiling and hardwood floor will have a long RT. So for this case, the material we choose for the theatre is important as the absorption coefficient of the value material will effect the absorption of the surface making the A higher which will then make the RT low.

References http://www.acoustic.ua/st/web_absorption_data_eng.pdf