Module 2 auditorium design PDF

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Republic of the PhilippinesSORSOGON STATE COLLEGECollege of Engineering and ArchitectureDepartment of ArchitectureINSTRUCTIONAL MATERIALSforACOUSTICS AND LIGHTSModule 2 : acousticalrequirements for auditoriumdesignPrepared byLUISITA F. FRANCISCO – GEGAJO, UAPAssociate Professor VLFF MODULE 2 ACOUSTI...

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Republic of the Philippines

SORSOGON STATE COLLEGE College of Engineering and Architecture Department of Architecture

INSTRUCTIONAL MATERIALS for ACOUSTICS AND LIGHTS

Module 2: acoust acoustical ical requirem requirements ents for auditorium design Prepared by

LUISITA F. FRANCISCO – GEGAJO, UAP Associate Professor V

Ar.Luisita F. Francisco – Gegajo, MA Arch., MAED

AUDITORIUM is a place for listening developed from the classical open – air theaters. It is a room intended for listening to music including theaters, churches, classroom, meeting halls. The design of various types of auditoriums has become a complex problem, because in addition to its various, sometimes conflicting, aesthetics, functional, technical, artistic and economical requirements, an auditorium often accommodate an unprecedentedly large audience. (https://www.slideshare.net/mominzaki/auditorium-acoustics) Acoustical Requirements for Auditorium Des Desiig n 1. There should be adequate loudness in every part of the auditorium particularly the remote seats. 2. Sound energy with in the room must be diffused. That is, there must be a uniform of sound. 3. The room must maintain optimum reverberation characteristics. The Reverberation Tune must allow favorable reception and efficient presentation. 4. The room should be free from acoustical defects such as echo, long delayed reflection, sound concentration, coupled spaces, etc. 5. Noise and vibrations which would interfere with listening or performing should be excluded or at least reasonably reduced to a minimum. Me th thods ods to Provide A Adequate dequate Lou Loudnes dnes dness s and Reduce Sou Sound nd E En nergy Loss 1. The auditorium should be shaped so that the audience is as close to the sound source as possible, thereby reducing the distance the sound must travel. Fan Shaped is recommended direct sound can be achieved with 140 degrees.

Figure 1. Fan shaped plan with 140 degrees received direct sound from sound source. Ar.Luisita F. Francisco – Gegajo, MA Arch., MAED

2. The sound source must be raised as much as feasible in order to secure a free flow of direct sound waves to every listener at least one (1) meter.(Figure 2)

Figure 2. SOUND SOURCE should be raised from the finished floor line so that there will be free flow of direct sound to the audience. The Floor is raked in the audience seating area.

3. The floor where the audience seated should be properly RAMP OR RAKED. Because sound is more readily absorbed when it travels the audience at grazing incidence. As an empirical rule the angle of elevation of the inclined floor in the auditorium should be not less than eight (8) degrees. (Figure 2) 4. The sound source should be closely and abundantly surrounded with large sound reflective surfaces in order to supply additional reflected sound energy to every portion of the audience.

Figure 3. Auditorium audience area divided into three parts for the material specification.

Ar.Luisita F. Francisco – Gegajo, MA Arch., MAED

5. The floor area and volume of auditorium should be kept at a reasonable minimum, there by shortening the distance that direct and reflected sound must travel. 6. Parallelism between opposite sound reflective boundary surfaces should be avoided to eliminate undesirable back reflections. Introduce rough surface so that sound waves be diffused. 7. The audience should occupy those parts of the seating area which are advantageous both for viewing and hearing. Provide window seating arrangement for every seat.

Figure 4. Window type seating arrangement row 2 seating position must be located in between the two seats of row 1.

8. If besides the primary sound source, which is normally located at the front part of an auditorium, additional sound waves exists in the other parts of the room, then these sound sources must also be surrounded by sound reflecting sources. Best Metho Method ds to create SOUND DIFFUS DIFFUSION ION 1. Provide surface IRREGULARITIES. 2. Provide random distribution of sound absorbing material, or the alternate application of reflective and sound absorptive treatment. Control of Reverberat Reverberation ion Reverberation TIME (RT) must not be too short nor too long. Using the formula on RT. the larger the room volume, the longer the RT the more absorption, the shorter RT.

Ar.Luisita F. Francisco – Gegajo, MA Arch., MAED

Im Impr pr proving oving Acoustical Defects There are different ways to eliminate various acoustical defects. Sound Absorbing materials are still the best form of ACOUSTICAL TREATMENT. Acoustical Requirements for the DESIGN of Auditorium Auditoriums s I.

THEATERS

Design and functional consideration which affect the acoustical conditions of theaters: 1. Shape Like size, the shape of auditorium will play a important role in determining the acoustics. Auditorium comes in many different shapes,. Generally avoid square rooms or narrow, rectangular room since parallel walls can cause sound waves to bounce back and forth. That is why many auditoriums have more of a FAN shape. Some auditoriums also feature curved walls, which helped diffuse sound. In addition to the general shape of a room, other architectural features like ceiling pitch and structures in the room will affect the way sound waves behave in the shape. (https://illuminated-integration.com/blog/7auditorium-acoustics-considerations)

a. FAN SHAPE Plan gives satisfactory results without introducing complications in the acoustical treatment of the hall.

Figure 5: Sample FAN SHAPE PLAN

b. SHOE BOX or RECTANGULAR HALL with the stage across one narrow end, may be excellent for music, where an audience can be seated farther away and a greater ratio reverberant sound is desirable. However, a rctangular geometry is suitable for small audience speech hall.

Ar.Luisita F. Francisco – Gegajo, MA Arch., MAED

Figure 6. Sample Plan of Box type or Rectangular Hall

2. Seating Capacity Auditorium seats are measured from “center to center”, significant from center of one armrest to the center of the other. Multiply that number of seats desired to fit the hall. The amount of space required for each auditorium depends on a number of factors but the following guides, based on a modern seating design can give of the area needed: For an auditorium with 300 seats needs 335 sq.m, 3600 sq.ft., for 200 seats; 270sq.m. 2900 sq.ft, for 150 seats; 190 sq.m. 2000 sq. ft; for 75 seats; 125 sq.m. , 1350 sq. ft. (https://www.google.com/search?q=seating+capacity+for+auditorium&client) There are two basic seating layouts can consider for an auditorium: 1. Multiple aisle This seating arrangement offers a formal setup, suitable for lecture halls and business conferences though the seat count can vary, the typical limit is a maximum of 14 – 16 chairs per row.

Figure 7: Sample of Multiple Aisle Seating Arrangement

Ar.Luisita F. Francisco – Gegajo, MA Arch., MAED

2. Continental This seating arrangement makes good use of space and is a preferred choice for open space auditoriums and amphitheaters. Having all seats turned toward the central arena in a concave fashion helps establish greater intimacy between the performers an the viewers.(https://blog.capterra.com/9 -auditorium-plan-templates-to-inspire-yournext-project)

Figure 8. Sample of Continental seating Arrangements

3. Size of Auditorium The size has an important influence on acoustics. Size includes the length, width and height of the room. Larger and smaller auditoriums come with their own acoustical advantages. A small room generally won’t allow music to ring out at richly as it will in a large room. When it comes to volume, it is easier in getting the whole audience to hear clearly in a small room, while a larger auditorium there is a need to incorporate other aspects to contribute good acoustics and good quality sound system. Another concern in the auditorium size is the REVERBERATION, larger rooms can cause longer reverberation times, which can become excessive. Smaller rooms can cause shorter reverberation times that may seem too short, making the room feel acoustically “dead” (https://www.google.com/search?q=seating+capacity+for+auditorium&client) 4. Audience Performer Relationship The audience is one of the two essential features of a live theatrical performance, along with the performer. The performing arts exist in a finite space and time; this means that

Ar.Luisita F. Francisco – Gegajo, MA Arch., MAED

Performance, which is the work of art in theatre, has a finite existence in time. In nondramatic theatre that performer generally acknowledges the presence of the audience and may even play directly to it. In dramatic theatre the actor may or may not do so. In the illusionary world of theatre or in the arena of spectacle, architecture, lighting and sound are united in a concentrated form and in limited space to satisfy a continuously demanding audience with a maximized impressive and enduring experience in a very restricted amount of time. It seems the stage design as an answer to this demand, could be

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(http://www.interactivearchitecture.org/between-stage-and-audience-testing-new-relationships between-performer-and-audience.html)

Types of stages used: 1. PROSCENIUM Stage Proscenium stages have an architectural Frame, known as the proscenium arch, although not always arched in shape. Their stages are deep and sometimes raked, meaning the stage is gently sloped rising away from the audience. Sometimes the front stage extends past the proscenium into the auditorium.

Figure 10. Sample Proscenium Stage

Proscenium stage, in theatre, the frame Or arch separating the stage from the auditorium, through which the action of a play is viewed. (https://www.britannica.com/art/proscenium) 2. OPEN Stage Open stage, also called thrust stage, or platform stage, theatrical stage without a proscenium, projecting into the audience and surrounded on three sides by the audience. The open stage /th square but may be semi-circular or half a polygon with any number

Ar.Luisita F. Francisco – Gegajo, MA Arch., MAED

Figure 11. Image showing the Thrust Stage at the Gulbenkian, University of Kent.

of sides. Such stages are often used to increase intimacy between actors and the audience.

3. Theaters in THE ROUND OR ARENA These have a central performance area enclosed by the audience on all sides. The arrangement is rarely ‘round’: more usually the seating is in a square or polygonal formation. The actors enter through aisles or passageway between the seating. Scenery is minimal and carefully positioned to ensure it does not obstruct the audience’s view.

Figure 12. Image showing the in-the-round auditorium at the Stephen Joseph Theatre, Scarborough.

Arena theatres are large scale auditoria and have a central stage area with audiences on all sides, similar to theatres in-the-round. The stage area is usually rectangular, more like a sports arena, with tiered seating. 4. BLACK – BOX OR STUDIO THEATHERS These are flexible performance spaces which when stripped to their basics are a single room painted black, the floor of the stage at the same level as the first audience row. Usually these spaces allow for the temporary setup of seating in a number of different configurations to enable a wide variety of productions to be presented.

Figure 13. Image showing the Studio at the Questors Theatre, Ealing.

5. PLATFORM STAGES

These usually consist of a raised rectangular platform at one end of a room. They can either have a level or raked sloping floor. The audience sit in rows facing the stage. Platform stages are often used in multi-purpose Ar.Luisita F. Francisco – Gegajo, MA Arch., MAED

Figure 14 Sample of Platform stage

halls where theatre is only one of the space’s uses. Where the stage is open and without curtains, they are sometimes known as end stages or open stages. 6. HIPPODROME THEATERS Hippodromes are similar to circuses and have a central circular arena surrounded by concentric tiered seating. Deep pits or low screens often separate the audience from the arena.

7. OPEN THEATERS

Figure 16. Type of Hippodrome theater(Hulme Hippodrome theaterstust. org.uk.

These are outdoor theatres that do not have a roof, although sometimes parts of the stage or audience seating will be covered. These stages may make use of the natural light as it changes during the day, particularly sunset. Figure 17. OPEN theaters Athens

Figure 18. Regents Park Open air Outdoor stage (pinterest.com.)

Figure 19. Drive – in Movies in UK

8. SITE SPECIFIC THEATRE Site-specific theatre is usually performed in a non-traditional theatre space such as a pub, home or warehouse, often reflecting the history, atmosphere or experiences of a particular location.

Ar.Luisita F. Francisco – Gegajo, MA Arch., MAED

9. PROMENADE Theatre This involves the audience moving from place to place following the actors and performance. (http://www.theatrestrust.org.uk/discover-theatres/theatre-faqs/170-what-are-thetypes-of-theatre-stages-and-auditoria)

II.

LECTURE HALLS AND CLASSROOM 

The most important requirements for lecture halls and classroom is the NOISE CONTROL.

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The optimum REVERBERATION time in lecture halls and classroom is 0.4 to 0.7 seconds.

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Lecture halls with volume of 425 to 570 cu.m. or audience of 150 – 200 persons does not require a Sound Amplification System.

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Classrooms with rectangular shapes, level floors, and floor area normally between 56-93 sq.m, seldom create any acoustical problems, even if rear wall is not treated acoustically.

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RECTANGULAR LECTURE ROOM, a diagonal seating layout is particularly recommended. ROOM FOR MUSIC

III. 

No music hall is built for one specific type or style of music, therefore, must always be a meticulously established compromise.

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Investigation show that music requires a longer RT than speech basically because musical sounds last longer that the syllables of speech.

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Balconies should not protrude too deeply. As much a possible the height should be roughly equal to the depth.

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The frequency range for music is much wider than that for speech.

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Floor Shapes of typical music halls: 1. Rectangular 2. Fan 3. Curvilinear 4. Horseshoe

 LIVE HALL an auditorium with a large volume relative to its audience capacity, with predominantly sound reflective enclosure.  DEAD or DRY HALL a hall with a relatively small volume compared to its audience capacity, with enclosures which are highly sound absorptive.

Ar.Luisita F. Francisco – Gegajo, MA Arch., MAED

 WARMTH the fine acoustical quality of a room with a relatively long RT at the lower frequency.  FULLNESS OF TONE a pleasant, noticeable characteristics of a room with a controlled RT over the entire audio frequency range.  DEFINITION possessed by a room where the sounds of different musical instruments played simultaneously are easily distinguishable.  GOOD BLEND a musical sound well mixed before they reach the listener. IV. 

CONCERT HALLS The floor area for the orchestra platform should be based on the space requirements of the musicians, their instruments, the conductor and soloist. Each musician requires a floor area of 1.1 to 1.4 sq.M, while each member of the chorus requires 0.3 to 0.40 sq.M

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Platform should be neither too deep nor too wide, a maximum depth of 9meters and a width of 18 meters is recommended. If chorus space is necessary, 3meters on either side or at the back can be added.

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Surrounding enclosures should have reflective treatment.

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The level of the platform should be elevated high enough above the audience floor level to provide ample direct sound to the audience, and to have a resonant space underneath to enhance instrumental bass radiation and reduce overpowering sounds of percussion instruments.

V.

OPERA HOUSES  An OPERA HOUSES is defined as a combination of a theater and a concert hall.  Performance in Opera house relies heavily upon colorful settings and scenery, thus proscenium stages are recommended.  As opposed to orchestra platform, Opera House use ORCHESTRA PITS, located at least 2.5 meters below the stage.

VI.

CHURCHES and SYNAGOGUES  One of the most difficult aspects in the acoustical considerations of Churches is RT CONTROL

Ar.Luisita F. Francisco – Gegajo, MA Arch., MAED

 A LONG RT is preferred to enhance organ sounds, chorus singing and even the chanting of words. However, speech intelligibility suffers.  CHURCHES usually consist of several coupled spaces (nave, chapel, baptistery, confessionals, etc.). Thus individual space must be provided with certain acoustical requirements.)  The CHANCEL AND PULPIT should be well elevated and surrounded by reflective enclosures.  Organ and Choir should also be surrounded with reflective enclosures.  COUPLED SPACES need individual reverberation control. VII.

MULTI – PURPOSE AUDITORIUMS AND COMMUNITY HALLS

 The problem with most multi-purpose auditorium is the UNRAKED or LEVEL FLOOR.  Level floors introduce the following: 1. Difficulty in providing direct sound 2. Flutter Echoes between level ceiling and floor 3. Lack of absorptive treatment  Community Halls and Auditoriums found at the basement of large churches offer a lot of acoustical problems, primarily the existence of an excessively long RT (5-8 secs). VIII. MOTION PICTURE THEATERS 

Motion Picture theaters represent an exclusively single purpose auditorium.

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The original sound source is not present but is a mere production, reflecting the acoustical character of the motion picture studio in which the films scene was shot.

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Motion Picture theaters should have a relatively short RT.

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Boundary surfaces should be treated in a manner which is favorable to SOUND DIFFUSSION.

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The room should be raked and fan shape, with the room length should not exceed 50 meters.

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Heavily upholstered seats should be used to counter act negative effects, defects caused by fluctuating attendance.

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Projection Room should be acoustically treated because of the noise it produces.

Ar.Luisita F. Francisco – Gegajo, MA Arch., MAED

IX. 

RECORDING STUDIOS Of all spaces which require acoustical attention, recording studios are the most COMPLEX.

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The receiver of sound in studios are microphone, which can easily detect long RTs, inadequate diffusion, all acoustical defects, and even the faintest noise or vibration.

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The frequency range considered in the acoustical design of studios is from 32 to 8000Hz.

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For rectangular studios certain room proportions are generally advocated: 1. For SMALL STUDIOS recommended ratio is: 1:1.25:1.6 (H:W:L) 2. For MEDIUM SIZE STUDIOS the ratio is : 1:1.5: 2.5 (H:W:L)

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The apparent RT in a studio, as eventually perceived by the listener, depends on the microphone pick up technology, different required RTs cannot be avoided so variable absorbers electronically controlled RT devices are used.
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