Design of auditoriums is one of most critical things which affectthe experience of users. Auditoriums nowadays are subjected to many designstrategies and new technologies.
This chapter will discuss the technical issuesrelated to auditoriums such as lighting and acoustic solutions. 5.2 AUDITORIUM DESIGN5.2.1 AUDITORIUM SCALE There is nostandard size for the auditorium, it varies according to the production and thecapacity. Each capacity and production will require certain dimensions like theones mentioned in figure 5.
1.5.2.2 STAGE STRUCTUREThe stage hasto be strong enough to withstand different productions that happened on it.
Itmay be required to support heavy scaffold structures, with several raisedlevels, stairs, ladders and walkways. The stage must be capable of adapting tovaried production requirements and this means that most of it should beremovable. “(NB: It is much easier to loosen some bolts and dismantle a steelstructure than it is to demolish reinforced concrete.)”. The under-stagestructure must also provide stable support for actors, dancers, musicians,scenery, props, mechanical effects and technical equipment. It might also attimes allow any of these things to appear or disappear through the floor intothe void below.”Various usefultechnical features may be built into a stage floor including projection screenboxes; dip traps (for hiding cables); float troughs (for downstage lightinginstruments); and carpet cuts (for fast removal of stage coverings).
Manystages are constructed with removable timber floor modules which make it simpleto open up large holes in the floor wherever needed.” (Judith Strong, 2010) 5.2.3 STAGE LIFTSStage lifts areused to raise and lower both larger items of scenery and groups of actors. Theyvary enormously in size and style, but may cover the entire stage area andtravel deep down into the basement.
More powerful lifts are capable of shiftingtens of tons of scenery and some will rise several meters above stage level tocreate instant raised acting platforms, often in modular form. To protectpeople Performing on stage from falling into the hole left by a lift, variousautomatic rising barriers or folding safety nets may be incorporated into thesystem and doors below stage need to be interlocked. Shear edges must haveprotective devices to reduce the risk of injury and even of amputation. (JudithStrong, 2010) 5.2.4 AIR VENTILATIONOne of the mostimportant consideration in designing auditoriums is the air changes within itwhich is almost 8 liters of fresh air per second per person. These largevolumes of air need to be delivered at low velocity because of the acousticcriteria.
Acceptable comfort conditions for audiences should be provided andthis includes maintain suitable levels of temperature, humidity and airvelocity, avoiding the extremes of stuffiness (stagnation) and draughts (too muchair movement). Ventilation could be natural by providing openings in theceiling as well as mechanical ventilation system. (Judith Strong, 2010) 5.3 LIGHTING 5.
3.1 LIGHTING IN THE PROSCENIUM SPACE Lighting in thestage is a very essential subject. Stage lighting should have the ability tolight any part of the stage from different range of angles. There are somefundamental positions to be followed. Lighting the performer’s face should beat around 45° above the horizontal to avoid unflattering shadows because a lowerangle may cause unwanted shadow on the set. Spotlights are usually directedcrossed at the actor and rarely directed straight. This mean that they arepositioned on a cross-section requires an angle in the order of 55° to achieve45° when crossed. The previousdiagram is showing the basic geometry of required positions of each lighting.
At point A, a luminaire lighting is used to light the performer’s face at 55° on the edge of the stage and 45°-50° when crossing. This angle will decrease as the performers movesaway from the edge of the stage.At point Q, theangle will be only 40° and 35° whencrossing which is the absolute minimum, and that’s why; it’s necessary to haveanother luminaire at point B to cover the area between Q and R. The diagramalso indicates the impact of the elevations of luminaires. For example, positionsA and B covers the same area as four positions set lower. Lighting bridgesshould be well-integrated with the ceiling design of an auditorium by treatedthe installations as a part of the room aesthetic while keeping the lightingsin their right positions.
(Judith Strong, 2010) 5.3.2 LIGHTING IN THE AUDITORIUMBOXBOOMS: These are located at the sides of the auditorium and they are so far,the most important lighting position in an auditorium. Box booms should havesafe and easy access.SLOTS:Many theatres have been designed with ‘slots’ lighting instead of box booms atthe side of the auditorium.
These positions are angled so that the lightsthemselves are hidden from the audience. Slots lighting should be wide enoughto allow a lantern to see both sides of the stage.ADVANCEDBAR: It is usually necessary to hang a bar or a bridge if the stage extendsthrough the proscenium creating a forestage. A bridge is preferable because itallows access for focusing and maintenance. HIGHFRONT LIGHT: The positions of these lights are required at an angle of about 45degrees from head height on stage. These positions are either provided with aseries of bridges above the auditorium or with rigging positions at the sidesand back of the auditorium.LIGHTINGBRIDGES: The spacing between the bridges depends on the size of the stage andthe auditorium, but all the bridges should be the full width of the auditoriumto give the widest possible angles of view onto the stage.
SLIPSOR ‘HIGH SIDES’: These are alternative to bridges and have advantages of abetter side angle than bridges.CIRCLEFRONTS: These are used when the theatre has tiers or circles which lightingpositions should be built into their fronts. These positions should follow allaround the curve of the circle front, and allow a lantern to be rigged anywherealong it.ADDITIONALAUDITORIOM POSITIONS AND TEPORARY CABLE ROUTES: The most flexible auditoriawill have a system built into the walls allowing lanterns to be hung inadditional unusual places.
There will also need to be a system for gettingcable to them discretely via carefully planned temporary cable routes. (JudithStrong, 2010) 5.3.3 LIGHTING CONTROL SYSTEMA stagelighting console will control the devices via control network which is likelyto be based on a computer network typology.
The console operator runs the showfrom the control room as well as controlling the lighting for a production. Any lightingconsole, no matter how brilliant, can be rendered useless in the wrong hands. Acalm, quick and knowledgeable operator is the essential addition to make asystem invisible to the designer and allow us to get on with the real job,lighting the show. NeilAustin, Lighting DesignerA lightingcontrol room should be located at the center- rear of the auditorium with anobservation window that gives a clear view of the stage. This window could beopened for direct contact with the auditorium if required. “The control room will require both white’work light’ lighting and localized performance lighting, adjustable forintensity and position and masked so as not to spill through the window. Manymodern lighting consoles have built-in touch screens: direct top light oftenrenders these illegible.
If LED task lights are to be specified, it should bechecked that these do not flicker when run at low levels.” (Judith Strong,2010) 5.4 ACOUSTIC CONSIDIRATIONS 5.4.1 SOUND CONTROL SPACESThe control room is located at the rear of the auditorium and couldbe used for different purposes at the same time (Lighting, stage management,automation, etc.), but it’s better to split the control rooms according tofunction like having separate rooms for lighting and sound. Effectiveness ofthe control room for sound will depend on the area of the opening window andthe depth of any balcony overhang in front.
(Judith Strong, 2010) 5.4.2 AUDITURUIM FORM AND VOLUMEThe task ofacoustician in auditorium is very important. Every member of the audienceshould be able to hear the performance clearly without coloration as well asthe ability of performers to hear each other to enable them to communicate andplay as an ensemble. There are many factors affect hearing ability inauditoriums. Listeners who are close to the stage, hears mostly direct sound,which dominates the weaker late reflections from the room surfaces.
Listeners who are further from the stage,hear a combination of direct sound and reflected sound arriving a series ofdiscrete reflections, spaced in time. The reflected sound should arrive in anordered way, maintaining the realism of the direct sound, reinforcing it andnot containing strong long-delayed reflections or echoes, which affect itsquality. It’s importantto establish the right volume of any performance room for a particularperformance type because the volume has a direct relationship to itsreverberation time. Figure 5.
9 is showing the reverberation for each volume aswell as the type of performance that suits each one of them. SPEECH: “For speech, the auditorium volume can be fairly low,around 5m3 /per person. Reverberation times should be appropriate to the use,around one second at mid-frequencies. In theatres, seating should be as closeas possible to the stage, favoring a fan-shaped seating plan and multiplebalconies. Good sightlines generally make for good acoustics as what the eyecan see the ear can also hear. Theatres for unamplified speech work well up toaround 1,000 seats but beyond this the skills of the acoustician are taxed.
“(Judith Strong, 2010)MUSIC: “Clarity is less significant and reverberance andenvelopment are more important. To provide this, the reverberation time shouldbe close to 2.0 seconds, with a rise in the bass. This means a volume of around10m3 / person or more. The shoebox form, often a double cube, was used in manyeighteenth-century concert halls and is still favored by many acousticians. Itguarantees high ratios of lateral energy, so important to instrumentlocalization and the listening experience. Audience size is optimum up toaround 1,800 seats, after which acoustic excellence becomes more difficult toachieve.
” (Judith Strong, 2010)MULTI PURPOSE AUDITORIMS: Many auditoriums are used for a range ofpurposes and that’s why, they require different acoustic conditions. Thesespaces tend to have staging and curtains used to reduce the reverberation timefor speech. An auditorium may have large reverberation chambers to increasereverberation times beyond 3 seconds.
There are also some treatments likeacoustic panels and curtains to vary reverberation time as well as movableceilings.5.4.
3 ACOUSTIC TREATMENTSREFLECTING SOUND: The sound is reflected from surfaces differentlydepends on the relationship between the size of the reflector and thewavelength of sound. A convex surface will disperse sound and it’s valuable insituations where reflection from a plane surface might produce undesirableeffects. By contrast, concave surfaces are particularly dangerous because theyfocus sound. (Michael Barron, 2010) The auditorium shouldbe designed in a way that control the directions and the amount of the sound.Figure 5.12 is showing an example of sound control. ECHO CONTROL:While many acoustic defects are a matter of degree, such as too muchreverberation or inadequate loudness, certain phenomena are alwaysdisagreeable. Echoes can certainly be obvious and pernicious.
There are manytreatments are used to control the undesirable echo materials that absorbs thesound. The next figure is showing some of the common treatments used. (MichaelBarron, 2010) 5.5 CONCLUSIONTechnicalissues related to auditorium are wide, but this chapter covered the mostimportant issues. Designing a comfortable auditorium that gives audience theability to see and to hear clearly, and gives the performers the ability todeliver their massage easily, is the aim of their design.
In the next chapter,conceptual subjects related to the building generally and the auditoriumspecifically will be discussed.
