11. MULTI-PURPOSE AUDITORIA, COMMUNITY HALLS:
In the acoustical design of these, often very
large, Auditoria,
• the "sending end" should be elevated as high as sight
lines will allow;
• a large amount of reflective surfaces (panels) have to
be located near the sound source, and, as necessary,
suspended from the ceiling to provide short-delayed,
reflected sound energy; these reflective surfaces have
to be oriented so as to secure evenly distributed
natural sound reinforcement throughout the entire
Auditorium;
• the stage should protrude as far as possible into the
audience area;
• an attempt should be made to accommodate a raked
or raised portion of the floor at least at the sides and at
the rear of the main audience area
• optimum R.T. should be secured for one-half of
capacity audience because a considerable fluctuation
has to be expected with the occupancy of these halls;
• the loudspeaker, if used, should be located somewhat
higher than it would be in an Auditorium with a
ramped floor.
For School auditoria a sound amplification
system will be necessary if the volume is in excess of the
following :
for Elementary Schools: about 40,000ft³
for High Schools: about 50,000ft³
for Colleges and Universities: about 60,000ft³ ROOM ACOUSTICS:
Multi-purpose Auditoria, Community Halls:
12. ROOM ACOUSTICS:
Multi- Purpose Auditorium in Montreal.
Seating capacity: 3100,dedicated in
1963.
Lower floor plan (top left),
1: vestibule,
2 and 3:sidelounges,
5: orchestra floor,
6: orchestra pit,
7:stage,
10: side stage.
Upper floor plan (top right),
2 and 3: side lounges:
4: balcony,
5and 6: box seats,
7: stage house.
Section,
1:vestibule,
3:auditorium,
4: stage house,
5:elevator machine room.
Multi-purpose Auditoria, Community Halls:
13. AUDITORIUM DESIGN
The three-dimensional
volume of an auditorium is
conditioned by
the need for all members of the
audience to be able to see the
whole of the platform or stage and
hear the actor, singer,
musician or speaker.
Visual and aural limitations
(a) plan : for a performer at center
stage B there is an arc Y
beyond which visual and aural
perceptions are impaired.
However, for performers nearer the
sides of the stage at A and C
produce more restrictive curves X,
14. Visual and aural
limitations
(a) plan : for a performer at center
stage B there is an arc Y
beyond which visual and aural
perceptions are impaired.
However, for performers nearer the
sides of the stage at A and C
produce more restrictive curves X,
(b) Section : Similarly, visual and limits
in section also set an arc
centred on the performer layout are
partly determined by this,
partly to give the audience an
appropriate level of comfort and
essentially to ensure a means of
escape in an emergency, such
as a fire, within the time required by
safety considerations and by
legislation.
15. 1) Design of the auditorium seat
The aim is to provide an appropriate standard of comfort. The range of human body dimensions is wide; while in
most auditoria a single size of seat is provided as shown in table below.
16. Design of the auditorium
seat
Auditorium seating: definitions of terms and
dimensional information:
a Plan,
b Section.
• Seat width: the minimum dimension as
stipulated by legislation is 500 mm with
arms and 450 mm without.
• For seats with arms a width of 525 mm is
the least for reasonable comfort.
• Seat height: 430–450 mm.
• Seat inclination: an angle to the horizontal
of 7–9°.
• Back height: 800–850 mm above floor level
(may be increased for acoustic reasons).
• Back inclination: angle to the vertical of 15–
20°.
• Seat depth: 600–720 mm for seat and back
depth overall, reducing to 425–500 mm
when the seat is tipped.
• The seat depth varies and depends on
thickness of upholstery and backing and if
the rear of the seat contains the air-
conditioning.
• For a modest seat with arms, the dimensions
can be as low as 520 mm deep, 340 mm
when tipped.
• The ability of the seat to tip, activated
silently by weight when not occupied, allows
a clearway (which is a critical dimension) to
pass along a row while limiting row to row
distance.
17. Design of the auditorium
seat
• Where space is severely limited
such as in studio theatres, an
especially slim seat, as shown in
figure can be used.
• Arm rests: 50 mm minimum width,
with the length coinciding with the
tipped seat to avoid obstructing
the clearway; the height about 600
mm above floor level; the upper
surface may be sloped or not.
• The permanent fixing of a seat can
be:
19. Levels in the auditorium &
Number of seats in a row
• With a single level only, the pitch of the rake requires
particular attention to achieve a sense of enclosure.
• The Greek amphitheater is the exemplar.
• Seating capacity within aural and visual limitations can
be increased by the addition of one or more balconies
within the overall permissible volume of the
auditorium.
• Similarly, boxes, side galleries and loges can be added
to the side walls, especially in the case of the
proscenium format.
• A maximum of 16 seats per aisle.
• 25 seats per aisle is permissible if one side exit door of
1 m width is provided per 3-4 rows.
• With traditional seating the maximum number is 22 if
there are gangways at both ends of the row, and 11
for gangway at one end.
• Thus in all but the smallest auditorium the gangways
divide the seating into blocks.
• Rows with more than 22 seats are permitted
20. Levels in the auditorium &
Number of seats in a row
• The term ‘continental seating’ is used for rows of seats
with an increased back-to-back dimension extending the
width of the auditorium with exits at both ends.
• This arrangement is only appropriate to proscenium
stages.
• Spacing is controlled by the clearway between the leading
edge of the seat (in an upright position, if tippable) and
the rear of the back of the seat in front, as shown in
figure. For traditional seating the minimum clearway for
people to passalong the row is 300 mm and this
dimension increases with the number of seats in a row.
• For continental seating the clearway is not less than 400
mm and not more than 500 mm.
• Legislation also dictates the minimum row-to row
dimension at 760 mm: this is usually not adequate and the
minimum should be 850 mm for traditional seating.
• As gangways are essential escape routes, their widths are
determined by the number of seats served.
• The minimum is 1100 mm.
• They can be ramped up to 10%, but only 8.5% if likely to
be used by people in wheelchairs.
25. Capacity of an auditorium
• In general, the maximum capacity of an
auditorium depends on the format selected,
and on aural and visual limitations set by the
type of production.
• Other factors include levels, sightlines,
acoustics, circulation and seating density, as
well as size and shape of platform/stage.
• An area of at least 0.5 m2 per spectator is to
be used for sitting spectators.
• This number is derived from a seat width x row
spacing of at least 0.45m2 per seat, plus an
additional minimum of 0.5m x 0.9m
i.e. approximately 0.05m2 per seat.
• Seats with arms and tippable seat can occupy a
space as small as 500 mm wide (less for seats
without arms) with a row-to-row dimension of
760 mm; but can be as large as 750 mm wide
by 1400 mm, as shown in the figure.
• The area per seat therefore varies between
0.38m2 and 3.05m2 .
• Increased dimensions reduces seating capacity.
• Minimum dimensions as laid down by
legislation offer a low standard of comfort and
should not be taken as a norm, but the social
cohesion of the audience may be lost if the
standards are too high.
26. Elevation of seating
• Elevation of seating (gradient) in the
auditorium is obtained from the lines of vision.
• Such lines are valid for all seats in the
auditorium (stalls as wellas circles).
• Since the spectators sit in ‘gaps’, only every
second row requires full sight elevation
(12cm).
• Special mathematical literature addresses the
subject of sight problems in theatres in which
the randomness of the distribution of different
sizes of spectators is also taken into account.
• The rows of spectators should be formed in a
circular segment with respect to the stage, not
just for better alignment but also to achieve
better mutual perception (feeling of
integration).
27. Complete vertical section through auditorium
Vertical sightlines, as shown in the figure, may be calculated by establishing:
• P Lowest and nearest point of sight on the platform or stage for the audience to see clearly.
• HD Horizontal distance between the eyes of the seated members of the audience, which relates to the row spacing
and can vary from 760 mm to 1150 mm and more.
• EH Average eye height at 1120 mm above the theoretical floor level: the actual eye point will depend on seat
dimensions.
• E Distance from the centre of the eye to the top of the head, taken as 100 mm or 120 mm as a minimum dimension for
the calculations of sightlines.
• For assurance that there is a clear view over the heads of those in the row in front this dimension should be a least
125 mm.
• D Front row of seats: the distance from point P to the edge of the average member of the audience in the front row.
• The relationship is shown in figure above.
• The longitudinal sect ion is a parabolic stepped floor as a theoretical rake produced by the sightline calculation.
• This gives every member of the audience similar viewing conditions.
28. Sightlines for a seated
audience
• This gives every member of the audience similar viewing
conditions.
• This may be reduced to a single angle or series of angles.
• When applied as described the rake will also be steep.
• This is satisfactory for a single tier of seating with no
balconies and is especially appropriate for open-stage
formats.
• If a balcony or balconies are introduced, the rake of the
lower bank of seats can be reduced, assuming vision to be
every other row allowing for point P being seen between
heads in the row in front.
• The vertical distance between point from eye to top of the
head for calculation purposes can be reduced to 65 mm if
seats are staggered.
• This is particularly applicable with the design of a large
auditorium where, within the visual and aural limitations,
the aim is to maximise the seating capacity.
• This implies a balance between sightlines, height of
auditorium and seating capacity.
• Reducing the accumulative height of the lower level of
seating allows more height for balconies.
• With the smaller auditorium, especially with the audience
partially or wholly surrounding the stage and a limited
number of rows of seats, an increased height of the rake
to the seating encourages a sense of enclosure of the
stage, while providing good sightlines. figure below shows
how the eye position relates to the seat and the stepped
floor.
29. Complete vertical section through auditorium
• The proscenium height should first be determined.
• The ratio in a stalls theatre of proscenium height to width should be 1:1.6.
• The golden section, or the physiological perception field, is included in this as shown in the figure below.
• After the proscenium height, the apron height, the banking of the stalls and the volume of the auditorium are determined; the
lines of the ceiling are obtained from the acoustic requirements.
• The aim should be for the reflected sound from the stage or apron to be equally distributed throughout the auditorium.
• In the case of circles, it should be ensured that the full depth of the stage can be seen, even from the upper seats.
• This might require an increase in proscenium height.
• The proportions of an experimental auditorium are shown on the following page.
• Neutral or open theatre auditoriums permit different arrangements of spectator seating and stage areas.
30. Proportions of auditorium
These are obtained from the spectator’s psychological
perception and viewing angle, as well as the
requirement for a good view from all seats.
• Good view without head movement, but slight
eyemovement of about 30°.
• Good view with slight head movement and slight
eyemovement approx. 60°
• Maximum perception angle without head
movement is about 110°, i.e. in this field
everything which takes place ‘between the
corners of the eyes’ is perceived. There is
uncertainty beyond this field because something
may be missed from the field of vision.
• With full head and shoulder movement, a
perception field of 360° is possible.
31. Horizontal sightlines
• Given a particular size and shape of the platform
or stage, horizontal sightlines limit the width of
the seating area in the auditorium.
• This is more critical with the proscenium stage
and with film, video and slide projection.
• Without head movement, the arc to view the
whole platform or stage on plan is 40° from the
eye, as shown in the figure.
• Debatable is an acceptable head movement,
where the seat is focused away from the platform
or stage, such as with side galleries requiring the
head to be turned by the member of the
audience, as shown in the figure.
• The horizontal sight line of the performer may
also need consideration, as shown in the figure.
32. Horizontal sightlines
• Regulations require a minimum of six places for
wheelchair users, or 1/100th of the audience
capacity, whichever if the greater.
• Their location as discrete areas can be at the rear,
front, side or within the seating, as shown in the
figure.
• Wheelchairs can be centrally positioned by
forming a bay off a cross-gangway.
• A wheelchair user should be able to sit with a
party of friends not in wheelchairs, as shown in
the figure.
• Sightlines from the wheelchair should be checked,
as should the sightlines of those audience
members behind.
• Some wheelchair users can transfer into
auditorium seats.
33. Fire norms
• The aim is for all in the auditorium to be able to escape to a
place of safety within a set period of time.
• The escape route is from the seat, a long the clearway and
gangway, and through exit doors immediately, or through an
enclosed corridor, to the place of safety.
• The maximum travel distance from seat to exit within the
auditorium is determined by the need to evacuate from each
level of the auditorium within 2½ minutes.
• For traditional seating the maximum travel distance is 18 m
measured from the gangway, for continental seating 15 m from
any seat.
• 1 m wide per 150 people (min. width 0.8m)
• From each level of the auditorium two separate exits must be
provided for the first 500 seats with an additional exit for each
further 250 seats.
• Each exit from the auditorium must lead directly to a place of
safety.
• The route must be a consistent width the same as the exit.
• There must be no bottlenecks and all doors within the route
must open in the direction of escape.
• Routes within the building should have fire-resistant enclosures.
• There are special requirements for all doors opening onto fire
escape routes.
• Staircase flights should have at least two risers and not more
than 12.
• All treads should be 300 mm and risers 150 mm.
• Wheelchair users should be provided with flat or ramped
escape routes which may be separate from other routes. Ramps
should not be longer than 4.5 m or steeper than 8.5%.
• While gangway lengths and widths are calculated as part of the
fire escape route, they also provide the circulation through
the auditorium, with possible additional gangways from the
audience entry points to individual rows and seats.
34. Stage area
There are three stage forms: full stage, small stage
and set areas.
• Full stage: More than 100 m2 of stage area.
• Stage ceiling more than 1 m above top of
proscenium arch.
• An essential feature of a full stage is an iron safety
curtain which separates the stage from the
auditorium in the event of an emergency.
• Small stage: Area no more than 100m2 , no stage
extension (secondary stages), stage ceiling not
more than 1 m above top of proscenium.
• Small stages do not require an iron safety curtain.
• Set areas: Raised acting areas in rooms without
ceiling projection.
• The peculiarity with set areas is in the regulations
with respect to curtains and scenery.
• They affect the operation, not the planning, of set
areas.
• Experimental auditoria fall within the set area
definitions.
• Stage proportions are developed from the lines of
vision from the auditorium.
• The stage area is the playing area plus walkways
(around the back of the stage) and working areas.
• The principle design of a traditional full stage
35. Stage area
• Mobile set areas are formed from height-adjustable
platforms or lifting podia.
• Variable shapes are achieved by splitting the area into
individual elements.
• Basic dimensions 1 m x 2m
• Means should be provided for ventilating smoke and
hot gases resulting from fire on the stage, e.g.
provision of haystack lantern light or fire ventilator
sited in highest point in roof over stage and as near to
centre of stage as is reasonably practicable.
• An additional fresh air inlet may prove effective.
