Acoustics for Auditoriums and Concert Halls 175(7-49)where,for y 0 = 0:The superelevation of the visual line should amount to
at least 6 cm (2.5 in).
For estimating the required basic sloping of tiers one
should keep in mind that the platform must be
completely observable from all seats during the perfor-
mances. The reference point to be chosen to this effect
should, if possible, be the front edge of the platform.
Using a reasonable platform height between 0.6 to 1 m
(2 to 3.3 ft), the results of the sloping values are shown
in Fig. 7-35A.
By increasing the distance between first tier and
viewing point (observable area of the platform) it is, of
course, possible to notably reduce the necessary sloping
of tiers, Fig. 7-35B.
With a plain parquet arrangement, which is the case
in concert halls serving also for banquets or with classi-
cistic architecture (Musikvereinssaal Vienna, Konzer-
thaus Berlin, Symphony Hall Boston, Herkulessaal
Munich, etc.), a certain though normally somewhat
dissatisfactory compensation is possible by means of an
appropriate vertical staggering within the performance
area (especially feasible for concert performances). For a
basic platform height of 0.6 to 0.8 m (2 to 2.6 ft) it is
possible to derive the theoretical required sloping heights
from Eq. 7-49. With a length of a plain seating area of
about 14 m (46 ft), a vertical staggering of the musicians
on the platform must be about 3 m (10 ft), and with 18 m
(59 ft) vertical staggering must be 4 m (13 ft). These
values are generally not easy to realize, but show the
necessity of an ample vertical staggering of the orchestra
on the platform in rooms with plain parquet arrange-
ment. However, if the optimum sloping of tiers
according to Eq. 7-49 is realized on principle, it is
possible for a sound source situated in the middle of the
orchestra about 6 m (20 ft) behind the front edge of the
platform to achieve the required view field angle by an
elevation of 0.25 m (|1 ft), and for the entire depth of the
orchestra arrangement this elevation amounts to only
about 1 m (|3.3 ft). In concert halls with a sufficient
sloping of tiers in the audience area, vertical staggering
of the orchestra plays no more than a subordinate role for
the unhindered direct sound supply to the audience area.7.3.3.3.2 Platform Configuration in Concert HallsWith concert performances, the performance area for
the orchestra (platform) must be an acoustical compo-
nent of the auditorium, which means that both sections
of the room must form a mutually attuned unity. This
unity must not be disturbed by intermediate or other
built-in elements. Any individual room-acoustical
behavior of its own of a too small concert stage enclo-
sure must be avoided. As used to be the case with many
opera houses, this has a sound coloration deviating from
that of the main auditorium and will be perceived as
alienated. The volume of a concert stage enclosure
should be at least 1000 m³ (35,300 ft^3 ).^36 The sloping
angles of the lateral boundary walls, referred to the
longitudinal axis of the room, should be relatively flat.
Takaku^36 defines an inclination index K according to Eq
7-50(7-50)where,
K is the inclination index,
W is the proscenium width,
H is the proscenium height,Figure 7-35. Effect of sloping tiers.yy 0 cx
d----- x
aln--- x
a= ++--- by– 0ycx
d----- x
aln--- bx
a----- -+=75319platform height 1 m (3.3 ft)9B. Sloping of tiers for constant platform height of 0.6 m
and different distance of 3 m and 6 m between first
row and reference point.1 2 5 8 11 14 17 20 231 2 5 8 11 14 17 20 237531platform height 0.6 m (2 ft)distance 1 row - reference point = 3 m (10 ft)distance 1 row - reference point = 6 m (20 ft)Tier – Steps, eye line – solid, sight line – dashed.A. Sloping of tiers for different platform heights of 0.6 m
and 1 m and constant distance of 3 m between first
row and reference point.KWH
S--------- wh
S------ -–D= -------------------------------