DESIGN GUIDE: MUSIC AND DRAMA CENTERS
DG 1110.3.120
C H A P T E R 3: THE HOUSE
JANUARY 1981
steep area at the rear is lifted to form the balcony,
acquiring an even steeper slope navigable by
steps. Entry/exit is distinctly "two-story". Finally,
lifting and tilting (the balcony) may enable it to
be moved forward slightly, bringing more front
row audience within range of the actor, and par-
tially obscuring the rear of the house where the
empty seats are.
Sitting under a very deep balcony can some-
times be like sitting in another room. The rear-
most row should at least be able to see the top
of the proscenium. Balconies also tend to blanket
an area acoustically, preventing reflected sound
from reaching back rows. The acoustically ac-
ceptable overhang can be greater for Drama than
for Music since the reverberant contribution is
smaller. Moreover, since speech intelligibility fa-
vors a proportionally high direct/reverberant ra-
tio it improves with steeper floor rake and short
throw.
If amplified or pre-recorded sound is employed,
correct positioning of loudspeakers may influ-
ence Room shape. Normally, a central loud-
speaker cluster is located over the stage so that
actor and loudspeaker are equidistant from lis-
tener. The acoustic shadow cast by a low balcony
can be a problem best dealt with by raising the
balcony. (see Fig. 3-5.14).
B. MUSIC HOUSES
1. Seating Area Dimensions
The acoustical importance of the audience area
is its contribution to the Room's total sound ab-
sorption, which is a significant factor in rever-
beration time. For a given Rt, absorption is pro-
portional to volume (three-dimensional size).
The design of chairs for Music audiences is a
critical concern because the most absorptive ele-
ment in the Room is people. The acoustic char-
acter of the Room should not vary greatly due
to attendance rates. Thus, the absorption spec-
trum of an empty chair should roughly approx-
imate one occupied by a human body.
Since people absorb sound, tighter average
spacing of seats (7-8 s.f.) may be called for to
reduce total absorption area. This is more likely
to be important for very large audiences when
conservation of sound energy is critical. It is the
total absorption of the Room that matters.
Hence, absorption influences criteria for sound
retentive construction as well as the volume
FREQUENCY SELECTIVE REFLECTION
F I G U R E 3-5.10
required.
3-26
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