DESIGN GUIDE: MUSIC AND DRAMA CENTERS
DG 1110.3.120
C H A P T E R 3: THE HOUSE
JANUARY 1981
To avoid flutter echoes, no two walls should be
2. Plan Arrangement with Respect to Stage
parallel. Reflecting walls are shaped to distribute
Plan geometry for Music has as much if not more
rebounding sound. Surface variations should in-
to do with wall positions than with the audience
clude a large range of sizes "seen" by various
distribution.
wavelengths in the audible range (from " =
20,000 cps to 50 feet = 20 cps) and especially at
The form of stage enclosure and its transition to
mid-frequencies (3-8 feet). Great variation yields
the house influences Room shape. Musicians
good diffusion and uniformity of blend.
may be located in the Room on an open stage,
or in an enclosure at one end. Small Frontal
Room length is related to potential for echo from
Rooms favor the orchestra-in-the-Room condi-
long delayed reflections off the rear wall. The
tion, larger Rooms the orchestra-in-enclosure.
wall may be tilted or rumpled for diffusion.
Because direct sound dominates the small Room,
Focusing curvatures are sometimes a problem
the directional enclosure is less advantageous
of large Rooms that conform to vision criteria for
than a high ceiling (for reverberant volume).
seating. Fan-shaped Rooms must be examined
With increased absorption (people) and distance
for potential sound traps (acute intersections)
from source, the reverse is true; large Rooms
and uneven distribution of reflections.
have directional enclosures to boost direct sound
levels.
3. Vertical Arrangement with Respect to Stage
Sound is a spherical phenomenon; similar con-
The smaller of plan dimensions (usually width)
siderations apply to both horizontal and vertical
may determine first reflection time (intimacy)
shape.
and also the potential for troublesome standing
waves. This dimension should be at least 30 feet
Floor slope affects the portion of direct sound
for Music, 15 for speech. It is normally a concern
received at distant seats. Tilting the audience
for small Rooms. In larger Rooms, the proximity
exposes them to a larger wedge of radiating en-
and orientation of surfaces near the stage control
first reflections.
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