Handbook for Sound Engineers

Sound System Design 1273

In any choice of coverage pattern, room obstacles,
microphone locations, and seating area should be consid-
ered. There is no reason, for example, to cover wide
aisles unless people will frequently be located there. In
addition, remember that the coverage pattern should be
calculated at about 4 ft above the floor for seated
listeners or 5 ft above the floor for standing listeners.

34.3.3.7.5 Equalizing the Distributed Ceiling System

Equalization is discussed in more detail in Section
34.5.2.2. However, in general, the equalization process
is the same as for a central cluster system. A typical lis-
tener position may be best chosen as in the overlap area
of the loudspeakers for a 50% overlap system, or about
20° off-axis of a single loudspeaker for an edge-to-edge
or minimum-overlap system. As in the central cluster
process, choose several typical positions and equalize
for a position that seems to be a good average as far as
the before-equalization response. In an acoustically dry
room (no significant reverberation field) the equalized
response should show more high frequencies than the
cluster system guidelines would indicate. This is
because there is no low-frequency reverberation to
boost the low frequencies artificially and bias the dis-
play on the real-time analyzer.

34.3.3.7.6 Distributed Systems in Rooms with Sloped
Floors or Ceilings

The traditional approach for a system with sloped floors
or ceilings is to divide the room into sections where the
ceiling height is relatively constant and design a loud-

speaker layout separately for each section. This will

result in fewer loudspeakers per unit area in the

higher-ceiling portions of the room as shown in Fig.

34-33. Additional power must be allocated to those

loudspeakers in the high-ceiling portions.

Another approach to a sloped-ceiling room is to

place the loudspeakers as if the ceiling was flat at the

lowest height and apply the same power to each loud-

Figure 34-31. Methods of square overlap for distributed
loudspeaker systems.

A. Edge to edge. B. Minimum overlay.

C. Center to center

(50% overlay).

Figure 34-32. Methods of hexagonal overlap for distributed

loudspeaker systems.

Square edge to edge 0.66 -3.69 4.35

Hexagonal edge to edge 0.95 -4.45 5.40

Square minimum 2.02 -0.02 2.04

Hexagonal minimum 1.36 -1.23 2.59

Square center to center 5.17 3.78 1.39

Hexagonal center to center 5.38 4.21 1.17

A. Edge to edge.

B. Minimum overlay.

C. Center to center (50% overlay).