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2-14
Once the critical polar angle has been determined, calculate the coverage area for a given speaker-
to-listener distance:
Coverage Circle Diameter = 2 D
2
tan
⎟
⎠
⎞
⎜
⎝
⎛
2
θ
Coverage Area = π
2
2
2
θ
tanD
⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛
⎟
⎠
⎞
⎜
⎝
⎛
Where D
2
is the distance from the speaker to the
listener and θ is the critical polar angle. (Refer to Figure 2-5, Speaker Coverage Diagram)
Equation 2-11. Coverage Area Calculations
The following table contains coverage areas calculated for Simplex TrueAlert Ceiling Mount
speakers at various ceiling heights with a listener height of 5 feet (1.5 meters).
Table 2-1. Simplex 4902 Speaker Coverage for Varying Ceiling Heights
Listener Height = 5 Feet
Listener Height = 1.5 Meters
Ceiling
Height
Coverage
Diameter
Coverage
Area
Ceiling
Height
Coverage
Diameter
Coverage
Area
8 ft 7.7 ft 46 ft
2
2.5 m 2.6 m 5.1 m
2
10 ft
12.8 ft 129 ft
2
3.0 m 3.8 m 11.6 m
2
12 ft
17.9 ft 252 ft
2
3.5 m 5.1 m 20.6 m
2
14 ft
23.0 ft 417 ft
2
4.0 m 6.4 m 32.2 m
2
16 ft
28.2 ft 623 ft
2
4.5 m 7.7 m 46.3 m
2
18 ft
33.3 ft 870 ft
2
5.0 m 9.0 m 63.0 m
2
20 ft
38.4 ft 1158 ft
2
5.5 m 10.2 m 82.3 m
2
6.0m 11.5 m 104.2 m
2
Some observations about speaker coverage area:
• Low ceilings require more speakers per square foot of floor space than high ceilings.
• The Simplex 4902 series 4-inch speakers cover an area with a diameter slightly larger than
twice the distance from the ear to the ceiling.
• The smaller the speaker, the wider the dispersion, therefore the larger the coverage area.
Continued on next page
Determining Critical
Polar Angle