Calculate how many ceiling speakers you need and how far apart to space them for even coverage using the edge-to-edge, edge-to-center, or center-to-center methods.
Edge-to-edge (EE): Speakers spaced so coverage circles just touch. Gives ~3 dB uniformity but maximum overlap — best for speech intelligibility in rooms where evenness matters more than loudness.
Edge-to-center (EC): Each speaker's coverage circle reaches the center of its neighbors. ~6 dB uniformity. Most common method for commercial paging and background music.
Center-to-center (CC): Coverage circles overlap only at the center point. Widest spacing, fewest speakers, acceptable for low-expectation background music only. Avoid for critical listening or speech.
Coverage radius at the listening plane = (ceiling height − listening plane height) × tan(speaker half-angle).
A speaker with 70° total dispersion mounted at 10 ft over a 4 ft listening plane gives coverage radius = 6 × tan(35°) = 4.2 ft. Coverage diameter = 8.4 ft.
Edge-to-center spacing = coverage diameter × 0.707 (since the center of an adjacent speaker must fall within the coverage circle of its neighbor) ≈ 5.9 ft.
For rooms where evenness is critical (conference, classroom, courtroom) use EE or EC. For big-box retail, warehouses, or paging-only, CC is often adequate and saves 30-50% on speaker count.
We model speaker coverage in EASE with actual speaker data files for real AVIXA-standard design.
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