In a hallway with normal traffic, ceiling mounted speakers should be placed ________ times the corridor height, minus the ________.

Spacing ceiling speakers at two times the corridor height establishes the correct coverage cone overlap for even sound distribution along the corridor length. Subtracting the average listener ear height (roughly 1.2 m) accounts for the actual listening plane below the ceiling, producing the effective on-center spacing distance.

The corridor width governs left-right speaker placement, not the along-corridor spacing; subtracting it instead of ear height removes a structurally irrelevant dimension.

A multiplier of three times the ceiling height overestimates spacing, creating gaps in coverage and uneven SPL along the hallway.

Both the multiplier of three and the use of corridor width are incorrect - three times the height overspaces speakers and corridor width is not the correct subtracted value.