A shopping mall atrium is the hardest acoustic environment for public address: glass curtain walls, hard floors, three or four storeys of open volume, and a reverberation time that easily passes two seconds. Adding loudspeakers raises the level and the reverberation together, so intelligibility gets worse.
The order that works: treat the reflections first, then use narrow-pattern loudspeakers aimed at people rather than at walls, then align zones with delay. Where the ceiling is very high, wall-mounted or column models beat ceiling speakers.
Do not tune by sound pressure alone. One STI or RASTI measurement usually shows the worst seats are the ones beside the glass — early reflections, not a lack of level.
- Above 2s reverb, treat surfaces before adding hardware
- Ceilings over 6m: wall or column, not ceiling
- Zone delay alignment beats turning everything up
