The convention hall was divided into four breakout zones using acoustic curtains. Each zone had its own PA. For the closing keynote, the curtains were pulled back to create one large room, but the four PA zones remained independently timed. The moderator sat in Zone 1. The panelists were in Zone 2. The audience spanned Zones 3 and 4.

When the moderator asked a question, Zone 1 heard it immediately. Zone 2 heard it 50ms later through their speakers. The panelist's response traveled from Zone 2 speakers back into Zone 1 at a different delay. The moderator heard the panelist's answer twice — once directly and once through Zone 1's speakers reproducing Zone 2's audio. The audience in Zone 4 heard everything three times.

What should have been a crisp panel discussion became a round-table of echoes where every response sounded like it was spoken in triplicate. The moderator kept pausing, unsure if the panelist had finished speaking or if the echo was still catching up. One panelist started talking over her own delayed voice, creating a vocal collision that confused both the audience and herself.

When combining separately zoned PA systems into a single coverage area, all zones must be re-timed relative to each other. The delay values that worked for four independent rooms are wrong for one combined room.

The Moral: Combining PA zones requires re-alignment. Use SonaVyx Transfer Function impulse response measurement at each zone boundary to verify that combined coverage arrives within the Haas window.