Building A had a conference room. Building B had a conference room. Someone scheduled a meeting between them using speakerphones on both ends. What could go wrong?

The call started normally. Pleasantries were exchanged. Then someone in Building A coughed, and Building B's speakerphone picked up its own speaker's reproduction of that cough and sent it back. Building A's speaker played the echo. Building B caught it again. Within two seconds, both rooms were filled with an oscillating howl that climbed in frequency like a theremin being attacked by a cat.

The IT manager muted Building A. The howl stopped. He unmuted. It returned instantly, as if it had been waiting. He tried reducing the speaker volume in Building B. The feedback stopped but now nobody could hear. He bought a dedicated conferencing system with acoustic echo cancellation. It worked — until someone placed their laptop with its own mic near the conference phone, creating a second acoustic path the AEC couldn't track.

Acoustic coupling between speakers and microphones in the same room creates a regenerative loop. Echo cancellers model and subtract the expected signal, but they need a single, predictable acoustic path. Multiple paths, room reflections, and movement break the model.

The Moral: Check for acoustic coupling between every speaker-mic pair in the room. SonaVyx Problem Detection identifies feedback frequencies so you can fix the physical setup, not just fight it with software.