The architect had won awards for this conference space. Floor-to-ceiling glass on three sides, polished concrete floor, exposed steel ceiling. It looked spectacular in the renderings. It sounded like speaking inside a crystal bell.

The CEO was launching a new product to 200 investors. The AV company set up a pristine line array, wireless lavalier, and confidence monitors. Rehearsal at 7 AM with an empty room went fine. By 9 AM, with 200 bodies absorbing some reflections but also 200 phones on silent creating a noise floor, it was a different room entirely.

The CEO hit her stride, raised her voice for emphasis — and the room answered back. A shimmering 2.8 kHz ring blossomed from every glass surface. The AV tech grabbed a graphic EQ and slashed frequencies, but each notch just moved the feedback to the next resonant mode. It was like squeezing a balloon: push here, it bulges there.

Glass is nearly perfectly reflective across the entire speech spectrum. With an RT60 around 2.2 seconds and specular reflections creating hotspots, the maximum stable gain was about 6 dB below what the CEO needed for her dramatic crescendos.

The Moral: Beautiful rooms are often terrible rooms. Run SonaVyx room analysis before the event, identify the danger zones, and set realistic expectations for maximum SPL.