Corporate AV: Conference Room Echo Eliminated

The Challenge: A Boardroom Built for Aesthetics, Not Acoustics

The executive boardroom of a Fortune 500 financial services company occupied a corner office on the 38th floor of a glass tower. Designed by a renowned architecture firm, the room featured floor-to-ceiling glass on two walls, polished marble flooring, a lacquered wood conference table, and a flat plaster ceiling. It seated 40 people and hosted critical board meetings, investor presentations, and daily video conferences with international offices.

The AV team had received persistent complaints about video call quality. Remote participants reported that speakers sounded like they were in a bathroom. In-room participants found it difficult to understand colleagues seated more than 5 metres away. The company had already spent over $200,000 on premium ceiling microphones, speakers, and DSP, but the problems persisted because the root cause was acoustic, not electronic.

Measurement: Quantifying the Problem

The acoustic consultant used SonaVyx RT60 and STIPA measurement at 6 positions around the conference table. The results confirmed what the complaints suggested:

• RT60 at 500 Hz: 1.8 seconds (target: 0.3 to 0.5 seconds for conferencing)
• RT60 at 2 kHz: 1.4 seconds
• STI from table centre to far end: 0.38 (poor)
• STI at ceiling microphone position: 0.41 (poor)
• Strong flutter echo between parallel glass walls (visible as periodic spikes in the impulse response)

The octave-band RT60 analysis showed that low frequencies (125 Hz and 250 Hz) were particularly problematic at 2.1 and 2.0 seconds respectively, due to the rigid glass and marble surfaces providing zero low-frequency absorption.

Diagnosis: Reflection-Dominated Environment

The AI diagnostic identified the combined effect of three highly reflective surface types:

• Glass walls (α = 0.03): Two full walls of floor-to-ceiling glass reflected 97% of all incident sound
• Marble floor (α = 0.01): The polished stone floor was essentially a perfect reflector
• Plaster ceiling (α = 0.04): The flat ceiling created a strong floor-ceiling flutter echo path

Total room absorption was only 12 Sabins for a 180 cubic metre room. The SonaVyx treatment calculator determined that 48 additional Sabins were needed at mid frequencies to reach the 0.45-second RT60 target.

Solution: Aesthetically Sensitive Treatment

Working with the interior design team, the following treatments were specified:

• 35 m² of fabric-wrapped acoustic panels (NRC 0.90) on the two solid walls opposite the glass, finished in the company's brand navy blue
• Suspended acoustic ceiling baffles over the table zone, integrated with the existing lighting rig
• High-performance carpet tiles replacing the marble floor under and around the conference table (marble retained at the perimeter for aesthetic continuity)

Results: Transformed Communication

Before/after comparison measurements confirmed the transformation:

Metric	Before	After	Improvement
RT60 @ 500 Hz	1.8s	0.45s	75% reduction
RT60 @ 2 kHz	1.4s	0.35s	75% reduction
STI (table centre)	0.38 (poor)	0.68 (good)	+0.30 points
Flutter echo	Clearly audible	Eliminated	—
Video call complaints	Weekly	Zero	Eliminated

The AV system's acoustic echo cancellation began working effectively once the room reverberation was controlled. Remote participants reported that the boardroom now sounded professional and clear. The investment in acoustic treatment was less than 15% of the cost of the existing AV equipment that it finally allowed to perform properly.

Lessons Learned

• AV equipment cannot fix acoustic problems: No amount of DSP processing can compensate for 1.8 seconds of reverberation in a conferencing environment.
• Measure at the microphone position: STI measured at the ceiling microphone position was the most relevant metric for video call quality.
• Low frequencies need mass: The carpet tiles and thin panels addressed mid and high frequencies, but the ceiling baffles with air gaps were essential for controlling the 125 Hz and 250 Hz bands.
• Aesthetics and acoustics are compatible: Modern acoustic products offer finishes, colours, and form factors that satisfy both interior designers and acoustic engineers.