With the rise of video conferencing systems like Zoom Rooms and Microsoft Teams Rooms, voice intelligibility has become the primary operational metric for corporate workspaces. Yet, many organizations spend heavily on expensive microphone arrays and DSPs, only to experience hollow, echo-filled audio because the physical room's acoustics were ignored.
This technical guide details the calculations and acoustic design guidelines needed to plan a professional corporate boardroom space.
1. Reverberation Time: The RT60 Metric
The most important mathematical measure of a room's acoustics is its Reverberation Time (RT60)—the time it takes for sound energy to drop by 60 decibels after the sound source has stopped.
For executive boardrooms and video conferencing environments, the targeted RT60 should sit strictly between **0.4 and 0.6 seconds**. Anything higher than 0.7 seconds will trigger echo and reduce voice clarity, forcing remote participants to struggle to understand speakers.
RT60 = 0.161 × V / A
Where V is the room volume in cubic meters, and A is the total absorption of the room in Sabins (calculated by multiplying the surface area of each material by its Noise Reduction Coefficient, or NRC).
For instance, concrete, glass, and drywall have very low absorption coefficients (NRC 0.05 to 0.1), while carpet, acoustic fabric panels, and acoustical mineral fiber ceilings have high coefficients (NRC 0.7 to 0.95).
2. Controlling Noise Criteria (NC)
Before designing audio systems, we must isolate external noise (HVAC, traffic, hallway chatter). The standard metric for background noise is the Noise Criteria (NC) rating.
For high-quality boardroom video conferencing, the background noise floor must not exceed **NC-30** (ideally NC-25). Ensure the HVAC ducts contain acoustical lining and air velocity is kept below 1.5 meters per second to meet this standard.
3. Beamforming Microphone Array Integration
Modern boardrooms utilize ceiling-mounted beamforming microphone arrays (e.g., Sennheiser TCC2, Shure MXA920). These microphones track the physical location of speakers dynamically and steer audio coverage beams directly to them.
| Mic Technology | Ideal Ceiling Height | Coverage Diameter | Best Suited For |
|---|---|---|---|
| Ceiling Beamforming | 2.7m to 3.6m | Up to 9m (30ft) radius | Medium-to-Large Boardrooms, Flexible Rooms |
| Tabletop Mic Arrays | Surface mount | 1.5m to 2.5m per pod | Small huddle spaces, U-shaped seating |
| Pendant Microphones | Suspended (adjust height) | 3m to 4m radius | High-ceiling townhalls, creative workspaces |
4. DSP Echo Cancellation & Sound Reinforcement
The **Acoustic Echo Canceller (AEC)** inside the digital signal processor (DSP) is the brain of the boardroom audio system. The AEC references the incoming far-end audio channel and removes that signal from the boardroom microphones before sending the feed back to the remote participants. This prevents the remote callers from hearing their own voice echo.
Ensure that speaker zones are configured with a slight delay if the room exceeds 12 meters in length to maintain sound localization matching the front-of-room displays.
Conclusion & Acoustic Layout Recommendations
To design a successful boardroom audio system:
- Avoid parallel glass walls. Angle glass partitions slightly or apply micro-perforated acoustic foils.
- Cover at least 30% of the room's total wall and ceiling surface area with high-efficiency sound-absorbing materials (NRC > 0.75).
- Place acoustic panels on opposing walls to eliminate "flutter echo" reflections.
Review our professional sound products on our Professional Audio solutions page, or schedule an acoustic analysis of your space with our integration team.