Conference Room Acoustics Glossary

Core acoustic terms

RT60 is reverberation time: the estimated time it takes sound energy to decay by 60 dB after a sound stops. In meeting rooms, RT60 is one of the clearest ways to describe echo or hollow speech.

T20 and T30 are practical RT60 estimation methods. Instead of waiting for a full 60 dB decay, they fit a smaller part of the decay curve and extrapolate to RT60.

C50 is a speech clarity metric comparing early sound energy to later reflected sound energy. Higher C50 usually means speech is easier to understand.

• RT60: reverberation time
• T20/T30: decay-fit methods used to estimate RT60
• C50: clarity ratio for speech intelligibility

Noise terms

Noise floor is the steady background sound in a room: HVAC rumble, projector noise, hallway bleed, or open-office spill.

SPL means sound pressure level and is normally measured in dB SPL with a calibrated meter. dBFS is a digital audio level relative to the maximum level a device can record.

RoomScore uses device-relative dBFS for app-based screening and trend comparison. Use calibrated SPL when certification or formal compliance is required.

Material and prediction terms

NRC means Noise Reduction Coefficient. It describes how absorptive a material is across a speech-relevant frequency range.

Sabine and Eyring are equations used to estimate reverberation from room volume and surface absorption. Sabine is simpler; Eyring handles higher absorption cases more realistically.

These equations are useful for estimating direction and treatment impact, but measured RT60 remains the stronger room-specific signal.

Call quality and coverage terms

Microphone coverage describes whether the room system captures speech clearly from the seats people actually use.

MOS means Mean Opinion Score, a call-quality scale often used by conferencing systems. MOS can reflect network and codec behavior as well as room capture quality.

Dropout rate describes moments where captured speech falls too low or disappears relative to the reference signal.

How RoomScore separates measurement from interpretation

Measured values such as RT60, noise floor, room volume, and coverage samples are treated as ground truth. Recommendations are interpretation layered on top of those measurements.

That split matters because a model can help explain what to fix, but it should not rewrite physics. If a measurement is low confidence, the honest answer is to retry the measurement.

Use this glossary as the vocabulary layer, then use the related guides to decide which measurement to run next.

For most troubleshooting conversations, the practical sequence is simple: measure RT60 when the room sounds hollow, measure noise floor when speech is masked by HVAC or open-office spill, and run coverage mapping when remote participants cannot hear every seat.

That keeps the conversation tied to evidence instead of brand preference.

FAQ

What is the most important acoustic term for conference rooms?
RT60 is usually the most useful first term because it directly describes reverberation time, the measurement behind many echo and hollow-speech complaints.

Is dBFS the same as dB SPL?
No. dBFS is relative to a digital recording device's maximum level, while dB SPL is calibrated sound pressure level. Use dBFS for app screening and dB SPL for calibrated measurement.

Why does microphone coverage matter if RT60 is good?
A room can have acceptable reverberation and still fail remote participants if the microphone pickup misses seats or weakens speech at the edges of the table.

Related Guides

• What Is RT60?
• Meeting Room Noise Floor
• Audio Coverage Mapping
• Conference Room Acoustics Benchmarks
• RT60 Target Calculator