Why Does My Conference Room Echo?

How Echo Works in Conference Rooms

When someone speaks in a room, sound travels in all directions. Some of it goes directly to the microphone (direct sound), while the rest bounces off walls, ceiling, and floor before reaching the mic (reflected sound).

The problem: reflected sound arrives slightly later than direct sound. This delay causes two issues:

• Speech becomes muddy. Consonants blur together because reflections from the previous syllable overlap with the next one.
• Listening becomes tiring. Remote participants' brains work harder to separate speech from reflections, causing fatigue in longer meetings.

In person, you don't notice this as much because your brain is good at filtering reflections in familiar spaces. But remote participants only hear what the microphone captures - and microphones capture everything.

Problem Surfaces

Some surfaces reflect almost all sound (bad for echo), while others absorb most of it (good). Here's how common conference room surfaces compare:

Highly reflective (problematic)

• Glass walls and windows: Reflect about 97% of sound. The most common echo culprit in modern offices.
• Drywall: Reflects about 95% of sound. Standard wall material, and a major contributor.
• Concrete or plaster ceilings: Reflect 95%+ of sound. Especially problematic with high ceilings.
• Whiteboards: Essentially mirrors for sound. Large whiteboards amplify echo.
• Hard floors: Tile, concrete, hardwood, and vinyl all reflect heavily.

Moderately absorptive

• Drop ceiling tiles: Absorb 50-70% of sound. A good baseline, but not enough alone.
• Upholstered furniture: Chairs with fabric help. Leather less so.
• Curtains: Heavy curtains absorb well. Thin blinds don't help much.

Highly absorptive (helpful)

• Acoustic panels: Purpose-built panels absorb 80-95% of sound. The most effective treatment.
• Thick carpet: Absorbs 30-50% of sound. Every bit helps.
• Acoustic ceiling clouds: Suspended panels that catch sound before it reflects off the ceiling.
• Heavy drapes: Thick, floor-to-ceiling curtains can substitute for wall treatment.

How Much Echo is Too Much?

Acousticians measure echo as RT60 - the time it takes for sound to decay by 60 decibels after the source stops. Here's what different RT60 values mean for conference rooms:

Room size matters: larger rooms naturally have longer RT60 because sound has farther to travel. A 0.6s RT60 is excellent for a large boardroom but may be high for a small huddle room.

Quick Echo Test

You don't need equipment to get a rough sense of your room's echo:

1. Stand in the center of the room (or where people typically sit).
2. Clap your hands once, sharply.
3. Listen to the decay.

What to listen for:

• Sound dies almost immediately: Good - echo is controlled.
• Sound lingers noticeably (like a short "tail"): Moderate echo - room would benefit from treatment.
• Sound rings, flutters, or seems to bounce around: Significant echo - this is likely causing problems on calls.

Try this in different parts of the room. Corners and areas near glass walls often have the worst echo.

How to Fix Echo

The goal is to add absorption to reduce reflections. You don't need to treat every surface - strategic placement matters more than total coverage.

Most effective placements

1. Wall behind seating (first priority). Sound from speakers reflects off the back wall directly into the microphone. Treating this wall has the biggest impact.
2. Ceiling above the table. Sound bounces between the table and ceiling repeatedly. Ceiling panels or "clouds" break this cycle.
3. Side walls at "first reflection points." The spots where sound from speakers first hits the side walls before bouncing to the mic. Usually about 1-2 meters from where people sit.
4. Glass walls. If you can't add panels, use heavy curtains or acoustic blinds. Even partially covering glass helps.

Treatment options (lowest to highest investment)

• Rugs: A thick rug under the table helps, especially on hard floors. Low cost, immediate improvement.
• Curtains: Heavy, floor-to-ceiling curtains on glass walls. Can be drawn back when not on calls.
• Acoustic panels: Fabric-wrapped fiberglass or foam panels. Most effective per square meter. 2-4 panels often enough for small rooms.
• Ceiling clouds: Suspended panels for rooms with high or hard ceilings. More involved installation but very effective.
• Professional treatment: For critical spaces, acoustic consultants can model the room and specify exact treatment.

How much treatment do you need?

As a rough guide:

• Small huddle room (15-25 m³): 2-4 m² of panels often sufficient.
• Medium conference room (40-80 m³): 4-8 m² typically needed.
• Large boardroom (100+ m³): 8-15 m² or more, plus ceiling treatment.

These are starting points. Rooms with more glass or hard surfaces need more treatment.