Treat a room for calls and recording in the right order

Part of our guide on conference room camera for 10 people and 20 ft table

Diagnose before you buy: a mirror, a clap and a phone recording tell you where your panels should go before you spend anything.

What you need

Most of this job needs things you already own. The only real purchases come after the diagnosis tells you what the room actually needs.

Gather the following before you start, and you can complete the whole diagnosis-and-treat cycle in a weekend.

• A small flat mirror (hand mirror is fine) for finding reflection points
• Your phone for clap tests, recordings and a measurement app
• Painter's tape or sticky notes to mark reflection points
• Absorption: 2-inch acoustic panels, rockwool panels, moving blankets, or a rug and bookshelves
• Command strips, picture hooks or freestanding panels for mounting without damage
• A tape measure and someone to sit in your usual chair

How to acoustically treat a room in the right order

The mistake most people make is buying panels first and working out where they go later. That produces a room with twelve panels on the walls and a client who still says you sound like you are in a bathroom.

The order below works because each step decides what the next one needs. Skipping ahead usually means treating the wrong surfaces. Before you commit to anything, it is worth looking at PTZ camera specs for meetings.

Follow this sequence:

1. Diagnose the problem with a clap test and a test recording
2. Treat your desk position first – it is free and often fixes half the problem
3. Find and treat the first-reflection points with the mirror trick
4. Cover the wall directly behind you
5. Add coverage until you hit the 15-25% target for your room size
6. Re-test with a recording and an RT60 app, and stop when it passes

Diagnose what is actually wrong before buying anything

Three problems get called 'echo' by everyone, and they need different fixes. Flutter echo is that metallic zinging sound when you clap – it comes from sound bouncing between two parallel hard surfaces. General reverb is the smeared tail a clap leaves. Boominess is a hollow, chesty sound on your voice that you hear when you speak normally.

Stand in the middle of the room and clap once, sharply. A metallic ring that hangs on is flutter echo; a longer, softer tail is reverb. Then record ten seconds of yourself talking at your desk on your phone, and listen on headphones – this is what clients actually hear. We cover 6-person huddle room setup in its own article.

Empty rooms with hard floors flutter badly. Carpeted rooms with furniture usually have reverb and boominess instead, which means the fix is thick absorption behind and beside you, not panels on every wall.

Free fixes first: your desk and what is behind you

Before any panel goes up, reposition the desk. Facing a wall or a window means your voice projects into absorptive distance and the microphone rejects the room behind you. Facing into the open room means your voice hits the far wall, bounces straight back, and every mic picks it up.

Sit facing a wall with the room behind you, if the layout allows. Pull the desk a foot off the wall so bass does not build up in the gap. Add a rug under and in front of the desk if you have hard floors. For the detail, see our notes on top conference speakerphones.

Bookshelves with books of varying depths are surprisingly effective diffusers and absorbers. If your desk faces one, you already have real treatment in the room.

Find first-reflection points with the mirror trick

First reflections are the earliest echoes from your mouth to the walls beside and above you, then into the microphone. They blur speech more than any later bounce, so they get treated first.

Here is the method. Have someone sit in your usual chair at the desk. Hold the mirror flat against the side wall and slide it along at the seated speaker's mouth height, around 110-125cm. Every spot on the wall where the seated person can see your mouth in the mirror is a reflection point. Mark each spot with painter's tape.

Repeat on the other wall, then on the ceiling between your mouth and the mic position if you are recording rather than just calling. Those marked spots are where your first panels go – a 60cm panel centred on each point.

How much coverage your room size needs

Small rooms need proportionally more treatment than the internet suggests, because close surfaces produce early, damaging reflections. Work to a coverage percentage of total wall area and adjust by ear.

Estimate your wall area: perimeter times ceiling height, minus doors and windows. Then apply the targets in the table. If the room still sounds boomy after reaching the target, add thickness (4-inch panels or a gap behind the panels) before adding more area.

Using a calculator or RT60 estimate

If you want numbers instead of percentages, a room acoustic treatment calculator does the arithmetic from your room dimensions and surface materials. Aim for a reverberation time (RT60) of 0.3-0.4 seconds for speech – that is a phone-call-clean room.

You can also measure rather than calculate: free phone apps estimate RT60 from an impulse or a clap. Treat, re-measure, and stop once you are under 0.4 seconds.

DIY options versus commercial panels

For voice calls, a moving blanket hung on the wall behind you costs a tenth of a commercial panel and does most of the same job. Where commercial panels genuinely win is appearance in a client-facing room and low-frequency absorption, which needs real thickness either way.

Rockwool or mineral wool in a timber frame, wrapped in fabric, is the DIY gold standard: it absorbs as well as commercial panels at a fraction of the price, and you can build panels 100mm thick for boomy rooms. Fat mattresses of foam sold as 'acoustic foam' tiles are the one thing to avoid – thin foam absorbs almost no speech-relevant energy.

Treating walls in old buildings without damage

Old plaster and leased offices rule out drilling in most cases, and plaster crumbles when you pull adhesive strips off anyway. The workarounds are all about loading the floor instead of the wall.

Freestanding acoustic panels on stable feet sit against the wall at your reflection points and need no fixing at all. Moving blankets can hang from tension rods wedged floor to ceiling, or from existing picture rails and curtain tracks – both common in older buildings and both safe for plaster.

If you must fix to masonry or lath-and-plaster, use picture hooks hammered at an angle into the plaster key rather than plastic wall plugs, and keep the load light. Check your lease before any drilling; most commercial leases require landlord consent for fixings.

Large rooms and high ceilings need different treatment

Everything above assumes a small room, because that is what most 1-50 person businesses are calling from. Large rooms and high ceilings change the physics: sound travels further before bouncing, so reflections arrive later and read as reverb rather than flutter.

In a tall room, the ceiling is your largest untreated surface and often your most important one. Hang baffles or panels above the meeting table if the ceiling is over 3 metres. Coverage percentages can be lower than in a small room, but spread it out rather than clustering it.

Also break up parallel surfaces: a bookshelf on one wall, a soft-seating area in a corner, or even a partition plant wall shortens the echo paths. One big cluster of panels on a single wall does far less than the same area distributed.

How to verify the treatment actually worked

Do not trust your ears in the room – your brain compensates within minutes. Re-run the original tests and compare.

First, repeat the clap test. Flutter echo should be gone entirely; the clap should sound short and dry, with no tail you can hear. Second, record the same ten seconds of speech at your desk on the same phone and listen on the same headphones. If you still hear room sound, note whether it is echoey (add coverage) or boomy (add thickness).

Third, if you used an RT60 app, take a new measurement. You want under 0.4 seconds. If you are there, stop buying panels – the room is done, and more treatment would make it sound dead.

What treatment cannot fix

Acoustic treatment changes how a room sounds; it does not stop sound leaving it. If the problem is that clients hear your colleagues through the wall, or the neighbours hear you, that is soundproofing – mass, decoupling and seals – and no amount of foam or rockwool inside the room will help.

Treatment also cannot fix a bad microphone in a bad position. If your mic sits 60cm away on a laptop, fix that first; a $20 headset closer to your mouth beats $500 of panels behind you. And it cannot stop HVAC hum or street noise – those need a quiet mic technique and a different room or time of day.

Common mistakes

These are the four errors that keep rooms sounding bad after money has been spent.

• Buying thin foam tiles -> use 2-inch absorbers minimum; thin foam does nothing for speech
• Treating only the front wall -> the wall behind you sends reflections straight back into the mic; treat it
• Mounting panels at standing height -> do the mirror trick seated at your actual call posture
• Expecting panels to block noise from other rooms -> that is soundproofing; treat echoes, isolate noise separately
• Covering one wall completely -> spread the same area across walls, or reflections just move elsewhere

Questions people still ask

I have set up call rooms in glass meeting rooms, plaster-walled Victorian offices and one garage – the mirror trick and a phone recording have never failed to find the real problem faster than any spec sheet.