Six Acoustic Mistakes That Spoil Speech on Air, and How to Avoid Them

The most common mistake I see is a studio that has been dressed in foam panels without anyone having measured the room first. Panels get bought because they look the part, stuck up where there happens to be wall space, and the team assumes the job is done. Then the presenter still sounds boxy, and nobody can say why.

A short measurement session tells you far more than instinct. We play a test signal, record the response at the presenter and guest positions, and look at how long the sound lingers and which frequencies ring. Priya Shah on our team does this routinely, and the results often surprise the people who work in the room every day.

Measure before you buy anything, and measure again afterwards. Without the second reading you cannot tell whether the treatment helped, did nothing, or made a different problem worse.

• Record the empty room and the room in use
• Note the positions of presenter, guest and microphones
• Keep the readings so changes can be compared

Thin foam tiles absorb high frequencies reasonably well, which is why a room treated only with them often sounds dull and yet still muddy. The low and low-mid energy that makes a male voice sound thick or a room sound hollow passes straight through. The result is speech that feels dead at the top and boomy underneath.

Controlling that range needs depth: thicker mineral wool panels, mounted with an air gap behind them, and bass trapping in the corners where low frequencies gather. This costs more and takes more wall depth, which is exactly why it is skipped, but it is the part that changes how a voice sits on air.

If the budget is limited, treat the corners and the wall behind the cameras properly rather than covering a large area thinly. A smaller amount of the right material beats a lot of the wrong one.

• Corners first, then the wall behind the presenter
• Use mineral wool with an air gap, not thin foam alone

Many news desks sit in front of a glass wall or a bare plasterboard partition because it looks good on camera. Two parallel hard surfaces produce flutter echo, a rapid metallic ringing that the ear tolerates in the room but microphones exaggerate badly. Viewers hear it as a harsh edge on every sentence.

You do not have to give up the look. Angle the set pieces slightly, add a bookcase with uneven contents, a fabric-backed set wall, or panels finished to match the set design. Tom Whitaker and I often agree these details together, because lighting and acoustic needs compete for the same wall space.

Clap your hands once in the empty studio and listen. If you hear a quick buzzing tail after the clap, you have flutter echo, and it will be on air.

Even a well-treated studio can sound poor if microphones sit in the wrong place. A lapel microphone clipped under a chin picks up chest resonance, while a desk microphone close to a hard tabletop catches the reflection a fraction of a second after the direct voice, which gives that hollow comb-filtered sound.

Moving a microphone by a few centimetres, adding a desk mat, or switching to a closer pattern can do more than any panel. This is why we test with the actual guests' seating and not an empty chair, since people lean, turn and shuffle during a live interview.

Check each position while someone talks at normal conversational level, not a sound-check shout, and listen on the same headphones the engineer will use during the show.

• Test with real speaking levels
• Add desk mats under table microphones
• Recheck after the set is dressed

Treatment improves how a room sounds inside, but it does little against noise coming in. Air handling, lighting transformers, corridor traffic and a neighbouring unit can all bleed into a microphone during quiet moments, and a live programme has no chance to fix it afterwards.

Walk the space at the time of day you will broadcast and listen with headphones, not just your ears. Fans on lighting and monitors are a frequent culprit in small studios, and they can often be moved, slowed or enclosed cheaply.

Where the noise is structural, such as a door that leaks sound, sealing gaps and fitting proper door seals gives a better return than extra wall panels. Fix the source where you can, and treat only what remains.

The last mistake is timing. Teams finish the treatment, run a quick sound check, and discover the real problems only when the programme goes out. By then the only option is to ride faders and hope.

Build a short listening rehearsal into the schedule with the presenter, a guest and the full crew present, and the lights and air handling running as they will on the day. Record it and play it back through the broadcast chain, not only the studio monitors.

Write down what you hear. A simple list of two or three things to adjust before the next broadcast keeps the room improving instead of staying as it was on the day it was first treated.

• Rehearse with lights and ventilation on
• Listen through the broadcast chain