The Tools We Use to Measure and Treat a Studio Room

Every acoustic job we take on starts with a measurement microphone, not a box of foam. A room that sounds muddy to the ear can be muddy for several different reasons, and each reason has a different fix. We set up a calibrated omnidirectional microphone at the presenter's head height, play a swept tone through a small speaker at the desk position, and record how the room answers back.

The result shows reverberation time across the frequency range and the ringing that builds up between parallel walls. Owen Tregear usually takes the readings on site, and we sit with them before any material is specified. It also gives us a record of how the room sounded before treatment, which is useful when someone asks later whether the work made a difference.

• Calibrated measurement microphone at presenter head height
• Swept tone played from the desk position
• Readings kept as a before-and-after record

Speech lives mostly between the low hundreds of hertz and a few thousand, so that is where we look hardest. Reverberation time in that band tells us how long a spoken word hangs in the air after it is said. Too long and consonants blur into the next syllable, which makes interviews tiring to listen to, especially over a poor domestic speaker.

We also look for room modes, the low resonances that make one note boom while its neighbour disappears. These are common in small voice booths, where the dimensions sit close together. A presenter who leans slightly forward can change how a mode behaves, which is why we measure at the real working position rather than the middle of the room.

The materials we reach for are fairly plain. Dense mineral wool panels in fabric-wrapped frames handle most of the work, because they absorb across a wide range when they are thick enough and spaced off the wall. Thin foam tiles do much less than people expect, mostly taming the very top of the range while leaving the low end untouched.

Where a studio is large enough, we add diffusion on the rear wall so the room does not become dead and airless. A completely absorbed space sounds oppressive to talk in, and presenters tend to push their voices to compensate. The aim is a room that feels natural to speak in and still gives the gallery a clean signal.

• Mineral wool panels in wrapped frames for broad absorption
• Corner traps for low-frequency build-up
• Diffusion on the rear wall in larger studios

Treatment inside a room does not stop sound getting into it. Air handling, lighting transformers and the rumble of a neighbouring corridor all find their way into open microphones. We walk the space with the studio running as it would on a transmission day, listening for fan noise, buzzing fittings and anything that cycles on and off.

The cheapest fixes are often mechanical rather than acoustic: a duct silencer, a loose panel re-fixed, a door seal replaced. We note what we find in plain language and rank it by how audible it is on air. Some items belong to the building owner, and we say so clearly rather than promising treatment that cannot cure a structural problem.

Once panels are up, we repeat the measurement and compare it with the first set. The numbers should show shorter, more even decay in the speech band, but the test that decides it is listening. We record a presenter reading a news script at normal pace, then play it back through gallery monitors and through a small, cheap speaker.

If words stay clear on the cheap speaker, the room is doing its job. We also ask the presenters themselves how it feels, since a room that measures well but makes people self-conscious will not be used properly. Small adjustments, such as moving a panel a hand's width, are normal at this stage and often make the difference.

• Repeat measurement against the original readings
• Recorded script played on gallery and small speakers
• Presenter feedback before sign-off

When the work is finished we hand over a short written summary: the readings before and after, the position of every panel, and the materials used with their thickness. Nothing in it is complicated, and the point is that someone else can maintain or extend the treatment later without guessing what was done.

We also mark the presenter and guest positions we measured from, because moving a desk by a metre can undo careful work. If a studio layout is likely to change, we say so at the start and plan the treatment with that in mind, rather than discovering it halfway through a series.