BEHIND THE BUILD

What Actually Goes Inside an Acoustic Panel?

The useful bit is hidden, but the details around it matter too.

An acoustic panel looks fairly simple from the outside. Fabric, timber, something soft in the middle. That is basically true, which is also why there are quite a few ways to build one badly.

Most of the work an acoustic panel does comes from the porous absorber inside it. The rest of the construction has a quieter job: hold that absorber securely, leave the right surfaces open to sound, survive being handled and hung on a wall, and look like something you actually want in the room.

So, rather than treating the panel as a mysterious box, here is what is actually going on inside one of ours.

The absorber does the acoustic work

At the centre is mineral wool. We use different densities and depths depending on what the panel is intended to do, but the principle is the same. Sound enters the porous material and makes the air within its fibre structure move. Friction and viscous losses convert a small amount of that acoustic energy into heat.

That last part sounds more dramatic than it is. The panel does not get warm. The important point is simply that acoustic energy is being dissipated rather than reflected straight back into the room.

This is why we build different products for different jobs. A relatively shallow broadband panel is useful for reflections and general room control. A deeper bass trap gives lower frequencies more material to travel through and can be positioned where low-frequency problems are strongest.

The frame should support, not get in the way

The timber frame gives the panel its shape and protects the absorber. Acoustically, though, a frame is not the star of the show. In fact, covering too much of the absorber with solid material can reduce the surface area available to incoming sound.

Our frames are designed to be rigid enough to stay square while keeping the useful absorbing faces open. It is a fairly unglamorous balancing act. A panel needs to survive manufacture, packaging, couriers, installation and years on a wall, but there is no acoustic prize for simply putting more timber around it.

The rear matters as well. Depending on the design, keeping the back acoustically open allows the absorber to make use of an air gap between the panel and wall. That gap can improve low-frequency performance without adding the same amount of extra absorber depth.

Fabric is more than decoration

The visible fabric is where acoustic performance and interior design meet. For a conventional broadband absorber, sound needs to be able to pass through the covering reasonably freely. A very dense, coated or impermeable fabric can reflect more high-frequency energy before it ever reaches the absorber.

That does not mean every acoustic fabric has to look like loudspeaker cloth. We use woven finishes because they allow us to make treatment feel like part of the room rather than equipment that has been reluctantly bolted to it. Different fabrics do behave slightly differently, so material choice is something we consider alongside the intended use of the panel.

There is also a practical side. Fabric needs to stretch cleanly around corners, remain stable over time and tolerate the occasional knock. Some beautiful upholstery fabrics become considerably less charming after you have tried to persuade them around eight corners in a workshop.

The small details are mostly about longevity

Backing fabric, fixings, clean corners and mounting hardware do not meaningfully improve an absorption coefficient, but they determine whether the finished object feels properly made. They also keep fibres enclosed and make the panel easier to handle and install.

This is one of the slightly odd things about making acoustic treatment. The physics can be described with absorption coefficients, wavelengths and flow resistivity, but a large part of building a good product is still ordinary making: measuring accurately, keeping frames square, getting tension right and noticing the tiny defect that nobody else would probably have spotted.

Simple does not mean interchangeable

Two panels can have the same outside dimensions and look broadly similar while behaving differently. Absorber type, depth, density, fabric, frame construction, air gap and placement all influence the result. None of those decisions is particularly exotic on its own, but together they determine whether the panel is appropriate for the job.

That is the bit we find interesting. Acoustic treatment does not need to be mysterious, and it certainly does not need a layer of studio folklore around it. It just needs the materials and construction to follow the physics, then enough care in the making that you are happy to put the finished thing on your wall.