There is a persistent misconception about curtains and acoustics. It usually goes something like this: the heavier and denser the fabric, the better the sound absorption. Sounds logical, right? A solid curtain that blocks out light should surely block sound as well. It doesn’t.
The blackout paradox
Time for a surprising fact. A blackout curtain, fully lightproof and often heavily coated, performs worse acoustically than a dimout. We are talking about an absorption coefficient (αw) of around 0.4 for blackout versus 0.8 for dimout. That is a significant difference.
How is that possible? The answer lies in how sound absorption works. Blackout fabrics are airtight. Sound waves hit the surface and bounce back, much like they do off glass or concrete. The curtain behaves like a hard wall: it blocks light, but reflects sound.
A dimout, on the other hand, allows air to pass through partially. Sound waves penetrate the fabric, lose energy within it, and what returns to the space is significantly weakened. That is absorption.
Heavy and dense, then, does not automatically mean acoustically effective. Often, it means the opposite.
Damping is not insulation
This leads to another common confusion. Curtains dampen sound; they do not insulate it. Two very different things.
Sound absorption reduces reverberation and echo within a space. It improves speech intelligibility, reduces that unpleasant “swimming pool effect” in large open areas, and contributes to overall acoustic comfort.
Sound insulation, by contrast, blocks sound between spaces: keeping traffic noise out, keeping conversations inside a meeting room. That requires mass and airtight construction. Curtains cannot do that, no matter how heavy they are.
For architects and interior designers, this distinction is important in advisory conversations. A curtain will not solve an insulation problem. But for absorption, to shorten reverberation time and soften the acoustic sharpness of a space, the right curtain can make a surprisingly big difference.
Why modern interiors work against themselves acoustically
The challenge is more relevant than ever. Many contemporary interiors are a recipe for acoustic discomfort: large glass surfaces, concrete floors, open layouts, little textile. Clean, minimal, light-filled, but every sound ricochets around like a marble in a glass jar.
In offices, this leads to concentration issues and fatigue. In restaurants, a lively buzz quickly turns into overwhelming noise. In open-plan homes, every conversation travels from kitchen to bedroom.
Traditionally, the solution has been absorptive panels, suspended ceilings, carpet. Effective, but not always compatible with the aesthetic clients want. And often, more absorption also means less daylight.
The transparent solution
This is where it gets interesting. What if a curtain could perform acoustically without blocking light?
Standard sheers do little for acoustics. They are too open, allowing sound waves to pass straight through with minimal interaction with the fibres. No resistance, no absorption.
There is, however, an in-between category: transparent fabrics with low air permeability. Sound waves penetrate the fabric and are partially absorbed. What passes through reflects off the wall behind and passes through the fabric again on its return, creating a second moment of absorption. This double interaction means that a visually light fabric can perform acoustically far better than expected.
The technology behind this requires specialised yarns, high weave density and specific finishing techniques. Balancing air resistance and light transmission is no simple task.
Acoustics as a design parameter
For those designing interiors, acoustics is gradually shifting from an afterthought to a design parameter. Just as we create lighting plans, the question is increasingly asked: what is the acoustic plan?
The key metric here is the weighted absorption coefficient, αw. Concrete and glass sit around 0.02. A standard sheer achieves 0.1 to 0.2. Acoustic panels score between 0.8 and 1.0. In between lies the range where curtains become relevant.
A dimout around 0.8. An acoustic transparent fabric between 0.5 and 0.7. These are values that make a tangible difference in spaces with many reflective surfaces.
ATOM: transparent and acoustic
With this in mind, we developed the ATOM family: AIR, ATOM and ION. Transparent fabrics made with Trevira CS yarns that reduce reverberation time and dampen sound, without severing the connection to the outside.
Their performance is based on the principle described above: low air permeability achieved through special flat yarns and high weave density, combined with the softness and transparency expected of a sheer. They meet European fire safety standards, making them suitable for the contract market.
For spaces dominated by glass, concrete or marble, they offer an alternative to the traditional choice between daylight and acoustic comfort. One element that combines both.
