Find out how to choose effective acoustic panels for your project.
Are you worried the panel will be too thin? That it won’t work? That the customer will hear an echo and come back with a complaint?
This worry is understandable. You’re designing an interior – beautiful, cohesive, with attention to every detail. But you know that poor acoustics can ruin the whole effect. After all, what’s the point of a sofa from the best furniture store, if the client can’t hear the conversation properly because of the reverberation and echoing sounds? What’s the point of using the finest materials if the space is noisy, tiring and difficult to enjoy?
In the world of interior design, there is increasing conversation about acoustics. But along with this growing interest comes a question:
Is a 9 mm thick panel enough to effectively soundproof a room?
Wouldn’t it be better to use something thicker? Perhaps something more reliable?
Before you order something ‘just in case’, find out what really determines the effectiveness of the panels and how the panels actually work.
Although it may seem otherwise, sometimes a thin acoustic panel is all it takes to create an impressive sense of silence, without altering the design or risking complaints.
If you’re not yet sure what acoustic panels are or how they work, take a look [here].
Why does the thickness of acoustic panels cause so much debate?
Because it’s one of those factors that seem simple and insignificant… until the moment of decision arrives.
Whether your project is an office, a hotel, a restaurant, or a home office – you need to choose something that actually works. Something that will genuinely reduce reverberation. The client has put their trust in you, and there is no room for mistakes. That’s when the debate begins: is 9 mm enough? Or should it be 12 mm or more? What’s the actual difference anyway, besides the looks?! What if the thinner panels turn out to be just for decoration, rather than a real solution?
To make things easier for you, let’s start with the facts. The thickness of a panel does affect its sound-absorbing capacity – that’s true. But it’s not the only factor, nor is it even the most important one. Effectiveness depends on many factors, such as:
- Material density and quality – the higher it is, the better the sound absorption,
- Surface structures – e.g., millings, perforations, grooves
- installation – location, layout, air gap behind the panel
- total coverage area – first and foremost.
That is exactly why panels, despite their small thickness of e.g. 9 mm, achieve an $\alpha_w$ = 0.85, which represents a high sound absorption class (B). What does this mean in practice? Even with such parameters, you will experience a real difference right away – conversations become clearer, echo disappears, and acoustic comfort grows from day one.
Why does acoustic panel thickness matter?
Whether your project is an office, a hotel, a restaurant, or a home office – what matters is not just that you install a sound-absorbing panel, but which panel you choose. Panel thickness affects how much sound it can absorb and across what frequency range. This directly translates into the acoustic comfort of the users. There is no single universal thickness for every interior. The key is to match the panel to the function and characteristics of the space so that it can actually work. In smaller rooms, thin and compact solutions are enough. In more challenging spaces with high reverberation, hard surfaces, and high ceilings, it is worth considering thicker variants or ceiling modules. Choosing the right thickness is a design decision that, when well-thought-out, makes a massive difference.
Where do 9 mm panels work best?
Contrary to common concerns, 9 mm panels made of high-quality PET felt perform excellently in most commercial and residential interiors. Their effectiveness has been proven not only by laboratory tests but also in hundreds of completed projects where the primary goal was to reduce reverberation and improve user comfort.
In open-space offices, wall panels such as TileFlex, combined with SilentScape ceiling systems, significantly reduce noise. The team can speak freely without raising their voices, and meetings do not disrupt the work of the rest of the staff.
In a home office, where clear voice quality during video conferences is crucial, a few PrintSlat panels on the wall can eliminate echo, which tends to be particularly troublesome in small spaces.
In restaurants or hotel lobbies, where acoustics directly impact guest comfort and their reviews of the venue, simply combining wall panels with ceiling clouds is enough to create a space where conversation is possible without shouting over one another.
Importantly, 9 mm panels offer the advantage of being sleek and thin. Unlike thicker alternatives, they do not heavily interfere with the interior composition or make the space look smaller. Plus, thanks to a vast palette of colors and patterns, they can serve both a practical and decorative purpose.
Is 9 mm a lot or a little? Find out what truly impacts silence in your project.
At first glance, 9 mm might not seem like much. In the world of building materials, where thickness often equates to sturdiness, it’s barely a centimeter. But in acoustics, this number takes on a completely different dimension. It’s not just thickness that matters, but what the panel is made of, its density, structure, as well as where and how you install it. Acoustic panels, despite being only 9 mm thick, are made of PET fiber – it is precisely this porosity and compressed structure that allow the panels to effectively absorb sound and achieve excellent performance metrics. What does this mean in practice? Not only do you hear less unwanted noise, but speech clarity, concentration, and overall room comfort are significantly improved. In projects where the balance between design and function is key, 9 or 12 mm is the sweet spot. They are thin enough not to overwhelm the interior, yet effective enough to genuinely improve the acoustics. This isn’t a compromise; it’s a conscious choice that delivers silence without sacrificing the room’s aesthetics.
What about thicker 18 or 24 mm panels? When is it worth choosing this option?
Sometimes, 9 mm may turn out to be insufficient. Not because the panels don’t work, but because the interior demands more – whether acoustically or aesthetically. In such cases, panels with a thickness of 18 to 24 mm or even more can be an excellent choice – a solution we offer for custom projects.
The difference might seem minor on paper, but 24 mm panels absorb slightly more sound, especially in the lower frequency range – the kind found in large conference rooms and spaces featuring concrete, glass, and hard surfaces. Thicker material also means greater mass, which results in better attenuation of sound energy.
In practice, 24 mm works best when you want maximum soundproofing with just a small number of panels. It is also ideal if you are designing a premium space and want the panel to make an even greater visual impact, or if the client expects solutions with elevated acoustic standards.
At Feltdecor, we prepare thicker panels as part of custom projects – a bespoke option that allows us to match the thickness, color, finish and layout of the panels exactly to the investor’s needs.
However, it is worth keeping in mind: thicker panels are heavier, may require a different installation system, and their price and lead time are usually higher. Therefore, before you choose them, check whether standard 9 mm or 12 mm panels won’t solve the problem just as effectively.
If you are designing a space where acoustics play a crucial role and aesthetics must be flawless, a thicker panel can be a great investment. But in the vast majority of cases, it is precisely a well-chosen 9 or 12 mm panel from our core collection that solves the problem without needing to go any further.
How to choose the right number of panels based on room size?
This is one of the most frequently asked questions. Let’s assume you have a project – you know the square footage, you know the wall height, you’ve already picked the panel design… but how many do you actually need for the soundproofing to work?
A simple yet rough rule of thumb applies here: to noticeably improve acoustics, it is worth covering 25–35% of the wall and/or ceiling surface with sound-absorbing material. You don’t need to soundproof everything; it’s all about strategically placing the panels where sound bounces off the most. In large rooms, combining wall and ceiling panels is an interesting solution that simultaneously delivers a spectacular visual effect.
Here are a few examples for acoustic panels with absorption class A or B:
- in a room with an area of 20 m² and standard height, it is worth planning for 5 to 7 m² of panels. This corresponds to 14–20 panels measuring 60×60 cm.
- in smaller interiors, such as a home office with an area of 10 m², all you need isapprox. 4–6 panels , placed behind the desk, above the monitor, or on the ceiling.
- in open-space offices and hotels, it is worth considering a combination of wall and ceiling panels – e.g., TileFlex compositions on the wall + SilentScape modules on the ceiling.
The best results are achieved when the panels are located in primary reflection zones – meaning where the sound “hits” immediately after being spoken. This means walls opposite the speakers, above workstations – ceilings, desk dividers, or around meeting areas.
Remember, it is sometimes better to thoughtfully arrange 8 panels than to stick 20 just anywhere. If in doubt, you can always consult the layout with us – we will help you choose the optimal arrangement for your specific interior.
A panel with an air gap behind it – meaning even better acoustics without changing the thickness.
If you want to increase the effectiveness of acoustic panels even further – regardless of their thickness – consider installation with an air gap behind the panel. This is a very simple technique that involves moving the panel a few centimeters away from the wall (usually 3–5 cm, and in demanding interiors up to 10 cm). Such a gap acts as an additional absorbing layer – sound waves pass through the panel and are partially trapped, which significantly improves their absorption, especially at lower frequencies, i.e., those that are particularly troublesome in commercial spaces. This provides better soundproofing without the need for thicker and heavier materials. 9 mm or 12 mm panels with an air gap can perform comparably to 20 or 30 mm, or even more effectively, because you gain not only a larger absorption surface but also better sound diffusion. A simple frame or spacers made of wooden or aluminum profiles, which are easy to design and install, are all it takes. If your project allows for it – it is definitely worth incorporating.
Summary
Peace and quiet is the greatest luxury today, but when well-designed, it can become the standard. Panel thickness is just one piece of the puzzle. What matters more is its effectiveness, proven both by technical parameters and real user experience.
In office spaces, restaurants, hotels, or home offices, a 9–12 mm Feltdecor panel is enough to create acoustic comfort that makes a real, tangible difference. Without unnecessarily weighing down the space or compromising on design. You can also use personalized, unique wall or ceiling panels to add extra character to the interior. With no risk of a dissatisfied client.
If you have a more demanding interior, need increased dampening, or are looking for something custom, then go for individual options. Thinking about thicker panels? We can custom-make them for you.
In [this] article for more advice for architects and designers.
Have doubts, not sure what to choose?! Contact us!