What Is PET Felt and Why Is It Used in Acoustic Wall Panels
PET felt: the material behind acoustic wall panels
PET felt has become the dominant material for acoustic wall panels in commercial and residential interiors over the last decade. It shows up in offices, restaurants, studios, schools, and homes. Most people who've sat in a well-designed open-plan workspace have been in a room with PET felt panels - they just might not have known what they were looking at.
Here's what the material actually is, why it's used for acoustics, and what its real properties are.
What PET stands for and where it comes from
PET stands for polyethylene terephthalate - the same polymer used to make plastic bottles, food packaging, and synthetic fabric. When we talk about PET felt in acoustic panels, we're talking about a non-woven material made from recycled PET fibres - typically sourced from post-consumer plastic bottles.
The production process takes shredded plastic bottles, melts and extrudes the polymer into fibres, and binds those fibres into a dense, felt-like sheet using heat and mechanical compression. No adhesive is needed - the fibres bond to each other under heat. The result is a dimensionally stable panel that holds its shape, takes a clean edge when cut, and has enough structural integrity to be used as a standalone panel, a backing material, or a decorative surface.
Why PET felt absorbs sound
Sound absorption in porous materials works through a straightforward mechanism: sound waves cause air molecules to vibrate, and when those vibrating molecules pass through a fibrous or porous structure, the friction converts the sound energy to a tiny amount of heat. The acoustic performance of any fibrous material depends on its density, thickness, and the size and distribution of the pores between fibres.
PET felt is a relatively dense material - typically 200 to 1000 g/m2 depending on the product - with a fine, consistent fibre structure. This combination gives it good mid and high frequency absorption, which is the range most relevant for controlling speech intelligibility and echo in interior spaces.
Thickness matters for low frequency absorption. A 9 mm PET felt panel will absorb mid and high frequencies effectively but will have limited effect on low-frequency reverberation. A 25 mm or thicker panel reaches further into the low-frequency range. In spaces with significant bass energy - music venues, home cinemas - thicker panels or complementary bass trapping is usually required alongside PET felt panels.
NRC values and what they mean
The noise reduction coefficient (NRC) is the most commonly cited metric for acoustic panel performance. It's a single number averaging absorption across four frequencies (250, 500, 1000, and 2000 Hz) on a scale from 0 (no absorption) to 1.0 (full absorption). A typical 12 mm PET felt panel achieves NRC values between 0.55 and 0.80 depending on the specific product and installation method.
Values above 0.70 are good for general acoustic treatment. Values below 0.50 from a panel material represent marginal performance. Always request the full absorption coefficient data across the frequency range, not just the NRC headline - the shape of the absorption curve tells you more about where the panel will and won't perform.
Why PET felt is used instead of alternatives
Mineral wool and glass wool are cheaper raw materials with good acoustic performance but require covering - they're not cleanly finishable as a visible surface. Foam panels are less durable and degrade over time. Natural felt from wool is more expensive and less consistent.
PET felt sits in a good position: it's acoustically effective, cleanly finished to a standard that works as a visible surface, available in a wide colour range, dimensionally stable, and - increasingly important in commercial specification - composed largely of recycled content. The sustainability credentials are genuine rather than marketing language.
