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The term “soundproof” is not governed by any regulations. Any curtain can claim to be soundproof, with any decibel rating. This page does not tell you what to buy; it provides a method for you to verify any product yourself, including ours.
On August 21, 2026, we reviewed the information each seller publishes to support its figures. We examined three groups: twelve French sellers identified through common search queries, eight listings from online marketplaces and large retailers, and nine European manufacturers of acoustic textiles. No products were measured; the review is based solely on the published information.
| Published Information | French sellers |
|---|---|
| A reduction value in decibels | 10 / 12 |
| A Lab Called | 2 / 12 |
| ISO/IEC 17025 Accreditation | 1 / 12 |
| An Attenuation Test Standard | 1 / 12 |
| A test report number | 2 / 12 |
| The overallRw index, distinct from the maximum value | 1 / 12 |
| The frequency of the maximum value | 1 / 12 |
| The mass of the finished product in kg/m² | 1 / 12 |
| Explicit limitations on what the product does not do | 2 / 12 |
Of the eight listings from online marketplaces and major retailers, seven list a decibel value ranging from 5 to 30 dB. None mention any certification, and none provide an overall rating or frequency.
Among the nine European professional manufacturers, the picture is reversed but remains unresolved: eight out of nine cite a testing standard, but it is almost alwaysISO 354 orISO 11654, which measureabsorption —the reduction of echoes within a space. None of the nine publishes an attenuation index. These manufacturers are rigorous; they simply measure a different parameter for a different purpose.
We’re both judge and jury—might as well say it right away. The only company on the panel that meets all the criteria for accreditation, testing standards, overall rating, and finished product weight belongs to our group. We’d rather state this explicitly than leave you to guess. The list also includes our own inconsistencies: two of our pages list different weights for similar products, and a website publishing under our brand displays a value linked to a standard that doesn’t match. We’re currently correcting these issues, and this page will be updated once that’s done.
Copy them and send them. The quality of the response will tell you just as much as the response itself.
| Question | Solid Response | Warning Signal |
|---|---|---|
| Which laboratory conducted the test? | Name of an organization | "Tested by an unnamed independent laboratory" |
| Is it ISO/IEC 17025-accredited? | Yes, by COFRAC, BELAC, or an equivalent body | "internal tests," "proprietary certification" |
| Which test standard? | ISO 10140-2 for attenuation; ISO 354 or ISO 11654 for absorption | no standard cited, or an absorption standard presented as insulation |
| What is the report number? | A phone number available upon request | "Confidential," or no number |
| What is the overall index, and how often does the maximum value occur? | The two values, published together, with the frequency | a single number, without a frequency |
| What is the mass per square meter of the finished product? | A value in kg/m², including linings | a fabric weight in g/m², or "heavy fabric" |
Absorption reduces echoes inside a room. It is measured by a coefficient α ranging from 0 to 1, or by a rating from A to E. It is not expressed in decibels.Attenuation reduces the sound that passes through. This is what you should focus on if the noise is coming from outside. These are two distinct quantities, measured by two different standards, and an α of 0.90 does not represent a 90% reduction.
Maximum attenuation is measured over a narrow frequency band, almost always in the high frequencies, where a textile is most effective. The overallRw rating is weighted across sixteen bands, ranging from 100 to 3,150 Hz. For a curtain, the difference between the two is structurally a factor of two or more. Both figures describe the same product—but a figure published without specifying which of the two it is, or at what frequency, is meaningless.
A specification listing 300 g/m² refers to the fabric alone. The assembled assembly, including linings and blackout fabric, weighs more. The two values differ by an order of magnitude, and only the second one is relevant from an acoustic standpoint.
There is a test you can perform on your own, without having to ask anyone for help. In acoustics, a flexible wall cannot block more noise than its mass allows. This is a law of physics, not a sales pitch.
| Reported surface mass | Maximum overall index permitted by the laws of physics |
|---|---|
| 230 g/m² | 3 dB |
| 300 g/m² | 4 dB |
| 520 g/m² | 7 dB |
| 900 g/m² | 11 dB |
| 1.35 kg/m² | 14 dB |
| 3.60 kg/m² | 22 dB |
Take the weight listed on the product sheet for the item you’re considering, enter it into the weight limit calculator, and compare it to the advertised figure. If the advertised figure exceeds the weight limit, that weight is impossible—and the question to ask the seller becomes very simple: What are the dimensions, and what is the weight of the finished product?
The calculator is calibrated for our own product, and it doesn't flatter us. Our 4-layer composite weighs 1.35 kg/m²: the mass law predictsan Rw value of 14 dB, and the laboratory measurement yields exactly 14 dB. The formula and weighting procedure from ISO 717-1 are posted on the page: the calculation can be replicated by anyone, even against us.
So that you can apply the method yourself: Daidalos Peutz Laboratory, BELAC-accredited according to ISO/IEC 17025 and NBN EN ISO 10140-2:2010, reports A-2020LAB-060-I766, I767, and I768.Rw (C;Ctr) = 14 (−1; −3) dB for the 4-layer composite; maximum attenuation of 28.2 dB at 5,000 Hz. Mass of the finished product: 1.35 kg/m². European Patent EP 3 440 965; M1 fire rating; Oeko-Tex Standard 100.
And the limitations—which apply to all acoustic curtains, including ours—are as follows: no curtain can replace building insulation; no curtain can make a room silent; and noise coming from a shared wall, a floor, or structural vibrations cannot be mitigated by fabric. A laboratory measurement indicates potential, not a contractual promise.
We also publish the in situ measurement protocol we use as open access under a Creative Commons license: DOI 10.5281/zenodo.22046256. And we maintain an open registry of test reports, where any manufacturer can submit their reports, which are published exactly as submitted.
The Cotton Silence " soundproof curtain " is designed to offer a simple, quick installation that anyone can do. Thanks to our mounting system, which is engineered to optimize acoustic and thermal performance, you’ll enjoy professional-quality results without any complicated work.
Unlike traditional curtains hung on a rod, our acoustic curtains perform best when installed on a suitable track. This system ensures optimal sealing on the sides and helps reduce sound leaks and heat loss. It's a crucial step to fully experience the sound reduction of up to 24.6 dB.
The installation is designed to be intuitive while still meeting acoustic requirements: the curtain opens at the bottom, multi-layers ventilate properly, and it's positioned optimally to create a shield against outside noise.
Cotton Silence curtains were designed by acoustics professionals with extensive experience in architectural projects. The goal was clear: to create a “true” noise-reducing curtain, one that is truly effective under real-world conditions and not just in a laboratory.
You'll find this expertise in every detail: from the choice of fibers and the design of the patented multi-layer to optimized weight, thermal performance, internal absorption, and reverb reduction.
Every single curtain is made right here in France by professional seamstresses. This local production means you get lasting quality, perfect finishes, and careful attention to the acoustic layers.
Even though they're super effective, our curtains are still stylish, easy to use, come in lots of colors, and work great for both homes and professional spots.
Once you've got it installed, your Cotton Silence curtain works like a real sound and thermal shield. It seriously cuts down on outside noise, reduces echoes in the room, makes it feel warmer, and instantly creates a calmer, cozier space.
With our version for everyone, you get the same awesome technology that architects and pros use, right in your own home – no big renovations or complicated gear needed!
Whether you're looking to insulate a window, a bay window, a door, or any opening, the Cotton Silence system fits right in and promises long-lasting effectiveness. Our video tutorial walks you through it step-by-step for a successful setup in just a few minutes.
If you need a hand, our team can also help you pick the right way to hang it and make sure your setup is compatible.