30 dB noise reduction curtain: what it really means
30 dB of attenuation is the figure you see on the spec sheets of soundproof curtains. In theory, it's the difference between a busy street at 70 dB and a library at 40 dB. In practice, that figure depends entirely on the measurement conditions, and most curtains sold as "soundproof" only reach 5 to 7 dB of real attenuation.
This guide breaks down what the advertised decibels really mean, why performance varies so much from one brand to another, and which concrete criteria to check before buying a soundproof curtain.
Understanding decibels: why 30 dB is not "a little more" than 20 dB
The decibel scale is logarithmic, not linear. In practice, remember three rules:
- +3 dB = the sound energy doubles. You barely perceive it. This is what most basic thick curtains deliver.
- +10 dB = your ear perceives a noise twice as loud. This is the threshold where you feel a real change.
- +20 dB = the perceived noise is multiplied by four. This is a radical transformation of your sound environment.
Direct consequence: the difference between a 20 dB curtain and a 30 dB curtain is not "50% better." It's double the perceived reduction. Here's what each level changes concretely if your street noise is at 70 dB:
| Attenuation | Resulting level | Perceived equivalent | Type of curtain |
|---|---|---|---|
| -5 to 7 dB | 63-65 dB | Barely perceptible difference | Basic thick curtain (150-300 g/m²) |
| -10 dB | 60 dB | Lively conversation, better but still bothersome | Entry-level soundproof curtain |
| -16 dB | 54 dB | Clear improvement, reduced background noise | Mid-range soundproof curtain |
| -22 dB | 48 dB | Quiet office, comfortable for remote work and sleep | High-performance made-to-measure curtain (Kurtens, 620 g/m²) |
| -30 dB | 40 dB | Library, perceived silence | Marketing promise rarely achieved in real conditions |
The last row of the table is the central point of this article: 30 dB is an attractive figure on a spec sheet, but the question is under which conditions it was obtained.
Why some manufacturers advertise 30 dB
The 30 dB advertised by some brands corresponds to a measurement over an optimal frequency band (generally 1,600-2,500 Hz, the high frequencies). It's a real performance, but a partial one: it doesn't reflect the average attenuation across the entire audible sound spectrum (125-4000 Hz). A curtain that displays 30 dB on the high frequencies may attenuate only 8-12 dB on the low frequencies (engine noise, music, deep voices), the hardest to block.
Kurtens advertises 22 dB measured in optimal conditions across the entire spectrum*, a figure that's reproducible in a real installation with a made-to-measure curtain covering the whole opening.
Why advertised performance varies so much from one brand to another
Browsing the offers on the market, you'll find soundproof curtains advertising 15, 22, 25 or even 30 dB of attenuation. These gaps aren't explained by product quality alone. They depend largely on the measurement conditions.
There is no single, mandatory standard for measuring the soundproofing performance of a curtain. The reference standard is NF EN ISO 10140 (laboratory measurement of the acoustic insulation of building elements), but its application to textiles isn't required. Some brands measure in a certified acoustic laboratory, others in supplier test conditions, and others extrapolate from the absorption coefficient of the fabric alone, which doesn't reflect the result at all once the curtain is installed in your home.
The 3 questions to ask before believing a figure:
- Does the test measure the attenuation of the installed curtain, or just the properties of the fabric? A fabric can have an excellent absorption coefficient (alpha sabine) in the laboratory while still letting noise through the sides once hung on a rod.
- Do the test conditions include a realistic installation? A curtain tested pressed tightly against a wall in an anechoic chamber will give a very different result from a curtain hung on a rod with side gaps.
- Is the advertised figure a maximum on certain frequencies or a weighted average? A curtain can attenuate 30 dB on the high frequencies (2,000-4,000 Hz) while blocking only 12 dB on the low frequencies of engines and trucks, the ones that bother you the most.
At Kurtens, we advertise 22 dB of attenuation measured in optimal test conditions*. We prefer to communicate a figure our product reaches reproducibly rather than a theoretical maximum you'll never get in your living room. It's a choice of transparency.
Comparison table: soundproof curtains by performance category
| Category | Real attenuation | Density | Layers | Made-to-measure | Indicative price |
|---|---|---|---|---|---|
| Thick "soundproof" curtain | 5 to 7 dB | 150-300 g/m² | 1-2 | No | 20-60 € |
| Mid-range soundproof curtain | 12 to 18 dB | 350-500 g/m² | 2-4 | Rarely | 80-200 € |
| High-performance made-to-measure curtain | 18 to 25 dB | 500+ g/m² | 3+ | Yes | 150-400 € |
| Reference: standard interior door | 18 to 27 dB | — | — | — | — |
Key point: a high-performance curtain (18-25 dB) offers insulation comparable to a closed interior door. A basic thick curtain at 30 € offers only a quarter of that performance. To go deeper into the comparison between categories, read our guide soundproof curtains: are they really effective against noise?
What 22 dB really changes in your daily life
22 dB of attenuation* means dividing the perceived sound volume by a little more than four. Concretely, here's what it transforms:
At night: a street noise of 65-70 dB drops to about 45-48 dB. The WHO recommends a level below 30 dB for restorative sleep (Environmental Noise Guidelines, 2018).
For remote work: you go from an environment where you have to turn up the headphone volume to cover the street to a background noise that disappears naturally. Video calls become comfortable again without closing the windows in the middle of summer.
In a baby's room: infants are more sensitive to sudden noise peaks than to constant background noise. The attenuation smooths these aggressive peaks and extends naps without interruption.
This result is only achievable on one condition: the curtain must fit your opening perfectly. A made-to-measure soundproof curtain, made to the exact dimensions of your window with a side overhang of 15 to 20 cm and a floor-length drop, eliminates the acoustic leaks that cut performance by 30 to 40% on a standard curtain.
The secret no one tells you: the installation matters as much as the fabric
This is the point most soundproof curtain sellers keep quiet about. You can buy the densest, most expensive fabric on the market: if your curtain leaves a 3 cm gap on the sides and 5 cm above the floor, the noise will rush through it like air through a slot.
Sound behaves exactly like a cold draft. It seeks the path of least resistance. An opening representing only 1% of the surface lets through up to 50% of the sound energy. This is why a poorly installed 30 dB curtain will perform worse than a perfectly fitted 22 dB curtain.
The 4 installation rules to maximize attenuation:
- Side overhang: 15 to 20 cm beyond the frame on each side.
- Height: from ceiling to floor (not from rod to windowsill). Rod positioned at least 10 cm above the top of the window.
- Bottom of the curtain: the drop should "break" slightly on the floor to close the lower junction. 2 to 3 cm of clearance maximum.
- Distance from the glazing: the space between the glass and the fabric creates a mass-spring-mass effect that reinforces insulation. Leave 5 to 10 cm between the curtain and the window.
For installation details and the choice of the right fixing, read the Kurtens fixings guide. To calculate the exact dimensions of your curtain (side overhang, height, distance from the floor), read our made-to-measure sizing guide
Kurtens soundproof curtain: 22 dB measured, 3 performances in 1 curtain
At Kurtens, every curtain is made to order to the exact dimensions of your opening. The high-density multilayer fabric of 620 g/m² combines three performances:
- 22 dB of measured soundproofing attenuation*
- 100% certified blackout*
- Up to 7 °C of thermal gain*
Available in 7 colors, with eyelets, pencil pleat or rod pocket, delivered in 2 to 3 weeks with free delivery in mainland France, Belgium, Switzerland and Luxembourg. Configure your dimensions to the exact centimetre on our collection of made-to-measure soundproof curtains.
For an overview of the effectiveness of soundproof curtains by category, read our complete guide soundproof curtains: are they really effective?. And if your problem also concerns the walls and floors, our article on soundproofing solutions without renovation work covers all the options.
*Data from tests carried out in optimal conditions.
Discover Kurtens soundproof curtains
22 dB of measured attenuation, 620 g/m², 7 colors, made to measure to your exact dimensions. Free delivery in France.
Frequently asked questions
Does a 30 dB soundproof curtain really exist?
30 dB of attenuation is technically possible on certain high frequencies (2,000-4,000 Hz) in laboratory conditions. But in real installation conditions (curtain hung on a rod, with side gaps), no textile curtain reaches 30 dB of weighted average attenuation. The best high-density multilayer models reach 18 to 25 dB. At Kurtens, we advertise 22 dB measured in optimal test conditions*, a reproducible figure rather than a marketing maximum.
How many decibels does a soundproof curtain really reduce?
Attenuation ranges from 5 to 25 dB depending on the product category. Basic thick curtains (150-300 g/m²): 5-7 dB, barely perceptible. Mid-range soundproof curtains (350-500 g/m²): 12-18 dB, clear improvement. High-performance made-to-measure curtains (500+ g/m²): 18-25 dB, comparable to a closed interior door. Fabric density and full coverage of the opening are the two determining factors.
What's the difference between 20 dB and 30 dB of attenuation?
On the logarithmic decibel scale, an extra 10 dB doubles the perceived sound reduction. A 20 dB curtain divides the perceived volume by four. A 30 dB curtain would divide it by eight. On a street at 70 dB, 20 dB of attenuation gives 50 dB (quiet office). 30 dB would give 40 dB (library). The difference is significant, but 30 dB is rarely achieved in real home installation conditions.
Why is a well-installed 22 dB curtain better than a poorly installed 30 dB curtain?
Sound rushes through the slightest opening. A gap representing only 1% of the curtain's surface lets through up to 50% of the sound energy. A curtain advertised at 30 dB but that leaves a 5 cm gap on the sides and 10 cm at the bottom loses most of its performance. A 22 dB curtain made to the exact dimensions of the window, with 15-20 cm of side overhang and a floor-length drop, uses 100% of its attenuation capacity.
Does a soundproof curtain work against noise from neighbors?
A soundproof curtain is effective against airborne noise passing through windows and doors: traffic, horns, voices of passers-by. It is ineffective against noise transmitted through party walls (the neighbor's music, conversations) or through the building structure (footsteps from the neighbor upstairs). These noises require treating the wall or floor insulation, not the curtain.
Should you choose a made-to-measure soundproof curtain or a standard size?
Made-to-measure offers 3 to 5 dB of extra performance compared to a standard size. The reason is physical: a standard-size curtain leaves gaps on the sides, top and bottom through which sound rushes. A curtain made to the exact dimensions of your window eliminates these leaks. On an attenuation of 22 dB, losing 3 to 5 dB through poor sizing represents 15 to 25% of the total performance.
Does a soundproof curtain replace double glazing?
No, it complements it. Double glazing reduces noise on the outside, the curtain adds an extra barrier on the inside. The performances add up. On single glazing (a major acoustic weak point), the curtain's gain is even more pronounced because the baseline loss is high. It's also the only removable and transportable insulation solution, ideal for renters.
At what weight does a curtain become effective against noise?
Below 500 g/m², sound attenuation remains marginal (5-7 dB). The mass law in acoustics is direct: the denser the material, the more it blocks sound. Mid-range soundproof curtains (350-500 g/m²) reach 12-18 dB. High-performance models exceed 500 g/m², with the best reaching 620 g/m² and more (18-25 dB). Weight alone isn't enough: the multilayer structure (3 layers minimum) is essential to exceed 15 dB of attenuation.
Is a 30 dB soundproof curtain enough for a noisy apartment?
It depends on the type of noise. For street noise passing through the windows (traffic, horns, pedestrians), a high-density curtain (620 g/m², 22 dB of attenuation) reduces the perceived volume by about 75%. If the noise comes from party walls or the ceiling (neighbors, music, footsteps), the curtain only acts on the window: you need to complement it with wall insulation or an acoustic ceiling. For a ground-floor studio on the street, a made-to-measure soundproof curtain is often the most effective and least expensive first step.
Soundproof curtain or double glazing: which to install first?
If your windows are single glazed, the curtain offers the best immediate cost-effectiveness: 150-350 EUR for 22 dB of attenuation, installed in 10 minutes, with no renovation work. Double glazing (800-1,500 EUR per window, mandatory renovation work) offers 25-35 dB but requires being a homeowner or having a co-ownership agreement. The ideal is to combine the two: the performances add up. For a renter, the made-to-measure curtain is the only solution that's portable and recoverable when moving out*.
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