Soundproof curtain: how to choose the right model
A soundproofing curtain reduces noise passing through windows and doors by creating a dense textile barrier between the opening and the room. Performance varies from 5 to 25 dB depending on the fabric density (150 to 620+ g/m²) and multi-layer construction. For true sound insulation, the minimum threshold is 500 g/m² and 3 technical layers, which allows for 18 to 25 dB of attenuation.
This guide details the technical criteria to check before buying, marketing pitfalls to avoid, and how to size a soundproofing curtain to achieve maximum performance. Every decibel counts: the difference between a well-chosen curtain and an unsuitable one is the difference between "nothing has changed" and "I can no longer hear the street."
What is a soundproofing curtain and how does it work?
A soundproofing curtain is a multi-layered technical curtain designed to absorb and block sound waves. It operates on two complementary physical principles:
- Absorption by mass: The dense fabric absorbs a portion of the sound energy instead of letting it bounce off. The heavier the fabric, the more it absorbs. The law of mass in acoustics predicts a gain of about 6 dB for each doubling of the material's surface mass.
- Air gap: The space between the window and the curtain (5 to 15 cm) creates a mass-spring-mass effect that dampens sound vibrations. This is the same principle as double glazing, applied to textiles.
A "soundproof" curtain that relies only on the thickness of a single fabric cannot achieve significant performance. It is the multi-layer construction (decorative fabric + high-density fleece + acoustic membrane) that allows for more than 15 dB of attenuation. The reference standard for measuring acoustic insulation is NF EN ISO 10140.
The 5 criteria for choosing an effective soundproofing curtain
Criterion 1: Fabric density (the #1 factor)
Fabric weight is the primary indicator of sound performance. Here are the actual thresholds:
- 150 to 300 g/m²: Standard thick curtain. Attenuation: 5 to 7 dB (barely perceptible). Blocks light, not noise.
- 300 to 500 g/m²: Mid-range soundproofing curtain. Attenuation: 12 to 18 dB (noticeable improvement). The best-known models on the market (Moondream: 16 dB max) fall into this category.
- 500 g/m² and above: High-performance soundproofing curtain. Attenuation: 18 to 25 dB (comparable to a closed interior door). This category includes Kurtens curtains (620 g/m², 22 dB measured*).
Below 500 g/m², soundproofing effectiveness remains limited. This threshold is not arbitrary: it corresponds to the point where the mass of the fabric becomes sufficient to significantly block vocal frequencies (300 to 3,000 Hz), which represent the bulk of urban noise.
Criterion 2: Multi-layer construction
A heavy single-layer fabric is not enough. Sound performance comes from the assembly of layers with complementary functions:
- Outer layer (decorative fabric): Absorbs initial sound reflections.
- Intermediate layer (high-density fleece): Absorbs sound energy through friction in the fibers. This layer does most of the work.
- Inner layer (technical membrane): Blocks residual waves and prevents direct transmission.
A 2-layer curtain achieves 12 to 18 dB. A 3-layer or more curtain achieves 18 to 25 dB. The difference is significant: an additional 6 dB means noise is perceived as half as loud.
Criterion 3: Complete coverage of the opening
A soundproofing curtain that leaves a 5 cm gap on the sides or 10 cm at the bottom loses 30 to 40% of its effectiveness. Sound, like air, rushes through the slightest opening. A gap representing 1% of the surface area can let through up to 50% of the sound energy.
This is why a custom-made soundproofing curtain consistently outperforms a standard-sized model by 3 to 5 dB. Exact dimensions eliminate side leaks. The curtain should extend 15 to 20 cm beyond each side of the window, the rod should be positioned at least 10 cm above the frame, and the bottom of the curtain should skim the floor (maximum 2 to 3 cm clearance).
Criterion 4: Measured and communicated performance
This is the most objective criterion and the one most sellers avoid. A soundproofing curtain worthy of the name displays a measured attenuation in decibels, not just a simple mention of "noise-reducing" or "sound insulation" on the product sheet.
Questions to ask:
- Is the dB figure communicated? If not, be wary.
- Does the test measure the installed curtain or just the fabric in the lab? A fabric can have a good absorption coefficient (alpha sabine) while still letting noise pass through the sides once installed.
- Is the figure a maximum on certain frequencies (high-pitched) or a weighted average? A curtain can attenuate 30 dB on high frequencies and only 12 dB on low frequencies.
At Kurtens, the advertised attenuation is 22 dB measured under optimal test conditions*. A reproducible figure, not a theoretical maximum. To understand what decibels mean, consult our article what 30 dB of attenuation really represents.
Criterion 5: Complementary functions
A quality soundproofing curtain does not only insulate against noise. The same properties (mass, density, multi-layer) that block sound also block heat and light. The best models combine three performances in a single curtain:
- Sound attenuation: 18 to 25 dB
- Thermal insulation: 5 to 7 °C gain
- Blackout: 95 to 100%
Kurtens custom-made soundproofing curtains combine 22 dB of attenuation*, 100% blackout*, and up to 7 °C of thermal gain* in a 620 g/m² fabric. Buying three separate curtains costs more and works less effectively than a single multi-layer curtain designed for all three functions.
Summary table: the 5 criteria to check
| Criterion | Minimum threshold | Optimal performance | Warning sign |
|---|---|---|---|
| Density | 500 g/m² | 600+ g/m² | "Thick curtain" with no stated weight |
| Layers | 3 technical layers | 3+ (fabric + fleece + membrane) | "Lined" with no composition details |
| Coverage | 15 cm overlap on each side | Custom-made to the nearest cm | Standard sizes only |
| Measured performance | dB communicated | 18-25 dB in realistic conditions | No figure, just "noise-reducing" |
| Triple function | Sound + thermal | Sound + thermal + blackout | Sound only without insulation |
What a soundproofing curtain can and cannot treat
A soundproofing curtain is very effective against airborne noise passing through windows and doors: traffic (70-80 dB), horns, passersby's voices, street works. Windows are responsible for approximately 40% of a dwelling's sound loss.
What it does not treat:
- Noise from neighbors through shared walls: Sound travels through the wall, not the window. The curtain cannot help. Solution: massive furniture against the shared wall (5 to 10 dB gain).
- Impact noise (from above): This is transmitted through the building structure. Solution: thick carpet with an acoustic underlay (10 to 20 dB on impacts).
- Very powerful low frequencies: Nightclub music, heavy construction vibrations. These frequencies require much greater mass to be blocked.
For a complete guide on insulating an entire apartment without major works, consult our article apartment soundproofing without major works: 5 solutions.
How to maximize the effectiveness of your soundproofing curtain
The curtain alone only reaches its full potential if it is correctly sized and installed. Here are the 4 installation rules:
- Side overlap: 15 to 20 cm beyond the frame on each side of the window.
- Height: Rod positioned at least 10 cm above the top of the window. The curtain should extend to the floor (maximum 2-3 cm clearance).
- Glass-curtain distance: 5 to 10 cm between the glazing and the fabric. This space creates the mass-spring-mass effect that enhances insulation.
- Window seals: Worn seals allow noise to pass around the frame. Replacing the seals (5-15 euros, 30 minutes) adds 3 to 5 dB to the curtain's performance. The combined gain of a curtain + new seals can reach 25 to 27 dB.
For dimensions, consult the size guide. For rod selection (a 620 g/m² curtain requires a solid fixing), consult the fixing guide.
*Data from tests conducted under optimal conditions.
Frequently Asked Questions
What is the difference between a soundproof curtain and a sound insulating curtain?
They are the same thing. "Soundproof curtain," "sound insulating curtain," and "noise-reducing curtain" all refer to a curtain designed to reduce noise passing through windows and doors. The difference that matters is not the name but the actual performance: a 5 dB curtain and a 22 dB curtain both carry the "soundproof" label, but only the latter truly changes your daily life.
From what weight is a curtain truly soundproof?
Below 500 g/m², sound attenuation remains marginal (5 to 7 dB for 150-300 g/m², 12 to 18 dB for 300-500 g/m²). From 500 g/m² with a multi-layer construction (minimum 3 layers), the curtain achieves 18 to 25 dB, comparable to a closed interior door. Kurtens curtains (620 g/m²) achieve 22 dB measured*.
Does a soundproof curtain block noise from neighbors?
A soundproof curtain blocks noise passing through windows and doors (traffic, horns, street voices). It does not block noise passing through shared walls (music, neighbor's voices). If neighbor noise enters through an open window or the front door, the curtain reduces it. If it passes through the wall, massive furniture against the shared wall is needed (5-10 dB gain).
Custom-made or standard size soundproof curtain: what's the difference?
Custom-made offers 3 to 5 dB of additional performance compared to a standard size. The reason is physical: a curtain that does not perfectly cover the opening leaves gaps through which sound rushes. A gap of 1% of the surface area can let through up to 50% of the sound energy. Custom-made eliminates these leaks and utilizes 100% of the fabric's attenuation capacity.
How many decibels can a soundproof curtain reduce?
From 5 to 25 dB depending on the category. Basic thick curtains (150-300 g/m²): 5-7 dB. Mid-range multi-layer (300-500 g/m²): 12-18 dB. High-performance custom-made (500+ g/m²): 18-25 dB. For reference, a standard interior door offers 18-27 dB. Every 10 dB reduction halves the perceived volume.
Can a soundproof curtain and double glazing be combined?
Yes, and it is recommended. Double glazing reduces noise from the outside, and the curtain adds an additional barrier on the inside. Performances are cumulative. Even with recent double glazing, windows remain the weakest acoustic link in a dwelling. The soundproof curtain fills this residual weakness.
Does a soundproof curtain also insulate against cold and light?
The best models do. A high-density multi-layer fabric (620 g/m²) blocks sound, heat, and light due to its mass and construction. Kurtens curtains combine 22 dB of sound attenuation*, 100% blackout*, and up to 7 °C of thermal gain*. One curtain, three measured performances.
How to further improve sound insulation beyond the curtain?
Three easy additions: replace worn window seals (+3 to 5 dB, 5-15 euros), add a door sweep if your front door lets in noise (+2-3 dB, 5-15 euros), and place a thick rug on the floor for impact noise (10-20 dB on impacts). The combined gain of a curtain + new seals can reach 25 to 27 dB.
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