Soundproof curtain vs. acoustic curtain: what's the difference and which one to choose?
A soundproof curtain blocks noise coming from outside (street, neighbours, traffic) by creating a dense multilayer barrier in front of your windows. An acoustic curtain absorbs echo and reverberation inside a room to improve sound comfort. Soundproofing insulates, acoustic treatment corrects. For a noisy apartment facing the street, choose a soundproof curtain. For a room that echoes (open-plan office, tiled living room), choose an acoustic curtain.
These two terms are often used interchangeably, which creates confusion at the point of purchase. Choosing the wrong type of curtain can leave you completely powerless against your noise problem. This guide compares the two solutions with technical data, a summary table and a decision tree so you invest in the right one.
What is a soundproof curtain?
A soundproof curtain is a multilayer textile barrier designed to stop outside noise from entering a room. Its goal is pure sound insulation: creating a shield against the sound waves that pass through your glazing or your front door. The best models reach 18 to 25 dB of attenuation, a reduction comparable to a closed interior door (18-27 dB).
The principle rests on the mass law in acoustics: the heavier and denser a material is, the less it vibrates under the impact of sound waves. To achieve this, soundproof curtains use multilayer assemblies: high-density cotton wadding, polymer or metallised membranes, technical linings. Total density generally exceeds 500 g/m², with the best-performing models reaching 620 g/m² and above.
Real-world use case: you live on the first floor of a busy street, and traffic noise reaches 70 dB with the window closed. A high-performance soundproof curtain (22 dB of attenuation*) brings that level down to 48 dB, below the threshold of a normal conversation. It is particularly effective on frequencies from 500 to 2,000 Hz (voices, engines, horns), which make up the bulk of urban noise.
What is an acoustic curtain?
An acoustic curtain corrects the sound environment inside a room; it does not insulate it from outside noise. Its job is to absorb the sound waves that bounce off hard surfaces (bare walls, tiles, patio doors) to eliminate echo and reduce reverberation time. A quality acoustic curtain can reduce reverberation time by 30 to 60%, with an absorption coefficient (NRC) of 0.5 to 0.9 depending on the material and thickness.
It is crucial to understand what it does not do: an acoustic curtain in no way blocks street noise. It only treats the sounds already present inside the room. Physically, it uses porous materials (thick cotton velvet, wool felt). The microscopic structure of these fabrics traps sound waves and converts acoustic energy into heat through friction.
Real-world use case: a 30 m² meeting room surrounded by glass walls where voices echo so much that video calls become inaudible. Reverberation time exceeds 1.5 seconds (the NF S31-080 standard recommends under 0.8 seconds for offices). Heavily pleated acoustic curtains, combined with wall panels, bring reverberation back below that threshold. It is also a standard in recording studios and open-plan offices.
Comparison table: soundproof vs acoustic
| Feature | Soundproof curtain (insulation) | Acoustic curtain (correction) |
|---|---|---|
| Main use | Block outside noise | Reduce internal echo and reverberation |
| Physical principle | Mass law and multilayers (barrier effect) | Porosity and wave absorption (sponge effect) |
| Performance | 18 to 25 dB of attenuation | NRC 0.5 to 0.9 (reverb reduction 30 to 60%) |
| Typical density | 500 to 620+ g/m² | 200 to 400 g/m² |
| Composition | Multilayer (wadding, blocking membrane) | Single or double porous fabric (velvet, wool, felt) |
| Recommended installation | As close to the glass as possible, 15-20 cm overlap minimum | Heavily pleated (1.5 to 2 times the fullness) to capture sound |
| Noise treated | Airborne outdoor (street, traffic, neighbours) | Indoor reverberation (echo, resonance) |
| Indicative price | 100 to 400 euros | 50 to 200 euros |
Key point: sound insulation requires higher density and multilayer engineering (500 g/m² minimum), which justifies a larger investment. Acoustic absorption relies on the surface texture and porosity of the material.
How to choose for your situation?
To work out which solution suits you, analyse the source of your sound discomfort. The decision follows a simple logical tree: does the noise come from outside, from inside, or both?
The noise comes from outside: go for a soundproof curtain.
Example: an apartment on the first floor of a busy boulevard, with double-glazed windows letting through the noise of scooters and raised voices at 60 dB. Plain velvet will not be enough. You need a multilayer barrier to stop the waves from passing through. Windows are responsible for around 40% of a home's sound loss. For these cases, our made-to-measure blackout, thermal and soundproof curtain combines sound insulation (22 dB*), thermal performance (7 °C*) and blackout (100%*).
The problem is internal echo: go for an acoustic curtain.
Example: an 80 m² open-plan architect's office with a polished concrete floor. The space echoes, conversations blur together, and listening fatigue sets in. The nuisance is produced inside. Wide, heavily pleated acoustic curtains (1.5 to 2 times the width of the window in fullness) absorb voice frequencies (500-2,000 Hz) and reduce reverberation by 30 to 60%. For an office project, see our dedicated guide to soundproof curtains in open-plan offices.
You have both: go for a combined curtain.
A common situation: a living room with a home cinema facing a busy street. You need to both block outside noise and improve the internal acoustics. A high-density multilayer curtain meets both needs: the mass blocks outside noise, while the porous textile face on the room side absorbs reverberation.
Can you combine soundproofing and acoustics in a single curtain?
Yes. A well-designed multilayer curtain layers materials with complementary functions: a porous decorative face (thick cotton velvet) to absorb indoor echo, paired with dense internal membranes to block outside noise. The porous face plays the acoustic role, the dense layers play the soundproof role.
The made-to-measure Kurtens soundproof curtains combine both functions. Each curtain is made to order to the exact dimensions of your opening, with a density of 620 g/m² that brings together three levels of performance:
- 22 dB of measured sound attenuation*
- 100% certified blackout*
- Up to 7 °C of thermal gain*
Made-to-measure is decisive for real soundproofing performance: a standard curtain inevitably leaves sound leaks on the sides and at the bottom. A curtain made to the exact dimensions of the window gains 3 to 5 dB compared with a standard size, thanks to the elimination of side leaks. Configurable online to the exact centimetre, delivered in 2 to 3 weeks.
*Data from tests carried out under optimal conditions.
Frequently asked questions
What is the difference between a soundproof curtain and an acoustic curtain?
A soundproof curtain blocks noise coming from outside (street, traffic, neighbours) thanks to its mass and multilayer construction. An acoustic curtain absorbs echo and reverberation inside a room thanks to its porous texture. Soundproofing insulates (stops noise from entering), acoustic treatment corrects (treats the noise already present). These are two different functions that solve two different problems.
Does an acoustic curtain block street noise?
No. An acoustic curtain reduces echo and reverberation inside a room, but it does not block outside noise. To block street noise, you need a high-density multilayer soundproof curtain (500 g/m² minimum). An acoustic curtain in velvet or felt (200-400 g/m²) improves indoor sound comfort but does not stop noise from coming in through the window.
Which curtain should you choose for a noisy apartment?
If the noise comes from the street (traffic, horns, roadworks): a high-density multilayer soundproof curtain installed in front of the windows. The best models attenuate 18 to 25 dB. If the noise is internal (echo in a large living room, reverberation in an office): an acoustic curtain in velvet or felt, heavily pleated. If you have both: a high-density combined curtain that blocks outside noise and absorbs indoor reverberation.
How many decibels does a soundproof curtain reduce?
Soundproof curtains on the market offer performance of 5 to 25 dB depending on the category. Basic thick curtains (150-300 g/m²): 5-7 dB, barely perceptible. Mid-range models (350-500 g/m²): 12-18 dB. High-performance made-to-measure curtains (500+ g/m²): 18-25 dB. Kurtens curtains reach 22 dB of measured attenuation* at 620 g/m². For reference, a standard interior door offers 18-27 dB.
Is a soundproof curtain also acoustic?
A high-density soundproof curtain naturally has a partial acoustic effect: its mass absorbs some of the indoor reverberation in addition to blocking outside noise. The reverse is not true: a lightweight acoustic curtain does not have the mass needed to block noise. Kurtens curtains (620 g/m², multilayer) combine both functions: sound insulation (22 dB*) and absorption of reverberation on the room side.
Does a soundproof curtain work on a front door?
Yes. The front door is often the second sound-leak point after the windows, especially in older apartments. A soundproof curtain installed in front of the door creates an extra barrier against noise from the hallway, the landing and the street. The curtain should overlap by 15 to 20 cm on each side of the frame and reach down to the floor for maximum effectiveness. A made-to-measure curtain guarantees this full coverage.
What NRC coefficient for an effective acoustic curtain?
The NRC coefficient (Noise Reduction Coefficient) measures a material's absorption capacity on a scale of 0 to 1. For an effective acoustic curtain, aim for an NRC of 0.5 minimum (absorbs 50% of sound waves). The best acoustic curtains in wool felt or thick velvet reach an NRC of 0.7 to 0.9. For comparison, a smooth concrete wall has an NRC of 0.02 (almost no absorption) and a thick carpet an NRC of 0.3 to 0.5.
Can you use a soundproof curtain in a recording studio?
A soundproof curtain blocks outside noise (useful if the studio is in a noisy environment) but is not enough for indoor acoustic treatment. A recording studio needs both: sound insulation to stop outside noise from contaminating the recording, and acoustic treatment to control reverberation and get a clean sound. A high-density multilayer curtain contributes to both, but must be complemented by dedicated acoustic panels on the walls and ceiling.
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