Do Curtains Block Sound

The question is often asked on audio forums and in comments. Many people wonder if curtains that block out the sound are worth the cost and actually offer significant sound protection for cars, noisy neighbors, or any other loud noises.

The quick answer is that yes curtains can be a significant barrier to sound, however, there are certain signs which indicate whether they’ll succeed.

Do Curtains Block Sound?

A soundproofing curtain provides a substantial amount of noise-blocking between partitions.

There are a variety of curtains or window treatments that advertise as sound-blocking or soundproofing, but do not have much impact on the sound! A lightweight, low-density curtain will offer little to no soundproofing.

  • The best soundproofing curtains will be dense and heavy.
  • They also contain an additional middle layer to serve the purpose of blocking out sound.
  • These middle layers are made of cloth or vinyl fabrics.
  • Curtains made of other curtain materials are less efficient.

The good news is that curtain panels can be thoroughly tested to accurately yo measure the accuracy of their sound transmission.


The Science Of Sound Blocking

The Science Of Sound Blocking

Curtains that are soundproof need to look for an item with a good STC rating. A curtain with an STC rating indicates that the claims made by the curtains are substantiated by the laboratory.

Acoustic Transmission Class (STC) is an assessment of how well a partition deflects the sound that is emitted by air. In the US it is extensively used to evaluate partitions for interior use, including ceilings/floors windows, doors, and wall designs. Partitions are tested using different frequencies to assess the transmission loss.

  • These losses in transmission at different frequency levels are then converted to create the STC rating.
  • Curtains and other partitions may be tested under conditions in a laboratory to obtain the STC rating.
  • The STC rating is roughly correlated to the amount of dB the material is able to block.
  • A noise reduction of 10 decibels can be interpreted as a half in the amount of noise.
  • An STC rating becomes less effective at a lower frequency.
  • The material could be extremely efficient at blocking voice, but it will be ineffective at blocking train rumblings with low frequency.

STC Ratings:

To serve as a reference point, the walls of interiors made from drywall, wood studs, and insulation are rated with the STC score of 33.

  • The most effective curtains come with STC ratings of between 20-30.

With every 10 increments to the STC rating the sound that passes through the curtain is reduced by half The more the STC is, the better the curtain is at blocking sound.

As with everything, there’s plenty of variance among products. There are many items that are advertised as soundproofing or noise-blocking but don’t have any evidence to prove their claims. The last thing to bear at hand is the fact that blocking sound isn’t always the best solution. Sometimes, the best option is to block the sound.


Sound Absorption Vs Sound Blocking

Curtains can also function to absorb sound. A sound blocker can help to stop sound from traveling across space.

Sound absorbers work to minimize echo or reverb inside an area. They can improve the acoustics or the reverberation in a room.

Soundproofing materials are typically thick and bulky, while the material that absorbs sound tends to be porous as well as light density materials. Read our post Sound Absorption Vs Sound Blocking for more information.



In short, you should Look for a product that appears to be large and thick and is backed by the STC rating to confirm the claims of their company aren’t just for marketing.

If the product isn’t able to come with an STC rating, it’s probably not something worth spending lots of money on.

Talk to the manufacturer to make sure the curtain is suitable for your issue.

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