Sound Curtains and Soundproofing
The two types of sound curtains: Acoustic room treatments to reduce echoes, and industrial noise control curtains.
A Soundproof Curtain?
Sometimes on the internet you'll read that soundproofing can be added to a room or window by using thick drapery or some other fabric. (Often "soft" fabric is recommended.) Are you a bit suspicious of this advice? If you're familiar with the basic
principles of soundproofing,
you should indeed be skeptical.
People who recommend curtains or draped fabric as soundproofing are usually trying to help someone save money by suggesting a way to solve a noise problem at low cost and with little effort. Other
commonly recommended materials
are egg cartons, carpet on the walls, mattresses, blankets, or specially-shaped foam panels. If only it were that easy! Noise would not be such a common complaint if people could fix it by hanging drapes.
These folks mean well, but they are confusing soundproofing with acoustic room treatment. Acoustic treatments are used to improve the acoustics within a room, using sound-absorptive materials and shapes to reduce echoing caused by sound reflecting off hard surfaces. These materials work wonders for improving the quality of sound within a recording studio or auditorium, or for reducing noise within a space that has an "echo-y" quality. But they do little or nothing to block sound from leaving or entering a room, as is needed for effective soundproofing.
Soundproofing Product or Acoustic Treatment?
How can you tell whether a given product is designed for soundproofing or for acoustic treatment within a room? Names of products don't always give a good clue, and can even be misleading. As a quick check, look to see which rating(s) are published by the manufacturer. A
sound transmission class (STC) rating
shows the material's soundproofing (sound blocking) capability. If the product literature displays only a noise reduction coefficient (NRC) rating, the product's primary purpose is sound absorption — not soundproofing.
Sound blocker or acoustic treatment?
Soundproof Curtains for Industrial Noise Control
There is a type of curtain that actually does have effective soundproofing properties:
Noise control curtains made for industrial use
The reason is that these curtains have a very heavy layer sandwiched between the sound absorption layers. For example, a sound curtain might be made of two panels of quilted fiberglass with a layer of
(MLV) in the middle. Depending on its thickness, the mass-loaded vinyl layer can weigh from 0.5 to 2.5 pounds per square foot (1 to 6 kg/m2
), and it's this mass that supplies the critical soundproofing element.
Depending on how much mass they contain, these industrial-grade acoustic curtains have an
of 25 to 33. This is comparable to a single-pane glass window (STC 26 to 30) or, at the high end, a typical interior wall of uninsulated drywall (STC 33).
Because of the stiffness of the MLV layer inside, these curtains are semi-rigid and do not bunch or fold as do ordinary curtains. They also require heavy-duty tracking systems or frames to support their weight. Noise barrier curtains are used to reduce noise from industrial machinery, compressors, generators, or pumps.
Window Panels that Block Sound
If you need to block sound coming through a window in a home or other non-industrial setting, an effective solution is to mount a flexible window panel made with a heavy sound-blocking material. A sound-blocking window panel
takes the technology used in industrial noise control curtains and packages it in more convenient sizes, with practical mounting options and an appearance more suitable for the home. It can even be transparent if desired.
A realistic STC rating for such a panel is 26 to 29, depending on how heavy it is (typically 1 to 1.5 pounds per square foot). The performance will also depend on how tightly the panel is mounted to the surrounding wall. It will be most effective against higher-frequency noise (such as voices).
Materials used in home soundproofing
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