Soundproof curtains improve the acoustics of a room by absorbing and dampening sound, but they don't prevent sound from entering or exiting a room. The four basic principles of soundproofing are mass, decoupling, absorption and damping. Mass is the principle that addresses sound blocking because heavy, thick, solid objects prevent sound waves from entering or exiting an area. Residential and commercial soundproof curtains absorb sound well, but their decorative purposes make them ineffective to block sound.
Residential and commercial soundproof curtains are made with dense fabrics such as twill, faux suede and velvet. The thickness of these fabrics makes them effective at absorbing sound. They come with lining that contains a layer of mass loaded vinyl, which increases the mass of the curtain, reinforcing sound absorption. However, because these curtains are designed to look like regular curtains, the mass loaded vinyl layer is not thick enough to block sound.
However, industrial soundproofing curtains are effective at blocking sound. There are no decorative concerns involved in the manufacture of these curtains, allowing the use of thicker and heavier materials. These curtains have a heavy layer of PVC or mass loaded vinyl between thick sound-absorbing materials such as fiberglass, reaching weights between 0.5 and 2.5 pounds per square foot. Industrial curtains are effective at blocking noise produced by construction, manufacturing and industrial sites.