Nobody likes hearing their neighbours' music, TV shows or loud conversations. Soundproof wall materials, however, can be quite thick and expensive. Swedish scientists have developed a thinner, less costly alternative, in the form of a spring-loaded sound-damping screw.
Known as the Revolutionary Sound Absorbing Screw (or the Sound Screw for short), the device was created by a team at Malm? University, led by senior lecturer H?kan Wernersson. It consists of a threaded section at the bottom, a coil spring in the middle, and a section with a flat head at the top.
The screw is inserted into a hole drilled through a drywall panel and into the underlying wooden joist. It is then turned until its threaded section is all the way into the wood, and its head is sitting flush against the outside surface of the drywall. The spring forms of a gap of a few millimeters between the joist and the drywall's underside.
When sound waves from an adjacent dwelling subsequently travel through the wooden joists and into a wall's Sound Screws, the compliant springs in the screws limit the transmission of the vibrations into the drywall. As a result, people in the room hear less of the noise.
In lab tests involving traditional drywall panels, it is claimed that Sound Screws reduced through-the-wall sound levels by 9 decibels, which worked out to about half the perceived sound when traditional screws were used. The technology also performed well when trialled on the ceiling of a hair salon, where the existing standard screws were simply replaced with Sound Screws.
Wernersson tells us that the screws are already available in Sweden (via spinoff company Akoustos), and that his team is interested in licensing the technology to a commercial partner in North America.
"The initial price is quite high for a screw, but cheap for a sound insulation system," he says. "The cost will decrease with volume."
Sources: Malm? University, Akoustos
