Imagine transforming noisy environments into Zen-like sanctuaries with the flip of a switch without needing bulky soundproofing equipment. Imagine your car, plane journeys, or even your own living room suddenly enveloped in a bubble of silence. Sounds too good to be true. But according to the bright minds at EPFL, the dream of an insulating silence may forward from the realm of science fiction into reality.
Combating noise with sound might seem counterintuitive, but that’s exactly how the innovative ionic plasma-based noise-canceling technology developed by EPFL researchers operates. Previously, noise cancellation on a large scale needed a conglomeration of speaker cones – big, lightweight membranes designed to generate pressure waves that counter incoming sound. However, the team from EPFL has created an ultra-thin, hyper-responsive system – a layer of just 17-mm-thick (0.6-inches) – capable of blocking low-frequency noise as effectively as a 4-m-thick (13-ft) wall.
Ionic speakers, the stars of this story, resemble sheets instead of stacks of cones. Much like ionic propulsion systems, they leverage magnetic acceleration of electrically charged air particles to establish pressure waves. The amount of air moved can be instantly regulated by simply adjusting the voltage, making them an exquisite instrument for immediate noise cancellation.
Stanislav Sergeev, the principal author of the study and a postdoctorate scholar at EPFL’s Acoustic Group, elaborates on this ingenious approach: “We first ionize the thin layer of air between the electrodes that we call a plasmacoustic metalayer. The same air particles, now electrically charged, can instantaneously respond to external electrical field commands and effectively interact with sound vibrations in the air around the device to cancel them out.”
The technology was put to the test with a 20 Hz sound wave, marking the low-frequency limit for our ears. For traditional noise reduction foams or sound-absorbing walls to silence this low-frequency sound, an infrastructure 4 m (13 ft) thick is usually required. The plasmacoustic metalayer, however, quashes this sound with just a 17 mm (0.6 in) layer.
“Not a smidgen of the incoming sound intensity is reflected back once conducted by the metalayer,” elucidates Hervé Lissek, senior scientist at EPFL’s Acoustic Group. Emphasizing the potential of this groundbreaking method, he adds, “We’ve discovered an entirely new mechanism of sound absorption that’s as thin and light as possible, unveiling untapped possibilities for noise control where space and weight are vital dimensions, especially at low frequencies.”
Hoping to bring this plasma-based technology to market, EPFL has handed the reins to Swiss firm Sonexos, who are in the midst of strategizing its commercial applications.
The CEO of Sonexos, Mark Donaldson, expressed his thrill about the groundbreaking technology when he stated, “We are tremendously excited about the immense potential of plasma technology in reducing noise and enhancing the acoustics of various interior environments, including vehicle and aircraft cabins, office spaces, and homes.”
As we eagerly anticipate the journey of this technology from laboratory boundaries to practical applications, it’s impossible not to marvel at the prospect of such an affordable, efficient, reliable, and handy noise-eliminating solution carving a silent path for a better quality of life.
The research Ultrabroadband sound control with deep-subwavelength plasmacoustic metalayers was published in Nature Communications.
