Scientists at École Polytechnique Fédérale de Lausanne (EPFL) have made a groundbreaking discovery in noise reduction technology with the development of an active “plasmacoustic metalayer.” Unlike conventional tools, this plasma transducer demonstrates superior noise reduction capabilities. The research team, led by Stanislav Sergeev, a postdoc at EPFL’s Acoustic Group, achieved this by exploiting the lightweight nature of air itself.
By ionizing a thin layer of air between electrodes, known as a plasmacoustic metalayer, the researchers transformed air particles into electrically charged entities. These charged particles, capable of instantaneously responding to external electrical fields, effectively interact with ambient sound vibrations, thereby canceling them out. Unlike traditional membranes, the plasmacoustic metalayer significantly reduces the weight factor, making it an ideal noise reduction solution.
One remarkable advantage of the plasma transducer is its ability to operate efficiently at both low and high frequencies, making it more versatile and compact compared to existing alternatives. Hervé Lissek, the senior scientist at EPFL’s Acoustic Group, emphasized that the metalayer absorbs 100 percent of the incoming sound intensity without reflecting any back, resulting in a compact plasma absorber. Remarkably, this absorber can cancel out audible sound frequencies as low as 20 Hz with a plasma layer as thin as 17 mm, in stark contrast to conventional noise reduction solutions that require a minimum thickness of 4 meters, rendering them impractical.
Lissek also expressed his enthusiasm for the concept, highlighting that unlike traditional sound absorbers, which rely on bulk materials or resonant structures, the plasmacoustic metalayer offers an ethereal quality. Its thin and lightweight nature opens up new possibilities in noise control, particularly in situations where space and weight are crucial factors, especially at lower frequencies.
Recognizing the immense potential of this technology, EPFL has partnered with Sonexos SA, a Swiss-based audio technology company, to develop active sound absorbers based on the plasmacoustic metalayer concept. Their collaborative efforts will extend noise reduction applications to a wide range of sectors, including automotive, consumer, commercial, and industrial. The partnership capitalizes on EPFL’s expertise in material science and acoustics, combined with Sonexos’ proven track record in delivering high-performance audio solutions, as explained by Mark Donaldson, CEO and Founder of Sonexos.
By combining scientific innovation with industrial partnerships, this groundbreaking discovery paves the way for a revolution in noise control, heralding a future where noise reduction can be achieved effectively, economically, and with minimal space requirements.