Silencing The Chaos: Plasma Based Noise Cancelling

Scientists at the école Polytechnique Fédérale de Lausanne (EPFL) have developed an innovative noise reduction technology using a thin layer of plasma created by ionizing air. This groundbreaking concept, known as an "active plasmacoustic metalayer," shows great potential for applications in noise control and room acoustics.

The plasmacoustic metalayer operates based on the principle of a plasma transducer. It involves generating an electric field in parallel wires that ionizes air particles. These charged ions are then accelerated along magnetic field lines. By utilizing ionized air particles that can instantly respond to external electrical field commands and interact with sound vibrations in the surrounding air, the system effectively cancels out the noise. This makes it efficient for high frequencies and adaptable to work at low frequencies as well.

A notable advantage of the plasma absorber is its compact size. For instance, to absorb low audible sound frequencies, the plasma layer only needs to be 17 mm thick. In contrast, most conventional noise reduction solutions would require a thickness of at least 4 meters.

Upon learning about this technology, I immediately envisioned the benefits it could bring to loud mechanical rooms in residential buildings. Potential use cases include:

• Automotive Industry: The technology could reduce engine noise in vehicles, enhancing the driving experience. It could also address noise issues in electric vehicles, where traditional engine noise is absent but other sounds like road or wind noise become more noticeable.
• HVAC Equipment / Compressor Bearing Equipment: Home appliances such as air conditioners and refrigerators could operate more quietly with the implementation of this technology, thereby improving the user experience. Imagine enveloping your mechanical room in a noise-cancelling blanket. I am quite sure that people like Marek Kozlowski would be very happy to have noise cancelling mechanical rooms in the building.
• Industrial Applications: In industrial settings, the technology could reduce noise from machinery, fostering a safer and more comfortable working environment for employees. Additionally, mitigating noise pollution in surrounding areas would be a definite advantage, even if people are not living near large industrial plants. Imagine Dave Fox that in future your team could not just be doing energy waste analysis but also noise audits in commercial factories.
• 4. Aerospace and Aviation: For individuals living near airports, this technology could significantly reduce noise. It could be used to create quieter aircraft cabins, enhancing passenger comfort. Furthermore, it has the potential to minimise noise impact on nearby communities by reducing noise around airports. As somebody who lives on the flight path of an airport I would welcome the application of this technology on aircraft.
• CrossFit Gyms: As someone who works out every night, I can attest to the intense noise generated in our gym. The loud music, clanging of bars, and the impact of wall balls against walls create quite a cacophony. I often feel sorry for the neighbouring tenants who must endure our noise. Gyms and stadiums of all kinds hosting loud sporting events would greatly benefit from this technology. My friend Bruce Passmore can attest to the noise generation of a few dedicated maniacs in a CrossFit, LLC gym.

I'm not an expert in this field and lack knowledge about air ionisation but I am sure there are practical safety considerations that need to be addressed. For instance, the technology's ionisation process involves generation of plasma which could have implications for the safety and health of people working in or near the mechanical room. The system must also be able to endure diverse environmental conditions including vibrations and fluctuations in temperature and humidity. That being said, there is no denying the immense excitement surrounding this groundbreaking technology.

The cost-effectiveness of this technology would likely depend on several factors, including material costs, energy requirements for plasma generation and maintenance, manufacturing and installation complexity, and the system's lifespan and maintenance needs.

EPFL has partnered with Sonexos SA, a Swiss audio technology company, to develop active sound absorbers based on the plasmacoustic metalayer concept.It will be fascinating to witness the real-world implementation of this technology.