Lausanne’s Sonexos raises €5.4 million to tackle low-frequency noise from fans, compressors and even data centres
Sonexos, a Lausanne-based DeepTech company, has raised approximately €5.4 million (CHF 5 million/USD 6.1 million) in new equity financing to take its solid-state noise control from working prototypes to industrial production.
The round was led by Valquest Partners, with participation from Robert Bosch Venture Capital GmbH (Bosch Ventures) and industry angels and private investors. Fadi Noureddine, founder and Managing Partner of Valquest Partners, has joined the Sonexos Board of Directors.
“Engineers have always had to trade space and weight for silence. Plasmacoustics removes that compromise. This financing carries it from working prototypes into our customers’ products, at scale,” said Mark Donaldson, founder and CEO of Sonexos.
Sonexos was founded in 2022 by Donaldson, who has built companies in active noise control, including SoundChip, which developed noise-cancelling smart audio codecs for headphones and earbuds from leading consumer electronics brands and was acquired by DSP Group, now part of Synaptics.
Sonexos develops solid-state acoustic technology that solves low-frequency noise where passive materials and speaker-based ANC (active noise cancellation) fall short.
It claims to be developing a new way to address low-frequency noise from fans, compressors and motors. According to the company, this persistent hum carries through walls and windows and is the hardest noise to eliminate.
It argues that conventional acoustic treatments become increasingly bulky at lower frequencies and can restrict airflow. It further notes that while loudspeaker-based active noise control works well in the confined space of a headphone, it struggles with the complex, three-dimensional sound fields of real-world applications.
The company claims that its patented Plasmacoustic Metalayer uses a software-controlled plasma layer to absorb sound at a surface. The system is thin, lightweight and has no moving parts.
The Plasmacoustic Metalayer platform enables electronically programmable sound control, allowing compact, lightweight, energy-efficient management of low-frequency noise in domestic appliances, HVAC, and industrial, infrastructure, automotive, and specialised acoustic applications.
The Swiss startup reported that prototype systems have achieved up to 20 dB of low-frequency noise reduction in ventilation systems and 16 dB in domestic appliances under application-specific test conditions.
The company’s Plasmapanel and Plasmadrive technologies are designed to overcome the practical limitations of conventional passive acoustic materials and traditional active noise control systems.
Sonexos’s Plasmapanel packages the actively controlled plasma metalayer into a sealed, inert-gas-filled module driven by proprietary low-power, high-voltage electronics. The company explains that, depending on the installation, Plasmapanel-enabled systems absorb sound from 30 Hz to 1,500 Hz and, compared with passive silencers with similar low-frequency performance, require less than a fifth of the space and weight. It highlighted that for OEMs, this frees room for more compact products or for features that bulky acoustic treatment would otherwise displace.
Sonexos states that it is developing an industrial ecosystem rather than manufacturing every component in-house. STMicroelectronics is supporting development of low-power, low-cost electronics. A strategic collaboration with Vandewiele Group, through its subsidiary Roj, provides a route toward series manufacturing for European OEM programmes, including electronics production, box-build and cabling.
Sonexos plans to offer turnkey panels with integration support, as well as an enterprise model in which larger OEMs build the technology into their own products and production lines using Sonexos components, such as Plasmadrive, and software.
The company is also planning expansion into AI data-centre cooling, where reduced fan noise could ease community concerns and help sustain cooling capacity under night-time noise limits. It is developing the Plasmapanel Radial Active Silencer to mount around a fan discharge and attenuate low-frequency sound without obstructing the airflow path.
In July 2026, the company announced a collaboration with Euronext Milan-listed SIT to integrate the technology with fan platforms for data centres, battery energy storage and industrial cooling. SIT is the first member of the Sonexos Certified Fan Partner Programme, and the companies plan to present a first working demonstrator at CES 2027.
“Sonexos is addressing a fundamental engineering constraint with a technology that opens a much larger design space for low-frequency noise control. The combination of differentiated science, a strong intellectual-property position and progress with leading OEMs gives the company a credible path toward industrial production,” said Noureddine.
The fresh capital will fund industrialisation of the core platform; customer integration, reliability testing, qualification, and regulatory compliance; expansion of engineering and applications teams in Switzerland and internationally; and broader international protection of its intellectual property.
Sonexos holds an exclusive licence from EPFL to grant foundational plasmacoustic patents in its field of use and has filed four additional patent families of its own, with two UK patents granted and applications pending in other major markets.
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