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Plasmacoustics

The Challenge

Compact Solutions for Reducing Low-Frequency Noise Remain Elusive

Conventional passive noise control is effective for high-frequency noise above 1kHz but requires large, heavy materials. This makes it impractical for compact, weight-sensitive applications like vehicle interiors and household appliances.

Active Noise Cancellation (ANC) can reduce low-frequency noise effectively but is complex to implement and difficult to scale. ANC provides only localized noise reduction, limiting its ability to suppress noise across larger areas.

No compact, subwavelength solution currently exists to address noise below 1 kHz in a lightweight form factor.

This presents a market challenge, as low-frequency noise is abrasive and fatiguing, with no practical, scalable solution available to date.

Siless Liner Sound Insulation
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Movement of the plasmacoustic metalayer under modulating control voltage

Core Enabler

Our unique technology for active sound control relies on the patented concept of the plasmacoustic metalayer.

This is formed by generating a local corona discharge in air or a selected gas suspension (typically a noble gas mixture) between two electrodes spaced no more than 3-5 mm apart.

The high-voltage (HV) electrode features an array of thin, evenly spaced tungsten wires, while the collector electrode is typically a plate of conducting material.

Upon application of a constant high voltage, the air or chosen gas near the HV electrode ionizes, creating positive ions.

A second modulating voltage is then applied across the same set of electrodes to control the movement of the ions.

This invisible, massless layer of charged gas immediately interacts with the surrounding air to produce sound, achieving a broadband frequency response without any undesirable phase shift relative to its electrical input.

Response of disabled Plasmapanel to an incident sound wave Response of enabled Plasmapanel to the same incident sound wave

The Solution

Plasmapanel® - Active Sound Control

Plasmapanel technology utilises the Plasmacoustic Metalayer to achieve efficient sound absorption through active control. A microphone positioned in front of the panel measures incoming sound and sends the signal to a controller for processing.

The controller generates a response that modulates the movement of the metalayer, adjusting the acoustic impedance across the panel’s surface to maximize sound absorption and minimize reflections.

Plasmapanel functions as a deep subwavelength absorber, reducing sound effectively across a wide frequency range, from just a few Hz to several kHz.

Its slim profile (less than 3 cm) and lightweight design (under 1.5 kg/mÇ) make it ideal for noise reduction in many applications.

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About us

Sonexos SA is a boutique, Swiss-based, international engineering consultancy providing expert strategic advice in the audio and sound domains to leading international brands operating in the consumer, automotive, mass transportation and industrial markets.

Our team of consultants have throughout their professional careers established a proven track record of strategic innovation in audio engineering, whether at the component or product level, as well as tangible success in the commercial exploitation of their solutions at scale.

At Sonexos, we offer customers access to a unique blend of professional consulting services that spans strategic planning and business development through to product innovation, supply chain management and intellectual property.

We also provide professional boards and investors with expert advice during their due diligence of prospective investee companies, where the nature and scope of our engagement can be tailored to suit.